Dissertationen zum Thema „Ruminants Feeding and feeds Evaluation“

Copies of the author's previously published articles inserted. Bibliography: leaves 142-159. Provides information on the significance of pea straw as a ruminant feed and the potential of two biological techniques for improving its feeding value.

Thesis (MScAgric)--Stellenbosch University, 1999.
ENGLISH ABSTRACT: The rate of hydrolysis of urea in the rumen of animals is a major limitation when considering the substitution of natural protein with urea in the formulation of rations. The aim of this study was to evaluate polymer coated urea prills with variable coating thickness and evaluate its potential as a slow-release NPN compound. A new slowrelease urea compound, made by coating prilled feedgrade urea with a co-polymer of urea-formaldehyde resin and a castor-coconut alkyd was initially evaluated for urea-nitrogen concentration in distilled water in order to evaluate its potential as a slow-release urea product for ruminants. Amino/alkyd or polyester blends are among the cheapest of the modern synthetic systems and are considered because it is non-toxic, low-cost, biodegradable and easy to manufacture. A 2 x 2 x 2 x 2 factorial design was used and 16 individual products were made and evaluated. The Wurster method was used to encapsulate urea prills. The slopes of the urea release curves represented the release rate of the encapsulated products and were compared to identify the process variables, which had an effect on release rate. Two of the coating variables, coating weight and alkyd: resin ratio, had a major effect (P = 0.0001) on the release rate of urea. The crushing strength of encapsulated products was significantly (P = 0.0001) higher than that of untreated urea. Results motivated the evaluation of the products in the rumen of sheep in terms of rumen ammonia and blood urea N concentrations. Four slow-release products were made after interpreting results from the first study, and differed on account of the coating weight and the composition of the co-polymer. Fifteen fistulated wethers were randomly allotted into 5 groups and intraruminally received an equivalent of 15g urea. Rumen ammonia and blood ammonia were taken at 0, 1, 2, 4, 6, 8, 12, 16, 20, 24, 36 and 48 h after administration of the various treatments. Slow release urea (SRU) resulted in significantly lower rumen ammonia peaks (P = 0.0001) than untreated urea, while the peaks were also significantly delayed. Untreated urea resulted in the maximum concentration at two hours after administration of the urea (P = 0.0685) while the SRU's reached a maximum at six hours after administration in the rumen. No significant differences between the four different SRU types were found. Responses in blood urea-N was similar to that observed for rumen ammonia nitrogen. The encapsulation was effective in decreasing the rate of ammonia release from the urea for up to six hours after administration. In a third trial four Dehne Merino wethers were used in a 2 x 2 Latin square design. They received a SRU product equivalent to 0.4 g urea per kg body weight orally. Rumen liquor and blood samples were taken at 0, 1, 2, 4, 6, 8, 12, 16, 20, 24, 36 and 48 h after intake. Difficulty was initially experienced with ingestion and palatability of the SRU products due to the strong formaldehyde and butanone odour present in the coating. The maximum rumen ammonia (NH3) concentration for the SRU were lower than that of untreated urea (17.5 mg N/dl vs. 66.9 mg N/dl). The time to reach blood urea levels also differed considerably (6 h vs. 24 h for blood urea nitrogen) between treatments. The encapsulation of urea prills shows potential solutions to reduce the solubility of urea and also reduce the hygroscopic nature of urea and improve the palatability and storage characteristics thereof. Keywords: Slow-release urea, encapsulate, copolymer, urea formaldehyde rumen ammonia, blood urea nitrogen, solubility, palatability, storage characteristics.
AFRIKAANSE OPSOMMING: Die vinnige tempo waarteen ureum in die rumen na ammoniak omgesit word, is die grootste beperking in die optimale benutting van ureum, as vervanging van natuurlike protein in herkouerrantsoene. Die doel van hierdie studie was om 'n stadig vrystellende ureumproduk te ontwikkel wat die rumenammoniakvlak gedurende 'n aansienlike periode van die dag bokant 'n sekere vlak kan hou. 'n Nuwe stadig vrystellende ureumproduk, vervaardig deur ureumkorrels met 'n kopolimeer van ureum-formaldehiedhars en 'n kastor-en klapperalkied te bedek, is geevalueer om die potentiaal as stadig vrystellende nie-protein stikstof (NPN)-produk vir herkouers te ondersoek. Die veiligheid, biodegradeerbaarheid, lae koste en maklike vervaardiging van amino/alkied-kopolimere maak dit een van die goedkoopste sintetiese sisteme om vir stadig vrystellende sisteme te oorweeg. 'n 2 x 2 x 2 x 2 Faktoriale antwerp is gebruik om 16 individuele produkte te vervaardig. Die Wurster-metode is gebruik om individuele korrels te enkapsuleer met die polimeer en die potentiaal van die produkte is aanvanklik geevalueer deur die ureumstikstofvrystelling in gedistilleerde water te meet. Die hellings van die vrystellingsgrafieke is vergelyk om die veranderlikes te bepaal wat die grootste invloed op die vrystellingstempo van ureum uit die ge·inkapsuleerde produkte het. Resultate dui dat twee verandelikes 'n betekenisvolle effek het op die vrystellingstempo, nl. dikte van die omhulsel, en die samestelling van die kopolimeer (P = 0.0001 en P = 0.0135, onderskeidelik) het. Die samedrukbaarheid van die ge ·lnkapsuleerde produkte was ook betekenisvol hoer (P = 0.0001) as die van onbehandelde ureumkorrels, wat lei tot verbeterde bergings- en hanteringseienskappe. lnterpetering van resultate lei tot die vorming van vier stadig vrystellende produkte. Vyf groepe van 3 volwasse rumengefistuleerde Dohnemerinohamels is in 'n proef gebruik om die potentiaal van die produkte verder te ondersoek. 'n Ekwivalent van 15 g ureum is direk in die rumen van elke dier geplaas en ammoniak-en bloed monsters is 0, 1, 2, 4, 6, 8, 12, 16, 20, 24, 36 & 48 ure na dosering geneem. Die stadig vrystellende ureumprodukte het 'n betekenisvol laer maksimum waardes vir beide ammoniak-en bloedstikstofureum getoon (P = 0.0001 ). Onbehandelde ureum het 'n maksimum rumenammoniakstikstof konsentrasie reeds twee ure na toediening bereik in vergelyking met ses ure vir die stadig vrysellende produkte. Geen betekenisvolle verskille in hierdie parameters is tussen die ge·lnkapsuleerde produkte gevind nie, terwyl geen interaksie is tussen hoofeffekte voorgekom het nie. In 'n derde proef is vier Dohnemerinohamels gebruik om die vrystellingstempos, in terme van rumenammoniak-en bloedureumstikstof te bepaal waar die stadig vrystellende produk en onbehandelde ureum direk aan die diere gevoer is . 'n Ekwivalent van 0.4 g ureum/kg liggaamsmassa is gevoer. Aanvanklik is inname- en smaakliksheidprobleme ondervind, moontlik as gevolg van die sterk butanoon-en formaldehiedreuk van die omhulsel. Die rumenammoniakstikstof het 'n laer maksimum (17.5 vs. 66.9 mg N/1 00 ml) as die van onbehandelde ureum gehad terwyl die tyd wanneer maksimum konsentrasie bereik word ook aansienlik later was. Die polimeer inkapsulering van ureumkorrels toon potensiaal as 'n stadig vrystellende ureumproduk deurdat dit die oplosbaarheid van ureum in die rumen verlaag. Bykomende voordele is dat die omhulsel die higroskopisiteit verlaag en die samedrukbaarheid verhoog, beide eienskappe wat die hantering-en bergingseienskappe bevorder. Sleutelwoorde: Stadig vrystellende ureum, enkapsulering, kopolimeer, ureumformaldehied, rumenammoniak, bloed ureum stikstof, oplosbaarheid, smaaklikheid, bergingseienskappe.

Includes bibliographical references (leaves 196-220) Studies the growth, body composition, feed intake of grazing animals, the use of anabolic agents, fatty acid composition of ruminants fats; and, the effect of saturated fat on human health.

Fire is generally used as a management tool for different vegetation types such as savannas and grasslands in southern Africa. In the False Thornveld of the Eastern Cape, fire is commonly used to control bush encroachment and to increase grass production, as grasses are important source of forage for domestic livestock. At the University of Fort Hare farm in the Eastern Cape, a trial was set up in 1980 to investigate the effect of burning frequency on vegetation. There are six treatments replicated twice in a completely randomized design on a 100 m x 50 m plots. The treatments comprise no burn, annual, biennial, triennial, quadrennial and sexennial burns. From this trial a study was conducted to investigate long term effect of burning frequency on species and soil seed bank diversity. Two 100 m line transects located 25 m apart were laid within each plot, and the herbaceous and woody species were identified and recorded along the line transects. Relative abundances (%) for each species were calculated for each treatment. Soil samples were collected at an interval of 13.3 m along the line transects. The samples were placed in paper bags and kept for use in a germination experiment. The seedling emergence germination method was used in the glasshouse to determine emerging seedlings, pots were filled with Hygromix growth medium and the soils from the fire trials 12 X 6 = 72 were spread on top. Soil from the control plots were also pre-treated with heat, smoke and the combination of heat and smoke. The experiment started in January 2010 and was terminated in April 2010. The Shannon-Weaver Diversity Index was used to determine species diversity for standing vegetation and germinated seedlings. Data were tested for normality and species abundances were transformed. Analysis of Variance (ANOVA) was applied to test treatment effects on geminated seedlings, species abundance and diversity at α = 0.05 significance level. Significant differences between treatment means were determined by post v hoc tests using Fischer‟s Least Significant Difference test at α = 0.05. The Pearson Moment Correlation test was used to test the relationship between vegetation and soil seed banks. Treatments had significant effects on herbaceous, woody species abundance and diversity (P < 0.05), but there was no significant treatment effect on soil seed bank diversity and on pre-germination treatments (P > 0.05). The annual, biennial and triennial burns were dominated by Themeda triandra while the quadrennial, sexennial and the control treatments were dominated by Sporobolus fimbriatus and Melica decumbens. A. karroo dominated the woody component across all treatments, but it did not change in abundance. S. fimbriatus was the most abundant in the soil seed bank across all the treatments and also in all pre-germination treatments. Species diversity was high in standing vegetation in the quadrennial, sexennial and the control treatments. There was no significant correlation between the standing vegetation and soil seed bank diversities (P > 0.05). Based on these findings it is apparent that fire can change vegetation in an area to be dominated by fire tolerant or fire intolerant species. Fire frequency, heat and smoke affects soil seed banks to a lesser extent in the False Thornveld. For the management of the False Thornveld of the Eastern Cape, less frequent burning is recommended as it increases aboveground species diversity.

The effect of treatment with 3% aqueous ammonia and 5.3% urea plus jackbean meal on the nutritive value of wheat straw was investigated. The moisture content of the straw was raised to 40% by addition of water. Crude protein and in vitro dry matter digestibility were highest for the bottom layers, which had the highest moisture. The mean temperature during the first 4 wk post treatment was 11.2 C. Four diets were fed to sheep: untreated straw 1) alone or 2) with 20 g/d urea at feeding time 3) ammonia-treated straw, and 4) urea-treated straw. All diets contained 80 g of liquid molasses, 10 g of NaCl and 6 g of Na 2 S04, and were calculated to be isonitrogenous except the control diet (untreated straw without urea supplementation). Straw was chopped prior to feeding. Crude protein content in wheat straw was tripled by ammonia and urea treatment. Dry matter digestibility in vivo and in vitro was enhanced by ammonia and urea treatment, and the effect was higher for ammonia treatment. Digestibilities of cell wall constituents were higher (P<.05) for ammonia treated straw, compared to urea-treated straw. Urinary N excretion was considerably lower (P<.01) and N retention was higher (P<.01) for lambs fed treated straws, compared to those fed urea at feeding time. Ruminal NH3-N and blood urea concentrations were higher (P<.01) for the lambs fed urea at feeding time, compared to lambs fed the others diets.
M.S.

Lupin seed has the potential to be used as a protein supplement in ruminant rations, but its usage is restricted by the presence of alkaloids. Experiments were conducted with the aim of determining whether the removal of specific toxic alkaloids, lupanine and 13-hydroxylupanine, from crushed lupin seed (CLS) would improve the organic matter intake (OMI) and average daily gains (ADG) in lambs, and also improve the lactation performance in dairy cows. Effects on liver function in lambs were also investigated. An additional study on the effects of the detoxification of CLS on the degradation of protein was conducted. In Experiment 1, 30 growing Corriedale lambs were fed five diets for 105 d according to a randomized complete block design (RCBD) with six blocks. Two diets contained intact CLS at 15% (LUI-15) or 30% (LUI-30) of DM; two other diets contained detoxified CLS at 15% (LUD-15) or 30% (LUD-30) and the control (CON) diet was supplemented with crushed sunflower seed, which was locally prepared, on-farm. All diets were formulated to be isonitrogenous (16% CP). The alkaloid content (lupanine and 13-OH lupanine) of the diets was.31,.70,.21 and.52% for LUI-15, LUI-30, LUD-15 and LUD-30, respectively. Thus, diets containing detoxified CLS contained approximately 30% less alkaloids than those with intact CLS. Estimates of ADG of lambs fed diets containing detoxified CLS was higher (P $<$.01) (120 g.d$ sp{-1}$) than that of lambs fed intact CLS (76 g.d$ sp{-1}$). The OMI (73 g/Wkg$ sp{0.75}$) was also higher, although not significantly, for lambs fed diets containing detoxified CLS. Feed conversion efficiency was increased (P $<$.05) by the detoxification of CLS. Lambs fed diets containing intact CLS consumed more OMI as time progressed, suggesting that adaptation to CLS might have occurred. Lambs fed diets containing intact CLS demonstrated increased trends in the activity in plasma of the enzymes glutamic oxaloacetic transferase (GOT) and $ gamma$-glutamyl transfer

Linseed meal (LSM) was fed to ovariectomized ewes exposed to estradiol 17-? (E2) implants over time, and LSM was supplemented to beef cows during late gestation and early lactation to evaluate the estrogenic potential of the phytoestrogen secoisolariciresinol diglycoside (SDG) found in LSM. Forty-eight ovariectomized ewes were fed a diet containing 12.5% LSM for 0, 1, 7, or 14 d and implanted with estradiol-17? (E2) for 0, 6, or 24 h before tissue collection. Uterine cellular proliferation, vascularity, and the expression of the angiogenic factors and their receptors were recorded. There was an interaction of LSM and E2 on uterine mass (P = 0.05). At 24 h of E2 exposure, proliferation was reduced (P < 0.001) when ewes were fed for 14 d compared to being fed 0 or 1 days. There was a LSM x E2 interaction (P ? 0.03) on VEGF receptor-2 (KDR) and hasicfihrohlast growth factor receptor (FGFR2) decreasing by 24 h E2 exposure. Exposure of LSM and E2 may impact the estrogenic response of sensitive tissue. Two studies were conducted to examine the effects of supplementing beef cows with LSM during late gestation or early lactation on calf growth and development. In Experiment 1, multiparous cows received either LSM or a control (CON) supplement (approximately 10% diet dry matter) for the last 60 d of gestation. Offspring weights, ADG, heifer age at puberty, conception percentage and steer carcass characteristics were recorded. In Experiment 2, multiparous cows received LSM or CON supplements (approximately 10% diet dry matter) during the first 60 d of lactation, and only heifer calf development performance was observed and recorded. Heifer calf weight, average daily gain, and attainment of puberty were assessed. For both experiments, birth weight, weaning weight and ADG were not affected (P > 0.31) by LSM supplementation. While final body weights were heavier (P = 0.04) for steer calves in Experiment 1, there was no effect (P = 0.09) of supplementation on carcass characteristics. In Experiment 1 and 2, attainment of puberty in heifer calves was not influenced (P > 0.58) by supplement type. Linseed meal supplementation during late gestation or early lactation does not appear to have a negative impact on calf growth, onset of puberty in heifer calves, or steer carcass quality, implicating that it may make a good supplement choice in cattle.

A replicated 3 x 3 latin square design (3 periods and 6 rumen fistulated steers) was utilized to investigate the effect of dietary concentrate levels (30, 60 and 90%) on the in situ disappearance of dry matter (ISDMD) and neutral detergent fiber (NDF) and kinetics of fiber digestion of alfalfa hay, wheat straw and steam processed and flaked milo (SPFM). Concentrate levels of 30 and 60% did not affect (P > .05) ISDMD or NDF disappearance from any of the substrates. However, ISDMD and NDF disappearance of all substrates were depressed (P < .05) by the 90% concentrate diet. The degradation of the potentially digestible fiber in these substrates followed first order kinetics at all concentrate levels. Fiber digestion kinetics were not affected (P > .05) by dietary concentrate levels of 30 or 60%. Incubation of substrates in animals receiving the 90% concentrate diet resulted in lower potential extent of digestion (P > .05) and decreased rate of degradation (P > .05) for all substrates. However, digestion was not complete even after incubations of 168-h, and thus, it is possible that the potential extent of digestion was underestimated. For all substrates lag time of digestion appeared to increase in the 90% concentrate diet. However, influx of NDF-like material into the bag during incubation makes the validity of the lag times obtained in situ questionable. Ruminal pH was depressed in animals consuming the 90% concentrate diet and could be at least one of the factors responsible for the decreased (P > .05) fiber digestibility in this diet. Mean ruminal pH of 6.5 (30 and 60% concentrate diets) did not depress (P > .05) fiber digestibility while a mean pH of 6.2 resulted in a lower (P > .05) fiber digestibility in the rumen.

A series of studies was conducted using SEM in conjunction with chemical analysis, in situ and in vitro digestion techniques, to characterize the anatomical components from barley, corn, sorghum and wheat grains which constitute "fiber" and investigate their susceptibility to rumen microbial digestion. Fractured grains were used to identify anatomical features and cell types prior to and after extraction or digestion. Certain anatomical features, including pericarp tissue, aleurone cells, endosperm cell walls, corneous and floury endosperm tissue and lemma and palea from barley, were easily identifiable in fractured and ground grains, and in neutral detergent extracted or digested residues. In situ and in vitro incubation conditions were varied to assess the effect of concentrate and/or reduction of pH on the disappearance of identifiable grain fractions. In situ incubations were conducted using steers adapted to 0-, 30- and 90% concentrate diets. In vitro inoculum buffered at pH 7 or 6 was provided by a steer fed 0- or 90% concentrate. Tissues resistant to rumen microbial digestion during extended (144-h) in situ incubations and shorter term (12- to 48-h) in vitro incubations were primarily those identified in NDF, and included pericarp, lemma and palea, and small amounts of corneous endosperm. Remaining tissues identified included barley lemma, palea and pericarp; corn pericarp, tip cap and small amounts of corneous endosperm; sorghum pericarp and corneous endosperm with matrix and protein bodies; and wheat pericarp. In vitro disappearance of isolated NDF after 48-h ranged from 43% for barley to 89% for corn. Labile structures included embryonic tissue and portions of endosperm cell walls, protein matrix and residual starch. Resistant tissues included pericarp, aleurone cell walls, tip cap and portions of the corneous endosperm. Relative rankings of NDF digestibility under all conditions studied were similar (corn > sorghum > wheat > barley) whether determined using isolated NDF or calculated from TIVDMD residues. Neither concentrate level fed to the host animal nor pH of the in vitro incubation flask affected rankings among grains, although increasing concentrate level and/or reducing pH appeared to reduce in vitro NDF disappearance. Evaluation of electron micrographs of fractured grains suggested that similar anatomical structures in the various grains differed in their resistance to microbial digestion. For example, pericarp from barley and wheat appeared to be more resistant than that from corn or sorghum. Endosperm of barley was less resistant than that of sorghum.

Thirty six: Holstein bull calves were assigned to a 3X3 factorial design with ration physical forms of chopped hay (CH), ground hay (GR) and all concentrate (CONC) and rumen degradable nitrogen (RDN) of 30, 45 and 60%. Metabolic body weight, liver weight and blood glucose were greatest in CONC-fed calves. Neither dry matter nor ash content of liver tissue was affected by either physical form or RDN. Within physical form, protein content was highest and fat lowest in livers of CH-fed caIves. Within RDN, livers of calves feel 30% RDN rations had lowest protein and highest fat content. RDN percent had no effect on carbon dioxide production. Livers from CONC-fed calves produced significantly· (P<.05) more carbon dioxide from [1⁻¹⁴C}propionate and [U⁻¹⁴C}lactate.Glucose production from propionate and lactate was greatest for CONC-fed and 60% RDN-fed calves, although significant only from lactate within physical form. Interaction between ration physical form and RDN makes interpretation of propionate data difficult. In 30% RDN-fed calves both lactate and propionate metabolism was similar for GR- and CONC-fed animals. At 45 and 60% RDN rations, CONC- and CH-fed calves had similar gluconeogenic rates from propionate but glucose from lactate was significantly greater in livers of CONC-fed calves compared to GR- and CH-feet animals. Ten lactating and five dry Holstein cows were liver biopsied at various stages of lactation (30,60,90,120,180 days postpartum and dry) and when fed two rations, control ( 18% CF) or high concentrate (HI CONC, 10.5% CF). Lactating cows at 30 and 60 days and dry cows were fed the control ration. After 60 days half the cows remained on the control ration and half the lactating cows were changed to the HI CONC ration. Milk fat percent was depressed in cows fed HI CONC ration. Milk fat percent was depressed in cows fed HI COCC ration. HI CONC cows consumed more dry matter and due to the higher energy content reached a positive energy balance before control cows. Rumen fluid volatile fatty acid production was not affected by stage of Lactation or ration fed. Both plasma glucose and plasma insulin nonsignificantly increased as lactation progressed. Liver tissue protein did not change over lactation but increased when HI CONC ration was fed. Stage of lactation affected (P<.0002) propionate metabolism to carbon dioxide with higher production at 120 days compared to 180 days. By ration, HI CONC cows' livers produced more carbon dioxide than control cows’ livers. Feeding the HI CONC ration significantly increased labelled glucose production. Increased production of both labeled carbon dioxide and glucose by liver from cows fed HI CONC ration was nonsignificant when based on liver protein content. Carbon dioxide/glucose ratio was similar for lactating (>60 days) and dry cows. Cows early in lactation (30 days) had significantly lower carbon dioxide/glucose ratios, indicating a higher glucose production. Ration and stage of lactation are important factors in ruminant metabolism.. Gluconeogenesis, a pathway especially important in ruminants, is affected by both factors. In calves and cows, concentrate rations increased glucose production. Ration RDN, studied in calves, affected lactate metabolism to glucose. The liver of lactating cows showed a greater response (increase in glucose production) to stage of lactation than ration fed demonstrating the importance of energy balance on ruminant metabolism.
Ph. D.

Bibliography: leaves 102-114. This study evaluates the difference in the nutritive value of rice straw varieties using chemical composition and digestibility measurements. It assesses several methods for improving the nutritive value of rice straw and the effect of urea treatment and rice straw quality on the colonisation of ruminal fungi and the characteristics of stem tissue structure.

A laboratory assessment and three in vivo trials were conducted to measure the nutritive value of whole soybeans subjected to various methods of heat treatment. No significant differences were found for ADG and feed conversion ratio. There was a significant reduced proportion of saturated-to unsaturated fatty acids in the loin eye area of pigs fed whole soybean products, when compared to soybean meal control. Extruded whole soybeans resulted in a lower degree of unsaturation than the other heat treated whole soybeans. Whole soybean products were evaluated for their digestibility in weanling (21 days) piglets. Feces were collected daily during two 5-day periods. It was found that the ether extractable portion of extruded whole soybeans has a higher digestibility than that of the remaining four soybean treatments. It was also found that CP is more digestible in animals at 6 weeks of age than in animals at 4 weeks of age. In conclusion: heat treated whole soybeans do not adversly affect the performance of weaners nor that of growing and finishing pigs, even at high dietary levels (25%). Feeding whole soybeans results in a higher degree of unsaturation in the carcass. The EE fraction of extruded whole soybeans is more digestible than whole soybeans of other heat treatments. (Abstract shortened by UMI.)

Thesis (MScAgric) -- Stellenbosch University, 2004.
ENGLISH ABSTRACT: The ruminant has the ability to utilize forages more efficiently than any other production animal. The utilization of forage fibre is an important aspect of ruminant production systems, as this is the main source of energy available to the animal. The availability of high-fibre forage nutrients is, however, restricted by cell wall degradability, and since low quality forages contribute a great deal to ruminant production systems worldwide, the improvement of this degradation process is of major economic importance. The use of exogenous fibre degrading enzymes has been proposed as a means of enhancing this process, with positive results being obtained from in vitro studies incorporating exogenous enzyme preparations. Positive in vivo results with regard to forage digestibility and other animal production parameters have consequently also been obtained following the addition of exogenous fibre-degrading enzyme preparations to the ruminant diet. Two initial screening experiments were undertaken in order to identify fungal enzyme preparations that may have a positive effect on in vitro fibre degradability. The initial screening employed an in vitro organic matter digestibility technique, and was successful in identifying at least six enzyme preparations displaying enhanced digestibility results that were statistically significant. A second in vitro gas production procedure was used to confirm results obtained from organic matter digestibility assays, as well as to increase screening capacity in order to evaluate new enzyme preparations more time-efficiently. Statistical analysis of results obtained from the secondary screening identified various enzyme candidates producing promising results. Only one of these, Abo 374, proved to be statistically superior to the control and other enzyme preparations. A growth trial was subsequently conducted to assess the performance of this enzyme in vivo. The trial involved individual feeding of 32 Dohne Merino ram lambs grouped according to weights into four groups consisting of 8 lambs each. Each group represented a specific application level of enzyme to the wheat straw component of a high fibre diet, amounting to 10, 5, or 1 ml enzyme supematant/kg straw. The enzyme was diluted with water at appropriate rates to obtain an application rate of 300ml/kg straw. The fourth (control) group was treated with water at the same application rate. The trial was conducted over a period of six weeks, during which feed intakes, weekly weight gains, as well as feed conversion efficiencies were recorded. Results suggested significant weight gains in the high (10ml/kg) and medium (5ml/kg) treatment groups, indicated by a P-value of 0.04. Similarly, feed conversion efficiencies were improved for above-mentioned groups (P=0.05), while feed intakes did not differ significantly between the four experimental groups.
AFRIKAANSE OPSOMMING: Die herkouer besit die vermoee om ruvoere beter as enige ander produksiedier te kan benut. Die gebruik van ruvoervesel is 'n belangrike aspek van herkouer produksiesisteme, aangesien ruvoere die hoof bron van energie aan die herkouer verskaf. Die beskikbaarheid van hoe-vesel ruvoer nutriente word egter beperk deur die degradeerbaarheid van die selwand, en aangesien lae kwaliteit ruvoere 'n groot bydrae tot wereldwye herkouer-produksiesisteme maak, is die moontlike verbetering van hierdie degraderingsproses van groot ekonomiese belang. In 'n poging om hierdie verteringsproses te help bevoordeel, is die gebruik van eksogene veselverterende ensieme ondersoek, en positiewe resultate is verkry wanneer hierdie ensieme in in vitro studies gebruik is. Goeie verbeterings ten opsigte van ruvoer verteerbaarheid en ander diereproduksie parameters is ook verkry deur middel van in vivo studies waar eksogene ensieme by die ruvoer van herkouers gevoeg IS. Twee eksperimente is ondemeem in 'n poging om ensiempreparate wat 'n moontlike positiewe effek op in vitro veselvertering mag he, te identifiseer. Die eerste, 'n in vitro organiese materiaal verteerbaarheid tegniek, was suksesvol in die identifisering van minstens ses ensiem preparate wat statisties betekenisvolle verbeterings ten opsigte van verteringsresultate geproduseer het. 'n Tweede in vitro gasproduksie prosedure is vervolgens gebruik om resultate verkry vanaf die eerste tegniek, te bevestig, asook om evalueringskapasiteit te vergroot en sodoende, nuwe ensiempreparate meer tydseffektief te evalueer. Statistiese evaluering van resultate verkry uit die tweede in vitro tegniek het 'n reeks ensieme met positiewe resultate opgelewer. Een van hierdie, Ab0374, het statisties betekenisvolle resultate ten opsigte van die kontrole, sowel as ander ensieme getoon. In 'n volgende eksperiment is 'n groeiproef gedoen om die effektiwiteit van hierdie ensiem in vivo te toets. In die proef is 32 Dohne Merino ramlammers op grond van hul gewig in vier groepe van agt skape elk verdeel, en individueel gevoer. Die groepe het verskillende toedieningsvlakke van die toetsensiem, toegedien tot die koringstrooi komponent van 'n hoe-vesel dieet, ontvang. Toedieningsvlakke was 10, 5, of lml ensiemkonsentraat/kg strooi. Elke groep se ensiemkonsentraat is verdun met die toepaslike hoeveelheid water om 'n toedieningsvlak van 300ml ensiemoplossing/kg koringstrooi te verkry. 'n Vierde groep is behandel slegs met water teen dieselfde toedieningsvlak, en het gedien as 'n kontrole. Die eksperiment is oor 'n periode van 6 weke uitgevoer. Tydens die proeftydperk is voerinnames, weeklikse gewigstoenames, sowel as voeromsetverhoudings, gedokumenteer. Resultate het betekenisvolle gewigstoenames in die hoe (lOml/kg) en medium (5ml/kg) groepe opgelewer, aangedui deur 'n P-waarde van 0.04. Voeromsetverhoudinge het ook verbeteringe getoon vir bogenoemde twee groepe (P=0.05), terwyl voerinnames nie merkbaar tussen die vier groepe verskil het nie.

Introduction : Family Poultry (FP) are birds of indigenous breeds living in almost symbiotic relationship with human communities. The chickens are usually free ranging, or have very limited restrains on their access to the village environment. African livestock population statistics for 1995 indicates poultry to be the most numerous species of farm animal (Anonymous, 1996a). More than 80% of poultry are kept in rural areas and contribute substantially to annual egg and meat production (Sonaiya, 1997). Throughout Africa poultry production stems from ancient traditional practices. FP is the most important type of poultry kept on the continent. In general, village producers keep small flocks of between 5 and 20 birds per household (Gueye, 1997a). Women and children play a key role in their management (Kitalyi, 1996). Because of its productivity, FP production has been neglected and is frequently considered by farmers as an insignificant occupation compared with other agricultural activities. Nevertheless, outside urban centers and especially in non-coastal areas, FP provides the population with a vital source of protein and income. In addition, they play an important role within the context of many social and/ or religious ceremonies. Although this type of poultry constitutes an important part of food security for rural households in South Africa, scientists have not explored this area of research for improving or recording this production system. Yet, FP survived for decades without being wiped out, in the interim, their keepers have gathered and stored a wealth of knowledge and experience, ensuring the survival of this genetic resource. The objective of this study was to collect the baseline data on FP production systems, determine their production constraints and achieve data for future use in the intervention strategies.

Studies were conducted to determine the effects of feeding lasalocid and monensin upon mineral status of ruminants, changes in digestive and renal physiology which bring about altered mineral status, and the effects of dietary K upon the actions of ionophores. Two 84-d grazing trials were conducted with steers fed no ionophore, 200 mg lasalocid, or 150 mg monensin. Monensin tended to increase gain of steers, but lasalocid had no effect. Feeding supplemental lasalocid and monensin altered Ca, P, Mg, Na, K, Cu, Fe and Zn status of grazing steers, but effects were not consistent. Twenty-four crossbred steers were individually fed in a 147-d finishing trial to study a possible K x monensin interaction. Steers were fed diets ad libitum containing .4% or 2.3% K, with or without 23 ppm monensin, dry basis. Feeding monensin with low K increased serum Na, Mg, inorganic P, Cu and Zn, but monensin fed with high K had no effect or decreased these serum minerals. Fifteen wethers, fitted with abomasal and ileal cannulae, were fed a basal diet alone or supplemented with 23 ppm lasalocid or monensin; Apparent absorption of Mg, K and Fe increased when ionophores were fed. Magnesium flow through the small and large intestines was decreased by lasalocid and monensin. Effects of lasalocid and monensin differed for metabolism, digestive tract flow and (or) partial absorption of Ca, P, Cu, Fe and Zn. Twelve ewe lambs were used in a renal clearance experiment. Lambs were fed a basal diet with no ionophore, 23 ppm lasalocid, or 23 ppm monensin, dry basis. Ionophores were fed starting on d 1 of the experimental period. Serial collections of blood and urine were made during d 1 and d 5 of the experimental period. Monensin reduced urine flow rate at d 1 and d 5. Feeding monensin lowered serum clearance and urinary excretion rates of Na and K at d 5. Serum clearance and urinary excretion rates of Ca were lower in sheep fed ionophores at d 1. Feeding monensin decreased serum clearance and urinary excretion rates of Cu at d 1. At d 5, urinary excretion rates of Zn were greater when lasalocid was fed, and lower when monensin was fed, compared to feeding no ionophore. These studies indicate that dietary lasalocid and monensin can alter mineral status of ruminants, although their effects may differ. The effects of ionophores may be dependent upon dietary K levels.
Ph. D.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Universidade Estadual Paulista (UNESP)
O objetivo do presente estudo foi avaliar a qualidade da carne de cordeiros mestiços Santa Inês alimentados com levedura (Saccharomyces cerevisiae) inativa da cana-de-açúcar em substituição ao farelo de soja. Foram ofertadas dietas com quatro níveis de substituição (0, 33, 66 e 100%) de levedura aos animais que foram abatidos com 35 kg de peso vivo. Foram realizadas as análises físicas e a determinação de umidade, proteínas, cinzas, gordura e colesterol no músculo Longissimus dorsi. Os níveis de substituição de 33 e 100% influenciaram a composição protéica da carne e os valores de lipídio não apresentaram diferença entre os tratamentos (P>0,05). O teor de colesterol foi menor para os animais que receberam dietas contendo levedura. O índice de fragmentação miofibrilar apresentou diferença entre os níveis de substituição. A maciez, quando analisado pelo método físico, foi satisfatória em carnes do tratamento 33% de substituição
This study aimed to evaluate Santa Inês lambs meat wich was fed with inactive yeast (Saccharomyces cerevisiae) instead of soy meal. The treatments offer were four levels (0, 33, 66 e 100%) of yeast to animals until the weight average 35 kg and they were slaughtered. The analyses were physical and humidity determination, protein, ash, fat cholesterol and in Longissimus dorsi muscle. The inclusion levels influenced in the protein composition of meat. The lipid values were similar (p> 0,05) between the treatments. The values of the tenderness fragmentation index showed variation between treatments. When the softness was analyzed by a physical method it confirmed that the meat has a satisfactory level of tenderness and cholesterol is similar to animals fed with yeast

Orientador: André Mendes Jorge
Coorientador: José Teodorico de Araújo Filho
Banca: Cledson Augusto Garcia
Banca: Paulo Roberto Meirelles
Banca: Cristiana Andrighetto
Banca: Janaina Haddich Conte
Resumo: O objetivo do presente estudo foi avaliar a qualidade da carne de cordeiros mestiços Santa Inês alimentados com levedura (Saccharomyces cerevisiae) inativa da cana-de-açúcar em substituição ao farelo de soja. Foram ofertadas dietas com quatro níveis de substituição (0, 33, 66 e 100%) de levedura aos animais que foram abatidos com 35 kg de peso vivo. Foram realizadas as análises físicas e a determinação de umidade, proteínas, cinzas, gordura e colesterol no músculo Longissimus dorsi. Os níveis de substituição de 33 e 100% influenciaram a composição protéica da carne e os valores de lipídio não apresentaram diferença entre os tratamentos (P>0,05). O teor de colesterol foi menor para os animais que receberam dietas contendo levedura. O índice de fragmentação miofibrilar apresentou diferença entre os níveis de substituição. A maciez, quando analisado pelo método físico, foi satisfatória em carnes do tratamento 33% de substituição
Abstract : This study aimed to evaluate Santa Inês lambs meat wich was fed with inactive yeast (Saccharomyces cerevisiae) instead of soy meal. The treatments offer were four levels (0, 33, 66 e 100%) of yeast to animals until the weight average 35 kg and they were slaughtered. The analyses were physical and humidity determination, protein, ash, fat cholesterol and in Longissimus dorsi muscle. The inclusion levels influenced in the protein composition of meat. The lipid values were similar (p> 0,05) between the treatments. The values of the tenderness fragmentation index showed variation between treatments. When the softness was analyzed by a physical method it confirmed that the meat has a satisfactory level of tenderness and cholesterol is similar to animals fed with yeast
Doutor

Thesis (MSc)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: South Africa, like many other developing countries throughout the world, has a rapidly growing human population, resulting in a consequent increased demand for food. Ironically, this increased food supply has to be produced on a smaller area of available agricultural land, which means that agricultural production processes have to become more efficient. Furthermore, the majority of the people in these countries are unschooled and poverty is a common phenomenon. Therefore, animal scientists are faced with the challenge and the responsibility to provide affordable, high quality food to these people. One way of reaching this objective is to improve the utilisation of low-quality, high roughage feedstuffs like crop residues and dry natural grass pastures. In the winter rainfall area of South Africa alone, about 460 000 ha of wheat straw are annually available. The ruminant animal has the ability to utilise the relatively unavailable energy (cellulose, hemi-cellulose and pectin) in the fibre component of these low-quality forages. Unfortunately, various factors, of which a N deficiency is the pre-dominant one, limit the utilisation of these feedstuffs. If the ability of the ruminant to utilise low-quality, fibrous energy sources is improved, these abundantly available and relatively inexpensive crop residues and natural pastures can be converted into high quality protein food for human consumption. Therefore, in order to rectify the N deficiency caused by these low-quality forages, the supplemental N requirement to optimise the fermentation and digestive processes of the ruminant animal has to be determined. The first study was conducted to determine the supplemental rumen degradable protein (RDP) requirement, to maximise the digestible organic matter intake (DOMI) of Dohne Merino sheep fed wheat straw. Keeping the high cost of natural protein supplementation in mind, the purpose of the second study was to determine the amount of true protein that can be replaced by nonprotein nitrogen (NPN) in RDP supplements fed to Dohne Merino sheep consuming wheat straw. In both trials animals had ad libitum access to low-quality wheat straw (3.2% CP; 74.2% NDF) and water. In the first trial, RDP (calsium caseinate: 90% CP; 100% rumen degradable) was intraruminally administered at 07hOOand 19hOO,at the following levels: 0, 40,80, 120 and 160 gld. Intake, fermentation and digestion were monitored to determine the RDP requirement to maximise DOM!. Digestible organic matter (OM) intake displayed a quadratic increase with elevated amounts of RDP (P < .01), and was maximised at an estimated 3.15 g RDPlkg BW·75 or 11.6% of DOM. Forage OM intake tended to increase quadratically (P = .15) with higher RDP levels. Microbial nitrogen (MN) flow to the duodenum and microbial efficiency increased quadratically (P ~ .04) and fluid dilution rate tended to increase in a quadratic manner (P = .15) with increased RDP supplementation levels. Rumina! ammonia nitrogen (NH3-N) and total volatile fatty acid (VFA) concentrations increased linearly (P ~ .07), while rumen pH exhibited a variable response to increased RDP levels (cubic; P = .08). Increasing RDP supplementation to Dohne Merino wethers consuming wheat straw, generally enhanced forage utilisation and DOM!. In the second trial, urea replaced different levels of casein N on an isonitrogenous basis, ranging from 0 - 100%. Since true protein is much more expensive than urea, the purpose of this study was to determine the maximum natural protein level that can be replaced by urea in RDP supplements, without adversely affecting intake and/or fermentation and digestive processes. The control treatment provided all of the RDP in the form of calcium caseinate (90% CP; 100% rumen degradable). The percentages of supplemental RDP from urea in the other treatments were 25, 50, 75 and 100%. The 100% urea treatment was balanced with maize starch to contain 40% CP and all other treatments received the same amount (150 gld) of starch. Intake of forage OM showed a weak decreasing trend (linear; P = .16) with increasing urea levels. Ruminal digestibilities of OM and NDF were not affected (P ;;::.:18) by urea level. Increasing urea levels resulted in linearly reduced total tract OM and NDF digestibilities (P ~ .10). As a result, DOMI declined (linear; P < .01) with increasing proportions of urea. Effects of increasing urea proportions on duodenal N flow, microbial efficiency and fluid dilution rate were minimal. Ruminal NH3-N tended to increase quadratically with increasing urea levels (P = .l4). Total VFA concentration decreased linearly (P = .03), while rumen pH increased in a linear manner (P = .08) with increasing urea proportions. Branched-chain volatile fatty acids (BCVFA's) and valerate decreased linearly (P ~ .05) with increasing urea levels, while other VFA's and the acetate:propionate ratio were generally not affected by treatment (P ;;:::.16). It appears as though ruminal and total tract OM and NDF digestibility criteria, as well as DOMI reached maximum values at substituting 25% of casein for urea. It is therefore concluded that replacing 25% of casein with urea in RDP supplements, will maintain effective utilisation of low-quality forages by sheep.
AFRIKAANSE OPSOMMING: Ontwikkelende lande, insluitend Suid-Afrika, word gekenmerk deur 'n vmmge bevolkingsaanwas. Dit lei tot 'n verhoogde vraag na voedsel, wat op 'n gevolglik kleinerwordende beskikbare kommersiële lanbbou-area geproduseer moet word. Die doeltreffendheid van produksieprosesse in die landbousektor moet dus noodgedwonge verbeter word. Die oorgrootte meerderheid van die bevolkings in ontwikkelende lande is ongeletterd en armoede en hongersnood is soms 'n algemene verskynsel. Veekundiges word dus gekonfronteer met die uitdaging en verantwoordelikheid om bekostigbare, hoë kwaliteit voedsel aan hierdie mense te voorsien. Een van die mees doeltreffende metodes om hierdie probleem aan te spreek, is om die benutting van lae kwaliteit, hoë-vesel voerbronne, bv. oesreste en droë grasweidings te verhoog. In die winterreënstreek van Suid-Afrika alleen, is 460 000 ha koringstrooi jaarliks beskikbaar. Herkouers beskik oor die besondere vermoë om die relatief onbeskikbare energie (sellulose, hemi-sellulose en pektien) in die veselkomponent van hierdie lae kwaliteit voere te benut. Verskeie faktore, waarvan 'n N-tekort die mees prominente is, beperk egter die benutting van hierdie voerbronne. Die uitdaging is dus om die herkouer se vermoë om hierdie voere te benut, te optimaliseer. Sodoende word 'n geredelik beskikbare, onderbenutte en relatief goedkoop voerbron omgeskakel in hoë kwaliteit proteïen vir menslike gebruik. Die N-aanvullingsbehoefte om die fermentasie- en verteringsprosesse van die herkouerdier te optimaliseer moet dus bepaal word, sodat die N-tekort in herkouers, wat soortgelyke weidings benut, reggestel kan word. Gevolglik was die doel met die eerste proef om die behoefte aan rumen degradeerbare proteïen-(RDP)-aanvulling, vir die maksimum inname van verteerbare organiese materiaal (VOM) van Dohne Merino skape wat koringstrooi ontvang, te bepaal. Weens die hoë koste van natuurlike proteïenaanvulling, was die doel met die tweede proef om die hoeveelheid ware proteïen in RDP-aanvullings, vir Dohne Merino skape wat koringstrooi ontvang, wat met nie-proteïen stikstof (NPN) vervang kan word, te bepaal. In beide eksperimente het die diere ad libitum toegang tot koringstrooi (3.2% RP; 74.2% NBV) en water gehad. In die eerste proefis RDP (kalsiumkaseïnaat; 90% RP; 100% rumen degradeerbaar) teen 07hOOen 19hOOintraruminaal toegedien, teen die volgende peile: 0, 40, 80, 120 en 160 gld. Inname, fermentasie en vertering is gemonitor om die RDP behoefte vir die maksimum inname van VOM te bepaal. Verteerbare OM-inname het 'n stygende kwadratiese tendens (P < .01) getoon met verhoogde RDP-peile en het 'n maksimum bereik by 'n aanvullingspeil van 3.15 g RDPlkg metaboliese liggaamsmassa (LM·75 ) of 11.6% van VOM. Organiese materiaalinname vanaf koringstrooi het geneig om kwadraties toe te neem (P = .15) met verhoogde RDP-peile. Mikrobiese stikstof-(MN)-vloei na die duodenum en mikrobiese effektiwiteit het kwadraties toegeneem (P :::;.;04) en vloeistof deurvloeitempo het 'n neiging vir 'n kwadratiese toename (P = .15) met verhoogde RDPpeile getoon. Rumen-ammoniakstikstof (NH3-N) en vlugtige vetsuur-(VVS)-konsentrasies het lineêr toegeneem (P :::;.;07), terwyl rumen pH 'n wisselende reaksie (kubies; P = .08) met stygende RDP-peile getoon het. Verteerbare OM-inname en benutting van koringstrooi is verbeter deur stygende peile van RDP aanvulling by Dohne Merino hamels. In die tweede proef is kaseïen op 'n iso-stikstof basis met verskillende ureumpeile, vanaf o - 100%, vervang. Omdat ureum baie goedkoper is as natuurlike proteïen, was die doel van die tweede proef om die hoeveelheid natuurlike proteïen in RDP-aanvullings te bepaal wat met ureum vervang kan word, sonder om inname, fermentasie en vertering te benadeel. Die kontrolebehandeling het 100% van die RDP in die vorm van kalsiumkaseïnaat (90% RP; 100% rumen degradeerbaar) voorsien, terwyl ureum in die ander behandelings onderskeidelik 25, 50, 75 en 100% van die kaseïen-N vervang het. Die 100% ureumbehandeling is met mieliestysel tot 40% RP gebalanseer en dieselfde hoeveelheid stysel (150 gld) is by al die ander behandelings ingesluit, om moontlike effekte van stysel op rumenfermentasie te elimineer. Organiese materiaalinname vanafkoringstrooi het 'n swak dalende tendens getoon met stygende ureum insluitingsvlakke (lineêr; P = .16). Rumenverteerbaarheid van OM en neutraal bestande vesel (NBV) is nie deur die ureumpeil beïnvloed nie (P ;;:: .18). Toenemende ureumpeile het gelei tot 'n lineêre afname in totale kanaal OM en NBVverteerbaarheid (P ~ .10). Gevolglik het VOM inname lineêr afgeneem (P < .01) met stygende ureum insluitingspeile. Die effek van behandeling op duodenale N-vloei, mikrobiese effektiwiteit en vloeistof deurvloeitempo was minimaal. Rumenammoniakstikstof-( NH3-N)-konsentrasie het 'n stygende kwadratiese tendens getoon (P = .14) met toenemende ureum peile. Totale vlugtige vetsuur-(VVS)-konsentrasies het lineêr gedaal (P = .03), terwyl rumen pH lineêr toegeneem het (P = .08) met stygende ureum insluitingsvlakke. Vertakte ketting VVS' e en valeriaansuurkonsentrasies het lineêr gedaal (P ~ .05) met stygende ureumpeile, terwyl die ander VVS' e en die asynsuur:propioonsuurverhouding oor die algemeen nie deur behandeling beïnvloed N; nie (P ;;:: .16). Dit blyk asof VOM inname, sowel as rumen- en totale kanaal verteerbaarheidsmaatstawwe, by 25% vervanging van kaseïen-N met ureum-N 'n maksimum bereik het. Die gevolgtrekking is gemaak dat die doeltreffende benutting van lae kwaliteit ruvoere deur skape, gehandhaaf sal word deur 25% van die ware proteïen in RDP-aanvullings met ureum te vervang.

Thesis (MSc)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: The use of fungal enzymes as ruminant feed digestibility enhancers was investigated. Currently, ruminants may not digest 38 to 80 % of fibrous forages' content. A renewed interest in the potential of feed enzymes for ruminants was prompted by the high costs of livestock production, together with the availability of newer enzyme preparations. Direct application of enzyme preparations can improve in vitro dry matter (DM) and neutral detergent fibre (NDF) degradation, indicating that direct-fed fibrolytic enzymes may be effective in enhancing in vivo digestion of forages. Two commercial enzyme products, Fibrozyme and Celluclast, and fungal extracellular enzyme extracts from Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, and Thermomyces lanuginosus were evaluated for enhancing in vitro feed digestibility. Fibrozyme addition to both wheat straw and lucerne hay did not improve their in vitro digestibilities, even after a two hour pre-incubation period. The four fungal enzyme extracts did not enhance wheat straw's digestibility, but marginal increases were evident for lucerne hay. Celluclast addition resulted in marginal increases in the digestibility of both oat hay and oat silage, with no enhanced effect on lucerne hay and NaOH-treated wheat straw. No relationship could be found between the level of enzyme activity and the degree of feed digestion in the in vitro assay. Enzyme hydrolysis with Celluclast, in the absence of rumen fluid, gave more conclusive results. All the feed samples tested showed a positive response to Celluclast addition, even the less digestible feeds, namely sugarcane bagasse and wheat straw. In vitro results show that the assays were unsuccessful, because almost all of the experiments conducted showed inconclusive results. Alternative feed evaluation assays, which include the in vivo, in sacco and in situ methods of analysis, as well as gas production measurement and in vitro analysis with the DAISyII system, should be evaluated. A more detailed study of feed digestibility should be motivated by determining which feeds are hydrolysable, their chemical composition, i.e. how accessible the feeds are, and also evaluation of feed mixtures. The enzyme supplements also need to be evaluated for optimum temperature and pH, as well as the compilation of enzyme cocktails.
AFRIKAANSE OPSOMMING: Die gebruik van swamensieme om die verteerbaarheid van herkouervoere te verhoog, is ondersoek. Tussen 38 en 80 % van veselagtige voere se inhoud is tans onverteerbaar. 'n Hernieude belangstelling in die potensiaal van voerensieme vir herkouers word deur die hoë koste van veeproduksie, asook die beskikbaarheid van nuwe ensiempreparate gedryf Direkte byvoeging van ensiempreparate kan die in vitro droëmateriaal (DM) en neutrale onoplosbare vesel (NOV) vertering verbeter, wat daarop dui dat fibrolitiese ensieme wat direk gevoer word, effektief mag wees tydens die in vivo vertering van voer. Twee kommersiële ensiemprodukte, Fibrozyme en Celluclast, en die vier ekstrasellulêre ensieme van vier swamme, naamlik Aureobasidium pullulans, Trichoderma reesei, Aspergillus aculeatus, en Thermomyces lanuginosus is vir hul vermoë om die in vitro verteerbaarheid van voere te verbeter getoets. Byvoeging van Fibrozyme by beide koringstrooi en lusernhooi het geen verbetering in hulonderskeie in vitro verteerbaarheid tot gevolg gehad nie, selfs nie eens na 'n twee uur vooraf inkubasieperiode nie. Koringstrooi se verteerbaarheid is nie verbeter deur die byvoeging van die vier swam-ensiempreparate nie, maar 'n minimale verbetering is wel waargeneem in die verteerbaarheid van lusernhooi. Byvoeging van Celluclast het 'n minimale verbetering in beide hawerhooi en hawerkuilvoer se verteerbaarheid tot gevolg gehad, maar geen effek op lusernhooi of NaOH-behandelde koringstrooi se verteerbaarheid nie. Geen verwantskap is tussen die vlak van ensiemaktiwiteit en die mate van vertering tydens die in vitro toets gevind nie. Ensiematiese afbraak met Celluclast, in die afwesigheid van rumenvloeistof, het meer konkrete resultate gelewer. Al die voermonsters het 'n positiewe respons op die byvoeging van Celluclast getoon, selfs ook die minder verteerbare voere, nl. suikerrietbagasse en koringstrooi. In die wyer konteks was die resulate van die in vitro verteringstoetse egter onbeduidend as gevolg van groot variasie in die metings. Alternatiewe voerontledingstoetse, wat moontlik beter resultate mag lewer, sluit in in vivo, in sacco en in situ analises, asook die meting van gasproduksie en in vitro analise met die DAISyII sisteem. 'n Meer uitgebreide studie van voerverteerbaarheid wat die bepaling van die afbraak van voere, hul chemiese samestelling, met ander woorde toeganklikheid van voere, en die ondersoek van voermengsels behels, behoort aandag te geniet. Die ensiemmengsels behoort ook ten opsigte van samestelling, optimum temperatuur en pH ondersoek teword.

Carbohydrates have variable digestibilities and metabolizable energy values in carnivorous fish. Simple sugars are generally more digestible than complex polysaccharides, and low levels of dietary carbohydrate may contribute more metabolizable energy than high levels. Two experiments were conducted to study the effects of dietary level and processing treatment of wheat starch on the digestibility of diets fed to sablefish (Anoplopoma fimbria), in different regions of the digestive tract. Moreover, an experiment was undertaken to determine if the dietary concentration of an indigestible external marker (chromic oxide) influenced its motility, relative to other ingredients in the ingesta, as it passed through the digestive tract. Lastly, a growth experiment was undertaken to compare the performance of sablefish fed formulated diets containing one of two levels of carbohydrate to that of fish fed a natural fish diet. The gastric evacuation of a formulated and a natural diet were also investigated. Apparent digestibility values for the nutrients in a formulated diet (containing 44.4% cooked wheat and 0.1% chromic oxide) fed to sablefish were noted to increase progressively from the anterior to the posterior regions of the intestinal tract. Within each region of the gut, the apparent digestibility values for most nutrients declined over three sample periods. Carbohydrate (nitrogen-free extract) digestibility down to the distal section of the intestine ranged from 51.0 to 82.8%. An experiment designed to assess the effect of carbohydrate treatment on the digestibility of four isonitrogenous, isocaloric diets met with partial failure. It was determined that the 1.0% chromic oxide marker flowed at a differential rate to the rest of the ingesta in the digestive tract, which violated the criteria for an effective marker. Consequently, diet digestibility was not determined in this experiment. Hepatic glycogen levels in fish receiving the dietary treatments were compared, and these values were used to estimate the relative availability (digestibility) of carbohydrate from the respective diets. According to this index, the sequence for digestibility was as follows: pregelatinized starch > cooked wheat > pregelatinized starch/cooked wheat > unprocessed wheat. Differential movement of chromic oxide relative to other ingesta was observed in sablefish fed on alternate days regardless of the dietary concentration of the indigestible marker (0.1 or 1.0%). It was surmised that the feeding protocol established the circumstances from which marker 'streaming' was observed in the results. Differential transport of Cr₂O₃ through the gut by ingested seawater was suggested as a possible mechanism for the phenomenon. Sablefish fed a natural fish diet had the highest growth rates, condition factors, liver lipid levels and the lowest feed conversion ratios and liver glycogen levels. Sablefish fed a diet containing 22.2% cooked wheat had a higher growth rate, condition factor, and a lower food conversion ratio, than those fed a diet containing 44.4% cooked wheat. Ingestion of the 44.4% cooked wheat diet resulted in the highest values for liver glycogen and hepatosomatic index. It was concluded that sablefish have a limited ability to metabolically utilize digestible carbohydrate and that most of the dietary non-protein energy should originate from high quality lipid for maximum protein sparing.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

In an attempt to reduce the costs and turn around times experienced with outsourcing starch analysis in finished feed products, the company decided to invest in a NIR instrument to carry out such analyses in house. The particular instrument purchased by the company comes with a build in calibration for specific finished feed products and the main objective of this investigation was to evaluate whether the instrumentation and build in calibration gives reliable analyses of a finished poultry feed. The results obtained showed that : - The NIR results obtained have a positive bias compared to the theoretical (formulation specified value) and also to the value obtained by enzymatic starch analysis. - Despite the positive bias, the starch values were well within the allowable limits - Repeatability measurements on the data generated by two different analysts showed that while the percentage relative standard deviations obtained (< 1.0 percent) were well within the company specifications of percentage RSD < 5.0 percent, the inter sample repeatability showed small, but significant variation. - The results for intermediate precision showed that there is no statistically significant difference between the results obtained by two different analysts, nor was there any difference in the results of the same samples analysed at different time periods. - Reproducibility could not be evaluated due to the lack of another instrument within the company that were similarly set up as the instrument used for the investigation. This investigation has shown that, given the restrictions enforced by the build incalibration of the NIR instrument, the use of NIR for the analyses of the finished feed product is valid, but will require that careful attention be paid to data collection procedures.

The potential of lignin and mannanoligosaccharides (MOS), as alternatives to antibiotic growth promoters was evaluated in broilers. Dietary treatments included: (1) negative control (CTL-, antibiotic free); (2) positive control (CTL+, 11 mg/kg virginiamycin); (3) MOS (diet 1 + Bio-Mos: 0.2% to 21 d and 0.1% thereafter); (4) LL (diet 1 + 1.25% Alcell lignin); (5) HL (diet 1 + 2.5% Alcell lignin). Bodyweight and feed conversion were not different when broilers were fed the CTL+, MOS, LL or HL diet. Birds fed MOS or LL had increased jejunum villi height (P < 0.05) and greater goblet cell number per villus (P < 0.05) when compared to those fed the CTL+ diet. MOS and LL increased (P < 0.05) the cecal populations of Lactobacilli and Bifidobacteria when compared to CTL+ fed birds. However, Lactobacilli and Bifidobacteria loads were lowest (P < 0.05) in birds fed the CTL+ or HL diet. Litter E. coli load was reduced (P < 0.05) when birds were fed MOS than when fed the CTL+ diet, but comparable to LL or HL fed birds. In birds challenged with pathogenic strains of E. coli (O2 and O88 serotypes) and fed the MOS or HL diet, the cecal population of total E. coli was lower (P < 0.05) than those fed the CTL+ diet; LL fed birds tended to have lower E. coli load than CTL+ fed birds. In summary, birds fed the MOS or LL diet had comparative advantage over CTL+ fed birds as evidenced by increased cecal populations of Lactobacilli and Bifdobacteria, increased villi height and greater goblet cell number in the jejunum, lower E. coli load in the litter, and lower cecal population of E. coli after an in vivo challenge with pathogenic strains of E. coli. Therefore, MOS and lignin could be regarded as natural alternatives to antibiotic growth promoters in poultry production.
Key words. Antibiotics, mannanoligosaccharides, lignin, gut health, broilers.

The chemical analysis of feed samples can be time consuming and expensive. The use of near infrared reflectance (NIR) spectroscopy was evaluated in a range of studies as a rapid technique to predict the chemical constituents in feedstuffs and compound ostrich feeds. The prediction of accurate results by NIR spectroscopy relies heavily upon obtaining a calibration set which represents the variation in the main population, accurate laboratory analyses and the application of the best mathematical procedures. This research project was designed to meet five objectives: The first objective was to determine the feasibility of using near infrared reflectance (NIR) spectroscopy to predict dry matter, ash, crude protein, crude fibre, oil content, and fatty acids such as palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2) in sunflower seed meal. The second objective was to develop calibration models to predict the dry matter, crude protein and oil content in milled canola seed, compared to whole canola seeds. The third objective was to investigate the feasibility of using NIR spectroscopy to predict the dry matter, ash, crude protein, crude fibre and oil content in milled lupin seeds, compared to whole lupin seeds. The fourth objective was to describe the development of near infrared reflectance (NIR) spectroscopy calibration equations for the prediction of chemical composition and amino acid content from different populations of alfalfa hay (Medicago sativa L.). The last objective was to determine the potential of NIR spectroscopy to predict the dry matter, ash, crude protein, crude fibre, ether extract, acid detergent fibre (ADF), neutral detergent fibre (NDF), calcium, phosphorus, in vitro organic matter digestibility (IVOMD) and amino acids such as lysine, methionine, threonine and arginine in compound ostrich feed samples. The results of this study indicate that NIR spectroscopy calibrations in sunflower seed meal are only applicable in sunflower breeding programmes for a fast screening as it was not suitable for prediction purposes. Screening of sunflower seeds by NIR spectroscopy represents a rapid, simple and cost effective alternative that is a great utility for users who need to analyse a large number of samples. Calibrations developed for crude protein and oil content in milled canola seeds proved to be better than calibrations for whole canola seeds. Although the results indicated that calibrations were better for milled canola seeds, it indicated values that were typical of equations suitable for screening purposes to select samples for more detailed chemical analysis. According to calibration statistics obtained for crude protein, crude fibre and oil content in whole lupin seeds, there is no need to grind the seeds to scan the meal as similarly accurate results were obtained by analysing whole seeds. Screening of whole lupin seeds by NIR spectroscopy represents a rapid, simple and cost effective alternative that may be of great utility for users who need to analyse a large number of samples with no sample preparation. The calibration and validation statistics obtained in the study to test the potential of NIR spectroscopy to predict the chemical composition and amino acid contents in alfalfa hay, showed the accuracy was too low for routine analysis, although NIR spectroscopy could be used as a screening tool. Further research needs to be done to improve the accuracy of the NIR spectroscopy analysis, including more samples from different cultivars and years. In the study to examine the possibility of using NIR spectroscopy to predict the chemical composition of compound ostrich feeds, the results indicated that NIR spectroscopy is a suitable tool for a rapid and reliable prediction of the crude protein, crude fibre, ether extract, IVOMD, ADF and NDF in compound ostrich feeds. Calibrations can be improved for amino acids if a larger sample pool is used to develop the calibrations. These studies indicated that NIR spectroscopy can be a rapid and successful tool for the prediction of the nutritive value up to certain amino acid contents of feedstuffs and compound ostrich feeds.

Four studies were conducted to determine the effect of synchronization of protein and starch degradation on nutrient utilization, microbial protein synthesis and milk production in dairy cows. In Experiment 1, five cereal grains and five protein supplements were compared for extent of solubility and degradability of their starch and nitrogen fractions. Results indicated large differences which permitted their ranking from high to low degradability as follows: grains, oats > wheat > barley > corn > milo protein supplements, soybean meal > cottonseed meal, (CSM) > corn gluten meal > brewers dried grains, (BDG) > blood meal. In Experiment 2, the five grains were incubated for varying times in vitro (with added amylase) or in situ to determine rate and extent of degradation of dry matter, crude protein and starch. Results showed that rate of starch degradation followed a similar, but slightly different trend than in trial 1 (wheat > barley > oats > corn > milo). Rates for DM and CP degradation were similar than those for starch. In Experiment 3, high (barley, HS) and low (milo, LS) degradable starch sources were combined with a high (CSM, HP) and a low (BDG, LP) degradable protein sources to formulate four diets; HSHP, HSLP, LSHP and LSLP. Diets were fed to 32 cows, starting two to four weeks postpartum, for a 60-d milk production and digestibility study. Apparent digestibility was calculated using chromium oxide. Organic matter digestibility was higher (P < .05) was found in nutrient output to the small intestine among diets and microbial CP synthesis was higher (P > .05) for barley diets.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011.
Includes bibliography.
ENGLISH ABSTRACT: Forages are the main feed components in ruminant production systems for the reason that they are often the major source of energy available to the animal. However, only 10 to 35% of energy intake is available as net energy because the digestion of plant cell walls is not complete. This can significantly affect livestock performance and profits in production systems that use forages as a major source of nutrients of the diet. As a result of low and variable nutritive values of forage feedstuffs, attempts to improve ruminal fibre degradability have been an ongoing research topic. The use of exogenous fibrolytic enzymes (EFE) has been proposed as means to improve forage digestibility. Positive results with regard to rumen forage digestibility and other animal production traits have consequently been obtained due to increased rumen microbial activity following EFE addition in ruminant diets. Two EFE (Abo 374 and EFE 2) and one commercial yeast preparation were firstly identified and selected for their potential to improve the cumulative gas production (GP) at 24 hours of a range of feed substrates using the in vitro GP system as a screening step to identify the superior EFE products. The different feed substrates were lucerne hay, wheat straw, wheat straw treated with urea and a commercial concentrate diet. An in vitro experiment was undertaken on these four different substrates in order to evaluate the two EFE and the yeast preparation. This was to identify the most promising EFE capable of producing a significant effect on feed digestibility using organic matter digestibility (in vitro true digestibility) and fermentation characteristics (in vitro GP system). Results from the in vitro evaluation showed that EFE significantly enhanced in vitro DM degradability and GP profiles (P < 0.05). Abo 374 enzyme showed potential to increase in vitro microbial protein synthesis (MPS) of GP residues of the concentrate diet. In addition, no correlation was found between the in vitro MPS and the 48 hours cumulative GP of all the tested substrates (P < 0.05; R2 < 0.30). Treatments were found to increase in vitro MPS, feed degradability and the cumulative GP of different quality forages and the concentrate diet, with Abo 374 being the best treatment (P < 0.05). However in vitro responses of EFE were variable depending on the energy concentration and chemical composition of different substrates. Variation in MPS was mostly due to the low recovery of purine derivates with the purine laboratory analysis. On the basis of these results, Abo 374 was selected and consequently further tested in another in vitro and in situ trial using a mixed substrate of lucerne hay and wheat straw. Abo 374 significantly improved the cumulative GP, in vitro DM and NDF disappearance of the mixed substrate (P < 0.05). In addition, no correlation was found between the in vitro MPS and the cumulative GP at 48 hours (P = 0.68; R2 < 0.25). The in situ disappearance of feed nutrients (DM, NDF and CP) with Abo 374 was similar to the control. The lack of significance of disappearance was probably due to the small number of sheep used in the study and the relatively high coefficient of variation associated with measuring ruminal digestion. Abo 374 significantly increased the in situ MPS (P = 0.0088) of the mixed substrate of lucerne hay and wheat straw. Evidence of the increased MPS and both in vitro and in situ disappearance of DM and NDF resulted from the Abo 374 activity during either the pre-treatment or the digestion process. The addition of Abo 374 to the mixed substrate of lucerne hay and wheat straw appeared to have been beneficial for microbial colonization of feed particles as a result of the increased rumen activity. It could be speculated that the primary microbial colonization was thus initiated, leading to the release of digestion products that attract in return additional bacteria to the site of digestion. This EFE may be efficient to produce some beneficial depolymerisations of the surface structure of the plant material and the hydrolytic capacity of the rumen to improve microbial attachment and the feed digestibility thereafter. Therefore, the mechanism of action by which Abo 374 improved the feed digestion can be attributed to the increased microbial attachment, stimulation of the rumen microbial population and synergistic effects with hydrolases of ruminal micro-organisms. With regard to these findings, the addition of EFE in ruminant systems can improve the ruminal digestion of DM, NDF and CP to subsequently enhance the supply of the metabolizable protein to the small intestine. Key words: crude protein (CP), exogenous fibrolytic enzymes (EFE), dry matter (DM), gas production (GP), neutral detergent fibre (NDF), microbial protein synthesis (MPS).
AFRIKAANSE OPSOMMING: Ruvoere is die hoof-voerkomponent in herkouer produksiesisteme aangesien dit dikwels die vernaamstebron van energie aan herkouer is. Slegs 10 tot 35% van die energie-inname is beskikbaar as netto-enrgie, omdat die vertering van selwande onvolledig is. Dit kan die prestasie en profyt in produksiesisteme drasties beïnvloed waar ruvoere as ’n hoofbron van nutriënte in die dieet gebruik word. Aangesien die nutriëntwaarde van ruvoere laag is en baie varieer, is navorsing vir verbeterde ruminale veselvertering steeds ’n voorgesette onderwerp. Dit is voorgestel dat eksogeniese fibrolitese ensieme (EFE) gebruik kan word vir verbeterde ruvoervertering. Positiewe resultate in ruminale ruvoerverterig en ander diereproduksie-eienskappe, is verkry as gevolg van toenemende rumen mikrobiese aktiwiteit na EFE aanvulling in herkouerdiëte. Twee EFE’s (Abo 374 en EFE 2) en `n gisproduk is geïdentifiseer en geselekteer vir hul potensiaal om die kumulatiewe gasproduksie (GP) na 24 uur met ’n reeks voersubstrate te verbeter met die gebruik van die in vitro GP sisteem as seleksiemetode om die superieure EFE produkte te identifiseer. Die verskillende ruvoersubstrate was lusernhooi, koringstrooi, ureumbehandelde koringstrooi en ’n kommersiële konsentraatdieet. ’n In vitro eksperiment was onderneem om die vier verskillende substrate te gebruik om die twee EFE’s en gisproduk te evalueer. Hierdeur sou die belowendste EFE’s identifiseer kon word wat ’n betekenisvolle effek op ruvoervertering het. Die vertering van ruvoer sal bepaal word deur organiese materiaal vertering (in vitro ware vertering), asook fermentasie-eienskappe (in vitro GP sisteem). Resultate van die in vitro evaluering het getoon dat EFE’s in vitro DM degradering en GP profiele verbeter. Dit blyk dat die Abo 374 ensiem ’n potensiële toemame in in vitro mikrobiese proteïensintese (MPS), soos bepaal deur die GP oorblyfsels van konsentraat diëte, tot gevolg gehad het. Daar was geen korrelasie tussen die in vitro GP en MPS van al die proefsubstrate nie. Dit blyk dat die behandelings ’n toename in in vitro GP, MPS en ruvoerdegradeerbaarheid van lae kwaliteit ruvoer- en konsentraatdiëte gehad het, waar Abo 374 die beste behandeling was. Die in vitro reaksies van die EFE’s was egter wisselend, afhangende van die energiekonsentrasie en die chemiese samestelling van die verskillende substrate. Variasie van MPS was meestal as gevolg van die lae herwinning van purienderivate tydens die purienanalise. Op grond van dié resultate, is Abo 374 geselekteer om verdere toetse in ander in vitro en in situ proewe te doen. Die substraat wat gebruik is, was ’n 1:1 mengsel van lusernhooi en koringstrooi. Abo 374 het die kumulatiewe RP, in vitro DM en NBV verdwyning van die gemengde substraat verbeter. Boonop is geen korrelasie tussen die MPS en in vitro GP gevind nie. In situ verdwyning van DM, NBV en RP was hoër vir Abo 374, maar nie betekenisvol nie. Die gebrek aan betekenisvolle verdwynings mag die gevolg wees van die klein hoeveelheid skape wat in die proef gebruik is, asook die relatiewe hoë koëffisient van variasie wat gepaard gaan met die bepaling van ruminale vertering. Abo 374 het die in situ MPS betekenisvol verhoog. Verhoogde MPS en in vitro en in situ verdwyning van DM en NBV is waargeneemwaarskynlik as gevolg van die aktiwiteit van Abo 374 gedurende die voorafbehandeling óf die verterings proses. Die byvoeging van Abo 374 tot die gemengde substraat van lusernhooi en koringstrooi blyk om voordelig te wees vir mikrobiese kolonisering van voerpartikels as gevolg van ’n toename in rumenaktiwiteit. Die primêre mikrobiese kolonisering het waaarskynlik gelei tot die vrystelling van verteringsprodukte wat addisionele bakterieë na die plek van vertering lok. Die EFE mag geskik wees vir voordelige depolimerisasie op die oppervlakstruktuur van die plantmateriaal, asook verbeterde hidrolitiese kapasiteit van die rumen om sodoende mikrobiese aanhegting, asook ruvoervertering te verbeter. Dus, Abo 374 se meganisme van aksie wat verbeterde ruvoervertering tot gevolg het, kan toegeskryf word aan `n verhoogde mikrobiese aanhegting, stimulering van die rumen mikrobiese populasie en die sinergistiese effek met hidrolases van rumen mikroörganismes. Ten opsigte van die bevindings, kan die byvoeging van EFE in herkouersisteme ruminale vertering van DM, NBV en RP verbeter, wat dan daaropvolgend die dunderm met meer metaboliseerbare proteïn sal voorsien. Sleutelwoorde: eksogene fibrolitiese ensieme (EFE), droëmaterial (DM), ruproteïen (RP), neutraal bestande vesel (NBV), mikrobiese proteïensintese (MPS), gasproduksie (GP).

The nutritional suitability of some Bangladeshi oilseed by-products (mustard, Brassica juncea; linseed, Linum usitatissimum; sesame, Sesamum indicum) as fish meal substitutes in carp diets was investigated. These protein sources were shown to cause depressed growth and feed efficiency when substituting 25% or more of the fish meal protein in semi-purified diets. However, the use of these oilseed meals in combination was found to be more effective than that of single sources. Supplementation of plant protein diets with crystalline EAA improved their nutritive value. Growth performance was better in fish fed diets supplemented with all deficient EAA than in fish fed diets supplemented with the first limiting EAA. Nutrient digestibility studies with these plant proteins suggested reasonable agreement between apparent protein digestibility (APD) and average apparent amino acid digestibility (AAAD). APD and AAAD values ranged from 78.9% to 85% and 82.4% to 85.8% respectively. Both aqueous and enzyme treatments were effective in reducing (49% and 57% respectively) the anti-nutritional factors (e. g. allyl isothiocyanate) in mustard oilcake. In linseed and sesame meals heat treatment was the most effective (reducing phytic acid levels by 72% and 74% respectively). Use of detoxified meals in diets improved growth performance and food utilization compared to untreated meals. Dietary phytic acid in the presence of increased levels of calcium and magnesium significantly (p < 0.05) depressed growth, food utilization and mineral bioavailability (especially Ca and Zn) in carp. Carp were shown to be tolerant of a dietary glucosinolate (allyl isothiocyante) level of 0.4 mg glucosinolate/g diet without inhibiting growth performance or adverse effects on fish health. However, fish fed diets containing higher levels of mustard oilcake or allyl isothiocyanate showed abnormal changes in thyroid tissues. The results of this study are discussed in relation to previously published research on fish and other monogastric animals.

Raspberry pomace, consisting of seeds, pulp and added rice hulls, is the residue from the pressing of raspberries for juice and concentrate production. Through the determination of chemical composition by laboratory analyses and the measurement of feeding value in animal trials, the pomace was evaluated as a feedstuff for growing pigs. Pomace contains 11.1% crude fat, 10.0% crude protein, 59.5% total dietary fibre, 7.4% soluble carbohydrates, and a gross energy level of 5220 kcal*kg⁻¹. The acid detergent residue of the pomace contains 11.7% lignin, 6.0% cutin, 2.2% acid detergent ash and 26.0% cellulose (by difference). The digestibility of dry matter, fat, protein and energy was determined. Pomace dried at 60 C, whole and ground (1mm) was fed to growing male pigs (30-35 kg) in a replicated 4X4 Latin Square design with treatments basal (B) , B plus 40% unground pomace, B plus 40% ground pomace and B plus 40% barley. Grinding of pomace significantly improved the digestibility of all parameters measured, however, the barley-soybean meal basal ration was consistently better digested than either of the pomace treatments. The digestibility of whole and ground pomace was respectively: dry matter 10.7% and 20.8% (S.E.M. 1.30), fat 24.1% and 79.7% (S.E.M. 3.47), protein 10.6% and 14.7% (S.E.M. 4.83) and energy 7.9% and 28.4% (S.E.M. 1.80). Protein quality of ground (1mm) and freeze-dried pomace was evaluated with rats in metabolism cages to produce the following values: true protein digestibility 36.0% (S.E.M. 0.66), biological value 91.0% (S.E.M. 3.46), and net protein utilization 32.7% (S.E.M. 1.15). In rat growth trials, where pomace replaced barley incrementally, growth rate was not affected at replacement levels up to 40%, although feed efficiency declined consistently as the level of pomace in the diet increased. It is suggested that raspberry pomace could replace up to 20% of an energy feedstuff in a ration for growing swine without significantly reducing growth rate or feed efficiency.
Land and Food Systems, Faculty of
Graduate

Bibliography: leaves 107-130. This study evaluates quality of fermentation of the silage and also its nutritive value to ruminants on the basis of "in vitro" and "in sacco" digestability. Animal response to the silage is also evaluated in an "in vivo" digestability and nitrogen balance trial with Australian Merino sheep. The objective of this thesis is to investigate the opportunities for utilising citrus pulp and poultry litter to improve the nutritive value of wheat straw.

Thesis (MScAgric) -- Stellenbosch University, 2009.
ENGLISH ABSTRACT: Ruminants have a compound stomach system that enables them to utilize forages more efficiently than monogastric animals. However, forages alone do not contain sufficient nutrients to meet the requirements of high producing dairy cows. Forages are high in fibre and their nutrient availability depends on the degree of cell wall degradability. Improvements in forage fermentation would increase energy intake and subsequently milk production and performance by dairy cows. It is therefore important to find ways to improve forage degradation and utilization in the rumen. The use of different non-fibre carbohydrate (NFC) sources has different effects on animal performance. Supplementing forage based diets with energy sources containing sugar, starch or pectin results in variation in performance measurements such as milk yield, milk composition and dry matter intake (DMI). This thesis reports on two studies in which the effect of energy supplementation on forage fermentation and digestion parameters was investigated. In the first study an in vitro gas production protocol was used to determine the effect of sugar (molasses), starch (maize meal) and pectin (citrus pulp) on total gas production and rate of gas production of different forages. The forage substrates included wheat straw (WS), oat hay, (OH) lucerne hay (LUC), ryegrass (RYE) and kikuyu grass (KIK). The three energy sources, as well as a control (no energy source) were incubated in vitro with each of the above mentioned forages. Rumen fluid was collected from two lactating Holstein cows receiving a diet consisting of oat hay, lucerne, wheat straw and a concentrate mix. Forages alone (0.25 g DM) and/or together (0.125 g DM) with either molasses (0.1412 g DM), citrus pulp (0.1425 g DM) or maize meal (0.125 g DM) were weighed into glass vials and incubated for 72 hours. The weights of the energy sources were calculated on an energy equivalent basis. Blank vials, that contained no substrates, were included to correct for gas production from rumen fluid alone. The substrates were incubated in 40 ml buffered medium, 2 ml of reducing solution and 10 ml rumen fluid. Gas pressure was recorded automatically every five minutes using a pressure transducer system and the method based on the Reading Pressure Technique (Mauricio et al., 1999). Gas pressure was converted to gas volume using a predetermined regression equation. In the first gas production trial, the gas production included gas produced by the energy sources, while in the second gas production trial, the energy source gas production was deducted from the total gas production to determine the effect of energy source on gas production of respective forage substrates per se. Data were fitted to two non-linear models adapted from Ørskov and McDonald (1979). Significant forage x energy interactions were observed for the non-linear parameter gas production (b) in Model 1 and for b and lag phase (L) in Model 2 in both trials. In the first gas production trial, the higher fermentability of the energy sources supplemented to forage substrates, increased b (Model 1 & 2) of the LUC and WS. The gas production rate was affected in different ways for different forages, with the most noticeable effect on WS when it was supplemented with energy sources. All the energy sources increased c of WS irrespective of the model used. Energy sources had no effect on the L of LUC, OH or RYE, but decreased the L of WS and KIK. In the second trial, maize meal had no effect on b for any of the forages (Model 1 & 2), while molasses (Model 1 & 2) decreased b for all forage substrates, and citrus pulp (Model 1 & 2) decreased b of OH and RYE, to lower values than those of the control treatments. Gas production rate was not affected by molasses for any of the forage substrates, while citrus pulp (Model 1 & 2) increased c of OH and maize meal increased c of OH and KIK. Lag phase was only affected by energy sources in WS and KIK, where all the energy sources had lower L values than the control treatment. It was concluded that forage fermentability is affected differently by different energy sources. These observations may have important implications, in practice, on rumen health and milk production, and the data obtained can potentially be used as guidelines in feed formulations. In the second study, in vitro digestibility trials were undertaken to determine the effect of sugar (molasses and sucrose), starch (maize meal and maize starch) and pectin (citrus pulp and citrus pectin) on neutral detergent fibre (NDF) and dry matter (DM) degradability of forages. Forage substrates used included wheat straw, oat hay, lucerne hay, ryegrass and kikuyu grass. Rumen fluid was collected from two lactating Holstein cows receiving a diet consisting of oat hay, wheat straw and a concentrate mix. In vitro degradability was done with an ANKOM Daisy II incubator and forage substrates were incubated with or without the respective energy sources for 24, 48 and 72 hours. The substrates were incubated in 1076 ml buffered medium, 54 ml of reducing solution and 270 ml rumen fluid. The residues were washed, dried and analyzed for NDF. In the study with the applied energy sources (molasses, maize meal and citrus pulp) there were a forage x energy source interactions. Supplementation with the applied energy sources all improved dry matter degradability (DMD) of forages (24 and 72 hours), when compared to the control treatment, except for RYE supplemented with maize meal and citrus pulp at 24 hours. Molasses seemed to have had the biggest effect on DMD in all forage substrates. Supplementation with maize meal had no effect on neutral detergent fibre degradability (NDFD) of any forage substrate, except for an improvement in NDFD of LUC at 72 hours. Molasses improved NDFD of LUC at 24h, but had no effect on the other forage substrates. Citrus pulp improved NDFD of OH (72 hours), as well as LUC and WS (24 and 72 hours). It is postulated that the NDF of the energy sources was more digestible than that of the respective forages, and that the improved NDFD values could be ascribed to the contribution of the energy source NDFD. Overall, pasture grasses had a higher NDFD than the hays and straw, and appear to be more readily fermentable by rumen microbes than the low quality hays and straw explaining the higher NDFD. In the study involving the purified energy sources (sucrose, maize starch and citrus pectin), forage x energy source interactions were observed. In general, supplementation with these energy sources improved DMD at 24 and 72 hours except for RYE and KIK (72 hours). Pasture grasses (RYE and KIK) had a higher NDFD than LUC, OH and WS. At 72 hours, NDFD was 37.1% for LUC, 42.5% for OH and 40.3% for WS, compared to 70.5% for KIK and 64.9% for RYE. A possible explanation is that KIK and RYE samples came from freshly cut material, harvested after a 28d re-growth period. In general, sucrose (24 and 72 hours) and citrus pectin (72 hours) had no effect on NDFD of forage substrates. However, supplementing oat hay (24 hours) with starch and citrus pectin, and wheat straw (24 and 72 hours) with starch lowered NDFD, when compared to the control treatment. It is hypothesized that microbes fermented the easily fermentable energy sources first, before attacking forage NDF. The study suggested that forage NDFD values are not fixed, and may be altered by type of energy supplementation.
AFRIKAANSE OPSOMMING: Die meervoudige maagsisteem van herkouers stel hulle in staat om ruvoer meer effektief te benut as enkelmaagdiere. Ruvoere alleen bevat egter nie genoeg voedingstowwe om die behoeftes van hoogproduserende melkbeeste te bevredig nie. Ruvoere is ryk aan vesel en hul voedingstofbeskikbaarheid word bepaal deur die graad van selwand degradeerbaarheid. ‘n Verhoging in ruvoerfermentasie sal energieinname verhoog en gevolglik ook melkproduksie en prestasie. Dit is dus belangrik om maniere te vind om ruvoerdegradeerbaarheid en -verbruik in die rumen te verbeter. Die gebruik van verskillende nie-vesel koolhidraat (NFC) bronne het verskillende uitwerkings op die prestasie van diere. Energie-aanvullings soos suiker, stysel en pektien tot ruvoer-gebasseerde diëte, beïnvloed prestasiemaatstawwe soos melkproduksie, melksamestelling en droëmateriaalinname (DMI) op verskillende maniere. Hierdie tesis lewer verslag oor twee studies waar die invloed van energie-aanvullings op ruvoerfermentasie en verteringsmaatstawwe ondersoek is. In die eerste studie is ‘n in vitro gasproduksieprotokol gebruik om die invloed van suiker (melasse), stysel (mieliemeel) en pektien (sitruspulp) op totale gasproduksie (b) en tempo van gasproduksie (c) van verskillende ruvoersubstrate te bepaal. Ruvoersubstrate wat gebruik is, was koringstrooi (WS), hawerhooi (OH), lusernhooi (LUC), raaigras (RYE) en kikuyugras (KIK). Die drie energiebronne, sowel as ‘n kontrole (geen energiebron), is in vitro geïnkubeer saam met elk van die genoemde ruvoere. Rumenvloeistof is verkry van twee lakterende Holsteinkoeie, wat ‘n dieet ontvang het bestaande uit hawerhooi, koringstrooi en ‘n kragvoermengsel. Ruvoere is alleen en/of in kombinasie met melasse (0.1412 g DM), sitruspulp (0.1425 g DM) of mieliemeel (0.125 g DM) in glasbottels afgeweeg en vir 72 uur geïnkubeer. Die massas van die energiebronne is op ‘n energie-ekwivalente basis bereken. Leë bottels wat geen substraat bevat het nie, is ingesluit om te korrigeer vir gasproduksie afkomstig vanaf rumenvloeistof alleen. Substrate is in 40 ml van ‘n buffermedium, 2 ml reduserende oplossing en 10ml rumenvloeistof geïnkubeer. Gasdruk is elke vyf minute outomaties aangeteken deur gebruik te maak van ‘n drukmetersisteem en die metode is gebasseer op die Reading gasdruktegniek. Gasdruk is omgeskakel na gasvolume deur gebruik te maak van ‘n voorafbepaalde regressievergelyking. In die eerste proef het totale gasproduksie die gas wat deur die onderskeie energiebronne geproduseer is, ingesluit. In die tweede proef is gasproduksie afkomstig van die energiebronne afgetrek van totale gasproduksie, om sodoende die invloed van die energiebronne per se op die gasproduksie van die onderskeie ruvoersubstrate, te bepaal. Data is met behulp van twee nie-liniëre modelle gepas. Betekenisvolle ruvoer x energie-interaksies is in albei proewe waargeneem vir die nie-liniëre parameter b (gasproduksie) in Model 1, en vir b en L (sloerfase) in Model 2. In die eerste proef het die energiebronne se hoë fermentasie gelei to ‘n verhoging in b (Model 1 & 2) van LUC en WS. Energie-aanvullings het die c-waarde van die onderskeie ruvoere verskillend beïnvloed, met WS wat die mees opvallende effek gehad het. Al die energiebronne het die c-waarde van WS verhoog, ongeag watter model gebruik is. Energiebronne het geen invloed op die L-waarde van LUC, OH of RYE gehad nie, maar het wel die L-waarde van WS en KIK verlaag. In die tweede proef het mieliemeel geen invloed op die b-waarde van enige van die ruvoere gehad nie (Model 1 & 2), terwyl melasse (Model 1 & 2) die b-waarde van alle ruvoere verlaag het, en sitruspulp (Model 1 & 2) OH en RYE se b waardes verlaag het tot laer as die kontroles. Melasse het geen invloed op die c-waarde van die onderskeie ruvoersubstrate gehad nie, terwyl sitruspulp (Model 1 & 2) die c-waarde van OH, en mieliemeel die c-waarde van OH en KIK, verhoog het. Energiebronne het slegs ‘n invloed op die sloerfase in WS en KIK gehad, waar dit L verlaag het tot laer waardes as dié van die kontroles. Daar is gevind dat ruvoer-fermenteerbaarheid verskillend beïnvloed word deur verskillende energiebronne. Bogenoemde resultate kan in die praktyk betekenisvolle invloede hê op rumengesondheid en melkproduksie en die data wat verkry is, kan potensieël gebruik word as riglyne in voerformulerings. In die tweede studie is in vitro verteerbaarheidsproewe gedoen om die effek van suiker (molasse en sukrose), stysel (mieliemeel en mieliestysel) en pektien (sitruspulp en sitrus-pektien) op neutraalonoplosbare vesel (NDF) en droë materiaal (DM) degradeerbaarheid van ruvoere, te bepaal. Ruvoersubstrate wat gebruik is, was WS, OH, LUC, RYE en KIK. Rumen vloeistof is verkry van twee lakterende Holstein koeie, wat ‘n dieet ontvang het bestaande uit hawerhooi, koringstrooi en ‘n konsentraat mengsel. Die in vitro degradeerbaarheidsproef is gedoen met ‘n ANKOM Daisy II inkubator. Ruvoersubstrate is geïnkubeer met of sonder die onderskeie energiebronne vir 24, 48 en 72 uur. Die substrate is geïnkubeer in 1076 ml buffer medium, 54 ml reduserende oplossing en 270 ml rumen vloeistof. Residue is gewas, gedroog en geanaliseer vir NDF. In die proef met toegepaste energiebronne (molasse, mieliemeel en sitruspulp), was daar ruvoer x energiebron interaksies. Toegepaste energiebron aanvullings het almal DMD van ruvoersubstrate (24 en 72 uur) verbeter, uitsluitend vir RYE wat aangevul is met mieliemeel (24 uur) en sitruspulp (24 uur). Van al die ruvoersubstrate het molasse die grootste effek gehad op DMD. Mieliemeel aanvullings het geen effek gehad op neutraal-onoplosbare vesel degradeerbaarheid (NDFD) van ruvoersubstrate nie, behalwe vir ‘n verbetering in NDFD van LUC by 72 uur. Molasse het NDFD van lucern by 24 uur verbeter, maar geen effek gehad op ander ruvoersubstrate nie. Sitruspulp het NDFD van OH (72 uur), asook LUC en WS (24 & 72 uur) verbeter. Daar word beweer dat die NDF van energiebronne meer verteerbaar is as die van ruvoersubstrate, en dat die verbetering in NDFD waardes toegeskryf kan word aan die bydraes van energiebronne se NDFD. Weidingsgrasse (RYE & KIK) het oor die algemeen ‘n hoër NDFD as hooie en strooi gehad. Rumen mikrobes blyk ook om dié grasse vinniger te verteer as lae kwaliteit hooie en strooi, wat gevolglik die hoër NDFD verduidelik. In die proef met suiwer energiebronne (sukrose, mieliestysel en sitrus-pektien) is ruvoer x energiebron interaksies waargeneem. Energiebronaanvullings het DMD by 24 en 72 uur verbeter, buiten vir RYE en KIK (72 uur). Weidingsgrasse het hoër NDFD as LUC, OH en WS. By 72 uur was die NDFD van LUC 37.1%, OH 42.5%, WS 40.3%, in vergelyking met 70.5% vir KIK en 64.9% vir RYE. ‘n Moontlike verklaring vir die hoër NDFD van KIK en RYE, is omdat dit vars gesnyde material is, geoes na slegs 28 dae hergroei. Oor die algemeen het sukrose (24 & 72 uur) en sitrus-pektien (72 uur) geen effek gehad op NDFD van ruvoersubstrate nie, terwyl stysel en pektien aanvullings tot OH (24 uur), en stysel aanvullings tot WS (24 & 72 uur) NDFD verlaag het. Daar word hipotetieseer dat mikrobes eers die vinnig fermenteerbare energiebronne fermenteer, voordat hulle ruvoer NDF aanval. Hierdie studie beweer dat ruvoer NDFD waardes nie vas is nie, en dat dié waardes beïnvloed mag word deur energiebron aanvullings.

Thesis (MScAgric)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: Statistical analysis was conducted on data from two Elsenburg herds, containing 105 Jersey and 232 Holstein cows. The data was examined for external factors which may affect milk yield and milk composition. The data consisted of 337 first lactation records, taken over a 20 year time period. Breed of cow had an effect on milk yield, butterfat and protein production, as did the year in which the cows were born and the age of the heifer at first calving. There was a significant interaction between the breed and year of birth. There are other external factors, which are difficult to quantify, which may have an effect on production. In the following trials, eight ruminally cannulated dairy cows (four Jerseys and four Holsteins) were used to determine the effect of breed on forage digestibility in the rumen. All cows received a high concentrate mixed ration, with supplementary wheat straw. An in situ rumen degradability trial was conducted with three different forages, viz. lucerne, wheat straw and NaOH-treated wheat straw. The bags were incubated in the rumen for time intervals of 2,4, 8, 12, 16,20,24, 36,48, 72 and 96 hours and samples were analysed for dry matter (DM) and neutral-detergent fibre (NDF). Higher rumen degradability values (P<0.01) ofDM and NDF were observed in Jerseys for all three forages. Differences were more apparent for wheat straw and treated wheat straw than for lucerne. The rate of passage of digesta from the rumen was measured in both breeds by a chromium mordanted wheat straw marker. The Holsteins manifested a higher rate of passage (P<0.05) than the Jerseys, while daily feed intakes were also higher (PAFRIKAANSE OPSOMMING: Statistiese analises is op data van twee kuddes te Elsenburg uitgevoer, bestaande uit 105 Jersey- en 232 Holsteinkoeie. Die data is ondersoek vir eksterne faktore wat melkproduksie en melksamestelling kan beinvloed. Die data het uit 337 eerste-laktasierekords bestaan, wat oor 'n periode van 20 jaar ingesamel is. Ras van die koei, sowel as die jaar van geboorte en ouderdom met eerste kalwing het 'n invloed op melkproduksie, bottervet- en proteienopbrengs gehad. 'n Betekenisvolle interaksie is tussen ras en jaar van geboorte waargeneem. Ander moeilik kwantifiseerbare faktore mag ook 'n invloed op melkproduksie he. In daaropvolgende proewe is agt rumen-gekannuleerde melkkoeie (vier Jerseys en vier Holsteins) gebruik om die invloed van ras op ruvoerverteerbaarheid in die rumen te bepaal. Al die koeie het 'n hoe-kragvoerdieet ontvang, aangevul met koringstrooi. 'n In situ rumendegradeerbaarheidstudie is met drie verskillende ruvoere, naamlik lusernhooi, koringstrooi en NaOH-behandelde koringstrooi uitgevoer. Die ruvoere is vir tye van 2, 4, 8, 12, 16, 20, 24, 36, 48, 72 en 96 ure in die rumen geinkubeer en monsters is ontleed vir droemateriaal (DM) en neutraal-bestande vesel (NDF). Hoer rumen-degradeerbaarheidswaardes (P