Dissertations / Theses on the topic 'Lambs'

9 pp.
As a general rule, lambs are not purchased until they are at least 8 weeks old and exceed 40lbs. in weight. The lamb should gain an average of .5 to .8 lbs. a day. This publication discusses how to feed a show lamb according to its nutrient needs.

The parasitic nematodes Teladorsagia (Ostertagia) circumcincta and Haemmonchus contortus are two of the most important pathogens of sheep and goats worldwide. The purpose of the work described in this thesis was to identify the mechanism of resistance to these parasites in young lambs. Lambs infected with T. circumcincta are incapable of controlling their worm burdens. However, it appears that some are capable of controlling the growth and therefore the fecundity of adult female worms. Work described in chapter three shows that the most important mechanism controlling the growth and fecundity of this parasite is the local IgA response. 933 lambs were studied over 5 years. Faecal egg counts were performed on these lambs and 485 of these lambs were slaughtered and the average female worm lengths determined. Analysis showed a highly significant effect of parasite specific IgA on worm length. Those lambs with higher IgA response to fourth-stage larvae had on average shorter worms. This response was heritable. Thus genetic resistance to T. circumcincta acts by reducing worm fecundity and works through a parasite-specific IgA response. In addition, this response is sex related with male lambs having the poorest response and females the best. Not only is the quantity of IgA important in determining host resistance, but also the specificity. Chapter four details work done in investigating the antigen specificity of the IgA response to T. circumcincta.

Includes bibliographical references (leaves 276-2970. Investigations presented involve 18 hour to 5 day old South Australian merino lambs. Some twin lambs were available for comparative studies. Examines the relationship between the strength of ewe-lamb bond and the lamb's ability to follow the mother, the energy availability and usage in the lamb, particularly for locomotion, and the metabolic and cardiorespiratory responses to locomotion.

Local anaesthetic administered epidurally at the base of the tail, and infiltrated into the testes, spermatic cords and neck of the scrotum eliminated the behavioural and plasma cortisol responses associated with castration and tail-docking, confirming that the pain observed was dependent on afferent activity from the affected areas. Having established the neural basis of the responses seen, attempts were made to modify the intensity of pain experienced so that measurement of the changes in behaviour and plasma cortisol concentration could be used to determine the usefulness of the behavioural and physiological indices adopted for the recognition and assessment of pain. Pretreatment with intravenous naloxone 0.2mg/kg I/V), which was anticipated to antagonise an endogenous opioid antinociceptive system activated following castration and tail-docking, provided limited evidence for an increase in pain intensity. 6 procedures which were proposed to represent a range of intensities and duration of noxious stimulation based on the amount and type of tissue involved were ranked in the expected order using the physiological and behavioural indices selected. A study was undertaken to determine if morphine (16mg) etorphine (10nmol) or xylaziantne (50g) by either the epidural or intrathecal route could provide a method by which pain intensity could be reduced in a dose dependent manner, to further improve the indices used for recognising and assessing pain. The results of these studies suggested that the pain produced by castration or castration and tail-docking cannot be eliminated by the doses of the drugs tested and the routes used. To confirm these results preliminary experiments were performed, morphine or xylazine was administered intrathecally to demonstrate active drug gained access to, and had the expected effect on the Sural-semitendinosus reflex in the lamb. Morphine failed to suppress the semitendinosus reflex which is consistent with the results obtained. The suppression of the semitendinosus reflex by xylazine is not consistent with the absence of analgesia in lambs to which either epidural or intrathecal xylazine (50g) had been administered prior to castration or castration and tail-docking, as the general view is that reflex suppression is highly correlated with the level of analgesia. The results of this study present data which shows physiological and behavioural indices can be used to recognise and assess a range of pain intensities in this age of lamb originating from the scrotum, testes and tail.

American lambs are often over-finished and lack consistent quality. It has been suggested that the use of intact ram lambs can decrease USDA YG and improve growth efficiency. However, ram lamb carcasses are underutilized because of potential issues, the most crucial being off-flavor development. Our hypothesis for this study is that U.S. producers can take advantage of intact ram lamb growth and performance with no detriment to product quality, as long as lambs are slaughtered before the attainment of puberty. Three breeds (Hampshire, Dorset, and Columbia), three slaughter weights (light, medium, and heavy) and two sexes (rams and wethers) were evaluated. Results indicate that ram lambs can provide a satisfactory eating experience, however, in one of our studies compounding of maturity and slaughtering intact rams increased incidence of off-flavors. It remains undetermined whether the small differences in sensory characteristics would be detectable by everyday consumers.

Thesis (MScAgric)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: The following study is to determine if a creep feed balanced for limiting essential amino acids (EAA) at a certain non structural carbohydrate (NSC) level will elicit greater responses than lambs reared on a commercial creep feed. Lysine, Threonine, Methionine, Isoleucine, Phenylalanine and Leucine were determined as the limiting amino acids for nursing lambs. These amino acids were incorporated into the creep feed treatments CF1 and CF2 representing 157 g CP/kg, 477 g NSC/kg and 179 g CP/kg, 508 g NSC/kg, respectively. A commercial creep feed with no optimisation for EAA is represented as CFC with 139 g CP/kg and 455 g NSC/kg. A negative control (CON) treatment represents lambs receiving no creep feed but with ad libitum access to suckle their dams while feeding on kikuyu pasture. A growth trial was conducted on Merino x Döhne-Merino cross twin lambs averaging a birth weight of 4.42 kg ± 0.11 for 60 days following with a digestibility trial towards the end of the trial. Half of the lamb crop was slaughtered at an average live weight of 23.6 kg ± 0.56. The M. longissimus dorsi was removed on both the left and right half of the carcass between the 2nd - 3rd last thoracic vertebrae and the 4th - 5th lumbar vertebrae. A sample from the rumen wall was taken at the rumino-reticular fold to determine development characteristics. Results indicate that the feed conversion ratio for the CFC lambs were better than CF1 (P = 0.052) but not more than CF2 (P = 0.307). The FCR was 0.88, 1.19 and 1.01 (kilogram feed required to gain 1 kg in bodyweight) for CFC, CF1 and CF2, respectively. Dressing percentage was higher for CF2 than for both CFC (P = 0.012) and CF1 (P = 0.077). Along with BUN data it was concluded that the high CP level of CF2 resulted in the higher fat deposition. The optimised creep feeds had higher nitrogen and energy balances than the commercial CFC, this implicates that the optimised creep feeds were more efficiently utilised. Optimised creep feed treatments had longer papillae than CON (P < 0.0001). Papillae of creep feed 2 was longer than CFC (P = 0.0537). Papillae width decreased as the NSC level increased thus it is surmised that higher NSC levels resulted in longer but thinner papillae. Rumen muscularization was equally developed between all the treatments and was ascribed to the lambs’ access to course roughage. Meat quality in terms of physical and chemical characteristics was found to be in range with that expected for lambs at higher slaughter weights (40 kg). In conclusion, the balancing of the limiting EAA increases the benefits of creep feeding while simultaneously being more efficiently utilised. Intensive sheep production systems may benefit from the feeding of such creep feeds provided it fits economically into their farming system.
AFRIKAANSE OPSOMMING: Die volgende studie is om te bepaal of 'n kruipvoer wat gebalanseerd is vir beperkende essensiële aminosure (EAA) by 'n vasgestelde nie-strukturele koolhidraat (NSK) vlak verbeterde groei sal ontlok teenoor lammers wat grootgemaak word op 'n kommersiële kruipvoer. Lisien, Treonien, Metionien, Isoleusien, Fenylalanien en Leusien is bepaal as die beperkende aminosure vir suipende lammers. Hierdie aminosure is opgeneem in die geoptimiseerde kruipvoer behandelings CF1 en CF2 wat 157 g RP/kg, 477 g NSK/kg en 179 g RP/kg, 508 g NSK/kg onderskeidelik verteenwoordig. 'n Kommersiële kruipvoer met geen optimalisering vir EAA is verteenwoordig as CFC met 139 g RP/kg en 455 g NSK/kg. 'n Negatiewe kontrole (CON) behandeling is verteenwoordig deur lammers wat geen kruipvoer ontvang het nie, maar wat ad libitum toegang tot hul ooi gehad het om te soog terwyl die ooi op ‘n kikoejoeveld wei. 'n Groei proef is uitgevoer met Merino x Döhne-Merino kruis tweelinglammers met ‘n gemiddelde geboorte gewig van 4,42 ± 0,11 kg vir 60 dae en 'n verteerbaarheids proef is na aan die einde van die studie uitgevoer. Helfte van die lam kudde is geslag by die lewende gewig van 23,6 ± 0, 56 kg. Die M. longissimus dorsi was op beide die linker-en regter helfte van die karkas tussen die 2de - 3de laaste torakale werwels en die 4de - 5de lumbale werwels verwyder. 'n Monster van die rumen wand is geneem langs die rumino retikulêre vou sodat die rumen ontwikkeling eienskappe daarmee bepaal kon word. Resultate dui daarop aan dat die voeromsetverhouding (VOV) vir CFC lammers beter was as vir CF1 (P = 0,052), maar nie meer as vir CF2 (P = 0,307) nie. Die VOV was 0,88 , 1,19 en 1,01 (kilogram voer wat nodig is om 1 kg liggaamsmassa aan te sit) vir CFC, CF1 en CF2 onderskeidelik. Uitslag persentasie vir CF2 was hoër as beide CFC (P = 0,012) en CF1 (P = 0,077). Saam met die bloed, urea en stikstofbalans data is daar tot die gevolgtrekking gekom dat die hoë RP inhoud van CF2 gelei het tot ‘n hoër vetneerlegging. Die geoptimaliseerde kruipvoere het ‘n hoër stikstof- en energiebalans gehad teenoor die kommersiële CFC behandeling wat dus impliseer dat die optimale kruipvoere doeltreffender benut was. Die geoptimaliseerde kruipvoer behandelings het langer papillae gehad as CON (P < 0,0001). Papillae lengte van die CF2 behandeling is langer as die van CFC (P = 0,0537). Papillae breedte het dunner geraak soos wat die NSK-vlak gestyg het dus word vermoed dat hoër NSK-vlakke langer maar dunner papillae tot gevolg het. Rumen bespiering is ewe ontwikkeld tussen al die behandelings en word toegeskryf aan die lammers se toegang tot growwe ruvoer. Vleis kwaliteit in terme van fisiese- en chemiese eienskappe was inlyn met wat verwag kan word vir lammers by hoër slaggewigte (40 kg). Ten slotte, die balansering van beperkende aminosure verhoog die voordele van kruipvoeding en word terselfdertyd doeltreffender benut. Intensiewe skaap produksie stelsels kan dus voordeel trek uit die voeding van sodanige kruipvoere mits dit ekonomies pas in die boerdery stelsel.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The aim of this study was to investigate the effect of feedlot production on the growth and carcass characteristics, as well as the distribution of the main tissues (muscle, fat and bone) and meat quality of Merino, South African Mutton Merino (SAMM) and Dorper lambs. The Merino and SAMM 2008 outperformed (P<0.05) the 2007 SAMM and both Dorper production groups in terms of average daily gain, while the Merino and both SAMM production groups achieved the best feed conversion ratio (P<0.05). The highest percentage A2 graded carcasses was achieved after 42 days under feedlot conditions by the Merino and both Dorper production groups, but it took only 21 days in the feedlot for the SAMM lambs to achieve the same result. Slaughter weight, carcass weight and dressing percentage all increased significantly with an increase in the number of days under feedlot conditions for all three breeds, while a decrease in the percentage head, trotters and red offal was also documented. The fatter retail cuts (thick rib, flank, prime rib and loin) increased (P<0.05) in percentage with an increase in the number of days under feedlot conditions. A significant decrease in the percentage leaner retail cuts (raised shoulder and hind-quarters) was found when the amount of days under feedlot conditions increased. The highest profit is obtained by the prime rib, loin and hind-quarters in a lamb carcass. For the Merino and Dorper lambs these three cuts, or a combination of the three showed the highest combined percentages after 42 and 63 days under feedlot conditions, respectively. The late maturing SAMM lambs achieved the highest percentages for these three cuts after 63 and 84 days under feedlot conditions in 2007 and 2008 respectively. Visceral and renal fat deposition increased throughout the production period for all breeds. The Dorper lambs attained the highest subcutaneous fat depth, and also produced the heaviest, but fattest carcasses. For A2-graded carcasses, Dorper lambs had the highest dressing percentage and lowest subcutaneous fat depth, followed by the SAMM and then Merino breed. A decrease in the percentage muscle and bone was found with an increase in the number of days under feedlot conditions, whilst an increase in the percentage fat was found under the same conditions. Meat quality was mostly affected by the 48h post mortem pH. This pH value is affected by the cooling rate of the carcasses, which in turn is affected by the level of carcass fatness. Carcass fatness increased with an increase in the number of days under feedlot conditions, resulting in a low 48h post mortem pH. A low 48h post mortem pH is accompanied by higher percentages of cooking and drip loss, as well as a high a*-colour reading for all three breeds.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van voerkraalproduksie op die groeivermoë, karkaseienskappe, verspreiding van spier, been en vet, en vleiskwaliteit van Merino, Suid-Afrikaanse Vleismerino (SAVM) en Dorperlammers te bepaal. Die Merino en SAVM 2008 produksiegroepe het hoër (P<0.05) gemiddelde daaglikse toenames getoon as die SAVM 2007 en beide Dorper groepe, terwyl die Merino en beide SAVM produksiegroepe die beste voeromset verhoudings bereik het (P<0.05). Die hoogste persentasie A2 gegradeerde karkasse is na 42 dae in die voerkraal deur die Merino en beide Dorper produksiegroepe geproduseer, terwyl dit slegs 21 dae onder dieselfde toestande vir die SAVM groepe geneem het om dieselfde resultaat te lewer. Daar is ‘n betekenisvolle verhoging in slagmassa, karkasmassa en uitslagpersentasie vir al drie die rasse gevind met ‘n toename in die aantal dae in die voerkraal, terwyl ‘n afname in die persentasie kop, pote en haarslag gevind was. Die persentasie vetter groothandelsnitte (dikrib, dunrib, ribtjop en lendesnit) het toegeneem (P<0.05) met ‘n toename in die aantal dae in die voerkraal. ‘n Betekenisvolle afname in die persentasie van die maerder groothandelsnitte (blad en boude) is gevind met ‘n toename in die aantal produksie dae in die voerkraal. Die hoogste inkomste van ‘n lamkarkas is afkomstige van die ribtjop, lende snit en boude. ‘n Kombinasie van hierdie drie snitte was die hoogste vir die lammers van die Merino en beide Dorper groepe na 42 en 63 dae in die voerkraal onderskeidelik. Die laat volwasse SAVM lammers het die hoogste persentasie van hierdie drie snitte bereik na 63 en 84 dae in die voerkraal vir die SAVM 2007 en SAVM 2008 onderskeidelik. Die neerlegging van pensvet en niervet het voortdurend toegeneem deur die produksieperiode vir al drie rasse. Die Dorperlammers het die hoogste onderhuidse vetneerlegging getoon, maar het ook die swaarste en vetste karkasse geproduseer. Dorperlammers het die hoogste uitslagpersentasie en laagste onderhuidse vetneerlegging vir A2 gegradeerde karkasse gehad, gevolg deur die SAVM en Merino. ‘n Afname in die persentasie spier en been in karkasse is waargeneem namate die lammers langer in die voerkraal was, terwyl ‘n toename in die persentasie vet onder dieselfde omstandighede waargeneem is. Die 48h post mortem karkas pH affekteer die meeste vleiskwaliteit eienskappe. Hierdie pH waarde word weer deur die tempo van karkasafkoeling beϊnvloed, wat op sy beurt deur die vetheidsgraad van die karkas bepaal word. Die vetheid van karkasse het toegeneem met ‘n toename in die aantal dae in die voerkraal, wat ‘n lae pH waarde 48h post mortem tot gevolg gehad het. ‘n Lae 48h post mortem pH waarde het gelei tot hoër persentasies kook- en dripverliese en hoë a* kleurlesings vir al drie rasse.

Lamb mortality remains a significant welfare and economic issue for sheep production. Two significant causes of mortality are dystocia and low lamb vigour; both requiring high levels of human care to ensure lamb survival. Genetic solutions to reduce lamb mortality and its main causes (dystocia and low vigour lambs) are desirable, with at least two possible solutions available: (i) use of suitable breeds or strains and (ii) intrabreed selection. Approach (i) requires the existence of breed/strain differences in the desired traits and approach (ii) needs sufficient intrabreed genetic variance. Reproductive and behavioural traits are, however, difficult to quantify and measure on farm. On dedicated research farms, lamb vigour has been measured using latencies to perform specific behaviours (e.g. standing and sucking) but this methodology is difficult to transfer to a commercial setting - timed behavioural traits are not as easy to measure on farm when compared with categorical indicator traits. Therefore, proxy methods (categorical scoring systems) are needed to measure behaviour traits in a manner that allows for collection of sufficient data to enable genetic analysis. The main purpose of this thesis was to develop such proxy methods, to estimate the heritability of lamb traits, and thus to investigate whether it is possible to improve the welfare of lambs through selection of parents with superior vigour and lambing ease characteristics. Scoring systems were developed for quantifying neonatal lamb fitness and behaviour traits. Detailed historical behaviour data were analysed to develop criteria for three scores: birth assistance (BA), lamb vigour (LV) and sucking assistance (SA). These scoring systems were then validated in a separate flock by simultaneously recording scores and the latency to perform certain landmark behaviours. The results obtained indicated that the scoring systems developed were a practical, reliable and sensitive indicator of lamb fitness traits. To determine whether neonatal lamb vigour traits were heritable, scores from the scoring systems previously developed and validated were recorded in an experimental flock of pure-bred Texel sheep for the purpose of estimating genetics parameters for each trait. Results indicated that heritabilities for all traits range from low-moderate, BA 0.43 (s.e. 0.063), LV 0.15 (s.e. 0.059), SA (0.27 (s.e. 0.045), suggesting there is sufficient variation present within this Texel sub-population to allow for selection for improved neonatal fitness traits. Thus far, we have determined that neonatal traits are heritable and can be measured using proxy scoring systems. The next step was to establish whether the proxy scores developed were feasible, in a commercial setting, for the mass data collection needed for estimation of genetic parameters and to determine the relationship between neonatal traits and later production traits, with the aim of integrating this data into breeding programmes. A total of 11,092 lambs with complete neonatal records, from 290 flocks belonging to the Industrial Partner, the Suffolk Sheep Society (UK), were analysed to report the genetic variance present within the UK population of registered pure-bred Suffolk sheep. The results from this analysis show that heritabilities were moderate for BA, 0.26 (s.e. 0.03), LV, 0.40 (s.e. 0.04) and SA, 0.32 (s.e. 0.03) with genetic correlations between neonatal traits all moderate to high and positive. This demonstrates that neonatal fitness traits can have heritabilities comparable to those of production traits. The analysis also shows that neonatal survival traits of birth assistance and sucking assistance are moderately heritable, when treated as a lamb trait rather than a sire or ewe trait, indicating the selection should target the lambs in order to successfully, and efficiently, improve survival. A possible alternative method for improving dystocia and lamb vigour would be to introgress genes for improved lambing ease and lamb vigour from the New Zealand strain of Suffolk sheep into the British Suffolk strains. However, there has been no published record of how much ‘NZ genetics’ would improve (or compare to) British Suffolk’s under standard UK management practises. Therefore, the objectives of this study were to examine possible differences in neonatal behavioural traits (birth assistance, lamb vigour and sucking assistance) between NZ and UK Suffolks when used as terminal sires on commercial cross-bred ewes. Thus, neonatal scores from cross-bred lambs sired by rams from one of the three main Suffolk strains currently used in the UK were compared. The analysis indicated there was no significant effect of sire strain on any of the neonatal traits, and that individual sire variation was greater than the variation between the strains. In conclusion, the work contained within this thesis shows that neonatal lamb behaviour traits can be measured accurately and easily using well-realised and biologically relevant scoring systems. Furthermore, these scoring systems are a feasible and practical method of measuring neonatal lamb vigour which may be used to evaluate management systems and to improve selection criteria for neonatal traits.

Crossbred lambs were injected with L-arginine hydrochloride (arg) to determine the effects of single of multiple arg challenges on growth hormone (GH) secretion. Indwelling jugular catheters were inserted. At the beginning of each of 3 trials, lambs were injected with saline and blood samples were collected for 90 min to establish baseline GH. Blood sampling continued at 5-min intervals until 1 h after the final injection, then at 10-min intervals for one additional hour. In trial 1 arg (.5g/kg) was injected into 6 lambs while the other 6 received a second saline injection. Trial 2 consisted of 3 arg injections given at 1-h intervals. Trial 3 utilized 4 arg injections given at 15-min intervals. Trials 2 and 3 were replicated using a switchback design. Serum GH and insulin were measured by double antibody RIA. Mean GH for treated lambs in trial 1 was 3.89 ng/ml versus 1.74 ng/ml in controls (P<.01). GH peaked 30 min after injection (9.47 ng/ml), declined to 5-times baseline and remained near that level throughout the sampling period. Serum insulin was not different between treatments. In trial 2 arg treated lambs had higher mean GH (2.57 ng/ml) than controls (.86 ng/ml; P<.01). Peaks of GH were observed 20 min after the first injection (7.59 ng/ml) and 1 h after the second injection (5.6 ng/ml). No increase in GH was observed after the third injection. Insulin tended to follow the same pattern, but was not significantly elevated in treated lambs. Differences in trial 3 mean GH between arg-treated lambs (5.25 ng/ml) and controls (1.16 ng/ml) were significant (P<.01). GH peaked (13.8 ng/ml) at 25 min after the first injection, surged again 100 min later (7.4 ng/ml), declined to levels 3-times baseline and remained elevated. Trial 3 insulin levels were significantly higher in treated lambs (.64 ng/ml) compared to control lambs (.15 ng/ml; P<.01). Control lambs showed no significant GH or insulin increases at any time. GH secretion patterns were significantly altered in lambs injected with arg. One arg injection caused GH to peak within 30 min. Further challenges resulted in smaller, delayed rise and persistence of elevated GH levels. Insulin levels tended to increase with arg stimulus, but were not significantly elevated except at extremely high doses of arg. The data reflects a consistent relationship between arg stimulus and serum GH.
Master of Science
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Five hundred, ninety-seven and 643 white face range ewes were used in a 2 year study, respectively, in a 3-way factorial arrangement to determine effect of supplemental linoleic oil on lamb serum metabolites, thermogenesis and lamb growth. During the last 45 ± 4 days of gestation ewes were group fed a daily supplement of either 0.23 kg•ewe-1•d-1 whole safflower seed (SS) or 0.34 kg•ewe-1•d-1 whole barley (C). Colostrum was collected from each supplement treatment and pooled according to treatment. At parturition, twin born lambs received either SS or C pooled colostrum. One h postpartum, lambs were placed in a 0°C dry cold chamber for 30 min. and lamb rectal temperature was recorded at one min intervals. Blood samples were taken prior to and after cold exposure. Lamb weights were taken at birth, turnout and weaning for growth. There was no difference (P > 0.10) in body temperatures between lambs born to ewes supplemented with SS vs. C or between lambs given pooled colostrum form SS or C supplemented ewes. At 0 minutes lambs born to SS supplemented ewes had lower glucose (P = 0.05), total protein (P = 0.05) and NEFA (P = 0.003) and higher BUN (P = 0.03) than lambs from C supplemented ewes. Lambs from SS supplemented ewes had lower NEFA (P = 0.01) after cold exposure (30 minutes). Total protein concentration was similar in year 1 but lower (P < 0.01) in year 2. Concentrations of aGP were higher in lambs from SS supplemented ewes at both 0 and 30 min in year 1. Lambs from SS ewes had higher (P < 0.01) blood aGP levels at both 0 and 30 min in year 1 than in year 2. No differences (P > 0.30) were detected between lambs from SS ewes vs. C for changes in any blood metabolites measured during cold stress period. No differences (P > 0.12) were detected for average date of birth, number of lambs born, number of lambs present at turnout and weaning or for weight of lambs at turnout or weaning for ewes receiving either SS or C supplements.

Neonatal lamb mortality is a major factor effecting profitability in the sheep industry. Lamb thermogenesis and immunocompetence are key elements in neonatal lamb survival. Research has shown an increase in lamb vigor, when ewes were supplemented during late gestation with algae-derived docosahexaenoic acid (DHA). However, the impact of DHA on lamb thermogenesis and immunocompetence has not been investigated. Eighty twin-bearing Targhee ewes were assigned randomly to 1 of 2 supplemental treatments to determine the effects of feeding (DHA) to ewes during late gestation and early lactation on lamb thermogenesis, immunocompetence, serum metabolites and hormones, and lamb growth. Treatments within supplements were: 1) 12 g/ewe daily of the product DHA Gold in the form of algal biomass (ALGAE), and 2) no DHA (CONTROL). Treatment supplements were individually fed daily during the last 30 d of gestation and pen fed (6 pens/treatment, and 6 or 7 ewes/pen) during the first 38 d of lactation. One h after lambing and before nursing, twin-born lambs were weighed, bled via jugular puncture, and placed in a dry cold chamber for 30 min (0°C). Lamb rectal temperatures were recorded every 1 min. After 30 min, lambs were removed from the cold chamber, bled, warmed for 15 min, and returned to their dam. Ewes were bled and colostrum samples collected 1 h postpartum. Ewe and lamb sera were assayed for glucose, non-esterified fatty acids (NEFA), cortisol, leptin and anti-Parainfluenza Type 3 (PI³) titers. Lamb rectal temperature, glucose, NEFA, cortisol, leptin, anti-PI³ titers, and birth weights did not differ between treatments. Thirty-eight-d BW was greater (P = 0.03) in lambs born to CONTROL-supplemented than lambs born to ALGAE-supplemented ewes; however, the colostrum of ALGAE-supplemented ewes had a greater specific gravity (P = 0.05), indicating greater IgG concentrations, than colostrum of CONTROL-supplemented ewes. Supplementation of DHA during late gestation and early lactation had a negative impact on lamb BW and did not affect indices of lamb thermogenesis, but may have improved IgG concentrations in ewe colostrum.

In the studies described in this thesis the amounts of Ca, P and Mg retained by growing lambs were determined following the slaughter of the lambs and their analysis. In experiment 1, the effects of growth rate on body composition and mineral retention were studied. The lambs were grown at different rates from 24 kg to 50 kg live-weight. The composition of empty-body gain (EBG) was estimated based on an initial slaughter group at the beginning of the trial. Fast growing lambs contained more fat and less protein, ash, Ca and P than slow growing ones. However, in the fat-free empty-body (FFEB), there were no significant differences found attributable to growth rate, except for Mg which was decreased with slow growth. Supplementary CaCO₃ significantly increased ash, Ca and P retention in FFEB of the fast growing lambs. In experiment 2, the retention of minerals from lambs fed either forage or concentrate diets was studied. Three groups of 8 Suffolk x Blackface wether lambs were (a) allowed to graze the grass outdoors (b) fed-concentrate indoors and (c) fed grass indoors. The lambs were grown from 24 kg and slaughtered at about 40 kg live = weight over 100 days. Retentions of Ca and P in empty-body gain (EBG) and fat-free empty-body gain (FFEBG) were significantly higher in grass-fed lambs. Higher mineralisation in the latter group was attributed to differences in acid-base balance between the diets and was not a function of either exercise or sunlight. Experiment 3 was designed to re-assess the requirements of Ca and P for growing lambs. Four groups of 10 Suffolk x Blackface lambs were fed concentrate diets containing different concentrations of Ca and P over a 93 day experimental period. Lambs fed on normal Ca-normal P diet (based on TCORN's (1988) new estimate) appeared to meet their requirement. Lambs fed on high Ca-high P diet showed no increase in mineral retention while those on low Ca-low P diet were more poorly mineralised. A high Ca-low P group had low concentration of P in blood and rumen liquor. Radiographic studies of the metacarpus and metatarsus from these trials were of limited value in predicting the mineral content of the empty-bodies of lambs.

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The aim of the study was to determine the effect of increasing levels of Maize silage in finishing diets for Merino lambs on their feed intake, production performance, feed conversion ratio, digestibility and meat quality. Concerns exist regarding the intake of high moisture and fibre containing silage in sheep due to the physical fill effect thereof. To determine the efficiency of silage as feed ingredient for sheep, maize was cut at 27% dry matter (DM), compacted into 220 litre plastic drums, sealed and left to ferment for 60 days. The silage produced was analysed for fermentation end products and the nutritive value determined. The silage produced had an optimum pH, starch and water soluble carbohydrate (WSC) content. The crude protein (CP) content (112.2 g/kg DM) was higher than expected. Four diets containing, on a dry matter (DM) basis either, 0, 20, 50 or 70% maize silage was formulated on an iso-nutrient basis with exception of neutral detergent fibre (NDF). The aim was to establish the effect of increasing levels of silage on animal production with regard to dry matter intake, growth, digestibility and meat quality. Diets were formulated on an iso-nutrient basis to match the 70% silage diet and therefore had relatively low specifications due to the high inclusion of silage from the 70% silage diet. A growth study and an in vivo and in vitro digestibility study were conducted to determine the effect of the different diets on feedlot sheep production. Meat quality was also determined to establish whether the experimental diets had an effect on meat quality. Forty lambs in a completely randomised block design, with four treatments, were used in a 60-day finishing study. The dry matter intake (DMI) of lambs decreased as silage inclusion increased above the 20% silage inclusion level. At the 20% inclusion rate, the feed intake of the animals was stimulated. This resulted in significant differences found between the cumulative intake of the low and the high silage diets. Feed conversion ratio (FCR) was poorer, however, for the control and 20% silage diets. The poor FCR most likely was related to the quality of the feed ingredients used in the formulation of the control feed and the concentrate in the 20% silage diet rather than the silage itself. Significant differences were also found in the dressing percentage of the slaughtered animals where the 20 and 50% silage diets had a higher dressing percentage than the control and 70% silage diets. It was concluded that silage can be successfully incorporated into sheep diets, especially at low levels where its inclusion stimulates intake. Eight animals per group were used in an in vivo digestibility study to determine the apparent digestibility of the experimental diets. Feed, faeces and urine samples collected during the trial period were analysed for the respective nutrients. The 20% diet, even though having the best overall apparent digestibility, did not result in better production responses. Lambs on the 20% silage diet had the highest daily DM intake, which resulted in them having the highest energy intake. There were no differences in total energy excreted between the silage-based diets. This resulted in the 20% silage diet also having the best energy retention. Nitrogen retention was the highest for the control and 20% silage diets. This can be ascribed to the low quality of the concentrate part of the diet. The 20% silage diet, as previously stated, had the highest apparent DM and organic matter (OM) digestibility, while the control diet showed the lowest overall nutrient digestibility. The low nutrient digestibility of the control diet can be ascribed to the relatively poor quality ingredients used. There were no differences in the crude protein (CP) digestibility between the control and the 20% diet. Both proved to be higher than the CP digestibility of the 50 and 70% silage diet. As the neutral detergent insoluble nitrogen (NDIN) was higher for the 50 and 70% diets, this observation was not surprising. Fibre content of the silage-based diets increased as the inclusion level of the silage increased, which resulted in a decrease in overall fibre digestion. Three cannulated sheep were adapted on each experimental diet for two weeks before rumen fluid was collected for the in vitro digestibility study. No differences between the silage based diets were found for in vitro true digestibility (IVTD). The IVTD of the 20, 50 and 70% diets were higher, however, than the IVTD of the control diet confirming earlier observations on the choice of ingredients used in the control diet to formulate iso-nutrient diets. Degradability coefficients were determined for the DM and NDF fractions of the different experimental diets and fitted to the non-linear model; p = a + b (1 – e-ct). The amount of DM that disappeared in a certain time (t) is represented by p. Constant a represents the fraction that was rapidly soluble, b represents the potential degradable fraction and c is the rate at which b was degraded. There were no differences between experimental diets for the rapidly soluble fraction. The silage-based diets had a higher potential degradable fraction (b) but did not differ in the degradability rate (c) from the control diet. Silage-based diets had higher overall effective degradability than the control but did not differ between one another. Constant a was not determined for NDF degradability since the NDF fraction did not have a rapidly soluble fraction. The control diet had the lowest potential degradable NDF fraction with the rate also being lower than the silage based diets. Effective NDF degradability was highest for the 50% silage diet. Lambs used in the finishing study were slaughtered and meat samples taken for meat quality tests. The pH, colour, drip loss, cooking loss, shear force and fatty acid composition were determined on the Longissimus dorsi samples collected at Roelcor (Malmesbury, Western Cape, South Africa). Proximate analysis was also conducted on the meat samples. The experimental diets did not have a significant effect on the proximate chemical composition of the meat. Colour differences were found; however no clear pattern could be established. There were no differences in fatty acid composition. It can be concluded that up to 70% maize silage can be included in the finishing diets of Merino lambs with no adverse effects on the meat quality. The study showed that 20% maize silage can be included in the finishing diets of Merino lambs without negatively affecting intake, production, digestibility or meat quality. Future research is needed to optimise the 20% silage diet, however, and to again look at the effect that it will have on animal production, including the effect thereof on total methane emissions.
AFRIKAANSE OPSOMMING: Die doel van die studie was om te bepaal of mielie kuilvoer doeltreffend gebruik kan word as ‘n komponent in die afronding van Merino lammers. Gedurende die proses is mielies gesny teen 27% droë materiaal (DM), en saamgepers in 220 liter plastiek dromme. Dit is toegelaat om te fermenter vir 60 dae. Die kuilvoer wat daaruit geproduseer is, is geanaliseer vir fermentasie eindprodukte, en die voedingstofwaarde is bepaal. Vier diëte met onderskeidelik 0 (kontrole), 20, 50 en 70% kuilvoer is geformuleer op ‘n iso-nutriëntbasis met die uitsondering van vesel (NDF). ‘n Groeistudie, tesame met ‘n in vivo en in vitro verteerbaarheidstudie is uitgevoer om die effek van die verskillende diëte op diere produksie te toets. Vleiskwaliteit toetse is ook gedoen om te kyk of die verskillende diëte ‘n effek op vleiskwaliteit het. Veertig lammers, in ‘n ewekeurige blokontwerp, is gebruik in ‘n 60 dae afrondingstudie. Dit is opgemerk dat die DM inname (DMI) afgeneem het soos die kuilvoer insluiting bo die 20% vlak toegneem het. By die 20% insluitingskoers, is voerinname by die diere gestimuleer. Dit het veroorsaak dat beduidende verskille gevind is tussen die kumulatiewe inname van die lae en die hoë kuilvoer diëte. Die voeromsetkoers (VOK) was egter hoër vir die kontrole en 20% kuilvoer diëte. Beduidende verskille is ook gevind in die uitslagpersentasie van die diere, waar die 20% en 50% kuilvoer diëte ‘n hoër uitslagpersentasie as die kontrole en 70% kuilvoer diëte gehad het. Agt diere is per groep gebruik in ‘n in vivo verteerbaarheidstudie om die skynbare verteerbaarheid van die eksperimentele diëte te toets. Voer, feses en urien monsters is gedurende die proefperiode ingesamel en geanaliseer. Die 20% kuilvoer dieet het die hoogste DM en organiese materiaal skynbare verteerbaarheid teenoor die kontrole diet wat die laagste gehad het. Daar was geen verskille in die ru- proteien (RP) verteerbaarheid van die kontrole en 20% kuilvoer diet nie. Beide was hoër as die RP verteerbaarheid van die 50% en 70% kuilvoer dieet. Die veselinhoud van die kuilvoergebasseerde diëte het toegeneem soos die insluitingsvlak van die kuilvoer toegeneem het, wat ‘n afname in veselvertering veroorsaak het. Lammers op die 20% kuilvoer dieet het die hoogste daaglikse DM inname gehad, wat die hoogste energie inname tot gevolg gehad het. Daar was geen verskille in die totale energie inname van die kuilvoergebasseerde diëte – dit het veroorsaak dat die 20% kuilvoer dieet ook die beste energie retensie gehad het. Stikstof retensie was die hoogste vir die kontrole en 20% kuilvoer dieet. Drie gekannuleerde skape is vir twee weke op elke eksperimentele dieet aangepas voordat rumenvloeistof ingesamel is vir die in vitro verteerbaarheidstudie. Geen verskille is gevind vir die in vitro ware verteerbaarheid (IVWV) tussen die kuilvoergebasseerde diëte nie. Hulle was egter hoër as die IVWV van die kontrole dieet. Degradeerbaarheid koëffisiënte is bepaal vir die DM en NDF fraksies van die verskillende eksperimentele diëte en is gepas in die model p = a + b (1 – e-ct). Die hoeveelheid DM wat verdwyn het binne ‘n sekere tyd (t) word voorgestel deur p. Die konstante a verteenwoordig die fraksie wat vinnig oplosbaar is, b verteenwoordig die potensieel degradeerbare fraksie en c is die koers waarteen b gedegradeer is. Konstante a is nie bepaal vir die NDF degradeerbaarheid nie, aangesien die NDF fraksie nie ‘n vinnig oplosbare fraksie gehad het nie. Daar was geen verskille in die vinnig oplosbare fraksie tussen eksperimentele diete nie. Kuilvoer gebasseerde diete het ‘n hoër potensieel degradeerbare fraksie gehad, maar daar was geen verskille in koers van degradering nie. Die kuilvoergebasseerde diëte het ‘n hoër DM effektiewe degradeerbaarheid as die kontrole dieet. Effektiewe NDF degradeerbaarheid was die hoogste vir die 50% kuilvoer dieet. Lammers in die studie gebruik is geslag en vleismonsters is geneem vir vleiskwaliteit toetse, insluitende pH, kleur, drupverlies, kookverlies en taaiheid. Proksimale analise is ook uitgevoer op die vleismonsters. Die eksperimentele diëte het nie ‘n beduidende effek op die proksimale chemiese samestelling van die vleis gehad nie. Kleur verskille is wel gevind, maar geen duidelike patroon kon vasgestel word nie. Daar was geen verskille in die vetsuur samestelling nie. Daar kan dus tot die gevolgtrekking gekom word dat mielie kuilvoer ingesluit kan word in die afrondingsdiëte van Merino lammers, tot by 70%, sonder enige negatiewe effekte op die vleiskwaliteit. Daar is tot die gevolgtrekking gekom dat mielie kuilvoer suksesvol geïnkorporeer kan word in skaapdiëte, veral teen lae vlakke (20%) waar die gebruik nie net inname stimuleer nie, maar ook geen negatiewe effekte het op produksie en verteerbaarheid nie.
Dr. Francois van de Vyver, Cape Wools and NWGA for providing funding in the form of post graduate bursaries

Antigen-specific and polyclonal serum immunoglobulin G (IgG) concentrations were measured in control (Con), vitamin A-deficient (A-def), and vitamin A-repleted (A-rep) lambs. In Trial, I ewe lambs were injected with primary and secondary antigenic challenges of ovalbumin (1mg) and lysozyme (.1mg). The A-def lambs were then repleted with vitamin A and all lambs were injected with primary and secondary antigenic challenges of human gamma globulin (HGG) (.1mg). In Trial II Con and A-def wether lambs were given primary and secondary antigenic challenges of ovalbumin (20μg). Half of the A-def lambs were then repleted with vitamin A. All lambs were subsequently given a primary and secondary challenge of HGG (20 μg). Spleen wt were similar for all treatments in Trial I while A-def V lambs in Trial II had greater spleen wt (P<.01) than Con or A-rep lambs. Polyclonal serum IgG concentrations were unaffected by treatment in Trial I while in Trial II concentrations were greater (P<.05) in the A-def lambs during the HGG challenge period. Antigen-specific IgG concentrations in both trials tended to be greater in the Con lambs towards the end of both the ovalbumin (Trial I and II) and lysozyme (Trial I) challenge periods. Control and A-rep lambs in Trial I responded similarly to the HGG challenges. In Trial II both the A-def and A-rep lambs had lower (P<.10) HGG specific serum IgG concentrations on the last 3 wk of the HGG challenge period as compared to A-def lambs. Humoral immune function appears to be impaired in A-def lambs and a 2-wk repletion period was not sufficient in this study to restore humoral immune function to normal levels.
Ph. D.

I studied the acquisition of foraging skills by lambs eating shrub or grass in three experiments. The general approach was to isolate those skills involved in prehending forage from those related to the acceptance of novel foods. Treatment lambs received 15 times more exposure to grass or shrub than did control lambs. Lambs were tested in 2.5 x 2.5 meter monocultures of shrub or grass 5 min/d, on two separate occasions. Height, bulk density and spatial arrangement of plant material were controlled during testing. In Experiment 1, I studied the acquisition of foraging skills by lambs on monocultures of shrubs. I found that inexperienced lambs ingested less forage per unit time than experienced lambs because they had less developed prehension skills. Lambs were more successful at plucking individual leaves than breaking twigs from branches or stripping 1 eaves. Lambs emphasized prehension patterns that were most successful. In Experiment 2, I explored the extent to which foraging skills gained on shrub or grass are specific to shrub or grass. Grass-experienced lambs were more successful at prehending and ingesting grass than were shrub experienced lambs. No statistical differences were observed between shrub- and grass-experienced lambs at prehending and ingesting shrub although numerical values were higher for shrub- than grass-experienced lambs. I hypothesize that a relationship exists between plant form, prehension pattern and foraging experience. In Experiment 3, I studied the degree to which lambs experienced with grass or shrub vary in their ability to prehend and ingest vegetative and flowering grass. Grass- and shrub-experienced lambs ingested more flowering than vegetative grass per unit time. Grass-experienced lambs were more efficient than shrub-experienced lambs at prehending and ingesting vegetative and flowering grass. Shrub-experienced lambs experienced more difficulty at prehending flowering compared to vegetative grass while grass-experienced lambs did not.

Recommendations for the transportation of lambs from a European Commission, which required rest stops of 6 or 24 h, every 8 h, were evaluated for efficacy of reducing stress indicators using Rambouillet x Suffolk lambs (17.6 ± 0.5 kg). The lambs were randomly assigned to one of three groups: 1) transported for 22 h (Continuous; n = 15); 2) transported for 8 h, unloaded and rested for 6 h, transported for 8 h, unloaded and rested for 24 h, transported for 6 h (Rested, n = 15); and 3) Control, which remained in home pasture throughout the study (n = 16). The rest stops were off-trailer; a different pen was used for each; and, a limited amount of grain and ad lib hay and water were provided. Mean temperature in the trailer during the study was 28.4° C with a range of 18.2° C to 39.6° C. Food deprivation in the Continuous lambs was reflected by a decrease in plasma glucose (P < 0.001) and an increase in blood urea nitrogen (P < 0.001), creatinine (P < 0.02) and total bilirubin (P < 0.001) relative to the Rested or the Control lambs. Electrolytes varied within and between all three treatments (P < 0.05), but no distinct pattern indicating dehydration was evident. Serum concentrations of cortisol were greater (P < 0.05) in Continuous lambs than in the Control lambs at 14 h and both the Continuous and Rested lambs had higher concentrations of cortisol (P < 0.05) compared to the Control lambs at 22 h. Plasma IgG antibody response to ovalbumin was suppressed (P < 0.05) in the Continuous and Rested lambs compared to the Control lambs. Lambs in both transported treatments ate grain immediately upon release into the rest pens and drinking occurred following the food consumption. The Continuous lambs lost a greater (P < 0.05) amount of initial BW at the conclusion of transport compared to the Rested lambs and had a lower BW (P < 0.05) than the Rested and Control lambs 8 d after the start of transport. Rest stops improved welfare by reducing physical stress of food deprivation and eliminating BW loss during transport. However, rest stops failed to completely alleviate immunosuppression and 52 h were required to complete the otherwise 22 h long trip. The additional costs of providing the benefits of the rest stops should be examined before these regulations are widely implemented.

The series of experiments described in this thesis were designed to investigate the role of suckling or late weaning in the response of young lambs to nematode infection. All experiments were conducted outdoors with grazing animals and no supplementation but for suckled groups of lambs whose counterparts were weaned to ryegrass – white clover swards. The parasite of interest was mainly Teladorsagia circumcincta solely but with mixed infection of Trichostrongylus colubriformis in one instance. In Chapter 3 (first experiment), the hypothesis that milk per se may have a direct effect on nematode development, rather than an indirect effect through enhancement of host immunity by superior nutrient supply was tested. Sixty, twinborn lambs were used, allocated to one of eight groups formed by either dosing lambs from 42 days of age or not with the equivalent of 1000 or 250 L₃ T. circumcincta larvae d⁻¹ until five days before necropsy, while a twin was either weaned at 39 days of age, suckled as single or twin until necropsy on day 84. The possibility that weaning one of a twin set onto pasture in close proximity to the ewe would cause abnormal ewe and lamb behaviour was tested by replicating the work in twins maintained as twins but in which one twin received equivalent of 250 and the other 1000 L₃ T. circumcincta larvae d⁻¹. This showed no abnormal ewe nursing or lamb suckling behaviour as a result of weaning a twin in a set. Relatively low faecal egg counts (FEC) and a two to three fold lower worm burdens suggest suckling could reduce larval establishment. Inability to detect peripheral titres of immunoglobulins supports this conclusion. An intra worm-population regulation of T. circumcincta, indicated by a pattern of greater egg-laying by a numerically smaller but physiologically better developed nematode population in suckled lambs measured in eggs 'in utero' and worm length made interpretation of FEC difficult. Suckling significantly improved weight gain and carcass weights, but early weaning did not reduce resilience to infection. In Chapter 4 (second experiment), 40 pairs of twin lambs, average age of 39 days, were either infected with the equivalent of 1000 L₃ T. circumcincta larvae d⁻¹ or not, while one twin was weaned and the other allowed to continue suckling. Necropsy was carried out on groups of five and six lambs from each of the uninfected and infected treatments, respectively, at mean age of 84, 112, and on six lambs from each group at 140 days of age. This serial slaughter allowed further confirmation of the hypothesis in Chapter 3 but also investigated the long-term effect of suckling on resistance or resilience of lambs at the trial when immune responses were anticipated to be developing. An in vitro direct larval challenge (IVDC) study, to monitor larval establishment, was carried out on tissue explants from necropsied lambs. Suckled lambs consistently showed lower FEC (P < 0.05) and worm burdens (P < 0.05) at every phase of the trial. Within the infected groups, % in vitro larval rejection suggested earlier immune responses in the weaned lambs by day 84, which was not consistent with lower worm burdens in suckled lambs but appeared similar in the subsequent necropsies. Lambs continued to show better growth due to suckling while weaning did not reduce the resilience of lambs confirming observations in Chapter 3. The immunoglobulin profile suggested the commencement of immune responses in lambs from the period after the 84th day necropsy, with significantly greater (P < 0.01) IgA titre in the infected groups, and the suckled lambs towards the end of the trial on day 140. A vaccinating effect of early exposure to parasites was coincidentally revealed as a result of unintentional pasture larval contamination, seen in suckled non-infected lambs shedding fewer eggs and harbouring fewer worms during the later necropsies compared with their weaned non-infected counterparts. In Chapter 5 (third trial), 93 pairs of twin lambs, 47 pairs of which received a vaccinating mixed infection of T. circumcincta and T. colubriformis larvae (60 L₃ / kg W / d) at ratio 40:60, respectively during the period 36 – 103 days of age, were either weaned early on day 51 or later on day 108. All lambs were drenched on day 108 and groups received challenge infections from day 116, at same rate with the vaccinating infection, or not, which ceased five days before respective necropsies. Necropsies were carried out on selected lambs on days 108, 184 and 218. The direct effect of milk on larval establishment appeared to feature only in the T. circumcincta populations on slaughter day 108. The long-term benefit of late weaning for development of resistance was conditional on lambs receiving the vaccinating infection, and appeared to be more pronounced in the small intestine, reflected by a greater reduction of T. colubriformis populations in that organ than of T. circumcincta populations in the abomasum. A negative consequence of enhanced immune response was the suggestion of an increased metabolic cost in reduced performance of lambs. In conclusion, the work provides support to the hypotheses that: (a.) suckling may reduce the establishment of nematode larvae through the direct effect of milk, (b.) may enhance rapid development of host immunity to infection, and (c.) it further suggests that lack of larval experience during suckling may have long term negative implications for host resistance. Finally, it suggests that milk may play little role in the enhancement of host resilience to infection and, on the contrary, that additional metabolic cost may be associated with a more rapid development of immunity resulting from larval challenge while suckling.

A reduction in voluntary feed intake is a major factor in the lost productivity of grazing lambs infected by gastrointestinal parasites yet the mechanisms involved are poorly understood. Potential pathways involved in parasite-induced feed intake depression were investigated in lambs with minimal previous exposure to parasites and artificially infected by the small intestinal parasite Trichostrongylus colubriformis. Six in vivo experiments were conducted on lambs housed in individual pens or metabolism crates with similar feeding and experimental procedures. In Experiment 1 (Chapter 4) the effect of T. colubriformis infection on short term feed intake in lambs and of some pharmacological agents on feed intake depression were investigated. Prior to and for the duration of infection, lambs were fed once per day and feed intake recorded at regular intervals over the day (8 h). Following the onset of feed intake depression in the infected group (9 weeks after commencing dosing), all animals were treated with an analgesic (codeine phosphate per os), an anti-inflammatory agent (indomethacin per os), a CCK antagonist (L364-718 by subcutaneous injection) or saline (control) in a replicated Latin square design (n = 8). Although the pattern of feed consumption was similar in infected and non-infected lambs, average daily intake was reduced 32 % and short term intake (recorded at 10 minute intervals for the first hour of feeding, 15 minute intervals for the second hour and hourly for the next 6 hours of feeding) reduced 40 % by infection. This identified the key component by which intake was depressed and enabled the use of a short term intake model and short duration of action compounds to identify the pathways involved in intake depression in this sequence of experiments. None of the pharmacological treatments increased intake in the infected group. These results suggest a reduction in the rate of consumption due to reduced hunger signals, rather than change of meal eating patterns, is the major cause of feed intake depression. Specific conclusions about the pathways investigated using the pharmacological agents could not be obtained. Experiment 2 (Chapter 5) was designed to investigate the roles of pain and osmolality on feed intake depression. Digesta samples collected prior to and during parasite infection and before and after feeding had similar osmolalities (240-260 mosmol/l) which indicated that feeding or infection had no effect on osmolality of digesta. Following the onset of feed intake depression in infected animals, all animals were treated in a Latin square design (n = 4) with no treatment, saline, local anaesthetic (xylocaine) or analgesic (codeine phosphate) solution 15 minutes before feeding, by slow injection into the duodenum. There was no effect of these treatments on food intake. In the second part of the experiment, hyperosmotic solutions (mannitol and NaCI) markedly depressed short term intake in non-infected animals, suggesting a role for osmoreceptors in intake regulation. However these effects were not blocked by local anaesthetic so the depressed intake may have resulted from generalised malaise rather than from specific osmoreceptor effects. In Experiment 3 (Chapter 6) the role of peripheral CCK on intake depression was examined by a dose-response study utilising the CCK antagonist, loxiglumide. Intravenous injection of 5, 10 or 20 mg/kg LW of loxiglumide to infected lambs 10-15 minutes before feeding (n = 6) had no effect on feed intake at any of the dose levels. In experiment 4 (Chapter 7) loxiglumide was infused intravenously for 10 minutes (30 mg/kg/h) before feeding and for the first 2 h (10 mg/kg/h) after feed was offered to minimise any effect of the rate of clearance of loxiglumide on the lack of feed intake response. As well, the rate of marker disappearance from the abomasum was recorded in both infected and non-infected animals. Continuous infusion of loxiglumide did not attenuate parasite induced intake depression nor did it have any effect on abomasal emptying. Abomasal volume was reduced by infection (66.3 vs 162 ml) as was the fractional outflow rate (2.2 vs 2.8 ml/min) but these differences were accounted for by the lower level of feed intake in the infected animals. In Experiment 5 (Chapter 8) brotizolam, a benzodiazepine appetite stimulant, thought to act on the hypothalamus, was administered in a dose-response study to infected and non-infected animals (n = 4) immediately prior to feeding or following termination of the first meal (45 minutes after feeding) and the feed intake response recorded. Brotizolam elevated both the short term (0-0.75 h), daily (22 h) intake and all time intervals in the first 5 h after feeding in infected and non-infected animals when administered after the first meal but when administered prior to feeding elevated intake only over the first 6 h of feeding. In both cases the magnitude of the response was greater in infected animals than in non-infected animals. Brotizolam appeared to increase the rate of eating without having a major impact on meal eating patterns when administered before feeding. Where administration was after the first meal, the effect was due to an "extra" meal being consumed. These findings showed that infected animals can respond to central stimulators of intake although the mechanism of the response is not known. Opioids were implicated in intake depression as the rate of intake rather than meal patterns appeared to be the major parameter depressed under parasitism. This was examined in experiment 6 (Chapter 9) where animals (n = 6) were fasted for 26 h or not fasted, then treated with saline (control), brotizolam (intake stimulant) or naloxone (opioid antagonist) immediately prior to feeding. Fasting stimulated feed intake in the short term (100 % increase in 75 min) and over the day (12 % increase) in both infected and non-infected animals. Following fasting, infected animals ate a similar amount of feed to the non-infected, fasted animals and more than the non-infected, non-fasted animals. The signals resulting from a one day fast were sufficient in the short term to override parasite induced mechanisms causing feed intake depression. Naloxone suppressed the intake stimulatory effects of a 26 h fast in both infected and non-infected animals, which supports a role for endogenous opioids as hunger signals. Where animals were not fasted, naloxone reduced intake only in the non-infected animals which suggested endogenous opioid levels may be lower in infected animals than in non-infected animals. In the final experiment (Experiment 7, Chapter 10) the role of central hunger and satiety mechanism were investigated. Infected and non-infected animals (n = 6) were treated with naloxone or saline by intravenous injection, or saline and met-enkephalinamide (an opioid analogue) by intracerebral infusion, or naloxone and the opioid analogue simultaneously to investigate the role of central opioids in feed intake depression. To determine the role of CCK induced satiety signals on feed intake at a central level, loxiglumide and CCK were infused separately and in combination for 30 minutes prior to feeding and for the first 60 minutes of feed on offer, into a lateral cerebral ventricle of the brain of infected and control animals (n = 6). The opioid analogue tended to increase intake in infected animals but the effect was not significant probably because the dose used was too low to elicit a response in sheep. Naloxone depressed intake only in the infected animals, which conflicted with the results of Experiment 4. As a consequence these results were inconclusive because of the single low dose of opioid analogue used and the conflicting naloxone responses. CCK alone depressed intake by 39-52 % only in infected animals and this effect of the 90 minute infusion was evident over the 8 h short term recording period. Loxiglumide attenuated the feed intake depressive effects of CCK in the infected animals to the extent that intake was elevated above control levels. Loxiglumide alone was an intake stimulant in both infected and non-infected animals. Intake was increased over the entire 8 h but mostly in the second hour when intake was increased by 188 % in infected animals and by 16 % in the non-infected animals and resulted in almost continuous eating. These results showed loxiglumide will temporarily block the effect of parasite infection on feed intake in sheep when administered centrally and the fact that it blocked the effects of exogenous CCK on intake indicated that the effect is mediated via CCK receptors. In conclusion GIT parasite infection reduced both short term and daily feed intake apparently by a change in rate of intake rather than any alteration in meal patterns. It was further suggested that anyone of a number of potential peripheral pathways, including changes to osmolality, gut emptying, pain and inflammation of the gut, alone is not involved in anorexia in sofar as the compounds used could block these factors and the results support the idea that intake depression is mediated via a central mechanism. Intake in infected animals responded to a much greater extent when fasting, i.c.v. loxiglumide or brotizolam were employed. Feed intake thus appears to be regulated through the same mechanisms in infected and non-infected animals. The results from compounds affecting the central mechanism suggest central CCK receptors are important in parasite induced anorexia, possibly by changing the onset of satiety or by interacting with endogenous opioids to reduce the rate of feed intake. Secondly reduced endogenous opioids may be causing the reduction in the rate of feed consumption alone or as a result of other interactions. It was concluded that intake in parasitised animals could be increased to that of control animals by employing procedures and compounds thought to act on the hypothalamus.

Bibliography: leaves 281-316. Presents investigations on pubertal development in South Australian merino ram lambs and examines the effect of active and passive immunizations against oestradiol-17ℓ or oestrone on testicular maturation.

Ten wether lambs were used to determine the effects of ergovaline consumption from endophyte infected tall fescue, on nutrient utilization and metabolism. Lambs were fed a diet of 23% endophyte free tall fescue seed (E-) and 77% concentrate from d -14 to -1 (adaptation phase). On d 0, five lambs were switched to an endophyte infected seed diet (E+) where they remained through d 14. Nutrient digestibilities tended to increase from adaptation through the acute (d 1 to 4) to subacute (d 10 to 14) phases when E- was fed. E+ digestibilities were highest (P < 0.05) in the acute phase. Lambs fed E+ had higher rectal temperatures in the acute (P < 0.01) and subacute phases (P < 0.05). Fecal recovery of ergovaline increased as day of collection increased in the acute and subacute phases. Lysergic acid fecal recovery increased with day of collection in the acute phase, but no effect was found in the subacute phase. Serum enzyme analyses did not indicate tissue damage from alkaloid consumption. These results demonstrate lambs try to adapt to endophyte infected fescue seed consumption through increased nutrient digestibilities and increased ergovaline and lysergic acid excretion.

Thesis (MScAgric)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The Dorper is numerically the second most abundent of all the sheep breeds in South Africa. It is the most numerous sheep breed in the dry arid areas of South Africa which make out a very big portion of the natural grazing in South Africa. In this study the feedlot performance was specifically investigated since so little research has been done in this regard. In the first study (Chapter 1), the production efficiency, body components and commercial yield of 13 Dorper and 12 Merino lambs were investigated. A pelleted diet was fed ad lib and the water intake per day was measured. Lambs were slaughtered at 30kg and at 40kg live weight and cut up according to the South African commercial cuts. The weights of the organs, head, feet, skin and carcass were also recorded. Results from the first study showed that Dorpers had a lower (P<0.05) water efficiency (285.97 mVkgO75/day) than the Merinos (240.07 mVkg075/day), but had a higher (P<0.05) nitrogen retention. The head, feet, skin, heart, lungs, kidneys and diaphragm of Merino lambs were heavier (P<0.05). Merinos had heavier (P<0.05) breast and shank and thick rib (only at 40kg live weight) cuts. But the Dorper had a significantly heavier hindquarter (buttock and loin) which is the high-priced cut of any carcass. It seems that the Dorper will do well under feedlot conditions, and would possibly make a better commercial meat producer than the Merino under all circumstances. In the second study (Chapter 2), the free-ranging Dorper on natural grazing were compared with 7 Dorper lambs in the feedlot study. The essential amino acids in the duodenal contents were compared. The free-ranging Dorpers were randomly slaughtered at 40 kg live weight and a duodenal sample was collected. The feedlot Dorpers were also slaughtered at 40 kg live weight and a duodenal sample was taken. The second study indicated no significant differences between the EAA composition of the duodenal samples, whether protein quantity was taken into account (gAA/100g crude protein (CP)) or not (expressed as % of lysine). The chemical scores indicated that the two most limiting amino acids in the duodenal digesta for whole empty body growth were: arginine and histidine. Excess levels of amino acids tend to be present in all three duodenal digesta samples (isoleucine, leucine, lusine, methionine, phenylalaline, threonine and valine). The whole empty body EAA composition (g AA/100 g crude protein) was as follows 7.10 arginine; 2.40 histidine; 3.31 isoleucine; 7.22 leucine; 6.61 lysine; 1.62 methionine; 3.91 phenylalanine; 3.77 threonine and 4.85 valine. The composition can serve as an example of the ideal EAA requirements for whole empty body growth between 30 and 40 kg live weight of Dorper ram lambs. The duodenal amino acid concentrations of the free-ranging Dorper compared well with those of the feedlot Dorpers which suggests that the microbial organisms have a big influence on the amino acid concentration which reaches the intestines.
AFRIKAANSE OPSOMMING: Die voerkraal prestasie en essentiele aminosuur behoeftes van groeiende Dorper lammers: The Dorper is getalgewys die tweede mees talryke skaapras in Suid-Afrika. Dit is die mees talryke skaapras wat in die drce woestynagtige gebiede van Suid-Afrika aangetref word. Die gebiede beslaan die grootste oppervlakte van Suid-Afrika se natuurlike weiveld. In die studie is voerkraal prestasie van die Dorper nagevors, spesifiek omdat daar so min navorsing op hierdie gebied gedoen is. In die eerste studie (Hoofstuk 1) is die produksie doeltreffendheid, liggaams komponente en kornrnersiele produksie van 13 Dorper- en 12 Merino lammers ondersoek. 'n Verpilde rantsoen is ad lib gevoer en die water inname per dag is ook gekontroleer. Die lammers is geslag op 30 en 40 kg lewende gewig en die karkasse is daarna opgesny volgens die Suid-Afrikaanse kornmersiele karkassnitte. Die resultate van die eerste studie het getoon dat Dorpers 'n laer water potentiaal (P<0.05) (285 97 mflkgO 75/dag) as die Merinos (240.07 mVkg075/dag) het. Dorper lammers het ook 'n hoer (P<0.05) stikstof retensie. Die kop, vel, pote, hart, longe, niere en diafragma van Merino lammers was swaarder (P<0.05). Merinos se brisket en dikrib snitte weeg ook swaarder (P<0.05). Die Dorper het 'n beduidende swaarder agterkwart (len de en boud) gehad, wat die duurste snit is van enige karkas. Die Dorper het baie goed gedoen in die voerkraal toestande en sal waarskynlik onder aile omstandighede 'n hcer vleisproduksie op die Merino lewer. In die tweede studie (Hoofstuk 2), is die vryweiende Dopers op natuurlike weiding vergelyk met die Dorpers in 'n voerkraal. Die twee groepe Dorpers se essensiele aminosuur samestelling in hul dunderms is bepaal en vergelyk om te bepaal of daar enige tekorte teenwoordig is. Die Dorpers in die veld en in die voerkraal is op 40 kg lewende gewig geslag en monsters van die dunderm inhoud is gekollekteer. Die monsters is ontleed om te bepaal of daar enige betekenisvolle verskille in die essensiele aminosure van die dunderm inhoud tussen die veld Dorpers en voerkraal Dorpers was. Die tweede studie het geen betekenisvolle verskille getoon tussen die dunderm monsters se essensiele aminosure, of die hoeveelheid proteien (gAA/100g) in aanmerking geneem is of nie (uitgedruk as % lisien). Die chemiese telling dui aan dat die twee mees beperkende aminosure in die dunderm inhoud vir lee liggaam groei arginien en histidien was. Oormaat vlakke van aminosure kom voor in al drie dunderm inhoud monsters (isoleusien, leusien, lisien, metionien, femielalanien, treonien en valien). Die totale lee liggaam essensiele aminosuursamestelling (g aminosuur/100g ruprotein) was soos volg: 7.10 arginien; 2.40 histidien; 3.31 isoleusien; 7.22 leusien; 6.61 lisien; 1.62 metionien; 3.91 fenielalanien; 3.77 treonien en 4.85 valien. Hierdie aminosuursamestelling kan as 'n aanduiding dien vir die ideale aminosuurbehoeftes van Dorper ram lammers vir totale lee liggaamsgroei vanaf 30 tot 40 kg lewende massa. Die dunderm aminosuur konsentrasie van die Dorper in die veld stem goed ooreen met die van die voerkraal Dorper. Dit toon waarskynlik dat die mikrobe organismes in die rumen In groot invloed het op die aminosuur samestelling wat die dunderm bereik.

Thesis (MScAgric)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The aim of this study was to determine whether a lamb finishing ration that is balanced for essential amino acids (EAA), at a specific level of non-structural carbohydrates (NSC) would yield better feedlot performance when compared to a standard commercial finishing ration. Metionine (Met) and Lysine (Lys) were identified as the first limiting amino acids for growing lambs. These two amino acids, as well as Threonine (Thr), Arginine (Arg), Leucine (Leu), Isoleucine (Ile) and Phenylalanine (Phe) were included in an optimized protein (OP) feedlot ration at optimal levels. This ration was formulated to contain 157 g/kg crude protein (CP) and 477 g/kg NSC, with Met, Lys, Arg and Thr at 2.48, 7.45, 8.51 and 8.12 g/kg on dry matter (DM) basis respectively. The second treatment, FIN, was a standard commercial lamb finishing feed without optimized amino acids and contained similar total protein and NSC to OP of 152 g/kg CP and 468 g/kg NSC but with Met, Lys, Arg and Thr at 2.08, 5.49, 7.47 and 4.80 g/kg on DM basis respectively. A third treatment, a low protein (LP) diet served as a positive control and was formulated on lower specifications (139 g/kg CP, 455 g/kg NSC) and was also not optimized for amino acids. This treatment contained Met, Lys, Arg and Thr at 1.93, 4.99, 6.66 and 4.73 g/kg on DM basis respectively. Lambs grazing kikuyu pasture served as the negative control (CON) group. These lambs also received additional supplementary feed at 500 g/day as a production lick to be comparable to a scenario where lambs are finished on grazing. Forty cross-bred Merino x Döhne-Merino lambs with an average weaning weight of 24.35 ± 0.648 kg were finished in a feedlot for 57 days where after they were slaughtered at an average weight of 41.41 ± 1.259 kg. During the feedlot trial lamb performance was measured by monitoring daily growth rates and feed intake. Also, an in vivo digestibility study was carried out on the OP and FIN lambs. During the slaughter process the rumen was removed which was done to collect a sample of the rumen wall from next to the rumino-reticular fold. These rumen samples were mounted onto slides so that the development of the rumen could be examined. The M. longissimus dorsi from both sides of the carcass between the 2nd and 3rd last thoracic vertebra and the 4th and 5th lumbar vertebra were removed. There was no significant difference (P > 0.05) between any of the concentrate feed treatments with regards to the average daily gain (ADG), feed conversion ratio (FCR) or dressing percentage (DP). The CON lambs, as expected, had lower growth rates (P < 0.05) than the concentrate fed lamb and thus showed significant differences (P < 0.05) in terms of ADG. The DP of 45.96 % ± 0.711 for the CON lambs differed significantly (P < 0.05) from the OP (51.44 % ± 0.358), FIN (52.72 % ± 0.653) and LP (51.74 % ± 0.611) treatments. As expected the concentrate feeds were much more effective in maintaining higher growth rates when compared to the CON lambs while the optimizing of EAA in the OP diet did not lead to improved feedlot performance as the FIN and LP treatments were able to achieve similar (P > 0.05) growth rates. Within the feedlot treatments there was no significant difference (P > 0.05) with regard to the papillae length and rumen wall thickness. There was however a numerical increase in the papillae length as the NSC levels in the feed increased. The CON lambs differed from the OP lambs (P < 0.05) in terms of papillae length. This illustrated the importance of having increased levels of NSC in a feedlot diet as it is this fraction that is responsible for the initialisation and maintenance of rumen morphological development. The in vivo digestibility study therefore confirmed that the commercial finishing feed was just as effective as the optimized feed in terms of nitrogen retention as well as in maintaining suitable energy balance. Although the in vivo digestibility for Met and Lys in the OP feed was higher (P < 0.05) than the FIN feed, this did not lead to improved feedlot performance of the OP lambs. The increased digestibility of these amino acids is due to the fact that the OP diet was higher in levels of bypass amino acids than the FIN feed. The in vitro true digestibility (IVTD) of the OP feed was higher (P < 0.05) than that of the FIN feed.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om te bepaal of ‘n lamafrond rantsoen wat gebalanseerd is vir beperkende essiensiële aminosure (EAA) teen ‘n spesifieke vlak van nie-strukturele koolhidrate (NSK) beter voerkraal prestasie teweeg sou bring wanneer gemeet word teen ‘n standaard kommersiële afrond rantsoen. Metionien (Met) en Lisien (Lis) is geïdentifiseer as die eerste beperkende aminosure vir groeiende lammers. Hierdie twee aminosure, asook Treonien (Tre), Leusien (Leu), Isoleusien (Ile) en Fenielalanien (Fen) is teen optimale vlakke ingesluit in ‘n geoptimeerde voerkraal rantsoen, OP. Hierdie rantsoen is geformuleer om 157 g/kg RP en 477 g/kg NSK te bevat asook Met, Lis, Arg en Tre teen 2.48, 7.45, 8.51 en 8.12 g/kg onderskeidelik. Die tweede behandeling, FIN, was ‘n kommersiële lamafrond voer waarin die aminosure nie geoptimeer is nie en het soortgelyke vlakke van proteïene en NSK bevat teen 152 g/kg RP en 468 g/kg NSK met Met, Lis, Arg en Tre teen 2.08, 5.49, 7.47, 4.80 g/kg onderskeidelik. ‘n Derde voer, LP, het gedien as ‘n positiewe kontrole en was ‘n lae proteïen voer met laer spesifikasies (139 g/kg RP, 455 g/kg NSK) waarin die aminosure ook nie geoptimeer is nie. Die LP voer het Met, Lis, Arg en Tre bevat teen 1.93, 4.99, 6.66 en 4.73 g/kg onderskeidelik. Die negatiewe kontrole behandeling, CON, is verteenwoordig deur lammers wat op kikuyu gewei het terwyl addisionele supplementêre voeding teen 500g/lam/dag voorsien is. Hierdie supplementêre voeding het gedien as ‘n produksie lek om sodoende vergelykbaar te wees met scenario waar lammers op weiding afgerond word. Veertig kruisgeteelde Merino x Döhne-Merino lammers met ‘n gemiddelde gewig van 24.35 ± 0.648 kg is vir 57 dae in ‘n voerkraal afgerond waarna hulle, teen ‘n gemiddelde gewig van 41.41 ± 1.259 kg, geslag is. Tydens die voerkraal proef is prestasie gemonitor deur die meet van daaglikse groei en voerinname. Hiertydens is daar ook ‘n in vivo verteringsproef op die OP en FIN lammers gedoen. Tydens die slagproses is die rumen verwyder waarna ‘n monster van die rumenwand langs die rumino retikulêre vou geneem is. Hierdie rumenmonsters is op skyfies geplaas sodat die ontwikkeling van die rumen ondersoek kan word. Die M. longissimus dorsi was aan beide kante van die karkas tussen die 2de en 3de laaste torakale werwels en die 4de en 5de lumbale werwels verwyder. Daar was geen betekenisvolle verskille (P > 0.05) tussen enige van die konsentraat behandelings ten opsigte van gemiddelde daaglikse toename (GDT), voeromset verhouding (VOV) of uitslag persentasie nie. Die CON lammers het egter, soos verwag, beduidend (P < 0.05) stadiger gegroei en het dus verskille getoon ten opsigte van GDT. Die uitslag persentasie van 45.96 % ± 0.711 vir die CON lammers het ook betekenisvol verskil (P < 0.05) van die OP (51.44 % ± 0.358), FIN (52.72 % ± 0.653) en LP (51.74 % ± 0.611) behandelings. Binne die voerkraal behandelings was daar geen betekenisvolle verskille (P > 0.05) ten opsigte van die papillae lengte en rumenwand dikte nie, alhoewel daar ‘n numeriese toename in papillae lengte was soos die NSK vlakke in die voer gestyg het. Die CON lammers het wel van die OP lammers verskil (P < 0.05) ten opsigte van papillae lengte. Hierdie bevinding het bevestig hoe belangrik NSK is in die inisiasie en instandhouding van die morfologiese ontwikkeling van die rumen. Die in vivo verterings studie het daarop gedui dat die kommersiële afrond voer net so effektief soos die geoptimeerde voer was in terme van stikstof retensie asook die handhawing van ‘n geskikte energie balans. Alhoewel die in vivo verteerbaarheid van Met en Lis in die OP hoër was (P < 0.05) as in die FIN voer, het hierdie verskille nie gelei tot beter groei in die OP lammers nie. Hierdie verskil in verteerbaarheid is toegeskryf aan die feit dat die aminosure in die OP voer meer rumen-beskermd was as dié in die FIN voer. Die in vitro verteringstudie het daarop gedui dat die OP voer beduidend beter (P < 0.05) verteer is as die FIN voer.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
The effects of supplementation with cashew nut meal (CNM) for sheep fed Tifton 85 (Cynodon sp.) grass hay as exclusive forage were evaluated on intake, digestibility, nitrogen balance and ingestive behavior of these animals. For this, we used twenty four male sheep, non-castrated, without defined breed and with an initial body weight (BW) of 16.2 + 3.1 kg and they were housed in metabolic cages. The animals received a control diet consisting basically of Tifton 85 hay. The CNM was used as supplementation to diets at three different levels, representing 6, 12 and 18% of the total feed supplied, with six replicates per supplementation level evaluated. The experimental variables were subjected to variance analysis and regression using SAS version 9.1 by the PROC GLM routine. We observed the linear, quadratic and cubic effects from the variance analysis. The regression equations were adjusted when there was a significance level of P<0.05, using SAS PROC REG (9.1). The CNM supplementation did not cause influence on dry matter (DM) and organic matter (OM) intake expressed in g/day (P> 0.05), neutral detergent fiber (NDF) and total carbohydrates (TC) intake expressed in g/day and g/kg BW0,75 (P> 0.05). As for crude protein (CP) intake (P = 0.0137) and ether extract (EE) (P <0.0001) expressed in g/day, and the DM (P = 0.0180) and OM (P = 0.0122) expressed in g/kg BW0,75, was observed influence of CNM supplementation, with increasing linear effect. The digestibility of DM, OM, EE, NDF and CT showed a quadratic effect with the CNM supplementation (P<0.0001). The CP digestibility showed an increasing linear effect with the CNM supplementation to diets (P<0.0001). The CNM supplementation also promoted influence on nitrogen (N) intake (P=0.0137), N retention (P<0.0001) and on the N balance (P=0.0002). The N intake, N retention and N balance showed an increased linear effect with the increasing in the CNM supplementation. For the ingestive behavior, CNM supplementation did not cause significant differences for time spent on eating, ruminating, total chewing time and leisure time (in hours), eating and ruminating efficiency expressed as grams of DM/h grams of NDF/h, number of ruminal bolus per day and number of chews (P>0.05). The number of ruminal bolus per day, was observe an increased linear effect with the CNM supplementation (P=0.0398). However, the time spent for chews per day it was observed a decreased linear effect with the CNM supplementation (P=0.0072). The CNM Supplementation up to 18% of the total diet for sheep fed Tifton 85 hay as roughage exclusive cause an increase for CP and EE intake, and increased the digestibility coefficients of these dietary nutrients. However, for the level of 18% of CNM supplementation there is reduction in digestibility of DM, OM, NDF and TC. Growing sheep fed with grass hay Tifton 85 as only forage source and supplemented with CNM up to 18% of the total diet do not show marked changes in ingestive behavior
O presente estudo foi conduzido com o objetivo de avaliar a influÃncia da suplementaÃÃo com o farelo de castanha de caju (FCC) para ovinos, recebendo feno de capim Tifton 85 (Cynodon sp.) como volumoso exclusivo. Foram avaliadas variÃveis de consumo, digestibilidade, balanÃo de nitrogÃnio e o comportamento ingestivo destes animais. Para isso, utilizou-se vinte e quatro ovinos machos, nÃo-castrados, sem padrÃo racial definido (SPRD) e com peso corporal (PC) mÃdio de 16,2 + 3,1 kg que foram alojados em gaiolas metabÃlicas. Os animais receberam uma raÃÃo controle, constituÃda exclusivamente por feno de capim Tifton 85. Utilizou-se a suplementaÃÃo com FCC em trÃs diferentes nÃveis, representando 6, 12 e 18% do total da raÃÃo fornecida, com seis repetiÃÃes por nÃvel de suplementaÃÃo avaliada. As variÃveis experimentais foram submetidas à anÃlise de variÃncia e regressÃo utilizando-se o SAS versÃo 9.1 por meio da rotina PROC GLM. Foram observados os efeitos lineares, quadrÃticos e cÃbicos a partir da anÃlise de variÃncia. As equaÃÃes de regressÃo foram ajustadas quando se observou um nÃvel de significÃncia P<0,05, utilizando-se o PROC REG SAS (9.1). A suplementaÃÃo com o FCC nÃo promoveu influÃncia sobre os consumos de MS e MO expressos em g/dia (P>0,05). TambÃm nÃo foi detectado efeito da suplementaÃÃo com FCC sobre os consumos de FDN e CT expressos em g/dia e g/kg PC0,75 (P>0,05). Jà para o consumo de PB (P=0,0137) e EE (P<0,0001) expressos em g/dia, bem como os consumos de MS (P=0,0180) e MO (P=0,0122) em g/kg PC0,75, foi observado influÃncia da suplementaÃÃo com FCC, apresentando efeito linear crescente. Os coeficientes de digestibilidade da MS, MO, EE, FDN e CT sofreram efeito quadrÃtico com a suplementaÃÃo do FCC (P<0,0001). Jà a digestibilidade da PB sofreu efeito linear ascendente com a suplementaÃÃo de referido subproduto Ãs raÃÃes (P<0,0001). A suplementaÃÃo com o FCC tambÃm promoveu influÃncia sobre o consumo de N (P=0,0137), N retido (P<0,0001) e sobre o BalanÃo de N (P=0,0002). O consumo e a retenÃÃo de N sofreram efeito linear crescente com o aumento da suplementaÃÃo de FCC. O mesmo comportamento foi observado para o balanÃo de nitrogÃnio. Para o comportamento ingestivo dos ovinos, a suplementaÃÃo com o FCC nÃo promoveu diferenÃas significativas entre os tratamentos experimentais para os tempos despendidos com alimentaÃÃo, ruminaÃÃo, tempo de mastigaÃÃo total e Ãcio (em horas), eficiÃncia de alimentaÃÃo e ruminaÃÃo, expressas em gramas de MS/h e gramas de FDN/h, nÃmero de bolos ruminais por dia e no nÃmero de mastigaÃÃes merÃcicas por dia (P>0,05). Jà para o nÃmero de bolos ruminais por dia, houve efeito linear crescente com a suplementaÃÃo de FCC (P=0,0398). Todavia, para tempo despendido em mastigaÃÃes merÃcicas por dia houve efeito linear decrescente com a suplementaÃÃo do FCC (P=0,0072). A suplementaÃÃo com FCC em atà 18% do total da raÃÃo, para ovinos recebendo feno de Tifton 85 como volumoso exclusivo, eleva o consumo de PB e EE, alÃm de aumentar os coeficientes de digestibilidades destes nutrientes dietÃticos. Entretanto, com o nÃvel de suplementaÃÃo de 18% de FCC, hà reduÃÃo na digestibilidade da MS, MO, FDN e CT. Ovinos em crescimento, recebendo feno de capim Tifton 85 como volumoso exclusivo e suplementados com FCC em atà 18% do total da raÃÃo, nÃo apresentam mudanÃas no comportamento ingestivo

Serum cortisol and immunoglobulin G (IgG) concentrations were measured to investigate the relationship between vitamin A status and immune function in lambs. Twenty-four crossbred ewe lambs were each fed 900 g·d-1 of a carotene—deficient diet composed of 95.5% whole oats, 3% molasses, .5% trace mineral salt and 1% limestone. All lambs were injected monthly with vitamins D and E and with selenium. The 12 control lambs also received a 100,000 IU oral dose of vitamin A palmitate in capsule form every 2 wk. All lambs were challenged by injecting them with 1 mg ovalbumin in 1 ml of Freund’s complete adjuvant. At the time of challenge, serum vitamin A levels for the control and A-deficient (A—def) lambs were 33.3 and 3.1 ug·dl-1 respectively. Blood was collected prior to and 6, 13, 20 and 34 d post—challenge. The lambs were then reschallenged using the same antigen and blood was obtained 1, 2, 6 and 22 d post—challenge. Lambs were sacrificed at the end of the second challenge period. Spleen weights were obtained and gross post—mortem observations were made at this time.
Master of Science

Human newborns exposed in utero to maternally administered SSRIs such as fluoxetine (FX) have an increased risk of adverse pregnancy outcomes including poor neonatal adaptation. This comprises respiratory difficulty, jitteriness, cyanosis when feeding and persists for several days after birth. Several potential mechanisms underlying these symptoms have been proposed: 1) acute toxicity to the drugs (i.e. serotonin syndrome), 2) withdrawal syndrome due to the sudden discontinuation of maternal-fetal placental drug transfer at birth or 3) an SSRIs-elicited alteration in fetal brain development. However, the actual mechanism has not been elucidated. In addition, the safety of SSRIs for the treatment of depression in children and adolescents is uncertain. Thus, we conducted experiments in which acute i.v FX (1mg/kg) and sterile water were given to FX and control groups in the lambs at ~ 3,10 days, 1,3,6 and 12 months of age. In another cohort, daily 50mg FX was given i.v to 5 pregnant ewes via implanted catheters during late gestation (131-132d, term = 147d) for 2 weeks. Plasma FX concentrations in the newborn acute FX group were within the range measured in human infants at the same age. There was a lack of significant acute FX effects on cardiovascular-respiratory, behavioral and endocrine functions in ~ 4 day old lambs. In the lambs exposed to FX prenatally, plasma FX at birth and postnatal day (PND) 2 were low and undetectable on PND 5,10,14. However, prenatal FX-exposed lambs were hyperactive during PND 4 to 14 and their heart rate variability (HRV) was significantly lower than control lambs on PND 2. Results suggested that SSRI toxicity and withdrawal are unlikely to be the mechanism underlying poor neonatal adaptation in human exposed to FX in utero. However, acute FX effects were seen in some, but not all, age groups. No acute FX effects were observed in the young lambs (10d and 3 months of age). However, hypoactivity, transient hypoxemia, hypertension and increased HRV occurred after acute FX administration in the older lambs (1,6 and 12 months of age). Hypoxemia and hypertension effects were more profound in males. No changes in HPA axis function were observed

Conjugated linoleic acid (CLA) is produced in the rumen by isomerization of linoleic acid and has been shown to be anticarcinogenic. The objective of this study was to determine the effects of feeding dietary CLA to pre-ruminant lambs or linoleic acid-rich safflower oil to weaned ruminating lambs. Fat content, CLA content and fatty acid (FA) composition of diaphragm, leg, rib, subcutaneous (SC) adipose and liver tissues were determined. The triacylglycerol (TAG) fractions of the total lipid (TL) from the diaphragm, rib and SC adipose tissues were analyzed for FA composition and FA positional distribution. The phospholipid (PL) fractions of the TL were analyzed for FA composition. The positional (PL) fractions of the TL were analyzed for FA composition. The positional distribution of FAs of liver PL was determined. Tissue fat content was affected by diet only in SC adipose tissue. Dietary supplementation with safflower oil increased the fat content of the subcutaneous adipose tissue whereas CLA supplementation resulted in decreased (P<0.05) fat content. Dietary supplementation with safflower oil increased (P<0.05) the CLA content of tissues by more than 200% whereas dietary supplementation with CLA did not affect CLA content. Positional distribution analysis indicated that CLA tends was localized to the sn-1/3 positions of TAG and the sn-2 position of the liver PL.
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