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1
Lee, GJ, e AJ Williams. "Nutritional responses in wool growth by four Merino genotypes of differing wool growth performance". Australian Journal of Agricultural Research 45, n. 6 (1994): 1171. http://dx.doi.org/10.1071/ar9941171.
Testo completoAbstract (sommario):
Sheep from four Merino flocks, different in annual clean fleece production when grazed together, were offered a range of nutritional treatments to compare their ability to digest dietary organic matter (experiment 1) and to compare the relationships of wool growth and fibre diameter with nutrient intake (experiment 2). The sheep were selected from a finewool (Fl), a strong wool (S), and two medium-Peppin (MP6 and MP10) flocks. The nutritional treatments varied intakes of two pelleted diets-B and F. Diet B consisted of oat grain, lucerne chaff, and oaten straw, while diet F was as for B but fortified with fishmeal. The digestibility of both diets was negatively related to the level of intake, and there were some differences between the flocks in their ability to digest organic matter. Clean wool growth per unit area of skin was curvilinearly related (P < 0.001) to N intake, but was not influenced by diet per se. The regression coefficient for the relationship of clean wool growth with N intake and the estimated maximum wool growth rate of flock F1 were less than the other flocks. However, flock MP10 grew less wool than flocks S and MP6 at any given intake. Variation in (fibre diameter)2 accounted for 0.6 of the variation in wool growth, with responses in fibre diameter to intake being similar to those observed in wool growth. The responses in plasma cystine of the flocks to N intake differed, with the relationship for flock F1 being curvilinear and reaching a maximum at an intake of 27 g N day-1, while the responses of the other flocks were essentially linear. The relationships between plasma cystine level and wool growth differed between the flocks such that wool growth of sheep from flocks S and MP6 was more responsive to increased plasma concentration of cystine.
2
Oddy, V. H. "Wool growth of pregnant and lactating Merino ewes". Journal of Agricultural Science 105, n. 3 (dicembre 1985): 613–22. http://dx.doi.org/10.1017/s0021859600059529.
Testo completoAbstract (sommario):
SUMMARYThe wool production of pregnant, lactating and non-pregnant, non-lactating (dry) Merino ewes eating one of three diets: chaffed oaten hay (OH), chaffed lucerne hay (LH), and a 50/50 (w/w) mixture of OH and LH, was determined. Measurements were made for 2 months prior to mating, during pregnancy and for 3 months after lambing, and for the dry ewes over the same period.Production of clean wool (Y, g/day) by dry ewes was linearly related to digestible organic matter intake (X, g/day):Y = 0·0301 X - 3·34, r = 0·97.Clean wool growth was significantly less (P < 0·01) than dry ewes in the 4th and 5th month of pregnancy and throughout lactation. During pregnancy the total deficit in clean wool growth (calculated as the difference between observed wool growth and that expected on the basis of the relationship between feed intake and clean wool growth of dry ewes) was 456 g for ewes bearing a single lamb and 578 g for those bearing twins, with no difference between diets. In lactation the total clean wool growth deficit increased as milk production increased, and for every litre of milk produced there was a deficit of 12 g clean wool.Wool fibre diameter was reduced during the 1st month of lactation. There was no consistent effect of pregnancy or lactation on the number of wool follicles per mm2, the ratio of primary plus secondary to primary wool follicles, or on the thickness of skin on the midside.Digestibility of dietary organic matter (DOM) was reduced during the last 3 months of pregnancy, and the first 2 months of lactation. However, this was insufficient to account for the magnitude of the decrease in wool growth seen during pregnancy and lactation.Wool sulphur content increased during pregnancy (P < 0·001), but not during lactation. The relationship between total plasma cyst(e)ine concentration and DOM intake during pregnancy was similar to that in dry ewes, but during lactation total plasma cyst(e)ine concentration was less than expected. It was calculated that during pregnancy the amount of sulphur saved through reduced wool growth was greater than that deposited in the conceptus, and during lactation the amount of sulphur saved in reduced wool growth matched that excreted as milk.These results are discussed in relation to control of wool growth during pregnancy and lactation.
3
Maddocks, S., Y. Chandrasekhar e BP Setchell. "Effect on Wool Growth of Thyroxine Replacement in Thyroidectomized Merino Rams". Australian Journal of Biological Sciences 38, n. 4 (1985): 405. http://dx.doi.org/10.1071/bi9850405.
Testo completoAbstract (sommario):
The effect on wool growth of thyroidectomy with subsequent thyroxine replacement at subnormal and supranormallevels has been investigated in Merino rams fed a restricted basal diet. Thyroidectomy without thyroxine replacement caused a greater than 60% reduction in wool growth. Provision of 30% of normal plasma thyroxine concentrations was sufficient to return wool growth to normal. Similarly, complete replacement of plasma thyroxine levels gave normal wool growth while increasing thyroxine concentrations to three times normal increased wool growth to levels slightly above normal. These results provide a possible explanation for the inability of other workers to correlate seasonal thyroxine patterns and annual wool growth variations.
4
Haque, Abu Naser Md Ahsanul, e Maryam Naebe. "Waste Wool Powder for Promoting Plant Growth by Moisture Retention". Sustainability 14, n. 19 (27 settembre 2022): 12267. http://dx.doi.org/10.3390/su141912267.
Testo completoAbstract (sommario):
Natural wastes are widely used as composts for plant growth. However, wool waste has received little attention in this regard, despite its nitrogen-rich chemical structure owing to amide groups. A few studies have been conducted for soil amendment using wool, mostly in raw or pellet form. However, despite the possible consistent mixing and more uniform effect of powders inside soil, wool has never been implemented in powder form in soil for improving moisture. This study demonstrates the effectiveness of using wool as a powder, facilitating better mixing and spreading in soil. Results show that wool powders are more effective in retaining soil moisture compared to wool pellets and are comparable to commercial fertiliser. The findings further indicate that a balanced amount of wool is required to maintain a proper moisture level (not too wet or dry) to promote actual plant growth.
5
Sun, Y. X., A. Michel, G. A. Wickham e S. N. McCutcheon. "Wool follicle development, wool growth and body growth in lambs treated from birth with recombinantly derived bovine somatotropin". Animal Science 55, n. 1 (agosto 1992): 73–78. http://dx.doi.org/10.1017/s0003356100037296.
Testo completoAbstract (sommario):
AbstractThe effect of recombinantly derived bovine somatotropin (bST) administration on wool follicle populations, wool growth and body growth was examined in young lambs. Romney × (Border Leicester × Romney) lambs were treated with bST at doses of 0·1 or 0·3 mg/kg live weight per day, or with excipient, commencing on the day of birth and continuing at weekly intervals until the last injection was given at 11 weeks of age. Concentrations of immunoreactive somatotropin in plasma were 19·2 (s.e. 2·1), 65·2 (s.e. 2·8) and 74·7 (s.e. 4·8) μgll in the control, low dose bST and high dose bST groups, respectively. Somatotropin treatment did not alter the density of primary (P) or secondary (S) follicles in the skin, or the S/P ratio, as measured by histological examination of mid-side skin biopsy samples at 14 weeks of age. Mid-side greasy and clean wool growth during weeks 2 to 14 of the study were increased (P < 0·05) in bST-treated lambs but treatment had no effect on wool growth during the immediate post-treatment period (weeks 14 to 22), or on yearling fleece weight or wool quality characteristics. Body growth was not altered by bST administration. It is concluded that bST treatment stimulates wool growth even in very young lambs but, contrary to the results of a previous study, does not alter the development of wool follicle populations.
6
Bond, J. J., P. C. Wynn, G. N. Brown e G. P. M. Moore. "Growth of wool follicles in culture". In Vitro Cellular & Developmental Biology - Animal 30, n. 2 (febbraio 1994): 90–98. http://dx.doi.org/10.1007/bf02631399.
Testo completo
7
Wuliji, T., IL Weatherall, RN Andrews, KG Dodds, PR Turner e R. Wheeler. "Effect of selection for wool growth on seasonal patterns of yield, fibre diameter, and colour in Romney lines". Australian Journal of Experimental Agriculture 35, n. 1 (1995): 27. http://dx.doi.org/10.1071/ea9950027.
Testo completoAbstract (sommario):
Seasonal wool growth and associated wool characteristics were measured in a Romney line selected for high fleece weight and an unselected control line in 1990 and 1991. Both had a significant (P<0.01) decline in wool growth rate in winter compared with summer. The wool growth rate advantage (P<0.001) of the selected line over the control averaged 19 and 33% for ewes, and 24 and 36% for hoggets, in summer and winter, respectively. Staple strength, yield, and fibre diameter differences were closely associated with wool growth. Colour analysis showed no difference between lines in either brightness (Y) or yellowness (Y - Z). However, both the Y and Z values were lower in spring and summer, while Y - Z was highest in summer. The results suggest that selection for high fleece weight also improves major wool characteristics and reduces the relative winter wool growth decline in Romneys.
8
Radcliffe, BC, PI Hynd, NJ Benevenga e AR Egan. "Effect of cysteine ethyl ester supplements on wool growth rate". Australian Journal of Agricultural Research 36, n. 5 (1985): 709. http://dx.doi.org/10.1071/ar9850709.
Testo completoAbstract (sommario):
L-Cysteine ethyl ester hydrochloride (CEE) was evaluated as a dietary sulfur amino acid supplement for increasing wool growth rate. In Experiment 1, eight sheep were offered 800 g chopped lucerne hay daily and wool growth was measured over a three-week control period. These sheep were then given a continuous infusion of either CEE per rumen, CEE per abomasum, cysteine per abomasum or continued on the basal diet alone, for three weeks, and wool growth was measured again. All supplements were equivalent to 25 mmol/day. Wool growth rate on tattooed patches in sheep given CEE per rumen or abomasum increased 67% and 75% respectively above the rates prior to infusion, while that of animals given cysteine increased 45%. Wool growth rate in the control sheep increased by only 15% in the same period. In Experiment 2, wool growth was measured in 24 sheep offered 800 g/day lucerne chaff, and again when CEE, cystine, or Na2SO4, each providing 21 mmol S/day, were combined with mineral mix and offered with the feed. CEE and cystine increased wool production by 1.9 g/sheep/day (P < 0.01) and 1.0 g/day (P < 0.05), respectively, above that measured in the control groups (nil- or Na2SO4- supplemented) which did not differ.
9
Contrisciano, Thomas M., e E. Jay Holcomb. "GROWTH OF BEDDING PLANTS IN MINERAL WOOL AND MINERAL WOOL/PEAT MIXES". HortScience 27, n. 6 (giugno 1992): 686b—686. http://dx.doi.org/10.21273/hortsci.27.6.686b.
Testo completoAbstract (sommario):
The objective of this research was to develop a mineral wool based growing medium for the horticultural industry. Two types of hydrophilic mineral wool, clean wool (CW) and unclean wool (UC) were used unamended, as well as both types in combinations with 25, 50, and 75 percent peat moss (PM). A control of 100 percent (PM) was also used. Unamended CW had a low bulk density, excellent water holding capacity, good aeration, but high pH. Once PM was added to CW, bulk density still remained low, water holding capacity and aeration remained good, and the pH dropped to a more suitable level. Unamended UW had a high bulk density, good water holding capacity, poor aeration, and high pH. Once PM was added to UW, bulk density decreased, water holding capacity remained good, aeration increased, and pH decreased to a more optimal level. Impatiens `Violet' and Begonia `Whiskey' were grown in the nine treatments for six and nine weeks respectively. At harvest, plant growth was evaluated by height, diameter, fresh weight, dry weight, and tissue analysis. Plant growth response showed plants grown in unamended CW, UW, and PM were smaller in size and lighter in fresh and dry weights than those in 50 percent wool/50 percent PM. The plants grown in 25 and 75 percent PM were similar to the 50 percent wool/50 percent PM in size and weight.
10
Davies, S. C., I. H. Williams, C. L. White e J. E. Hocking Edwards. "Tunicamycin reduces wool growth by slowing the mitotic activity of wool follicles". Australian Journal of Agricultural Research 48, n. 3 (1997): 331. http://dx.doi.org/10.1071/a96055.
Testo completoAbstract (sommario):
Reductions in wool growth have previously been observed in ewes exposed to low levels of corynetoxins, the causal agents of annual ryegrass toxicity. In this experiment, tunicamycin, a commercially available and closely related toxin, was infused into an isolated area of skin on the abdominal flank. Eleven sheep were continuously infused for 5 days with saline on one side and a total dose of either 35 or 350 µg tunicamycin/kg affected skin on the other side. Both fibre length (P < 0·05) and fibre diameter (P < 0·01) were reduced by tunicamycin treatment. Cell division in the wool follicle bulb was also reduced by tunicamycin (P < 0·005), indicating that the toxin is able to have a direct effect on the follicles and their ability to produce wool. The permeability of the vascular system increased in the skin tissue treated with tunicamycin, but only at the highest toxin dose (P < 0·05); therefore, poor nutrient supply to the follicle may be a minor contributor to reduced wool growth. The direct effect of tunicamycin on the wool follicle explains why wool growth is reduced by low levels of corynetoxins independently of, and prior to, effects on the whole animal.
11
Cronjé, P. B., e M. Smuts. "Nutrient partitioning in Merino rams with different wool growth rates". Animal Science 59, n. 1 (agosto 1994): 55–60. http://dx.doi.org/10.1017/s0003356100007509.
Testo completoAbstract (sommario):
AbstractThe aim of this experiment was to determine whether there is any physiological basis for concerns that selection for fleece mass may decrease fitness by increasing the partitioning of nutrients to wool at the expense of other body functions.Forty-five Merino rams (24 months old) were given food at an ad libitum and a maintenance level of nutrition. Animals were grouped into high, average or low clean fleece growth-rate categories on the basis of measurements made during the ad libitum feeding period. During ad libitum feeding, high producers grew proportionately 0·42 more clean fleece, and deposited proportionately 0·36 more energy and 0·42 more nitrogen (N) as greasy fleece than average producers. This was achieved by partitioning a higher proportion of N consumed to wool (0·08 v. 0·06), and not by increased energy or N retention. High producers adapted to the maintenance diet by decreasing clean wool growth rate proportionately by 0·32. There were no differences between high and average wool producers in clean wool growth rate or the percentage of N or energy intake partitioned to wool at the maintenance level of feeding. Although there were no differences in initial live mass between groups, low producers gained proportionately 0·45 more live mass during the experiment than average producers.It was concluded that Merino rams of high clean-wool production potential are not more efficient, but partition more of the available nutrients to wool production at the cost of body tissue deposition.
12
Lee, GJ, e AJ Williams. "Relationship of feed intake with cystine availability and wool growth in Merino wethers". Australian Journal of Agricultural Research 44, n. 5 (1993): 973. http://dx.doi.org/10.1071/ar9930973.
Testo completoAbstract (sommario):
Two experiments were conducted to characterize the relationship between nutrient supply and the rate of wool growth. We concentrated on the accepted view that the rate of wool growth in Merino sheep is primarily limited by the availability of sulfur amino acids, which are largely determined by diet intake and its interaction with microbial fermentation in the reticulo-rumen. In the first experiment, the effects of variable intakes of two diets (one including 10% fishmeal) by sheep on the rate of irreversible loss of cystine and plasma cystine concentration were investigated. Nitrogen intake (N) was positively and linearly related to both the irreversible loss rate and the plasma concentration of cystine, with no effects of diet per se. In the second experiment, the same dietary treatments were imposed on 39 wethers for 16 weeks following an 8 week pre-experimental period. The monthly rates of wool growth, average fibre diameter and sulfur content of the wool were measured and related to various components of intake. The rate of wool growth responded in a positive curvilinear decreasing manner to changes in intake, the response requiring 2 months to stabilize. There was no significant effect of diet when daily intake was expressed as g N kg-0.75 liveweight. Including the covariate (wool growth when fed the standard diet), the quadratic linear model accounted for 90% of the total variation in wool growth. Responses in fibre diameter and its variation, and wool sulfur content were similar to those of wool growth, in that they were positive and did not equilibrate quickly. A saturation kinetics model of the relationship between daily N intake (g N kg 0.75 liveweight) and wool growth accounted for a similar proportion of the variation as did a linear (with quadratic term) model without the covariate. It is concluded that the saturation kinetics model may be useful for more comprehensive comparisons of both the genetic potential and the sensitivity of wool growth to environmental changes.
13
Barnes, A. L., K. P. Croker, J. G. Allen e N. D. Costa. "Lupinosis and reproduction reduce the wool growth of Merino ewes". Australian Journal of Experimental Agriculture 37, n. 5 (1997): 515. http://dx.doi.org/10.1071/ea97004.
Testo completoAbstract (sommario):
Summary. Lupinosis was induced in Merino ewes by subcutaneous injections of phomopsins. Liver damage and impairment of liver function was measured by increases in plasma activities of glutamate dehydrogenase and gamma glutamyl transferase, plasma concentrations of bilirubin, and plasma clearance of bromosulfthalein. The wool growth of the ewes during and after exposure to phomopsins at different periods relative to mating was measured, and the impact of lupinosis on annual wool production assessed. Phomopsin administration decreased the length of staple grown during, and for at least 6 weeks after, exposure to phomopsins. Mean fibre diameter of wool grown during this time was also reduced. Annual wool production of the ewes was affected by exposure to phomopsins, with effects noted on fleece weight, yield, fibre diameter, strength and position of break. These effects were minor and varied between experiments. The adverse effects of reproduction on annual wool production were more significant than those of phomopsins.
14
Hynd, P. I., e R. E. James. "The effect of trenbolone acetate and trenbolone acetate plus oestradiol-17β on wool growth". Journal of Agricultural Science 108, n. 2 (aprile 1987): 501–3. http://dx.doi.org/10.1017/s0021859600079557.
Testo completoAbstract (sommario):
There is currently considerable interest in the use of anabolic compounds to improve the efficiency of animal growth and to produce leaner carcasses. While the majority of work has centred on beef production, the growth performance of sheep is also improved (Galbraith & Topps, 1981). However, little is known of the effects of anabolic steroid hormone administration on wool growth. The few experiments which have been conducted indicate that exogenous oestrogens depress wool output (Slen & Connell, 1958) while exogenous testosterone has consistently enhanced both greasy and clean wool yields (Slen & Connell, 1958; Osborne, 1968; Southcott & Royal, 1971). Little is known, however, of the effects of the synthetic steroids on wool growth. Coehlo, Galbraith & Topps (1981) reported a reduction in wool per unit body weight in sheep implanted with trenbolone acetate and oestradiol-17β, suggesting lowered efficiency of wool growth. Similarly Yasin & Galbraith (1981) noted that trenbolone acetate, in combination with either oestradiol-17β or zeranol, reduced wool output per unit body weight. Neither of these trials attempted to isolate the effects of trenbolone acetate alone from those of the androgenplus-oestrogen combination.
15
Pritchard, DA, e PK O'Rourke. "Factors differentiating between high and low wool producing sheep in western Queensland". Australian Journal of Agricultural Research 43, n. 6 (1992): 1367. http://dx.doi.org/10.1071/ar9921367.
Testo completoAbstract (sommario):
Four experiments were carried out to examine factors which may influence the phenotypic expression of wool growth. High wool producing sheep (HPS) and low wool producing sheep (LPS) were selected from a commercial flock and studied under grazing and controlled feeding conditions. Results are discussed in relation to management of HPS for increased wool production. In the paddock experiment, advantages to HPS in wool growth per unit surface area were least (7%) when pasture quality was low (11 g N/kg DM) and greatest (20%) when pasture quality was best (21 g N/kg DM). Despite the greater live weight of HPS compared with LPS (16%), the HPS produced 25% more clean wool per unit of live weight. Daily clean wool production was always greater in HPS than in LPS. Values ranged from 9.1 v. 7.5 g/day to 15.1 v. 11.6 g/day. During the period following the peak in nitrogen content of the pasture, HPS produced a greater volume of fibre than LPS (194 v. 167 8m3/dayx103), this difference being primarily associated with the greater fibre diameter of wool from HPS (25.4 v. 24.6 8m). In pen experiment 1, the efficiency of conversion of feed to wool was determined under controlled feeding conditions. Differences in wool growth between HPS and LPS at maintenance (M) and above maintenance (M+) were 21% and 49% respectively. Relative efficiency of conversion of feed to wool was 5% higher for HPS during the period immediately following the change in ration and greatest (38-48%) after sheep had made liveweight gains. Wool growth differences between HPS and LPS in pen experiment 2 could not be attributed to either differences in follicle density (66 v. 64 follicles/mm2) or the ratio of secondary to primary follicles (24 : 1 v. 22 : 1). The efficiency of retention of apparently absorbed nitrogen was similar (21.4 v. 20.8%) for HPS and LPS at below maintenance (M-) but differed at M-t (26.8 v. 11.7%). Rumen dry matter turnover time at M- was faster in HPS than in LPS (29.8 v. 38.4 h) but similar at M+ (30.4 v. 34.4 h). At M-, volumetric fibre production of HPS increased from 79 to 106 ,8m3/dayx 103 and from 59 to 75 ,8m3/day x103 for LPS following the subcutaneous administration of the sulfur containing amino acid methionine. These increases were associated with increases in both fibre diameter (1.5 8m) and fibre linear growth (42 8m/day) in HPS, but only linear growth (52 ,8m/day) in LPS. At M+, when basal wool growth was high, there was little increase in wool growth by either group following supplementary methionine. Wool growth responses to methionine were 25 and 19% for HPS and LPS respectively at M+ in pen experiment 3.
16
Stephenson, RGA, GR Suter e CJ Howitt. "Wool growth responses to DL-methionine administration and factors affecting the value of supplementation". Australian Journal of Experimental Agriculture 31, n. 4 (1991): 471. http://dx.doi.org/10.1071/ea9910471.
Testo completoAbstract (sommario):
Wool growth responses to methionine administration were assessed using Peppin Merino wethers on various planes of nutrition. In experiment 1, sheep were fed 700 g/day of lucerne pellets to maintain liveweight. DL-methionine (5.8 g) administered subcutaneously resulted in 0.29 mg/cm2.day (36%) more wool (P<0.01) and a 2.5 �m (15.2%) increase in fibre diameter (P<0.05). In experiment 2, two levels (700 and 1400 g/day) of lucerne pellets were offered, with and without methionine administered subcutaneously (5.8 g). Main treatment analysis indicated a significant (P<0.01) effect of nutrition on wool growth and fibre diameter, with no effect of methionine, except for a reduction (P<0.05) in liveweight gain. Methionine administration was associated with a non-significant increase (39%) in wool growth for the 700 g diet and no change for the 1400 g diet. In experiment 3, two levels (1.75 and 2.5 g/day) of methionine were infused (4 h daily) when sheep were fed a submaintenance ration of Rhodes grass chaff, supplemented with nitrogen and sulfur. Significant (P<0.05) wool growth responses at both levels of methionine infusion were similar, with absolute (0.21 and 0.23 mg/cm2.day) and percentage (52 and 58%) increases for 1.75 and 2.5 g/day methionine treatments, respectively. Methionine administration only increased wool production at nutritional levels of liveweight maintenance or below when wool growth values for control treatments were 0.63,0.59 and 0.40 mg/cm2.day for experiments 1, 2 and 3. Fibre diameters of sheep in untreated groups were 16.4 and 18.8 pm for experiments 1 and 2. These wool growth and fibre diameter values are 25-40% below what might be expected for this strain of Merino. The values of positive correlations between wool growth and fibre diameter were increased with increased nutrition and the administration of methionine in experiment 2. This result and the nil response at high basal wool growth, together with the low potential net return on the cost of methionine, suggest that the use of methionine could be unprofitable.
17
McCloghry, Elizabeth, Andrew Foldes, David Hollis, Allan Rintoul, Colin Maxwell, Jeff Downing, Peter Baker, John Kennedy e Peter Wynn. "Effects of pinealectomy on wool growth and wool follicle density in Merino sheep". Journal of Pineal Research 13, n. 3 (ottobre 1992): 139–44. http://dx.doi.org/10.1111/j.1600-079x.1992.tb00068.x.
Testo completo
18
Antram, RJ, SN McCutcheon, HT Blair, J. Lee e LA McClelland. "Wool sulfur concentration and output in fleeceweight-selected and control Romney rams". Australian Journal of Agricultural Research 42, n. 2 (1991): 269. http://dx.doi.org/10.1071/ar9910269.
Testo completoAbstract (sommario):
Wool sulfur concentration and output of Romney sheep from fleeceweight-selected and control lines were measured with a view to determining their potential use as genetic markers for fleeceweight. Midside wool samples were collected at 28 day intervals from 4 to 14 months of age from 35 fleeceweight-selected and 30 control rams. Clean wool growth during each sampling period was calculated. Wool samples were digested using an open wet digestion method and the wool sulfur concentration was determined by plasma emission spectrometry. Fleeceweight-selected rams had significantly greater midside wool growth than the control animals throughout the trial except on day 56. Average wool sulfur concentration in both lines increased over the sampling period to a peak at day 308. The wool sulfur concentration of control rams was significantly higher than that of fleeceweight-selected rams only on days 28 and 280. Total sulfur output (the product of midside wool growth rate and sulfur concentration) was significantly higher in the fleeceweight-selected than in the control rams on days 84-140 (March-May) and 196-308 (June-October). It is concluded that midside wool sulfur concentration and output of 4 to 14 month-old-Romney hoggets are unlikely to be useful genetic markers for fleece production.
19
Bray, M., D. K. Revell, C. S. Bawden e P. I. Hynd. "Keratin gene expression in Merino sheep with divergent wool growth". Australian Journal of Agricultural Research 56, n. 3 (2005): 203. http://dx.doi.org/10.1071/ar03253.
Testo completoAbstract (sommario):
South Australian Merino sheep were selected on the basis of high or low estimated breeding values (EBV) for wool growth rate (W), but with similar bodyweight, follicle density, and mean fibre diameter. Differences in the level of expression of keratin genes were examined in the skin of these sheep to test the hypothesis that divergence in EBV for wool growth is related to the production of wool proteins differing in sulfur (S) content. Further, it was proposed that this differential gene expression would be most pronounced when the supply of S amino acids to the animal was increased. Sheep selected for high EBV (+W) produced more wool per day than low EBV sheep (–W) (on average 32.5 v. 17.7 g/day clean wool, respectively; P < 0.05) but the S content of the wool did not differ between selection groups (2.77% v. 2.87% S, respectively; P = 0.2). Expression of keratin genes including keratin-associated protein KAP 2 (a high S gene), KAP 4 (an ultra-high S gene), KAP 6 (a high glycine/tyrosine gene), and the intermediate filament gene K 2.10, did not differ significantly between +W and –W groups. KAP 2 and K 2.10 each accounted for approximately 5% of the variation in wool growth rate (WGR) but expression of none of the genes examined was significantly related to the S content of the fibre produced. This suggests that differential keratin gene expression was not the source of genetic divergence in WGR. Instead the latter likely reflects a combination of differential cellular rate and growth processes (e.g. rate of bulb cell production, hypertrophy of cortical cells), differences in the relative production of inner root sheath and fibre from the follicle bulb cell population, or differential nutrient uptake into the follicle.
20
De Barbieri, I., R. S. Hegarty, V. H. Oddy, M. C. Barnett, L. Li e J. V. Nolan. "Sheep of divergent genetic merit for wool growth do not differ in digesta kinetics while on restricted intakes". Animal Production Science 54, n. 9 (2014): 1243. http://dx.doi.org/10.1071/an14319.
Testo completoAbstract (sommario):
Sheep selected for high wool growth were previously shown to exhibit higher microbial protein outflow from the rumen and higher uptake of amino nitrogen in portal blood than those selected for low wool growth. This suggests that genetic selection for wool growth may induce changes in foregut physiology. This study was undertaken to determine whether differences in digesta kinetics, especially mean retention mime (MRT), are associated with differences in fleece production between sheep with low or high estimated breeding values (EBVs) for fleece weight. Twenty mature Merino wethers with uniform EBVs for liveweight were allocated to two groups of 10 animals on the basis of high or low EBVs for yearling fleece weight. Five sheep with low-EBVs and five sheep with high-EBVs for fleece weight groups were allocated in a crossover design to low and high feeding-level treatments, which comprised a blended hay diet fed at maintenance or 1.5 times maintenance. All sheep were given single doses of chromium-mordanted fibre and cobalt-EDTA as inert, non-digestible markers. Digesta kinetics was determined by analysis of the faecal marker excretion patterns using a compartmental model. Higher feed intakes from animals fed 1.5 times maintenance were associated with higher rates of wool growth and higher masses of indigestible fibre in the gut, but reduced MRT of digesta. Although sheep with higher EBVs for fleece weight had higher wool growth rates, there was no indication that these wool growth differences were associated with differences in digesta kinetics. The lack of interaction between feeding level and genotype suggests that MRT did not contribute to genotype differences in wool growth in sheep fed restricted intakes. The differences in wool growth among commercial Merino sheep with divergent fleece weight EBVs achieved by multi-trait selection are not attributable to differences in digesta kinetics, at least when feed is not available ad libitum.
21
Zahid, Noosheen, Mehdi Maqbool, Abdul Hamid, Muhammad Shehzad, Majid Mahmood Tahir, Khuram Mubeen, Hafiz Muhammad Rashad Javeed et al. "Changes in Vegetative and Reproductive Growth and Quality Parameters of Strawberry (Fragaria × ananassa Duch.) cv. Chandler Grown at Different Substrates". Journal of Food Quality 2021 (15 giugno 2021): 1–9. http://dx.doi.org/10.1155/2021/9996073.
Testo completoAbstract (sommario):
Growth substrates (polyester wool, rice husk, and wheat straw), along with soil as control treatment, were compared for vegetative growth, yield, and quality of strawberry cv. Chandler. All growth substrates tested showed good results in terms of growth rate as compared with control. Strawberry plants grown in polyester wool showed the highest (89.50%) survival rate as compared to rice husk (70.50%), wheat straw (64.63%), and control (67.56%). Moreover, a significant increase was observed among number of flowers, fruits, and yield in plants grown in polyester wool. Besides, a significant high amount of total soluble solids (TSS) (12.38 ºBrix), titratable acidity (TA) (1.21%), ash (0.72%), vitamin C (37.39 mg/100 g), total carotenoids (3.90 µg/100 g), and total anthocyanins (3.47 cyanidine-3-glucoside/100 g) was recorded in fruits grown in polyester wool as compared to control. From these results, it can be concluded that the use of polyester wool as a growth substrate for strawberries can give higher yield and better fruit quality.
22
Sherlock, R. G., P. M. Harris, J. Lee, G. A. Wickham, J. L. Woods e S. N. McCutcheon. "Intake and long-term cysteine supplementation change wool characteristics of Romney sheep". Australian Journal of Agricultural Research 52, n. 1 (2001): 29. http://dx.doi.org/10.1071/ar00031.
Testo completoAbstract (sommario):
Sulfur amino acid supplementation increases wool production in sheep at low planes of nutrition but it is unclear whether there is any benefit of supplementation at planes of nutrition above maintenance and what implications this might have for wool quality characteristics. This experiment directly investigated the interaction between sulfur supplementation and plane of nutrition in terms of wool growth and fibre characteristics. Twenty-four Romney ewes, acclimatised in individual metabolism units over a 7-week pre-treatment period, were allocated to 1 of 4 treatment groups based on a 22 factorial arrangement. Groups were low (L) or high (H) intake (0.8 or 1.3 maintenance, respectively) with continuous intravenous infusion of either saline (–Cys) or cysteine (+Cys, 2 g/day). During the 3-month treatment period, measurements were obtained for liveweight, plasma cysteine concentration, wool sulfur concentration and output, clean wool growth, mean fibre diameter (MFD), length growth rate (LGR), colour, loose wool bulk, handle, and crimp frequency and character. Clean wool growth response (P < 0.05) to cysteine supplementation was greater for the L sheep (6.06 v. 4.31 g/100 cm2) than the H sheep (7.20 v. 6.13 g/100 cm2). The response to supplementation in LGR (P < 0.01) was similar in both H (14%) and L (20%) sheep. There was no response in MFD due to sulfur supplementation, although fibre diameter measurements made along the fibres suggest that there was a response in L but not H sheep (P < 0.1). Wool sulfur concentration and output increased as a result of cysteine supplementation but concentration increased more in L (30.6 v. 24.5 mg S/g; P < 0.01) than in H sheep (28.4 v. 26.2 mg S/g). Qualitative electrophoresis analyses suggested that the increase in wool sulfur was achieved primarily by an increase in ultra-high-sulfur proteins. Crimp frequency and character were both significantly (P < 0.01) enhanced by cysteine supplementation. It is concluded that cysteine supplementation, at feed intakes that commonly occur in the commercial situation, can produce a useful increase in wool growth. This growth increase is primarily accomplished by increasing length growth rate rather than fibre diameter, which should also improve the value of the wool fibre produced.
23
Wang, H. Y., S. W. Li, T. H. Wu, Z. H. Wu e J. X. Guo. "The effect of androgen on wool follicles and keratin production in Hetian sheep". Brazilian Journal of Biology 81, n. 3 (settembre 2021): 526–36. http://dx.doi.org/10.1590/1519-6984.224056.
Testo completoAbstract (sommario):
Abstract To investigate the optimal androgen concentration for culturing Hetian sheep wool follicle and to detect effects of androgen concentration on wool follicle cell proliferation and apoptosis using immunofluorescence labeling and real-time quantitative fluorescence determinations of wool keratin-associated protein gene expression levels. Wool follicles were isolated by microdissection and wool follicles and skin pieces were cultured in various concentrations of dihydrotestosterone (DHT) in culture medium. Next, daily lengthwise growth measurements of wool follicles were obtained using a microscopic micrometer. Cultured Hetian wool follicles were stained using the SACPIC method to reveal wool follicle structure, while sheep skin slices were used to observe cell proliferation by immunostaining and cell apoptosis using the TUNEL method. At the molecular biological level, keratin-associated protein (Kap) gene expression was studied using wool follicles cultured for various numbers of days in vitro. Effects of androgen concentrations on Hetian wool follicle growth and development were experimentally studied. EdU proliferation assays revealed that androgen promoted cell proliferation within wool follicle dermal papillae. TUNEL apoptosis detection demonstrated that androgen treatment could delay cell apoptosis. Quantitative reverse transcription polymerase chain reaction (qPCR) results demonstrated that gene expression level patterns of Hetian mountain sheep super-high sulfur protein. Kap1.1, KIF1.2, Kap2.12 and Kap4.2 gene expression level of the mountainous experimental group was significantly higher than plains Hetian sheep. An androgen concentration of 100 nM can promote the growth of Hetian wool follicle cells in vitro, resulting in overexpression of some genes of the Kap family.
24
Doyle, PT, RA Love e TW Plaisted. "Mineral supplementation and wool production of young Merino sheep on the south coast of Western Australia". Australian Journal of Experimental Agriculture 35, n. 4 (1995): 437. http://dx.doi.org/10.1071/ea9950437.
Testo completoAbstract (sommario):
Wool-free liveweight change (LWC), wool growth rate, annual wool production, and wool characteristics of young Merino wethers fed supplements of lupins with gypsum or a multi-element mineral lick were examined in 12 experiments at 5 farms between 1989 and 1992. The source of sheep varied between experiments; age was 4.5-6.5 months and liveweight 28-37 kg at the beginning of supplementation. Sheep were fed lupins, lupins coated with gypsum (15-20 g/kg lupins), or lupins along with access to the mineral lick (offered at 140 g/sheep.week). The amount of lupins offered in all treatments within any experiment was the same. Supplementary feeding varied between experiments from 150 to 240 days. The sheep grazed annual pastures at stocking rates of 8-1 6.7ha. Average lick intake was 12-18 g/sheep. day. During supplementary feeding, there was considerable variation in LWC (-80 to +110 g/day) and clean wool growth rates (3.8-15.1 g/day) within and between experiments. However, there was no significant positive effect of gypsum or mineral lick supplementation on LWC or clean wool growth rates during or after supplementary feeding in any experiment. There were positive (P<0.01) relationships between LWC and clean wool growth rates during supplementation. Also, for some spring-shorn sheep types, staple strength of wool was linearly related (P<0.01) to LWC in the period before the position of break in the wool staple. Annual wool production, average fibre diameter, and staple strength of midside wool were not significantly increased by supplements of gypsum or mineral lick in any experiment.
25
Reis, P. J., D. A. Tunks e S. G. Munro. "Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth". Journal of Agricultural Science 114, n. 1 (gennaio 1990): 59–68. http://dx.doi.org/10.1017/s0021859600071008.
Testo completoAbstract (sommario):
SUMMARYMerino sheep were given abomasal infusions of various amino acids or mixtures of amino acids. Effects on wool growth were measured using autoradiography or a clipping procedure and changes in the concentration of amino acids in plasma were measured in some experiments.Mixtures of five (28 g/day) or ten (45 g/day) essential amino acids (both mixtures containing 3 g methionine) stimulated wool growth of sheep receiving a maintenance ration; on average, the volume of wool grown increased 48% and 86%, respectively. When cysteine completely replaced methionine in these mixtures, wool growth was markedly reduced, but two-thirds of the methionine could be replaced by cysteine without affecting wool growth. Homocysteine was partially effective in replacing methionine and, when supplemented with betaine, folic acid and vitamin B12, the mixture was still significantly inferior to that containing methionine. In contrast, abomasal supplements of methionine or homocysteine alone were equivalent as supplements for wool growth. The results indicated a specific role for methionine in the control of wool growth, other than the provision of cysteine. This role was postulated to be related to some function of S-adenosylmethionine.Infusion often essential amino acids caused appreciable increases in the concentrations of cystine, methionine, cystathionine and taurine in plasma; total essential amino acids increased threefold whereas nonessential amino acids decreased in concentration. The replacement of methionine in the infusion by cysteine or homocysteine significantly altered the concentration of cystine, methionine and cystathionine in plasma.Evidence was obtained that the adverse effects on wool growth of high abomasal doses of methionine (10g/day) could not be reduced or prevented by provision of additional glycine and were not related to the supposed toxic effects of 3-methylthiopropionic acid, a metabolite of the transamination pathway.
26
Greeff, J. C., B. Paganoni e R. P. Lewer. "Use of part records in Merino breeding programs — the inheritance of wool growth and fibre traits during different times of the year to determine their value in Merino breeding programs". Australian Journal of Experimental Agriculture 45, n. 4 (2005): 347. http://dx.doi.org/10.1071/ea03122.
Testo completoAbstract (sommario):
Fibre diameter can vary dramatically along a wool staple, especially in the Mediterranean environment of southern Australia with its dry summers and abundance of green feed in spring. Other research results have shown a very low phenotypic correlation between fibre diameter grown between seasons. Many breeders use short staples to measure fibre diameter for breeding purposes and also to promote animals for sale. The effectiveness of this practice is determined by the relative response to selection by measuring fibre traits on a full 12 months wool staple as compared to measuring them only on part of a staple. If a high genetic correlation exists between the part record and the full record, then using part records may be acceptable to identify genetically superior animals. No information is available on the effectiveness of part records. This paper investigated whether wool growth and fibre diameter traits of Merino wool grown at different times of the year in a Mediterranean environment, are genetically the same trait, respectively. The work was carried out on about 7 dyebanded wool sections/animal.year, on ewes from weaning to hogget age, in the Katanning Merino resource flocks over 6 years. Relative clean wool growth of the different sections had very low heritability estimates of less than 0.10, and they were phenotypically and genetically poorly correlated with 6 or 12 months wool growth. This indicates that part record measurement of clean wool growth of these sections will be ineffective as indirect selection criteria to improve wool growth genetically. Staple length growth as measured by the length between dyebands, would be more effective with heritability estimates of between 0.20 and 0.30. However, these measurements were shown to have a low genetic correlation with wool grown for 12 months which implies that these staple length measurements would only be half as efficient as the wool weight for 6 or 12 months to improve total clean wool weight. Heritability estimates of fibre diameter, coefficient of variation of fibre diameter and fibre curvature were relatively high and were genetically and phenotypically highly correlated across sections. High positive phenotypic and genetic correlations were also found between fibre diameter, coefficient of variation of fibre diameter and fibre curvature of the different sections and similar measurements for wool grown over 6 or 12 months. Coefficient of variation of fibre diameter of the sections also had a moderate negative phenotypic and genetic correlation with staple strength of wool staples grown over 6 months indicating that coefficient of variation of fibre diameter of any section would be as good an indirect selection criterion to improve stable strength as coefficient of variation of fibre diameter for wool grown over 6 or 12 months. The results indicate that fibre diameter, coefficient of variation of fibre diameter and fibre curvature of wool grown over short periods of time have virtually the same heritability as that of wool grown over 12 months, and that the genetic correlation between fibre diameter, coefficient of variation of fibre diameter and fibre curvature on part and on full records is very high (rg >0.85). This indicates that fibre diameter, coefficient of variation of fibre diameter and fibre curvature on part records can be used as selection criteria to improve these traits. However, part records of greasy and clean wool growth would be much less efficient than fleece weight for wool grown over 6 or 12 months because of the low heritability of part records and the low genetic correlation between these traits on part records and on wool grown for 12 months.
27
Stephenson, RGA, GR Suter, DA Pritchard e MDJ Martin. "Studies of wool growth responses to 2-hydroxy-4-(methylthio) butanoic acid, Alimet, an analogue of methionine". Australian Journal of Experimental Agriculture 30, n. 4 (1990): 477. http://dx.doi.org/10.1071/ea9900477.
Testo completoAbstract (sommario):
An analogue of DL-methionine, Alimet, was evaluated for its commercial potential for increasing wool growth in Merino sheep in pen and grazing experiments. This was done by administering Alimet as a drench, in drinking water, or via rumen or abomasal fistula, and measuring wool growth rate and plasma methionine concentrations. In vivo data indicated that significant wool growth responses (23-35%) to Alimet as a drench or in drinking water occurred at low rates (estimated 5-6 g/sheep.day) of basal wool production when sheep were fed a lucerne diet to maintain liveweight. At higher rates of clean wool growth (10-12 g/sheep.day) when sheep were eating above-maintenance diets (lucerne ration or pasture), Alimet treatment was associated with variable and reduced response. A significant (P<0.05) negative correlation (r2 = 0.699, n = 11) between wool growth responses (x � s.d. = 0.11 � 0.067) to the 3 mL dose rate of Alimet and wool growth in control treatments (y �: s.d. = 0.70 � 0.202) confirmed the above trend. Four hours after administration of Alimet via either rumen or abomasal fistula, comparative plasma concentrations of methionine, 28 and 168 �mol/L respectively, suggest that Alimet is susceptible to degradation in the rumen. The corresponding values for DL-methionine, via either rumen or abomasal fistula, were 64 and 350 �mol/L, respectively. The small rises (40%) in plasma methionine values associated with significant increases in wool production indicate that a dose of 3 mL is as effective as 4 mL of Alimet when the basal nutritional regime is limiting. While administration of Alimet in drinking water during dry seasons is possible, the profitability of supplementation would need to be tested further.
28
Masters, DG, CA Stewart e PJ Connell. "Changes in plasma amino acid patterns and wool growth during late pregnancy and early lactation in the ewe". Australian Journal of Agricultural Research 44, n. 5 (1993): 945. http://dx.doi.org/10.1071/ar9930945.
Testo completoAbstract (sommario):
Pregnancy and lactation result in depressed growth, fibre diameter and tensile strength of wool. Competition for nutrients between wool follicles, maternal tissues and the foetus may cause these changes. Changes in the concentrations of individual free amino acids in plasma, during late pregnancy, were used as indicators of limiting amino acids in this experiment. A group of pregnant ewes was maintained in the animal house during late pregnancy and early lactation and measurements made on amino acids in plasma. Liveweight, wool growth and quality characteristics and sulfur in wool were also measured. Comparisons were made between the different time periods in pregnancy and lactation and between the reproducing ewes and a group of non-reproducing ewes maintained under the same conditions. During the last 3 weeks of pregnancy, there was a 31% decline in the concentration of the total, free essential amino acids in plasma. There was also a significant decline in the concentration of arginine (60%), lysine (55%) and threonine (48%). The concentrations of these amino acids increased during the first 3 weeks of lactation. There was no change in concentration of methionine or cystine. Wool growth rate was lowest in the last 3 weeks of pregnancy and the reproducing ewes had significantly lower wool growth, fibre diameter, staple strength and sulfur in wool than the non-reproducing ewes. The results indicate that a lack of the sulfur-containing amino acids is unlikely to be limiting, but a lack of arginine, lysine or threonine may be limiting wool growth and protein deposition in late pregnancy.
29
Powell, BC, SK Walker, CS Bawden, AV Sivaprasad e GE Rogers. "Transgenic sheep and wool growth: possibilities and current status". Reproduction, Fertility and Development 6, n. 5 (1994): 615. http://dx.doi.org/10.1071/rd9940615.
Testo completoAbstract (sommario):
Merino wool is the result of generations of selection, yet improvements in wool quality and performance are still being sought. Through gene manipulation, sheep transgenesis offers possibilities of understanding the relationship between wool keratin protein composition and fibre structure and properties and of introducing novel changes to fibre properties and growth rates. We have established an efficient sheep transgenesis programme with an overall transgenic rate of 2.1% of zygotes injected. However, by incorporating in vitro culture and assessment of injected zygotes, this equates to a transgenic rate of 13% from 516 lambs born. With the first keratin gene construct, a wool keratin type II intermediate filament gene, four live F0 transgenic sheep have been produced and all express the transgene. In one of them, the highest expressor, phenotypic and ultrastructural changes were evident in the fleece. To improve wool growth rate by increasing the supply of cysteine to the follicle, transgenic sheep are being produced carrying the two genes necessary for endogenous cysteine synthesis. Three promoters have been tested driving the cysteine synthesis genes: two general promoters, the Rous sarcoma virus long terminal repeat and mouse phosphoglycerate kinase promoter, and a rumen-specific promoter from the sheep small proline-rich protein gene. To date, one transgenic sheep (bearing the small proline-rich protein promoter constructs) has produced cysteine in the rumen, although the amount was low at 3 months of age and not detectable at 6 months.
30
Pickering, FS, e PJ Reis. "Effects of abomasal supplements of methionine on wool growth of grazing sheep". Australian Journal of Experimental Agriculture 33, n. 1 (1993): 7. http://dx.doi.org/10.1071/ea9930007.
Testo completoAbstract (sommario):
Seven experiments are reported in which methionine supplements were given directly into the abomasum of Merino wethers grazing either improved or native pasture at Armidale, New South Wales. In 4 experiments where initial wool growth was 0.4-0.8 mg/cm2.day of clean dry wool, significant increases in wool growth (at 2.4 g methionine/day in 3 experiments and 0.6-4.8 g/day in the fourth) and fibre diameter were obtained when methionine was given once daily in capsules. In the fourth experiment the response to methionine was quadratic, with a maximum at 2.4 g/day. In the remaining 3 experiments, where initial wool growth was >1.1 mg/cm2.day, no significant response to methionine was obtained, whether it was given once daily or infused continuously.
31
Banks, R. G., e D. J. Brown. "Genetic improvement in the Australasian Merino – management of a diverse gene pool for changing markets". Animal Genetic Resources Information 45 (ottobre 2009): 29–36. http://dx.doi.org/10.1017/s1014233909990290.
Testo completoAbstract (sommario):
SummaryThe Australasian Merino population has declined significantly over the last 15 years in response to a decline in the price of apparel wool, both in absolute terms and relative to the price of sheep meat. Over the same period, a national genetic evaluation system based on BLUP methods has been introduced, that is achieving steady growth in adoption by breeders. Genetic parameter estimates for the population provide evidence for considerable genetic diversity for all recorded traits, providing ample opportunity for genetic improvement. More recently, there is considerable evidence for increasingly rapid progress, both in fleece traits and a range of meat production and adaptation traits. The Merino population is evolving towards two broad types – one focused on high quality apparel wools finer than 19 µm and used in enterprises with a wool/meat income ratio of about 3:1, and the other a more dual-purpose animal producing 19–21 µm wool and an enterprise wool/meat income ratio between 1.5:1 and 1:1. Underlying these trends is a growing focus on adaptation traits including worm resistance; reduced need for veterinary interventions; and increased early growth, fertility and mothering ability. Together these trends point to increasingly ‘easy-care’ sheep and exploitation of the available genetic diversity to rapidly increase profitability.
32
White, C. L., G. B. Martin, P. I. Hynd e R. E. Chapman. "The effect of zinc deficiency on wool growth and skin and wool follicle histology of male Merino lambs". British Journal of Nutrition 71, n. 3 (marzo 1994): 425–35. http://dx.doi.org/10.1079/bjn19940149.
Testo completoAbstract (sommario):
The aims of this work were to quantify the requirements of Zn for wool growth in growing male Merino lambs, and to describe the histological lesions of Zn deficiency in skin and wool follicles. Four groups of male Merino lambs (n 4) weighing 22 kg were fed ad lib. for 96 d on diets that contained 4 (basal diet), 10, 17 or 27 mg Zn/kg. Sheep in a fifth group were fed on the diet containing 27 mg Zn/kg, but were pair-fed to sheep on the 4 mg Zn/kg diet. Zn was added to the basal diet as ZnSO4 to give the respective treatment concentrations. Sheep fed on the diet containing 4 mg Zn/kg showed clinical signs of Zn deficiency and lower feed intakes and wool growth than sheep in the other groups. Their wool fibres were improperly keratinized and the wool follicles contained a higher proportion of apoptotic bodies than other groups. There was no evidence of parakeratosis and the rate of bulb-cell production was not affected. Sheep from other groups showed no clinical signs of Zn deficiency, and mean feed intakes and growth rates did not differ significantly between sheep fed on diets containing 10, 17 or 27 mg Zn/kg. However, wool growth was reduced in sheep fed on the diet containing 10 mg Zn/kg compared with those fed on diets containing 17 or 27 mg/kg. The mean concentration of Zn in the plasma at which wool growth was 90 % of maximum was 0.5 mg/l. The equivalent value for the diet was 12 mg/kg, with 95 % confidence intervals of 8 to 16 mg/kg. The results suggest that Zn deficiency reduces wool growth through a specific mechanism, perhaps involving impaired protein synthesis.
33
Butler, LG, e GM Head. "Photoperiodic rhythm of wool growth and its contribution to seasonal wool production by the Merino, Polwarth, and their reciprocal crosses in southern Australia". Australian Journal of Experimental Agriculture 34, n. 3 (1994): 311. http://dx.doi.org/10.1071/ea9940311.
Testo completoAbstract (sommario):
Twelve wethers of each of the Merino and Polwarth breeds and their reciprocal crosses were fed at1 of 2 levels in individual pens for 14 months. Periodic clean wool weight, yield, fibre diameter, and the coefficient of variation (CV%) for fibre diameter were measured from midside patches harvested every6 weeks.There was a significant effect of time of wool harvest on clean wool weight per cm2, yield, fibre diameter(all P<0.01), and its CV% (P<0.05). A trough in wool production occurred about August-September and a peak in January. The amplitude of the photoperiodic rhythm of wool growth (difference between maximum and minimum wool growth per cm2 per 42 days as a percentage of the average) was 40%. Yield also displayed a substantial photoperiodic rhythm, but that of fibre diameter was less pronounced. Mean staple strength was 32.3 N/ktex, the mean break occurring at a distance of 60% of the staple length from the tip; there was no effect of genotype or level of feeding. From comparison with published Tasmanian field data, the seasonal wool growth pattern of sheep at pasture appears similar to the photoperiodic rhythm but occurs about a month earlier. It was concluded that the photoperiodic rhythm of wool production of Tasmanian Merino-based breeds should not be a barrier to manipulation of wool quality (staple strength and fibre diameter) by nutritional management.
34
Campbell, N. J., P. D. Hanrahan, I. M. Russell, G. S. Roberts e B. J. Horton. "Modelling pesticide residues on greasy wool: experimental studies". Australian Journal of Experimental Agriculture 38, n. 5 (1998): 441. http://dx.doi.org/10.1071/ea98047.
Testo completoAbstract (sommario):
Summary. A model has been fitted to results from experimental application of organophosphates, synthetic pyrethroids and insect growth regulators to sheep mostly in long wool. The model relates the rate of breakdown of pesticide to the chemical used, the method of application and the length of wool at the time of treatment. A genetic algorithm was used to combine a range of experimental results for each chemical group to determine the rate of breakdown, and also the effect of application method and length of wool on breakdown. Organophosphates break down very quickly when applied to the surface of the wool (initial half-lives of 9–12 days), but the rate of breakdown gradually slows as the proportion of pesticide near the surface of the wool decreases. When the pesticide is applied deep into the wool by hand jetting or dipping, the rate of breakdown is slower (average half-lives of 27–42 days) and more uniform. Synthetic pyrethroids applied by hand jetting or backliner to sheep with 6–9 months wool growth initially break down with half-lives of 32–39 days, but the rate of breakdown decreases to 59–215 days giving average half-lives of 48–103 days over the 3–6 months between application and shearing. Cyromazine applied by hand jetting to sheep with 6–8 months wool growth has an average half-life of 79–96 days, but less if applied by automatic jetting race. The other insect growth regulators have longer half-lives: triflumuron, off-shears backliner, 119 days; and diflubenzuron, long wool jetting on to 7–9 months wool, >119 days. The model allows for different breakdown rates due to the method of application and length of wool and for changes in the rate of breakdown between application and shearing. It can be used to estimate the expected residue on wool at any time after a specified treatment, provided the amount of chemical applied is known. Conversely, the amount applied can be estimated from the residue and treatment details.
35
Revell, Dean K., Suzanne K. Baker e D. Barrie Purser. "Nitrogen and sulfur mobilised from body tissue can be used for wool growth". Australian Journal of Agricultural Research 50, n. 1 (1999): 101. http://dx.doi.org/10.1071/a98068.
Testo completoAbstract (sommario):
The hypothesis was tested that when nitrogen (N) and sulfur (S) are mobilised from body tissue the rate of wool growth is determined both by the amount of N and S apparently digested and by the amount of N and S mobilised from body tissue. The experiment consisted of seven 5-day periods (Periods 1–7) and N and S retention were measured during each period in 12 mature Merino wethers. During Periods 2 and 3, casein and methionine were infused into the abomasum of all sheep to increase the amount of N and S absorbed in the small intestine. Three nutritional regimes were used in order to manipulate the amount of N and S mobilised from body tissues after the cessation of the abomasal infusion: one group of sheep (n = 4) was fed ad libitum throughout the experiment (Group A), another group (n = 4) was fed at a level calculated to maintain liveweight throughout the experiment (Group M), and the third group (n = 4) was fed ad libitum pre-infusion and during the infusion but was then fed at a level calculated to maintain liveweight after the infusion ceased (Group AM). The infusion of the supplement increased wool growth, and when the infusion ceased, it took 10 days for wool growth to return to a steady rate of growth. Wool growth per unit of apparently digested N or S increased markedly when N or S was mobilised from body tissue, indicating that mobilised protein was used for wool growth. Based on the relationship between the apparent retention of N and S in body tissues excluding wool, and changes in plasma amino acid concentrations, it appeared that the supply of S-containing amino acids from body tissue limited the use of mobilised protein for wool growth.
36
Contrisciano, Thomas M., e E. Jay Holcomb. "Growth of bedding plants and poinsettias in mineral wool and mineral wool/peat substrates". Communications in Soil Science and Plant Analysis 26, n. 3-4 (febbraio 1995): 485–501. http://dx.doi.org/10.1080/00103629509369313.
Testo completo
37
Hynd, PI, e WG Allden. "Rumen fermentation pattern, postruminal protein flow and wool growth rate of sheep on a high-barley diet". Australian Journal of Agricultural Research 36, n. 3 (1985): 451. http://dx.doi.org/10.1071/ar9850451.
Testo completoAbstract (sommario):
Variations in the wool growth rate of sheep fed diets containing cereal grains were investigated. In experiment 1, eight sheep consuming similar quantities of a pelleted diet of barley grain and lucerne chaff (60:40 by weight) were selected for high (n = 4) or low (n = 4) wool growth rate. These wool growth differences were eliminated by feeding a high-protein, predominantly roughage diet. Subsequent reintroduction of the high-grain diet regenerated wide between-sheep variance, but there was little evidence of repeatability of performance on this ration. These variations in wool growth were examined in experiment 2 in terms of rumen fermentation pattern and postruminal protein flow. Ten sheep with simple cannulae in the rumen and abomasum were given a pelleted lucerne chaff diet for 14 weeks and the high-grain diet of experiment 1 for a further 16 weeks. The variance of all measured characters was low on the lucerne diet, but the high-barley diet generated wide variance in rumen fermentation pattern, protein flow from the rumen and wool growth rate. Fermentations characterized by high ammonia level, high minimum fluid pH and high butyrate molar proportion were associated with high urinary nitrogen output, high diet digestibility and low postruminal protein flow. Wool growth rate was closely related to protein flow on the high-grain diet alone (r2 = 0.77, P < 0.01) and for the high-grain and lucerne diets considered together (r2= 0.86, P < 0.001).
38
Shi, Ruijun, Shuwei Li, Penggang Liu, Shuhui Zhang, Zhenhui Wu, Tinghui Wu, Shujuan Gong e Yu Wan. "Identification of key genes and signaling pathways related to Hetian sheep wool density by RNA-seq technology". PLOS ONE 17, n. 5 (25 maggio 2022): e0265989. http://dx.doi.org/10.1371/journal.pone.0265989.
Testo completoAbstract (sommario):
Hetian sheep is a breed of sheep unique to the Hetian area of Xinjiang whose wool is used for producing blankets. Individual differences and hair follicle density are the key factors affecting wool production. Therefore, this study aimed to assess the Hetian sheep having different wool densities to statistically analyze the wool traits and hair follicle parameters. Furthermore, the transcriptome sequencing analysis was performed on the skins with different wool densities. The results showed that wool quantity and total hair follicle density of the high wool density sheep was significantly higher than low wool density sheep. The sheepskin with high wool density was found to grow more and finer wool than sheepskin with low wool density. A total of 1,452 differentially expressed genes were screened from the two sets of samples, including 754 upregulated and 698 downregulated genes. The differentially expressed genes were involved in the TGF-β/BMP and MAPK signaling pathways related to hair growth. Eleven differentially expressed genes belonging to the KAPs and KIFs might affect the fineness of the wool. The key genes, like the TNF, MAP2K2, INHBA, FST, PTPN11, MAP3K7, KIT, and BMPR1A, were found to probably affect the growth and density of the wool. The qPCR verified eight genes related to the MAPK pathway whose gene expression trends were consistent with the transcriptome sequencing results. This study furnishes valuable resources for enhancing the quality and production of wool in the Hetian sheep.
39
Wynn, PC, ALC Wallace, AC Kirby e EF Annison. "Effects of Growth Hormone Administration on Wool Growth in Merino Sheep". Australian Journal of Biological Sciences 41, n. 2 (1988): 177. http://dx.doi.org/10.1071/bi9880177.
Testo completoAbstract (sommario):
The effects of daily administration of 10 mg of highly purified ovine growth hormone (GH) for a period of 4 weeks on wool growth have been measured in 12 Merino ewes fed either a calculated maintenance energy intake or 1�6 times this amount (six on each ration). Concentrations of hormones, glucose, urea, a-amino N and amino acids in the blood were monitored and faeces and urine collected for measurement of nitrogen balance.
40
Fenn, PD, e RA Leng. "Wool growth and sulfur amino acid entry rate in sheep fed roughage based diets supplemented with bentonite and sulfur amino acids". Australian Journal of Agricultural Research 40, n. 4 (1989): 889. http://dx.doi.org/10.1071/ar9890889.
Testo completoAbstract (sommario):
In two experiments, sheep were offered a roughage-based diet supplemented with either cysteine or bentonite as a solid, or bentonite, cysteine or methionine added to their drinking water. Supplementation with cysteine as a solid had no effect on wool growth, while supplementation via drinking water had no effect on wool growth or cysteine entry rate into the blood. Supplementation with methionine via drinking water increased the entry rate of methionine into blood by 69% (P< 0.05) as measured by a continuous infusion of [35S]-methionine. This coincided with subsequent increases in wool growth of 16% (P< 0.05) compared to sheep fed a basal diet alone. Compared with the basal diet alone, supplementation with 30 g/day bentonite as a dry powder or 60 g/day as a suspension in drinking water increased wool growth by 19 and 20% respectively. Bentonite given as sole supplement did not increase the entry rate of either cysteine or methionine into the blood of sheep. When bentonite and sulfur amino acids were complexed or mixed, wool growth was not increased above that for bentonite or the amino acid alone.
41
Reis, PJ, DA Tunks e SG Munro. "Effects of abomasal protein and energy supply on wool growth in Merino sheep". Australian Journal of Agricultural Research 43, n. 6 (1992): 1353. http://dx.doi.org/10.1071/ar9921353.
Testo completoAbstract (sommario):
The relative importance for wool growth of energy-yielding nutrients compared with amino acids required for incorporation into wool proteins was assessed in an experiment in which most nutrients were supplied via the abomasum. Nine nutritional treatments, providing three levels of protein (53, 99 and 145 g/day) to the intestines at three levels of energy (5.2, 7.5 and 9.7 MJ/day), were given to 12 Merino sheep during three consecutive periods of 3 weeks in a balanced lattice design. Abomasal nutrients consisted of varying proportions of casein, whole milk, glucose and glycerol. There was a large effect of protein supply on all components of wool growth, but there was no significant effect of energy. There was a significant interaction between the effects of protein and energy supply on diameter, length growth rate and volume of wool, but it was small relative to the main effect of protein. Extra energy appeared to enhance wool growth at the highest level of protein but reduce it at the lowest level of protein. The concentration of urea, cystine, methionine and other essential amino acids in plasma increased with protein level. Increasing energy supply reduced the concentration of urea and essential amino acids in plasma but not that of cystine or methionine. The experiment confirmed the major role of amino acid supply in controlling wool growth but indicated that there may be a small interaction with energy supply.
42
Terrill, T. H., G. B. Douglas, A. G. Foote, R. W. Purchas, G. F. Wilson e T. N. Barry. "Effect of condensed tannins upon body growth, wool growth and rumen metabolism in sheep grazing sulla (Hedysarum coronarium) and perennial pasture". Journal of Agricultural Science 119, n. 2 (ottobre 1992): 265–73. http://dx.doi.org/10.1017/s0021859600014192.
Testo completoAbstract (sommario):
SUMMARYAreas of sulla (Hedysarum coronarium) and pasture (Lolium perenne/Trifolium repens/Holcus lanatus) were grazed by young sheep (29·5–34·8 kg initial liveweight) in four experiments, and effects upon body growth, wool growth and rumen metabolism were measured.Sulla contained 40–50 g condensed tannins (CT)/kg DM, whilst the pasture contained small amounts of CT (2–6 g/kg DM). After chewing during eating, a lower proportion of total CT was readily extractable and greater proportions were protein-bound and fibre-bound. Nutritional effects attributable to CT were assessed by oral administration of polyethylene glycol (PEG), which binds and inactivates CT, to half the animals grazing each forage. Rates of body growth were consistently higher for lambs grazing sulla than those grazing pasture, with the CT concentration in sulla being neither stimulatory or inhibitory to body growth or voluntary feed intake (VFI). The action of CT reduced carcass fatness in sheep fed both diets, in the one experiment where this was measured. CT present in both sulla and pasture decreased rumen ammonia concentration and decreased molar proportions of iso-butyrate and iso and n-valerate. During spring and early summer, when wool growth rates were highest, CT present in both pasture and sulla increased wool growth rate; when wool growth rates were low during winter, CT had no effect upon the wool growth of sheep grazing either forage. Numbers of protozoa and molar proportions of n-butyrate in rumen fluid were increased by CT in sheep grazing sulla but not pasture.It was concluded that the higher rates of body growth and VFI in lambs grazing sulla was most likely to be due to its very high ratio of readily fermentable: structural carbohydrate.
43
Masters, D. G., C. A. Stewart, G. Mata e N. R. Adams. "Responses in wool and live weight when different sources of dietary protein are given to pregnant and lactating ewes". Animal Science 62, n. 3 (giugno 1996): 497–506. http://dx.doi.org/10.1017/s1357729800015034.
Testo completoAbstract (sommario):
AbstractWool growth, staple strength and fibre diameter are reduced during pregnancy and lactation. This may be due to the increased requirement for protein for foetal growth, udder development and milk production causing a lack of amino acids for wool. Responses in wool production, ewe live weight, lamb birth weight and growth, plasma amino acids and levels of cortisol, insulin and growth hormone were measured when different sources of protein were offered. Either lupin seed (L), fish meal (F) or formaldehyde-treated egg white (E) were included in an oaten hay-based diet offered during the final 3 weeks of pregnancy and first 3 weeks of lactation. Provision of diets containing E or F resulted in significant (P < 0·001) increases in wool growth and trends towards increased staple strength (4 to 6 N/ktex) and clean fleece weights (0·17 to 0·38 kg) compared with the sheep given L. Feeding the E diet increased the concentration of cystine in plasma and sulphur in wool in late pregnancy. Feeding the F diet increased the concentrations of arginine, histidine, lysine and threonine in plasma in early lactation. Ewes given E had higher circulating insulin and increased insulin resistance, compared with sheep given L, on 2 of the 4 days of sampling during pregnancy and lactation during the treatment period. There were no treatment effects on lamb birth weight or growth but ewes given the E diet were significantly (P < 0·05, 3·3 kg) heavier than the ewes given L after 3 weeks of lactation. The results indicate that a lack of protein available for absorption in the small intestine causes reduced wool growth during late pregnancy and early lactation. Wool growth is more sensitive to a reduced protein supply than foetal growth, maternal weight or milk production.
44
Cobon, DH, RGA Stephenson e PS Hopkins. "The effect of oral administration of methionine, bentonite, methionine/bentonite and methionine/oil homogenates on wool production of grazing and penned sheep in a semi-arid tropical environment". Australian Journal of Experimental Agriculture 32, n. 4 (1992): 435. http://dx.doi.org/10.1071/ea9920435.
Testo completoAbstract (sommario):
Penned and grazing sheep were supplemented in 3 experiments with either methionine (Me 2.5 g/sheep.day), bentonite (Bent 5 or 10 g), Me + Bent (1 : 2 and 1 : 4) or Me/oil homogenates. These supplements were added to the drinking water or in molasses-based licks for treatment periods of 4-6 weeks duration. The effects of supplements on wool growth, liveweight, and ammonia concentration in rumen liquor were determined. In experiment 1, penned sheep fed a maintenance diet (750 g/sheep.day) of pelleted lucerne and supplemented via the drinking water, showed increased (P<0.05) mean wool growth for the 4 treatment periods of 31% (Me + bent), 16% (Bent), 18% (Me/tallow) and 21% (Me). Factorial analysis revealed main effects of 12% for bentonite (P<0.05) and 17% for Me (P<0.01) supplements. In experiment 2, grazing sheep supplemented via the drinking water, increased (P<0.01) wool growth over 5 treatment periods by up to 32% (Me + bent), 15% (Bent), 20% (Me) and 26% (Me/oil). In experiment 3, penned sheep fed a maintenance diet of pelleted lucerne were supplemented with molasses licks containing Me, Bent, or Me + bent, mixed using either artesian bore water or rain water. No individual treatment effect on wool growth was recorded. However, factorial analysis revealed an 18% wool growth advantage (P<0.05) for bentonite supplements mixed in artesian bore water. Treatment had no consistent effect on liveweight of sheep or level of ammonia in rumen liquor. Responses in wool production to supplements were greatest when rumen ammonia values were >5 mg%. Considerable variation in apparent wool response occurred between treatments and treatment periods for both bentonite and methionine supplements. The greatest responses to methionine supplements occurred in experiments 1 and 2 when basal wool production in the control treatments was lowest. The homogenisation procedures used to prepare Me/oil supplements, did not demonstrate any consistent advantages in terms of extra wool response.
45
Thompson, A. N., M. W. Hyder e P. T. Doyle. "Effects of differential grazing of annual pastures in spring and age of sheep on pasture and sheep production". Australian Journal of Experimental Agriculture 37, n. 7 (1997): 727. http://dx.doi.org/10.1071/ea96036.
Testo completoAbstract (sommario):
Summary. The effects of controlled grazing through spring on the production of young (age 1 year; liveweight 38.3 ± 0.09 kg; condition score 3.0 ± 0.03) and mature (age 3 years; liveweight 61.9 ± 0.36 kg; condition score 3.1 ± 0.04) Merino wethers was examined. The grazing treatments involved adjusting sheep numbers to maintain green feed on offer near target amounts of 800, 1200, 1600, 2000, 2400 and 2800 kg dry matter/ha. Liveweight and wool growth measurements were made on 8 sheep per plot, with additional animals added or removed as necessary to maintain pasture near the target feed on offer. Changes in wool-free liveweight were linear between days 0 and 42 (period 1), and days 42 and 111 (period 2) for both classes of sheep grazing low feed on offer treatments. Hoggets lost less liveweight than mature animals while grazing low feed on offer during period 1 and gained liveweight faster (P<0.05) than mature animals for any feed on offer during period 2. Curvilinear relationships existed between feed on offer and clean wool growth rate and fibre diameter, with feed on offer accounting for 65 and 81% of the variations in wool growth rate, and 65 and 73% of the variations in fibre diameter, for hogget and mature sheep respectively. There was no significant difference in wool growth rate between animal classes. Annual clean wool production, fibre diameter and staple length increased linearly (P<0.05) with increasing feed on offer. Staple strength was higher (P<0.05) in mature sheep compared with hoggets, but was greater than 30 N/ktex for both classes of sheep irrespective of feed on offer. These results indicate that intensive grazing in spring to predetermined feed on offer is a useful tactic for manipulation of wool growth and fibre diameter, but factors other than feed on offer also contribute to liveweight change and wool growth.
46
WARD, MP, e RTF ARMSTRONG. "Residues of insect growth regulators on Queensland wool". Australian Veterinary Journal 76, n. 10 (ottobre 1998): 698–99. http://dx.doi.org/10.1111/j.1751-0813.1998.tb12287.x.
Testo completo
47
Safari, E., N. M. Fogarty, A. R. Gilmour, K. D. Atkins, S. I. Mortimer, A. A. Swan, F. D. Brien, J. C. Greeff e J. H. J. van der Werf. "Across population genetic parameters for wool, growth, and reproduction traits in Australian Merino sheep. 2. Estimates of heritability and variance components". Australian Journal of Agricultural Research 58, n. 2 (2007): 177. http://dx.doi.org/10.1071/ar06162.
Testo completoAbstract (sommario):
Precise estimates of genetic parameters are required for genetic evaluation systems. This study combined data from 7 research resource flocks across Australia to estimate variance components and genetic parameters for production traits in the Australian Merino sheep. The flocks were maintained for several generations and represented contemporary Australian Merino fine, medium, and broad wool bloodlines over the past 30 years. Over 110 000 records were available for analysis for each of the major wool traits, and 50 000 records for reproduction and growth traits with over 2700 sires and 25 000 dams. A linear mixed animal model was used to analyse 6 wool traits comprising clean fleece weight (CFW), greasy fleece weight (GFW), fibre diameter (FD), yield (YLD), coefficient of variation of fibre diameter (CVFD), and standard deviation of fibre diameter (SDFD), 4 growth traits comprising birth weight (BWT), weaning weight (WWT), yearling weight (YWT), and hogget weight (HWT), and 4 reproduction traits comprising fertility (FER), litter size (LS), lambs born per ewe joined (LB/EJ), and lambs weaned per ewe joined (LW/EJ). The range of direct heritability estimates for the wool traits was 0.42 ± 0.01 for CFW to 0.68 ± 0.01 for FD. For growth traits the range was 0.18 ± 0.01 for BWT to 0.38 ± 0.01 for HWT, and for reproduction traits 0.045 ± 0.01 for FER to 0.074 ± 0.01 for LS. Significant maternal effects were found for wool and growth, but not reproduction traits. There was significant covariance between direct and maternal genetic effects for all wool and growth traits except for YWT. The correlations between direct and maternal effects ranged from –0.60 ± 0.02 for GFW to –0.21 ± 0.10 for SDFD in the wool traits and from –0.21 ± 0.03 for WWT to 0.25 ± 0.08 for HWT in the growth traits. Litter effects were significant for all wool and growth traits and only for LS in reproduction traits. The mating sire was fitted in the models for reproduction traits and this variance component accounted for 21, 17, and 8% of the total phenotypic variation for FER, LB/EJ, and LW/EJ, respectively. The implications of additional significant variance components for the estimation of heritability are discussed.
48
Albers, GAA, GD Gray, Jambre LF Le, LR Piper, IA Barger e JSF Barker. "The effect of Haemonchus contortus on liveweight gain and wool growth in young merino sheep". Australian Journal of Agricultural Research 40, n. 2 (1989): 419. http://dx.doi.org/10.1071/ar9890419.
Testo completoAbstract (sommario):
Results of three crossover experiments on a total of 1078 Merino lambs were used to estimate the effect of a single infection of 11 000 Haernonchus contortus larvae on liveweight gain, clean wool growth and wool fineness. Estimates were obtained by direct comparison of six groups of infected and matched uninfected iambs under field conditions. Infections were terminated after 5 weeks, at which stage some mortality had occurred and haematocrits had in five out of six cases declined to less than 24%. Over an 8-9 week period, beginning at the time of infection, liveweight gains of infected lambs were reduced by on average 1.29 kg (range 0.83-1.71 kg) amounting to 38% (12-64%) of liveweight gain in uninfected controls. The detrimental effect of infection was most severe towards the end of the infection period. There was a lag phase of 3-6 weeks between larval administration and the onset of wool growth depression. The reduction of wool growth persisted for at least 14 weeks after termination of infection. The size of this reduction was very variable. Over a 4 month post-infection period, reductions ranged from 11 to 97 g clean wool (mean 46 g) or 1.4 to 157% (mean 6.8%) of clean wool grown by uninfected lambs. Estimates of reduction of fibre diameter over the same period ranged from 0.39 to 0.79 8m (mean 0.57 8m).
49
Morcombe, P. W., M. Gillibrand, B. J. Horton, R. T. F. Armstrong, N. J. Campbell, D. J. Best, W. Barr e J. Karlsson. "Modelling pesticide residues on greasy wool: surveys of the insect growth regulators triflumuron and diflubenzuron". Australian Journal of Experimental Agriculture 39, n. 5 (1999): 529. http://dx.doi.org/10.1071/ea98174.
Testo completoAbstract (sommario):
Surveys have examined the relationship between louse and flystrike treatments on farms and the resulting residues of insect growth regulators on greasy wool. These results have been summarised using a model of the on-farm survey data. The model estimated the amount of chemical taken up by the wool at application. This was based on experimental breakdown rates of these insecticides on wool determined in controlled trials. The data indicated that the backliner, triflumuron, when used off-shears within 24 h of shearing, was normally applied at slightly higher than the recommended rate on-farm and left an average residue of 30 mg/kg greasy wool at the following shearing 12 months later. Diflubenzuron, applied by dipping or jetting, was usually applied at lower than the recommended rates, and left an average residue of 40 mg/kg on the wool at shearing 12 months later. When treatment was applied to very short wool (<3 weeks after shearing) the residue was only about 20 mg/kg, but when applied at later times after shearing the residue at the following shearing was not closely related to the time of treatment. The model can be used to estimate the expected residue level and likely range of results from most standard insect growth regulator treatments. This will improve advice to producers so most can meet specified industry standards.
50
Masters, D. G., A. D. Peterson, G. Mata e S. M. Liu. "Influence of liveweight, liveweight change, and diet on wool growth, staple strength, and fibre diameter in young sheep". Australian Journal of Agricultural Research 49, n. 2 (1998): 269. http://dx.doi.org/10.1071/a97093.
Testo completoAbstract (sommario):
The effects of initial liveweight, liveweight change, and composition of the diet on wool growth and staple strength in weaner sheep were investigated. Weaner wethers (64) were allocated to treatments in a factorial design (23). The factors were initial liveweight (heavy, 33 kg; light, 25 kg), liveweight change (fed at maintenance for 56 days, or 28 days at 0 ·6×maintenance then 28 days at 1·6×maintenance), and diet (lupin seed based diet or canola meal based diet). The heavier weaners grew approximately 1·9 g/day more wool than the light sheep during the experimental period and this resulted in a higher clean fleece weight (1·8 v. 1·4 kg), staple strength (37 v. 27·4 N/ktex), and fibre diameter (18·0 v. 17·4 µm). Substituting canola meal for lupin seed increased wool growth during the experiment and clean wool yield, but did not affect clean fleece weight or staple strength. The weaners fed to lose and then gain weight grew wool with a lower staple strength than the weaners fed to maintain weight through the experiment (28·6 v. 35·8 N/ktex), but there were no differences in any of the other fleece characteristics. The ratio of wool growth to dry matter intake (DMI) was higher in the sheep fed canola meal than those fed lupins (by approximately 1·5 g/kg DMI) and higher in weaners losing weight than those fed to maintain weight (by approximately 4·5 g/kg DMI). From a practical perspective, these results indicate that initial liveweight and liveweight change both influence staple strength and wool growth and need to be included in any management strategy to improve wool quality of young sheep.