Some effects of three glucocorticoid analogues on wool growth and their efficacy as defleecing agents in sheep

1975 ◽  
Vol 15 (73) ◽  
pp. 193 ◽  
Author(s):  
BA Panaretto ◽  
RE Chapman ◽  
AM Downes ◽  
PJ Reis ◽  
ALC Wallace

Some effects of the parenteral administration of three glucocorticoid analogues, namely Opticortenol (dexamethasone-21 -trimethylacetate), Decadron phosphate (dexamethasone-21 -phosphate) and the heterocyclic corticosteroid, Cortivazol, were observed on wool growth in sheep. None of the glucocorticoids was satisfactory for defleecing sheep, principally because of variation between sheep and between body regions in the wool growth response. Four main types of response to dosing with glucocorticoids were observed : Firstly, with some animals there was no obvious effect on wool growth. In a second category there was a well-defined 'break' in some wool fibres but the fleece as a whole was retained by other unbroken fibres. Thirdly, complete or partial shedding of the fleece was seen, unshed portions usually being present on the head, neck and shoulder regions and consisting mainly of broken wool fibres but also a proportion of whole fibres. Finally, prolonged wool growth depression without shedding of the fleece during the experimental period was also seen. Results indicated that to obtain shedding of the fleece in 15-20 days after dosage, wool growth needs to be reduced below 20 per cent of its pre-treatment values and regrowth must be rapid.

1975 ◽  
Vol 15 (73) ◽  
pp. 167 ◽  
Author(s):  
IA Barger ◽  
WH Southcott

Wool growth rates of grazing sheep that were resistant to infection with the intestinal nematode Trichostrongylus colubriformis were measured in the presence and absence of a larval challenge. In one experiment, resistant sheep exposed to a moderate level of larval challenge grew 11 per cent less wool than unchallenged resistant sheep grazing the same paddock. A second experiment confirmed the previous results but showed that the magnitude of this wool growth depression did not depend on the severity of the challenge


2021 ◽  
Vol 161 ◽  
pp. S805-S806
Author(s):  
S. Tandon ◽  
M. Gairola ◽  
P. Ahlawat ◽  
S. Purohit ◽  
P. Umesh ◽  
...  

1974 ◽  
Vol 14 (66) ◽  
pp. 17 ◽  
Author(s):  
KW Entwistle ◽  
G Knights

The performance of unsupplemented Merino ewes grazing dry season semi-arid tropical pastures was compared with that of other sheep supplemented with either urea-molasses or molasses. Over the experimental period from September 1970 until late January 1971 mean daily intakes per head of urea and molasses respectively were: low urea group, 11.7 g and 35.1 g; high urea group, 15.2 g and 45.6 g; molasses, 38.9 g. Monthly estimates of the proportions of animals consuming the supplement over the period September to January varied from: urea-molasses-71 per cent to 97 per cent; molasses-75 per cent to 96 per cent. Unsupplemented sheep lost significantly more liveweight than did supplemented groups in the period September to February. However, during the period of greatest nutritional stress from December to February, sheep recewing molasses lost significantly more weight than did those supplemented with urea-molasses, and liveweight loss was greater in the low urea group than in the high urea group. Wool growth rates were significantly higher in groups receiving urea-molasses, with highest wool growth rates in animals on the high level of urea. Total fleece weights were unaffected by treatment as were the reproductive factors examined. Faecal nitrogen levels declined until the onset of pasture regrowth in February and were associated with low digestibility of the available forage. Compensatory liveweight gains following pasture regrowth outweighed any advantage of the dry season supplementation. It was concluded that urea-molasses supplements were of little direct benefit to sheep grazing these pastures.


1999 ◽  
Vol 50 (4) ◽  
pp. 497 ◽  
Author(s):  
D. G. Masters ◽  
G. Mata ◽  
S. M. Liu

There is limited evidence that the response in wool growth resulting from feeding protected protein supplements continues after the feeding has stopped. Feeding such proteins, alternated with traditional supplements, may increase wool growth as much as continuous feeding but at a lower cost. This experiment aimed to determine whether the response to protected protein continued after the sheep were switched to a cereal supplement. Over a 2-month experimental period, 56 weaners (5 months old, weighing 26 kg) were used in a 2 × 2 factorial experiment. Half were fed a diet containing 25% canola meal [partially protected protein with high concentrations of sulfur amino acids (SAA)] mixed with oaten hay, urea, and minerals. The other half were fed the same diet but with lupin seed (highly degradable protein with low concentrations of SAA) replacing the canola meal. Within each of the 2 dietary treatments and in each of 2 months, half of the weaners were fed the diet continuously, the other half were fed the diet for 2 weeks followed by 2 weeks of a barley, oats, hay, urea, and minerals diet. Another group of 8 weaners was fed the oats–barley diet continuously for 2 months. All sheep were fed to lose 35 g liveweight/day. Weaners fed canola meal grew 11% more wool during the experiment and had a higher rate of protein synthesis in the skin than weaners fed lupins. The response to canola meal of wool and skin was the same whether feeding was continuous or alternated with oats–barley, indicating that the benefits from feeding partially protected proteins continues after feeding has stopped.


2009 ◽  
Vol 49 (12) ◽  
pp. 1100
Author(s):  
B. J. McGuirk

Early work in the 1950s on the wool growth response of sheep from diverse genotypes for wool production in response to varying planes of nutrition at pasture did not show the significant genotype × environment interactions exhibited in later pen studies with the same or very similar genotypes. However, this early study used a log-transformation on all traits to adjust nutritional effects for scale. Re-analysis of the original (i.e. untransformed) data shows that superior genetic merit for clean fleece weight, different sire progeny groups or selection flocks is more apparent when hogget ewes are fed a high plane of nutrition at pasture. However, only in the case of flocks was the interaction statistically significant, and this interaction was insignificant when data were either log-transformed, or when an appropriate test that accounts for scale-type effects was applied. When left untransformed, the data are, thus, in agreement with the subsequent pen studies that examined data on untransformed clean wool production.


1973 ◽  
Vol 13 (63) ◽  
pp. 351 ◽  
Author(s):  
IA Barger ◽  
WH Southcott ◽  
VJ Williams

Two experiments are reported. In experiment 1, light infections with the intestinal nematode Trichostrongylus colubriformis reduced wool growth of sheep by 42 per cent compared with pair-fed controls. There was no significant difference in wool growth between those sheep given a cystine supplement as an intraperitoneal pellet and those given a daily intra-duodenal injection of cystine, although cystine was poorly absorbed from the peritoneal cavity. In experiment 2, fifteen sheep were fed a maintenance ration and their wool growth rates defined. When six of the sheep were given a daily intra-duodenal drip containing 2 g cysteine hydrochloride, and six sheep were given the same drip intravenously, their wool growth rate increased by a mean of 33 per cent compared with the wool growth of the three untreated sheep, irrespective of the route of administration of the cysteine. Three sheep in each group of six were then lightly infected with Trichostrongylus colubriformis and the wool production of all sheep was measured in the presence and absence of the daily cysteine supplement via the two routes. The infection depressed wool growth, but did not influence the wool growth response to either route of cysteine supplementation. It was concluded that the reduced wool growth induced by trichostrongylosis could not be attributed to malabsorption of cysteine. Evidence was obtained that sheep resistant to Trichostrongylus colubriformis produced less wool when subjected to a larval challenge.


1958 ◽  
Vol 1958 ◽  
pp. 13-17 ◽  
Author(s):  
T. R. Preston ◽  
V. Rochanasaroj ◽  
Isoline Gee

It is now widely accepted that the subcutaneous implantation of stilboestrol or hexoestrol increases the rate of live-weight gain in lambs and cattle. In sheep it is generally considered that for a feeding period of up to 12 weeks a single implantation of hormone produces an adequate growth response. Perry et al.(1951), Stephens & Thompson (1952) and Bell et al.(1954) reported no advantage from repeated implantations during the experimental period. In a series of experiments at this Institute (Preston & Gee, 1957a) it has been noticed that the major part of the increased weight gain takes place during the first six weeks after hexoestrol implantation.


Author(s):  
N. Malik ◽  
M. Maganti ◽  
M. McQuestion ◽  
M.C. Tjong ◽  
D. Keilty ◽  
...  

1990 ◽  
Vol 41 (5) ◽  
pp. 987 ◽  
Author(s):  
PJ Murray ◽  
JB Rowe ◽  
EM Aitchison

The feed additive flavomycin, a glycolipid antibiotic, was evaluated for its potential to improve wool growth in sheep fed two pelleted diets: one based on lucerne chaff and lupin grain and the other on wheat chaff and fishmeal. Seventy-eight weaner ewes, approximately 20 months of age and mean weight of 32 kg (s.e. � 0.3), were placed in individual pens and fed the pelleted diets at a level equivalent to 3.5% of the mean liveweight of the group. The experiment consisted of an initial period (8 weeks) during which all animals received their respective diets with no flavomycin, followed by an experimental period (9 weeks) during which the animals received their diets with flavomycin. Flavomycin was included at three different rates (l0, 20 and 40 ppm) in both diets (nine sheep/level) during the experimental period and twelve sheep were fed each of the unmedicated diets (no flavomycin). Feed intakes were measured daily and animals weighed weekly. Wool growth was measured for the initial and experimental periods by clipping a mid-side patch of about 100 cm2. In sheep fed the lucernellupin based diet, flavomycin increased liveweight gain ( P < 0.05) at 20 ppm but had no effect on wool production, whereas in those fed the hay/fishmeal diet, there was a linear decrease in liveweight gain (P < 0.001) (161, 151, 142, 130 g day-1) and a dose related increase in clean wool production (P<0.01) (12.9, 14.5, 15.2, 15.3 g m-2 day-1) with increasing rates of flavomycin (0, 10, 20, 40 ppm respectively). There was no significant effect of flavomycin on fibre diameter in the sheep fed either diet. The inclusion of flavomycin in both diets significantly increased the molar proportions of propionate in the rumen fluid and in sheep on the hay/fishmeal pellet it reduced the concentration of rumen ammonia. The time animals took to eat their ration was increased with the inclusion of flavomycin in the hay/fishmeal diet.


1969 ◽  
Vol 72 (2) ◽  
pp. 251-259 ◽  
Author(s):  
J. B. Coombe ◽  
G. K. Preston

SUMMARYIndividually-penned adult Merino wethers were fed for 16 weeks on a basal diet of ground, pelleted oat straw or Phalaris straw. Urea was supplied either in a salt-urea block containing 30% urea, or as crystalline urea incorporated into the pellets. A commercial mineral supplement was given during the first 8 weeks, but this was replaced with a laboratory-prepared mineral mix during the second 8 weeks.Urea supplementation significantly reduced live-weight loss. Over the 16 weeks control sheep lost a mean of 14·5 kg, and supplemented sheep 8·7 kg body weight. Most of this response to urea occurred during the second half of the experimental period.Food intakes of all sheep increased over the first 2 weeks and then fell. In the unsupplemented groups, levels of intake then remained fairly low, whereas in the sheep fed urea food intakes rose over the final 6 weeks of the experiment. There was a significant linear regression of live-weight change on food intake only with the urea-fed sheep. Intakes of urea-N from the blocks were extremely variable between individual sheep and between periods within sheep; in most cases, however, they appeared to be adequate, as this type of supplementation gave results similar to those obtained by mixing urea throughout the roughage.There was no significant effect of urea on total wool growth during the experimental period, although wool growth in the supplemented shepp showed a rise towards the end of the experiment. Wool growth in any 4-weekly period was closely related to food intake and live-weight change during that period.


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