Sublethal exposure to corynetoxins affects production of grazing sheep

1996 ◽  
Vol 36 (6) ◽  
pp. 649 ◽  
Author(s):  
SC Davies ◽  
CL White ◽  
IH Williams ◽  
JG Allen ◽  
KP Croker
Keyword(s):  
Birth Weight ◽  
Liver Damage ◽  
Fibre Diameter ◽  
Clinical Signs ◽  
Wool Fibre ◽  
Embryo Survival ◽  
Weaning Weight ◽  
Wool Growth ◽  
Low Levels ◽  
Production Losses

This paper reports the production losses resulting from treating sheep with sublethal doses of corynetoxins, the causal agent of annual ryegrass toxicity. Merino ewes were given 3 levels of corynetoxins twice weekly for 11 weeks from 26 days before the start of joining to day 51 of pregnancy, giving a cumulative dose of 0 , 0.4 or 0.8 mg/kg liveweight. The effect on ovulation, pregnancy, lamb birth weight, lamb survival and weaning weight were measured along with the liveweight and wool growth of the ewes. Corynetoxin treatment depressed (P<0.005) the activity of uridine diphospho-N-acetylglucosamine: dolichol-phosphate N-acetylglucosamine-1-phosphate transferase and liver damage was detected in ewes on the high toxin treatment (P<0.05). Ewe liveweight was unaffected by treatment but wool growth and wool fibre diameter were reduced by 10 and 7%, respectively (P<0.05). Corynetoxin treatment appeared to increase ovulation (P<0.05) and, as there was no effect on conception and embryo survival, this resulted in a 30-35% increase in the number of lambs weaned. Lamb birth weight and survival were not affected by treatment but weaning weight of the low toxin group was depressed (P<0.05). While reproduction was not adversely affected, the sheep in this trial were exposed to extremely low levels of corynetoxins which did not accumulate to levels capable of causing detectable liver damage until 23 days after joining. Even at these levels of intake, well below those required to show clinical signs (3-5 mg/kg liveweight), wool growth was reduced, suggesting that sheep grazed on mildly toxic pasture experience wool production losses in the absence of signs of the clinical disease.

Liveweight and wool growth responses to a Mediterranean environment in three strains of Merino sheep

1998 ◽  
Vol 49 (8) ◽  
pp. 1187 ◽  
Author(s):  
N. R. Adams ◽  
J. R. Briegel
Keyword(s):  
Body Composition ◽  
Fibre Diameter ◽  
The Other ◽  
Wool Fibre ◽  
Growth Responses ◽  
Mediterranean Environment ◽  
Protein Loss ◽  
Broad Group ◽  
Wool Growth ◽  
Sources Of Variation

The present study examined changes in wool growth, liveweight, and body composition in groups of fine, medium, and broad wool Merino wethers grazed together at pasture in the highly seasonal Mediterranean environment, to determine the sources of variation in wool growth that may affect staple strength (SS). Seasonal changes in wool growth were measured using 6 dyebands placed at times of seasonal change in the nutrient supply from pasture, and liveweights were recorded fortnightly. Dilution of deuterated water was used to determine changes in body composition between the beginning of summer and the end of autumn. The sheep lost liveweight over this period, but loss of protein relative to fat over this period was unexpectedly high (7 : 1). The relative changes in liveweight, and loss of its components (fat and lean) during summer and autumn, were similar in all 3 groups, even though the Broad group was heavier than the other 2 genotypes at all times (P < 0·01). In contrast to the similar pattern of liveweight change, wool growth rates and changes in the fibre diameter were less variable throughout the year in the Broad group than the other 2 groups (P < 0·001). Stepwise regression indicated that the characteristics related to SS were standard deviation in fibre diameter (SDfd; P < 0·001), mean fibre diameter (P < 0·001), and variation in diameter within a 200-mm length of wool fibre (Sdfdwithin; P < 0·05). However, the relative importance of different factors for SS differed within each group. The most important factors were mean fibre diameter in the Fine group, the variation in fibre diameter along the staple (SDfdalong) in the Medium group, and the variation in diameter between fibres (SDfdbetween) in the Broad group. It is concluded that SS is a complex characteristic, depending on both the fibre diameter and several sources of variation in fibre diameter, all of which can differ among flocks. Protein loss made a disproportionate contribution to liveweight loss over summer and autumn, but the amino acids made available did not contribute substantially to wool growth or SS.

Wool production and heterosis by the Merino, the Polwarth, and their reciprocal crosses

1993 ◽  
Vol 33 (4) ◽  
pp. 397 ◽  
Author(s):  
LG Butler ◽  
BJ Horton ◽  
PM Williams ◽  
RG Banks
Keyword(s):  
Maternal Effect ◽  
Reciprocal Cross ◽  
Fibre Diameter ◽  
Similar Amount ◽  
Or Efficiency ◽  
Weaning Weight ◽  
Wool Production ◽  
Wool Growth ◽  
Fleece Weight ◽  
Lower Production

Tasmanian Merinos and Polwarths were mated in each of 2 years to produce 2 drops of Merino, Polwarth, and F1 reciprocal cross progeny. Polwarths had weaning weights similar to Merinos but were 14% heavier as hoggets. Polwarths grew a similar amount of wool of 11% greater (P<0.001) fibre diameter; however, wool production was 9% less efficient based on metabolic weight. Polwarths displayed an advantage in resistance to footrot. There was a marked Polwarth maternal effect of about 16% on weaning weight but no elfect on hogget weight. The Polwarth maternal effect on fleece weight and efficiency was 9% (P<0.001). In a comparison with a single-born male, ewes weighed 5% less at weaning and 7% less at hogget shearing and produced about 6% less wool (P<0.001), although of comparable fibre diameter. Twins weighed 17% less at weaning, but only 3% less at hogget shearing (P<0.001). They grew about 5% less wool, which was of 2% greater fibre diameter (P<0.001) and 5% higher wool score, but efficiency was 2.5% lower. Production was generally lower (except for yield and wool score) in the 1988 drop than the 1987 drop by 3-10%. Differences in productivity between ram sources were of only slightly lesser magnitude than differences between breeds. The number of feet affected by footrot was reduced by 17% in the 1988 drop. Severe footrot affecting more than 1 foot reduced liveweight but did not significantly reduce fleece weight. There appeared to be some heterosis for weaning weight (10%) and hogget weight (6%), but little heterosis in wool growth (2-3%) or efficiency (-2%).

Effect of light and temperature on wool growth

1978 ◽  
Vol 90 (2) ◽  
pp. 329-334 ◽  
Author(s):  
A. A. Elsherbiny ◽  
H. A. Eloksh ◽  
A. S. Elsheikh ◽  
M. H. Khalil
Keyword(s):  
Seasonal Changes ◽  
Seasonal Pattern ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Atmospheric Temperature ◽  
Wool Fibre ◽  
Wool Growth ◽  
Dim Light ◽  
Normal Light ◽  
Winter Time

SummaryWool samples were collected from 39 rams representing five breed groups of sheep: Merino (M), Ossimi (0), and the crosses between them, viz. ¾ Ossimi–¾ Merino (¾ O), ½ Ossimi–½ Merino (½ O) and ½ Ossimi–¾ Merino (¼ O) maintained at Sakha Experiment Station, Kafrelsheikh, Egypt, with the objectives of detecting the effect of the seasonal changes in normal light rhythm and temperature on wool fibre length and diameter. Animals were divided into two light treatments groups, the first consisting of four animals from each breed kept under continuous dim light conditions throughout the year and the second of three animals from Ossimi and four from each breed group kept inside an open pen free to sunlight and shade zones under daylight rhythm throughout the year. It was found that fibre length as well as fibre diameter in normal light exceeded that in dim light except in winter time. Breed groups showed different responses to the absence of light especially the Ossimi and the ¾ O whose fibre lengths were most affected. The breed groups had larger fibre diameters in normal light than in dim light except Merino and ¼ O. Seasonal changes in temperature had a highly significant effect on fibre length but not on fibre diameter. Higher temperature coincided with lower increases in fibre length. Season to season variation in wool growth seemed to suggest that the number of light hours per day and atmospheric temperature counteracted each other resulting in a non-significant seasonal pattern.

Tunicamycin reduces wool growth by slowing the mitotic activity of wool follicles

1997 ◽  
Vol 48 (3) ◽  
pp. 331 ◽  
Author(s):  
S. C. Davies ◽  
I. H. Williams ◽  
C. L. White ◽  
J. E. Hocking Edwards
Keyword(s):  
Direct Effect ◽  
Vascular System ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Annual Ryegrass ◽  
Wool Growth ◽  
Wool Follicle ◽  
Low Levels ◽  
A Minor ◽  
Annual Ryegrass Toxicity

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.

Responses to feeding canola meal or lupin seed to pregnant, lactating, and dry ewes

1996 ◽  
Vol 47 (8) ◽  
pp. 1291 ◽  
Author(s):  
DG Masters ◽  
G Mata
Keyword(s):  
Birth Weight ◽  
Treatment Period ◽  
Fibre Diameter ◽  
Canola Meal ◽  
Wool Production ◽  
Rumen Degradation ◽  
Wool Growth ◽  
Lupin Seed ◽  
Average Fibre

Responses in wool production, ewe liveweight, lamb birth weight, and growth were compared when the major source of protein in the diet was either lupin seed or canola meal. The diets were fed to ewes during the final 3 weeks of pregnancy and first 3 weeks of lactation, and for a similar period of time to a group of dry ewes. All ewes were fed to maintain conceptus-free liveweight. The diet containing canola meal increased (P < 0.001) wool growth in the reproducing ewes (50-63%) and the dry ewes (12.5-20%) during, and for 3 weeks after, the treatment period. Fibre diameter of wool grown during the treatment period was increased (P < 0.025) by 0.5-1.5 pm in the ewes fed canola meal compared with ewes fed lupins. The ewes fed canola meal gained slightly (P = 0.06) more weight during the experiment than the ewes fed lupins. Lambs from the ewes fed canola meal were lighter (P < 0.05) at birth (480 g) than lambs from ewes fed lupins. The reproducing ewes had lower fleece weights, average fibre diameters, and staple strengths and lengths than the dry ewes. These fleece characteristics were not significantly affected by diet. Canola meal is partially protected from rumen degradation and is less expensive than other sources of similar proteins and may therefore provide a practical option for commercial sheep producers.

Effects of defaunation of the rumen and supplementation with amino acids on the wool production of housed Saxon Merinos. 4. Cottonseed meal, analogues of methionine and avoparcin

1988 ◽  
Vol 28 (6) ◽  
pp. 707 ◽  
Author(s):  
DJ Cottle
Keyword(s):  
Amino Acids ◽  
Cottonseed Meal ◽  
Fibre Diameter ◽  
Cost Effective ◽  
Wool Fibre ◽  
Growth Responses ◽  
Wool Production ◽  
Wool Growth ◽  
Fleece Weight ◽  
Ciliate Protozoa

Ten groups, each of 6 superfine Merino wethers were individually penned indoors and hand-fed at maintenance level a ration of 70% oats and 30% chopped lucerne hay (w/w). The groups of sheep were fed 3 different supplementary pellets rotationally during three 9-week periods. Each group received 3 of the following 7 pellets: (1) control, (2) cottonseed meal (CSM), (3) CSM plus hydroxymethyl-methionine (MEP), (4) CSM plus methionine hydroxy analogue (MHA), (5) CSM plus avoparcin (AV), (6) CSM plus MEP plus AV, and (7) CSM plus MHA plus AV. The rations were offered 3 times a week. Half of the sheep had no rumen ciliate protozoa. Wool production was measured during the 7-month period. Defaunation resulted in a 6.9% increase in greasy fleece weight and a 7.7% increase in clean wool production. Average wool fibre diameter increased by 0.6 pm in defaunated sheep. The clean wool growth responses compared with sheep fed the control pellets were 4, 5, 12, 0, 3 and 9% respectively for sheep fed pellets 2-7. The most cost-effective supplement was the CSM plus MHA pellet, which increased clean wool production by 0.5 glday compared with sheep fed the CSM pellet but did not significantly affect wool quality. It was concluded that supplements containing MHA could be economically fed to housed superfine Merino wethers ('Sharlea'), but MHA appears to be relatively inefficient in supplying methionine to the intestines.

Intake and long-term cysteine supplementation change wool characteristics of Romney sheep

2001 ◽  
Vol 52 (1) ◽  
pp. 29 ◽  
Author(s):  
R. G. Sherlock ◽  
P. M. Harris ◽  
J. Lee ◽  
G. A. Wickham ◽  
J. L. Woods ◽  
...  
Keyword(s):  
Growth Rate ◽  
Treatment Period ◽  
Fibre Diameter ◽  
Wool Fibre ◽  
Amino Acid Supplementation ◽  
Sulfur Concentration ◽  
Treatment Groups ◽  
Length Growth ◽  
Wool Growth ◽  
Pre Treatment

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.

Growth and gastrointestinal nematode parasitism in lambs grazing either lucerne (Medicago sativa) or sulla (Hedysarum coronarium) which contains condensed tannins

1995 ◽  
Vol 125 (2) ◽  
pp. 281-289 ◽  
Author(s):  
J. H. Niezen ◽  
T. S. Waghorn ◽  
W. A. G. Charleston ◽  
G. C. Waghorn
Keyword(s):  
Medicago Sativa ◽  
Condensed Tannins ◽  
Average Daily Gain ◽  
Fibre Diameter ◽  
Parasite Burden ◽  
Superior Performance ◽  
Wool Fibre ◽  
Trichostrongylus Colubriformis ◽  
Wool Growth ◽  
Hedysarum Coronarium

SUMMARYTwo grazing experiments were undertaken to evaluate the effects of sulla (Hedysarum coronarium) which contains condensed tannins (CT) and lucerne (Medicago sativa), which does not contain CT, on the performance of parasitized and non-parasitized lambs. The work was carried out near Palmerston North, New Zealand in 1992 and 1993.Experiment 1 used lambs which were either genetically ‘conventional’ or ‘resistant’ to gastrointestinal nematodes and which had a naturally acquired heavy parasite burden (faecal egg count (FEC) 1300–2500 eggs per gram faeces (epg)). They were either drenched to remove all the parasites or remained undrenched when allocated to pure swards of either sulla or lucerne for the 28-day experimental period. Liveweight gains of drenched lambs were higher with sulla (mean 302 g/day) than with lucerne (mean 245 g/day; P < 0·02) and rates of gain were not reduced (P = 0·10) by genetic resistance to nematodes. Undrenched lambs had mean faecal egg counts of 1090–2220 epg after 28 days, with higher counts in lambs grazing lucerne than in those grazing sulla (P < 0·05). Lambs grazing lucerne also had a much lower average daily gain (ADG) (mean 50 g/day) than those grazing sulla (mean 206 g/day; P < 0·0001). Resistant lambs had reduced (P = 0·07) ADG in the sulla treatment only.In Expt 2, lambs with a relatively low worm burden (average FEC 250 epg) were either drenched to remove all worms or dosed with 20 000 Trichostrongylus colubriformis infective larvae and grazed on pure sulla or lucerne swards for 42 days. Drenched lambs had a similar liveweight gain (mean 190 g/day) and wool growth when grazing either sulla or lucerne. Undrenched lambs grazing sulla had a greater ADG (mean 129 g/day) than those grazing lucerne (mean −39 g/day; P < 0·0001) and a higher rate of wool growth from mid-side patches (P < 0·009) and larger wool fibre diameter (P < 0·05) than those grazing lucerne. Undrenched lambs grazing sulla had lower FECs (P < 0·05) on days 14, 21, 35 and 42 than those grazing lucerne and lower (P < 0·05) Trichostrongylus colubriformis worm burdens at slaughter. Undrenched lambs had less perineal faecal contamination when grazing sulla rather than lucerne. Parasite-induced anorexia was evident in the lambs grazing lucerne but not in those grazing sulla.These findings demonstrate that the performance of lambs infected with nematode parasites can vary substantially when given feeds of a similar chemical composition. The superior performance of lambs grazing sulla was probably caused by condensed tannins, which decrease protein degradation in the rumen and can increase post-ruminal protein availability.

scholarly journals Modelling a Transition from Purebred Romney to Fully Shedding Wiltshire–Romney Crossbred

Animals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2066
Author(s):  
Lydia Jane Farrell ◽  
Stephen Todd Morris ◽  
Paul R. Kenyon ◽  
Peter R. Tozer
Keyword(s):  
Fibre Diameter ◽  
Wool Fibre ◽  
System Dynamics Model ◽  
Dynamics Model ◽  
Sheep Farm ◽  
Wool Growth ◽  
Model Predictions ◽  
Farm Profit ◽  
On Farm ◽  
Harvesting Costs

Considering the current low prices for coarse wool (fibre diameter > 30 µm), a grading up transition to a shedding flock may eliminate wool harvesting costs and increase sheep farm profit. This transition could be achieved by breeding non-shedding ewes with Wiltshire rams. A bio-economic system-dynamics model of a pastoral sheep farming enterprise was used to simulate this grading up transition from 2580 Romney ewes to a similarly-sized flock of fully shedding third or fourth cross Wiltshire–Romney ewes. The total annual sheep feed demand was constrained within a ±5% range to minimise disruption to the on-farm beef cattle enterprise. Wool harvesting expenses were eliminated after seven years of transition, and with reduced feed demand for wool growth, the post-transition shedding flocks had more ewes producing more lambs and achieving greater annual profit compared with the base Romney flock. The net present values of transition were 7% higher than the maintenance of the base Romney flock with a farmgate wool price of $2.15/kg. Results suggest that coarse wool-producing farmers should consider a grading up transition to a shedding flock, and the collection of data on the production of Wiltshire–Romney sheep in New Zealand would improve the accuracy of model predictions.

The effects of short-term undernutrition and adrenocortical stimulation on wool growth

1972 ◽  
Vol 15 (1) ◽  
pp. 39-46 ◽  
Author(s):  
C. J. Thwaites
Keyword(s):  
Fibre Diameter ◽  
Wool Fibre ◽  
Minor Role ◽  
Short Term ◽  
Similar Treatment ◽  
Wool Growth ◽  
Prolonged Effect ◽  
Maintenance Ration ◽  
Maintenance Group

SUMMARYSeven daily doses of 60 or 120 mg cortisol administered to mature sheep given a maintenance ration depressed wool fibre diameter by approximately 10%. Similar treatment with 120 mg cortisol for 14 days produced a more severe and prolonged effect, though fibre diameter was unaffected by a series of seven injections of 40 IU ACTH given every second day.Fourteen days at 10% of maintenance and 14 days' cortisol treatment were applied to mature sheep fed either continually at 150% maintenance, or at 75% followed by 150% maintenance. Cortisol treatment was associated with a significant reduction in fibre diameter only in the animals fed at 150% maintenance. Restriction to 10% maintenance for 14 days had no such effect. Approximately 20% of fibres were shed following cortisol treatment in both nutritional groups, but a marked ‘break’ in the fleece occurred only in the 75% maintenance group.A low plane of nutrition is confirmed as a major factor predisposing to ‘tenderness’ and ‘break’, and short-term adrenocortical stimulation is shown to be sufficient to produce the reduction in fibre diameter and increased fibre shedding associated with these faults. However, semi-starvation (represented by restriction to 10% of maintenance) appears to have played a relatively minor role in their development.

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