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.

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.

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.

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.

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.

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.

Wool growth of pregnant and lactating Merino ewes

1985 ◽  
Vol 105 (3) ◽  
pp. 613-622 ◽  
Author(s):  
V. H. Oddy
Keyword(s):  
Organic Matter ◽  
Fibre Diameter ◽  
Wool Fibre ◽  
Total Plasma ◽  
Wool Growth ◽  
Digestible Organic Matter ◽  
Pregnancy And Lactation ◽  
The Difference ◽  
The Relationship ◽  
Growth Deficit

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.

Effect of daily infection with Ostertagia circumcincta larvae on food intake, milk production and wool growth in sheep

1982 ◽  
Vol 99 (2) ◽  
pp. 249-259 ◽  
Author(s):  
V. Leyva ◽  
A. E. Henderson ◽  
A. R. Sykes
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Milk Production ◽  
Fibre Diameter ◽  
Wool Fibre ◽  
Bodyweight Loss ◽  
Mean Values ◽  
Wool Growth ◽  
Pregnant Sheep ◽  
Pregnancy And Lactation

SUMMARYForty pregnant sheep were allocated to four groups and maintained indoors in individual pens on a pelleted diet. During the last 6 weeks of pregnancy and the first 6 weeks of lactation groups were infected daily with 4000 larvae of Ostertagia circumcincta or remained as controls in a cross-over design. Thus groups were either not infected (CC), infected only during pregnancy (IC), during lactation (CI) or during both pregnancy and lactation (II). Food was offered on the basis of body weight at the beginning of pregnancy and lactation. Food intake, body-weight change, faecal egg counts, plasma pepsinogen and milk production were measured weekly, wool growth and fibre diameter during 21-day periods and tensile strength of wool over the whole experimental period.Eggs were seen in faeces of only three sheep infected during pregnancy, but in all sheep infected during lactation; maximum mean values were 467 ± 144 and 222 ± 58 eggs/g fresh faeces in CI and II sheep, respectively. Pepsinogen concentrations rose after 1 week of infection during pregnancy and lactation; peak values were 868 + 57 and 1104 ± 146 m-u/l, respectively.Infection reduced food intake by 16% during lactation but had no effect during pregnancy. There were significant interactions between pregnancy and lactational treatments on intake during lactation. Infection during lactation increased bodyweight loss; mean values were 57, 40, 114 and 78 g/day for groups CC, IC, CI and II respectively. Milk production was decreased during weeks 4–6 of lactation, mean values being 1·59 and 1·32 kg/day in control and infected groups, respectively.Infection reduced wool growth and wool fibre diameter by 20 and 7%, respectively, during the final 3 weeks of infection during lactation. The staple strength of wool grown during the experiment was reduced by 14, 45 and 23% in IC, CI and II groups, respectively. Infection moved the point of greatest wool tenderness from parturition in control sheep to a time during the period of infection, particularly when infection occurred during lactation.

Effectiveness of intravenous and abomasal doses of mimosine for defleecing sheep and effects on subsequent wool growth

1978 ◽  
Vol 29 (5) ◽  
pp. 1043 ◽  
Author(s):  
PJ Reis
Keyword(s):  
Fibre Diameter ◽  
The Body ◽  
Wool Fibre ◽  
Merino Sheep ◽  
Wool Growth ◽  
Intravenous Infusions ◽  
Fibre Growth ◽  
Minimal Rate ◽  
Average Fibre ◽  
Rapid Removal

Four Merino sheep were given intravenous infusions of mimosine for 2 days at a rate of 110–120 mg/kg/day. Wool fibre growth stopped by about 1 day after the start of the infusions, and the sheep were subsequently manually defleeced. It was estimated that, on average, fibre growth stopped for about 12 days. Wool growth rates were above the pre-infusion rates in the early regrowth (3–5 weeks after dosing), and the mean fibre diameter was still about 2 µm above pre-infusion values at 11 weeks after dosing. Groups of Merino sheep were given intravenous infusions of mimosine for 2 days at rates ranging over 40–320 mg/kg/day. The minimal rate of infusion required to produce consistent defleecing was 80 mg/kg/day; infusions at a rate of 60 mg/kg/day were sometimes effective for defleecing, but at 40 mg/kg/day produced no discernible effects on the strength of wool fibres. No adverse effects were observed at a mimosine infusion rate of 80 mg/kg/day, but one out of four sheep died when dosed at a rate of 160 mg/kg/day, and higher rates (240 and 320 mg/kg/day) were lethal. The concentration of mimosine in plasma was related to the rate of infusion of mimosine. Consistent defleecing was associated with a concentration of mimosine in plasma approaching 100 µmoles/l; lethal doses resulted in plasma mimosine concentrations above 300 µmoles/l. Abomasal infusions of mimosine at a rate of 80 mg/kg/day were equivalent to intravenous infusions. Single injections of mimosine into the abomasum did not influence the strength of wool fibres; pIasma concentrations foIlowing injections indicated rapid absorption of mimosine and rapid removal from the body.

Sign in / Sign up

Export Citation Format

Share Document