Wool growth responses to DL-methionine administration and factors affecting the value of supplementation

1991 ◽  
Vol 31 (4) ◽  
pp. 471 ◽  
Author(s):  
RGA Stephenson ◽  
GR Suter ◽  
CJ Howitt
Keyword(s):  
Fibre Diameter ◽  
Growth Responses ◽  
Rhodes Grass ◽  
Factors Affecting ◽  
Net Return ◽  
Wool Production ◽  
Wool Growth ◽  
Treatment Analysis ◽  
Positive Correlations ◽  
The Cost

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.

Effects of defaunation of the rumen and supplementation with amino acids on the wool production of housed Saxon Merinos. 2. Methionine and protected methionine

1988 ◽  
Vol 28 (2) ◽  
pp. 179 ◽  
Author(s):  
DJ Cottle
Keyword(s):  
Amino Acids ◽  
Fibre Diameter ◽  
High Energy ◽  
Previous Trial ◽  
Growth Responses ◽  
Wool Production ◽  
Low Protein ◽  
Wool Growth ◽  
Protein Diets ◽  
Ciliate Protozoa

In experiment 1, 6 groups, each of 10 superfine Merino wethers, were individually penned indoors and hand-fed oats, wheat straw and whole lupins, either alone or with 2 g/day of DL-methionine or 6.6 g/day of fatty acid coated methionine (Ketionin) for 23 weeks. Following shearing the 6 groups were hand-fed lucerne-chopped hay in experiment 2 either alone or with hydroxymethyl-methionine (Mepron) or Ketionin for 23 weeks. In both experiments the rations were fed at maintenance level and were offered 3 times a week. Half of the sheep had no rumen ciliate protozoa following treatment in a previous trial. In experiment 1, defaunated sheep produced an additional 6.5%clean wool on the supplemented oats plus lupins rations. Inclusion of Ketionin in the ration of defaunated sheep resulted in an 11% increase in clean wool growth, without affecting wool quality. In experiment 2 defaunated sheep produced an additional 6% clean wool on the lucerne-chopped hay ration. No responses to defaunation occurred on the supplemented rations. Inclusion of both forms of protected methionine in the ration (providing 2 g methionine/sheep.day) resulted in 23% and 13% higher clean wool production in the faunated and defaunated sheep respectively. Fibre diameter of wool was increased by 0.7 pm in sheep receiving Mepron and 0-5 pm in sheep receiving Ketionin. The wool grown by suppiemented sheep remained suitable for the 'Sharlea' trade (< 17.5 �m). It is concluded that wool growth responds more to defaunation on high energy-low protein diets. Wool growth responses to supplementation with protected methionine were greater on 100% roughage diets than on high grain diets. Further study is needed before an optimal ration for superfine wool production is formulated.

Factors differentiating between high and low wool producing sheep in western Queensland

1992 ◽  
Vol 43 (6) ◽  
pp. 1367
Author(s):  
DA Pritchard ◽  
PK O'Rourke
Keyword(s):  
Linear Growth ◽  
Phenotypic Expression ◽  
Fibre Diameter ◽  
Live Weight ◽  
Unit Surface Area ◽  
Growth Responses ◽  
Wool Production ◽  
Pasture Quality ◽  
Wool Growth ◽  
Commercial Flock

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.

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.

Effects of defaunation of the rumen and supplementation with amino acids on the wool production of housed Saxon Merinos. 3. Cottonseed meal and hydroxymethyl-methionine

1988 ◽  
Vol 28 (6) ◽  
pp. 699 ◽  
Author(s):  
DJ Cottle
Keyword(s):  
Amino Acids ◽  
Cottonseed Meal ◽  
Growth Response ◽  
Fibre Diameter ◽  
Diameter Ratio ◽  
Design Experiment ◽  
Growth Responses ◽  
Wool Production ◽  
Wool Growth ◽  
Ciliate Protozoa

In experiment 1 six groups, each of 10 superfine Merino wethers were individually penned indoors and hand-fed chopped lucerne hay with either control pellets, cottonseed meal pellets (CSM) or cottonseed meal plus hydroxymethyl-methionine pellets (CSMEP). Following their shearing, the 6 groups in experiment 2 were hand-fed 1 of 3 chopped lucerne hay:oat rations [75: 25,50: 50,25: 75% (w/w)]. Each sheep was also fed either control pellets (25 g/day) or CSMEP pellets (75 g/day) in a cross-over design experiment. In both experiments, the rations were fed at maintenance level and were offered 3 times a week. Half of the sheep had no rumen ciliate protozoa. In experiments 1 and 2, wool production was measured during a 4 and 6 month period respectively. In experiment 1, defaunation resulted in a 6% increase in clean wool production on the unsupplemented chopped lucerne hay ration. Inclusion of CSM and CSMEP pellets resulted in clean wool growth responses of 16% and 19% respectively. Unacceptable increases in fibre diameter were associated with the increased wool production. In experiment 2, the clean wool response to defaunation was highest (12%) on the 75% chopped lucerne hay ration, when the control pellet was fed. Inclusion of the CSMEP pellet resulted in clean wool growth responses of 0.73, 0.98 and 0.99 g/day in sheep fed on the 75,50 and 25% chopped lucerne hay rations respectively. The wool production responses due to the CSMEP pellet were associated with increases in fibre diameter (0.3 �m), length (4 mm/year) and length/diameter ratio (0.4 �m/day.�m) of the wool grown. It was concluded that CSMEP pellets are best fed with a mixed ration containing more grain than chopped lucerne hay. The wool growth response to feeding hydroxymethyl-methionine was considered uneconomic.

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.

Relationship of feed intake with cystine availability and wool growth in Merino wethers

1993 ◽  
Vol 44 (5) ◽  
pp. 973 ◽  
Author(s):  
GJ Lee ◽  
AJ Williams
Keyword(s):  
Sulfur Content ◽  
Fibre Diameter ◽  
Kinetics Model ◽  
Similar Proportion ◽  
Standard Diet ◽  
Growth Responses ◽  
Irreversible Loss ◽  
Wool Growth ◽  
Saturation Kinetics ◽  
The Relationship

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.

Effect of time of joining and rate of stocking on the production of Corriedale ewes in southern Victoria. 3. Wool growth and the composition and availability of pasture

1975 ◽  
Vol 15 (73) ◽  
pp. 159 ◽  
Author(s):  
PA Kenney ◽  
IF Davis
Keyword(s):  
Fibre Diameter ◽  
Late Pregnancy ◽  
The Other ◽  
Early Lactation ◽  
Stocking Rate ◽  
Wool Production ◽  
Wool Growth ◽  
The Mean ◽  
Brome Grass ◽  
Stocking Rates

A study was made during a three year period (1 968-1 970) of wool production by a flock of 540 ewes grazing annual pasture at Werribee, Victoria. The ewes were stocked at three rates (5, 7 1/2 and 10 ewes ha-1) and lambed between July 6 and August 20 or between September 10 and October 29 each year. Fibre diameter and length of wool samples were measured in 1968, 1969 and 1970 ; in 1970 growth of greasy wool was calculated from staples of dye-banded wool. Wool growth was reduced in all ewes during late pregnancy and early lactation but was not affected during late lactation in ewes lambing in September. The proportion of tender fleeces from all ewes was greater in 1970 and the weight of fleeces from only those ewes bearing single lambs was less in all years for ewes lambing in July than for ewes lambing in September. More ewes were barren and fewer ewes had twins in July and consequently the mean fleece weights of all ewes from both groups were similar. Fleeces from ewes stocked at 10 ha-1 were lighter, shorter and finer than fleeces from ewes stocked at 5 and 7 1/2 ha-1, but the proportion of tender fleeces did not differ between the groups. Wool production of ewes stocked at 5 and 7 1/2 ha-1 increased from 1968 to 1970, whereas that of ewes at 10 ha-1 did not. This was associated with differences in pasture availability and composition. At 10 ewes ha-1 less pasture was present in winter and spring in 1970 than in 1968, whereas at the other stocking rates it was greater. In 1970 the density of weeds in autumn was greater and in spring more silver grass (Vulpia spp.) and less brome grass (Bromus spp.) was available at the high stocking rate.

Nutrition during fetal life alters annual wool production and quality in young Merino sheep

1996 ◽  
Vol 36 (3) ◽  
pp. 259 ◽  
Author(s):  
RW Kelly ◽  
I Macleod ◽  
P Hynd ◽  
J Greeff
Keyword(s):  
Management Strategies ◽  
Fibre Diameter ◽  
The Body ◽  
Fetal Life ◽  
Maternal Weight ◽  
Wool Production ◽  
Maternal Undernutrition ◽  
Staple Strength ◽  
Pregnant Ewe ◽  
The Cost

The effect of maintenance v, submaintenance diets of pregnant ewes in 1991 and 1992 on establishment of the wool follicle population in their progeny, and its effect on the progeny's wool production (quantity, quality and variation across the body of the animal) to 1.4 years of age was examined. The experimental protocol used cloned animals created by bisecting embryos at day 6 of pregnancy. Each clone was placed in a ewe, which was subsequently fed from about day 50 to 140 of pregnancy at maintenance or submaintenance. Ewes on maintenance nutrition maintained liveweight throughout pregnancy, while submaintenance ewes were 12.1 kg lighter (P<0.001) 10 days before lambing. In 1991, a total of 74 lambs were born, including 17 sets of surviving clones. In 1992, 102 lambs were born, including 18 sets of surviving clones. Only data for the 35 sets of genetically identical 'twin' progeny and their dams are reported. Birth weights of lambs born to ewes fed at the submaintenance rate were 0.5 kg lighter (P<0.01) than their 'twins' born to ewes fed at maintenance. Midside secondary:primary (Sf: Pf) ratios for mature wool follicles were less (P<0.01) at birth, lamb and hogget shearing (1.4, 1.5 and 2.1 units respectively) for the progeny born to ewes fed at submaintenance. Progeny from ewes on the submaintenance treatment produced less clean wool, 0.1 kg to 0.4 years of age (P<0.01) and 0.14 kg between 0.4 and 1.4 years of age (P = 0.10), than their maintenance counterparts. Hogget wool was 0.1 pm broader (P<0.05), with a 0.5% units lower coefficient of variation of fibre diameter (P<0.01), and a position of break closer to the staple tip (P<0.001) for progeny of submaintenance ewes than their maintenance counterparts. There were no significant differences in yield, staple length, staple strength and percentage of fibres greater than 30 pm in diameter. Differences in mean fibre diameter arose between 1 and 1.4 years of age, coinciding with the period that the animals were grazing high quality pasture. Effects of maternal undernutrition on mean fibre diameter and Sf: Pf follicle ratios of progeny were most pronounced on the hind leg (P<0.01), and not significant on the front leg. However, variations in other wool quality traits across the body of the hoggets, expressed as a percentage of the midside value, were not significantly affected by maternal undernutrition. Clearly when evaluating management strategies for the pregnant ewe, the effect on lifetime production and quality of wool of their progeny needs to be considered. Merino hoggets that produce an extra 0.14 kg clean wool that is 0.1 pm finer will compensate for some extra management and feeding of their dams during pregnancy to prevent weight loss. If these effects continue throughout the life of the animal, then it will increase the cost effectiveness of feeding to maintain maternal weight over pregnancy.

The influence of protein quality on the effect of flavomycin on wool growth, liveweight change and rumen fermentation in sheep

1990 ◽  
Vol 41 (5) ◽  
pp. 987 ◽  
Author(s):  
PJ Murray ◽  
JB Rowe ◽  
EM Aitchison
Keyword(s):  
Protein Quality ◽  
Rumen Fluid ◽  
Initial Period ◽  
Fibre Diameter ◽  
Experimental Period ◽  
Feed Additive ◽  
Wool Production ◽  
Wool Growth ◽  
The Mean ◽  
Wheat Chaff

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.

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%).

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