Greasy Wool Weight Research Articles

Effects of Sumac (Rhus coriaria) Seeds and Exogenous Fibrolytic Enzymes on Wool Growth of Awassi Male Lambs

Nutrition can have a significant effect on animal production. In recent years, many compounds have been widely used as feed additives to stimulate animals’ appetites and consequently improve animal productivity. Exogenous fibrinolytic enzymes are one of these feed additives, which have been used as a digestive stimulant in different types of animals. Sumac (Rhus coriaria) seeds and leaves have been widely used as an appetite stimulant. Therefore, this study aimed to determine the dietary effects of using 0.3% exogenous fibrolytic enzymes and 3% of grinds Rhus coriaria seeds on wool production and some physical traits of the Awassi lambs. Twenty-four male Awassi lambs with an average age of 4 months were randomly assigned to four dietary treatments, each containing six animals. The control group received a basal diet equivalent to 2% of body weight. The second group received the same diet supplemented with 3% sumac (Rhus coriaria) powder. The third group received the basal diet supplemented with 0.3% exogenous fibrolytic enzymes (protease, amylase, and cellulase). The fourth group received the basal diet supplemented with both 3% Rhus Coriaria powder and 0.3% exogenous fibrolytic enzymes. The experiment lasted 130 days in the animal house belonging to the College of Veterinary Medicine in Iraq. Some wool traits, including wool staple length, clean wool weight, greasy wool weight, wool fiber length, and wool fiber diameter, were measured. The results revealed significant differences in all measured wool quality traits among the treated groups compared to the control group. The group receiving the diet supplemented with a combination of exogenous fibrolytic enzymes and Rhus coriaria powder exhibited the most significant improvements in wool growth, overall wool production, and physical characteristics. These findings highlight the potential of using exogenous fibrolytic enzymes and sumac as effective appetite stimulants and enhancers of wool production in Awassi lambs.

Five SNPs Within the FGF5 Gene Significantly Affect Both Wool Traits and Growth Performance in Fine-Wool Sheep (Ovis aries).

Fibroblast growth factor 5 (FGF5) gene, a member of fibroblast growth factor superfamily, plays significant roles in the regulation of the hair growth cycle during the development of mammalian hair follicles as well as the skeletal muscle development. In this study, DNA sequencing was used to scan the putative SNPs within the full-length of FGF5 gene, and SNPscan high-throughput technique was applied in the individual genotyping of 604 crossbred sheep. 10 SNPs were identified within FGF5 gene while five of them located in intron 1 could be genotyped, namely SNP1 (g. 105914953 G > A), SNP2 (g. 105922232 T > C), SNP3 (g. 105922244 A > G), SNP4 (g. 105922334 A > T) and SNP5 (g. 105922340 G > T). All these SNPs were in accord with the Hardy-Weinberg equilibrium (P > 0.05), and displayed the moderate polymorphism with PIC values ranging from 0.302 to 0.374. Thereafter, the correlation analysis between each SNP locus and economic traits including wool length, greasy wool weight and growth performance of sheep was systematically implemented. In our results, SNP1, SNP3, SNP4 and SNP5 were significantly associated with wool length, greasy wool weight and growth traits of SG sheep (P < 0.05); SNP1, SNP2, SNP3, and SNP4 were significantly correlated with wool length and growth traits of SSG sheep (P < 0.05). Meanwhile, our study revealed a strong linkage disequilibrium (LD) relationship among these SNPs (r2 > 0.33), except for SNP3 and SNP4 sites (r2 = 0.30). Combination genotype analysis showed that combination genotypes were significantly associated with mean fiber diameter of SG (P < 0.05), and body weight trait of SSG (P < 0.01). The above findings suggested that these SNP loci might affect economic traits synergistically and could be regarded as potential molecular markers for improving both wool production and growth performance of fine-wool sheep, which lay a molecular foundation for the breeding of fine dual-purpose sheep thereby accelerating the pace of sheep breeding.

Farklı Yetiştirici Koşullarında Norduz Koyunlarının Kırkım Sonu Canlı Ağırlığı ve Kirli Yapağı Verimi

In this study, the live weight after shearing, the greasy wool weight and, the clean fleece percentage of Norduz ewes in different breeding conditions were investigated. The animal material consisted of a total of 260 head of Norduz ewes including 52 head ewes at the different flocks raised in Dolayli (farm 1), Gecerli (farm 2), Geziyurt (farm 3), Oguldami (farm 4) and, Tasinacak (farm 5) neighbourhoods of Gurpinar province in Van city. Norduz ewes were sheared using shearing scissors between end of June and beginning of July. After shearing, ewes were weighted by using electronic digital weighing scale. Then, the sampling for clean fleece percentage were performed from area of the last rib on the right shoulder of 12 head of ewes in each flock. When all the farms were generally evaluated, the effect of live weight after shearing on the greasy wool weight was statistically significant (p<0.01). Least squares means for greasy wool weight at farm 1, farm 2, farm 3, farm 4 and, farm 5 were 2.03, 2.05, 2.05, 2.06 and, 2.06 kg, respectively. When all the farms were generally evaluated, the effect of age of ewe and farm on the live weight after shearing was statistically significant (p<0.01) in Norduz ewes. Least squares means for live weight after shearing at Dolayli, Gecerli, Geziyurt, Oguldami and, Tasinacak neighbourhoods were 53.21, 54.30, 51.25, 55.08 and, 54.93 kg, respectively. Means of clean fleece percentage were 64.25%, 67.76%, 63.50%, 66.68% and, 64.06% for Dolayli, Gecerli, Geziyurt, Oguldami and, Tasinacak neighbourhoods, respectively.

Ectopic expression of FGF5s induces wool growth in Chinese merino sheep

Fibroblast growth factor 5 (FGF5) has been recognized as an inhibitor to cease animal hair growth, while in contrary, FGF5 short alternative transcript (FGF5s) can induce hair growth by antagonizing FGF5 function. To investigate the role of FGF5s in wool growth in Chinese Merino sheep, we generated transgenic sheep of ectopic expression of FGF5s by injection of recombinant lentivirus into zygote. Totally 20 transgenic sheep were obtained and 12 were alive after birth. Characterization of the transgene revealed that the transgenic sheep showed variety of integrant, ranged from 2 to 11 copies of transgene. The ectopic expression of FGF5s was observed in all transgenic sheep. Further study on the effect of ectopic expression of FGF5s revealed that the wool length of transgenic sheep were significantly longer than that of non-transgenic control, with 9.17cm of transgenic lambs versus 7.58cm of control animals. Notably, besides the increase of wool length, the yearling greasy fleece weight was also concordantly greater than that of wild-type (p<0.01), with 3.22kg of transgenic sheep versus 2.17kg of control lambs (p<0.01) in average. Our results suggested that overexpression of FGF5s could stimulate wool growth and resulted in increase of wool length and greasy wool weight.

The Effects of Use Nigella Sativa and / or Trigonella Foenum Graecum Seeds as Feed Supplemtations on Some Wool Growth and Its Physical Traits of Awassi Male Lambs

The experiment was carried out at animal farm, College of Veterinary Medicine, Baghdad University from 1/July /2009 up to 28/February2010.Twenty Awssi male Lambs were equally divided into four groups and each animal fed on concentrate diets 2% of body weight with grazing for 3-5 hours a day. The first group(C) was kept as control group , the second group (N) was daily fed with same amount of concentrate diet contain 7.5% ground Nigella sativa seeds , third group (F) also fed with same amount contain 7.5% ground fenugreek seeds ,while the fourth group(NF) group fed the 2% concentrate diet supplemented with both (7.5% of Nigella sativa and 7.5% fenugreek seeds respectively ) as group feeding .The results revealed that using Nigella sativa or Fenugreek seeds as well as using both of them as a mixed feed supplemented with concentrated diet of Awassi ram lambs showed significantly ( P&lt; 0.05 ) increasing and improvements in greasy wool weights , clean wool weights ,wool fiber lengths ,wool staple lengths ,wool fiber diameters compare with control group while NF group recorded significantly ( P&lt; 0.05 ) higher than both of F and N groups in all of these parameters.

Legumes, herbs or grass for lamb performance?

Lamb performance was evaluated for three consecutive summer-early autumn periods on ryegrass (Lolium perenne), white clover (Trifolium repens), chicory (Cichorium intybus), plantain (Plantago lanceolata) or lotus (Lotus corniculatus). Lamb liveweight gains, fasted liveweights at slaughter and hot carcass weights tended to be highest on legumes and chicory and lowest on plantain and ryegrass. Greasy wool weights were significantly higher on lotus and white clover than on chicory, plantain and ryegrass. Greasy wool weight was significantly related to fasted liveweight (R2=0.94-0.99). Protein (%) in herbage accounted for 83-92% of the variability in animal performance; food intake accounted for 57-69% of the variability and was negatively correlated with hemicellulose and cellulose (R2=97.2 and 80.9%, respectively). Thus quality of feed was more important than intake alone in determining animal performance. Keywords: carcass weight, Cichorium intybus, greasy wool weight, intake, lamb performance, Lotus corniculatus, Lolium perenne, Plantago lanceolata, Trifolium repens

Assessing Wiltshire Horn-Merino crosses. 1. Wool shedding, blowfly strike and wool production traits

Wiltshire Horn-Merino (WH-M) crosses of 1/2, 5/8 and 3/4 Merino content were compared over 10 years for wool shedding, blowfly strike frequency and wool production traits. Merinos and 1/2 Merino WH-M were compared over 4 years. For wool production traits, 1/2 and 5/8 Merino WH-M ewes were compared to Border Leicester-Merino (BL-M) ewes over 2 years. Shedding increased with age for all WH-M genotypes, with 3/4 Merinos showing less shedding than 1/2 Merinos at all ages. At 1 and 2 years of age, 5/8 Merinos were intermediate between the other 2 WH-M genotypes, but at later ages they were similar to 1/2 Merinos. All genotypes showed less shedding at the belly site than the head, neck and breech as lambs, but not at older ages. Phenotypic correlations between sites on the same sheep were high, averaging 0.85. Repeatability estimates for each site ranged from 0.26 to 0.45. Shedding increased most with age in the 1/2 Merinos, and least in the 3/4 Merinos. Little or no shoulder and back wool was shed by most sheep. All 1/2 and 5/8 Merinos and most 3/4 Merinos had bare legs and points. Blowfly strike incidence was far higher in Merinos than 1/2 Merinos, in all years. Among WH-M, blowfly strike incidence increased as Merino content increased, in all years. All WH-M were far inferior to both Merinos and BL-M in total greasy wool weight and all its components, and also in clean fleece weight, with their level of inferiority increasing as their Merino content declined. Wool fibre diameter for all WH-M was coarser than for Merinos, but was a little finer than for BL-M. Fibre diameter increased in the WH-M as their Merino content declined. All WH-M had lower wool yields than the Merinos or BL-M. In some years the 314 Merinos had lower wool yields than the 1/2 and 5/8 Merinos, which were similar in all years. Shedding caused numerous genotype x age interactions in wool weight and its components, as Merinos and BL-M did not shed, and with the WH-M shedding increased most with age in the 1/2 Merinos, and least in the 3/4 Merinos. Due to preferential shedding from the belly and other low-value areas, the WH-M inferiority in total wool weight was less severe for fleece weight. Winter shearing succeeded in harvesting some wool from WH-M that would be shed before a summer shearing, but not enough to alter rankings among genotypes. All WH-M genotypes have wool too coarse, and not enough of it, to compete as a wool sheep with the Merino at current wool prices under usual Australian pastoral conditions. In areas where mustering is difficult or blowfly strike unusually severe, WH-M genotypes may find a niche.

Differences between strains of Bacteroides nodosus in their effects on the severity of foot-rot, bodyweight and wool growth in Merino sheep.

The effects of 3 ovine and one bovine strains of Bacteroides nodosus on the severity of foot-rot, bodyweight and wool growth were compared in Merino sheep in a field experiment. Based on the severity of the induced foot lesions, one strain was classed as virulent (causing underrunning lesions in most feet), one was benign (causing lesions of the interdigital skin only), and 2, including the bovine strain, were of intermediate virulence (causing underrunning lesions in a small proportion of feet). Differences among strains in their effect on foot-rot severity and bodyweight were significant when compared over the whole experimental period, but were not significant at any single time of measurement, because of large differences between replicates. Bodyweight loss and severity of foot-rot caused by the virulent strain were significantly greater than that caused by the benign strain. The intermediate strains lay between these 2 extremes in terms of both bodyweight and foot-rot scores but were not significantly different from either in a statistical sense. Total greasy wool weight did not differ among groups over the whole experiment, but the rate of wool growth during the period when foot lesions were most prevalent and severe was reduced appreciably by the virulent strain and to a lesser extent by the intermediate strains.

Response to selection in Australian Merino sheep. VI. Inheritance of abnormal staple crimp; estimates of phenotypic and genetic parameters

The heritability of abnormal crimp in wool at various ages and the genetic and phenotypic cotreiations of crimp abnormality with several wool and body characters were estimated for Peppin Merino sheep. When examined by half-sib analyses of variance, the heritability of abnormal crimp scored at ages less than 4.5 years was low, whereas abnormality at 5.5 years and older was highly inherited. Heritabilities estimated by intra-sire dam-daughter regression analyses with fewer degrees of freedom did not show such a clear-cut pattern, although the estimates tended to increase with age. The genetic correlations of crimp abnormality scores at ages up to 4.5 years with scores at older ages were mainly low. Crimp abnormality scores at most ages had genetic correlations with wool and body characters at 15–16 months of age as follows: strong positive with fibre diameter, weak positive with greasy and clean wool weight, wrinkle score and staple length, and weak negative with fibre number. Genetic correlations with body weight, percentage clean yield, face cover score and crimp frequency were inconsistent. The phenotypic variance of crimp abnormality increased with age, owing almost entirely to an increase in the additive genetic variance. The environmental variance was approximately the same at all ages. Phenotypic correlations among crimp abnormality scores were generally higher between scores at close ages, and particularly at older ages. Crimp abnormality scores at all ages had positive phenotypic correlations with fibre diameter and wrinkle score and negative correlations with fibre number per unit area of skin and percentage clean yield.Crimp abnormality at old ages also had positive phenotypic correlations with greasy and clean wool weights. Environmental correlations of crimp abnormality with greasy wool weight, clean wool weight body weight and fibre number per unit area of skin were negative, and those with percentage clean yield and fibre number positive. Predicted correlated responses in crimp abnormality differed in some respects from correlated responses observed previously in groups of Peppin Merino sheep selected for high and low values of percentage clean yield, clean wool weight, fibre number per unit area of skin and fibre diameter. Methods of selection of sheep which would be expected to reduce crimp abnormality are outlined.

Effect of implanted testosterone propionate on the growth and wool production of Merino wethers

The effect of subcutaneous implantation of testosterone propionate in fine-wool Merino wethers at pasture was studied in four experiments over a 5-year period. The wethers were maintained virtually free of posthitis so that the observed responses to implantation were physiological in origin. In nine comparisons two implants of 70 mg testosterone propionate per annum increased liveweights significantly. Annual greasy wool weights increased by amounts ranging from 0.03 to 0.25 kg per head, the differences being significant on five occasions. Annual clean wool weights increased by a maximum of 0.13 kg per head. Fleece weight indices used as a measure of the gross efficiency of wool production were similar in the implanted and control wethers in all experiments. Also no significant change in efficiency was recorded where direct measurements were made of wool grown and food intake. Implantation tended to reduce the percentage yield of clean wool, the effect being greatest in the first year of treatment. Measurement and assessment of wool traits of commercial importance showed negligible differences between treated and control wethers and the average value per kilogram greasy wool was similar.

Genetic and phenotypic parameters for wool characteristics in fine-wool Merino, Corriedale, and Polwarth sheep. II. Phenotypic and genetic correlations, heritability, and repeatability

Estimates of heritability, repeatability, and phenotypic and genetic correlations were calculated from data involving about 1050, 720, and 250 dam-daughter pairs for Merino, Corriedale, and Polwarth breeds respectively; data on daughters were taken at both 18 and 30 months of age. Phenotypic and genetic correlations in general were of the same order of magnitude and similar between breeds; the estimates substantiated the results obtained by other workers. Estimates of repeatability of most fleece traits between 18 and 30 months of age were significantly lower than estimates based on later ages. However, the differences were not large, and the use of a single figure for repeatability, either the younger age estimate or a pooled estimate, would give a reliable prediction for subsequent performance. Estimates of heritability of all traits in each breed were high; however, the heritabilities of greasy and clean wool weights of Merino and Polwarth ewes were about 40% smaller at 18 months than at 30 months, the estimates at 30 months being generally similar to previous estimates at 18 months. Relative to selection at 18 months, wool production, either greasy or clean, would increase at a greater rate per annum with selection of Merinos and Polwarths at 30 months; for Corriedales, selection at 30 months is more efficient for greasy, but not for clean wool production.

The wool production and liveweight of wethers in relation to stocking rate and superphosphate application

In an experiment lasting three years in the Upper Goulburn Region of Victoria, Merino wethers grazed at from 2 to 8 an acre on plots to which 50, 150, or 250 lb of superphosphate an acre was applied annually. The land had previously received about 1800 lb an acre superphosphate. Mean live weights were recorded monthly and mean clean wool production calculated annually from greasy wool weights and the yield of clean scoured wool from a mid-side sample. In the third year of the experiment, but not the earlier years, mean minimum live weight and mean clean wool production were greater where 150 and 250 lb of superphosphate an acre was applied than where 50 lb an acre was applied. Mean clean wool production per sheep was closely related to mean minimum live weight in all years.

Relationships between body weight and some follicle and fleece characters in an Australian fine-wool Merino flock

Phenotypic correlations between body weight, follicle characters, and fleece characters have been investigated in a flock of 95 fine-wool non-Peppin Merino wethers, reared in the same locality under the same conditions. The results indicated that three follicle characters, follicle chord, follicle depth, and the index of follicle bending, were independent of body weight. It was found, in agreement with the results of other workers, that body weight was highly correlated with both greasy and clean wool weights (r = 0.53 and 0.51 respectively). It was also found that follicle characters were significantly correlated with most of the fleece characters which contribute to the clean fleece weight per unit area of skin. The correlation coefficient of wool weight per unit area of skin with follicle chord was 0.33, with follicle depth 0.28, and with follicle bending index –0.35. The follicle characters were also correlated with greasy and clean fleece weights. Crimp number per inch was predicted for individual animals by using as criterion the length of the follicle chord. A highly significant correlation coefficient of 0.67 was obtained between predicted and observed crimp number. The close relationship between crimp chord and follicle chord reported in previous work was confirmed. It is suggested that simultaneous selection for body weight and certain follicle characters may have an additive effect on the production of clean wool. It is also suggested that the genetic antagonism between clean wool weight and number of crimps per inch can be explained in anatomical terms.

Corrigendum - Response to selection in Australian Merino sheep. I. Selection for high clean wool weight, with a ceiling on fibre diameter and degree of skin wrinkle. Response in wool and body characteristics

Direct and correlated responses are reported for two groups of sheep selected for high clean wool weight. The work covers two periods. In the first (1950–59), both groups had selection against high average fibre diameter and high degree of skin wrinkle, but in one group (S) the performance of the ram's half-sibs was considered as well as his own, while in the other (MS) mass selection was practiced for rams. For ewes, mass selection was practiced in both groups. In the second period (1961–64), mass selection was used for both sexes in both groups, with selection against high diameter and degree of wrinkle in one group (S), and against low crimp frequency and high degree of wrinkle in the other (MS). In both periods response to selection was assessed by comparison with a random control group. In the first period, response in clean wool weight was similar in S and MS, both for rams measured at 10–11 months, when a preliminary selection on them was carried out, and for ewes measured at 15–16 months, when final selection was made for both sexes. The annual rates of increase in clean wool weight for S and MS were 2.1 and 1.8% for rams and 2.4 and 2.7% for ewes, the lower rate in rams being due to the fact that response at 10–11 months is a correlated response to the final selection at 15–16 months. As the rates of increase in the two groups are similar, it can be concluded that examination of half-sibs is not worth while; this would in fact have been predicted from the high heritability estimates for clean wool weight. There were negligible trends in fibre diameter and wrinkle score, indicating that counter-selection has been effective in preventing an increase in these characteristics. Fibre number per unit skin area made the greatest contribution to the increases in clean wool weight, the annual rates of increase for S and MS being 2.0 and 2.2% for rams and 2.0 and I .8% for ewes. Greasy wool weight, percentage clean yield, body weight, and staple length also showed increases with increasing clean wool weight in both selected groups. In spite of the fact that fibre diameter did not increase, crimp number per unit of staple length decreased in both groups. This is a further confirmation of the strong negative genetic correlation between clean wool weight and crimp number, and of the lack of a strong association between crimp number and fibre diameter. In the second period, no further response was observed. It is impossible to say at this stage whether a selection plateau has been reached or whether drought conditions interfered with response.

Response to selection in Australian Merino sheep. I. Selection for high clean wool weight, with a ceiling on fibre diameter and degree of skin wrinkle. Response in wool and body characteristics

Direct and correlated responses are reported for two groups of sheep selected for high clean wool weight. The work covers two periods. In the first (1950–59), both groups had selection against high average fibre diameter and high degree of skin wrinkle, but in one group (S) the performance of the ram's half-sibs was considered as well as his own, while in the other (MS) mass selection was practiced for rams. For ewes, mass selection was practiced in both groups. In the second period (1961–64), mass selection was used for both sexes in both groups, with selection against high diameter and degree of wrinkle in one group (S), and against low crimp frequency and high degree of wrinkle in the other (MS). In both periods response to selection was assessed by comparison with a random control group. In the first period, response in clean wool weight was similar in S and MS, both for rams measured at 10–11 months, when a preliminary selection on them was carried out, and for ewes measured at 15–16 months, when final selection was made for both sexes. The annual rates of increase in clean wool weight for S and MS were 2.1 and 1.8% for rams and 2.4 and 2.7% for ewes, the lower rate in rams being due to the fact that response at 10–11 months is a correlated response to the final selection at 15–16 months. As the rates of increase in the two groups are similar, it can be concluded that examination of half-sibs is not worth while; this would in fact have been predicted from the high heritability estimates for clean wool weight. There were negligible trends in fibre diameter and wrinkle score, indicating that counter-selection has been effective in preventing an increase in these characteristics. Fibre number per unit skin area made the greatest contribution to the increases in clean wool weight, the annual rates of increase for S and MS being 2.0 and 2.2% for rams and 2.0 and I .8% for ewes. Greasy wool weight, percentage clean yield, body weight, and staple length also showed increases with increasing clean wool weight in both selected groups. In spite of the fact that fibre diameter did not increase, crimp number per unit of staple length decreased in both groups. This is a further confirmation of the strong negative genetic correlation between clean wool weight and crimp number, and of the lack of a strong association between crimp number and fibre diameter. In the second period, no further response was observed. It is impossible to say at this stage whether a selection plateau has been reached or whether drought conditions interfered with response.

Vital statistics for an experimental flock of Merino sheep. V. The effects pf age of ram, maternal handicap, and year of measurement on 10 wool and body characteristics for unselected rams

Estimates were made of the effects of the following factors on 10 fleece and body characteristics measured on rams aged 1½ to 5½ years in a randomly bred control flock, for rams born 1953 to 1957 inclusive: age of ram, single or twin birth, age of dam, and the year in which measurements were made. Changes with age were present in all characteristics and the ranges of the age deviations from the overall mean were larger in magnitude than the corresponding figures for ewes. Greasy and clean wool weights showed a similar pattern of change with age as ewes. For greasy wool weight the age deviation increased from –2.4 lb at 1½ years to 1.1 lb at 3½ years and then declined to 0.5 lb at 5½ years of age. The corresponding figures for clean wool weight were –0.7 to 0.5 lb. falling to –0.2 lb at 5½ years of age. Other characteristics showed different patterns of change with age from the corresponding figures for ewes. Staple length, crimps per inch, yield, and fibre population density decreased with age over the range available, whilst face cover, body weight, fibre diameter, and wrinkle score increased. The fitted mean difference in clean wool weight between rams and ewes was 33%, largely attributed to differences in body area (25%) with a smaller contribution from staple length (7%). Twin-born rams cut 0.28 lb of clean wool weight per year less than single-born rams over the five shearings, whilst the progeny of 2-year-old dams did not differ significantly from the progeny of adults. Large between-year differences occurred for most characteristics. For clean wool weight the range was from –1.52 to 1.44 lb, fibre volunme being the most important component, while for body weight the range was –18.6 to 19.7 lb.

Genetic and phenotypic relationships between fertility and wool production in 2-year-old Merino sheep

Records of the lambing and weaning performance (fertility) of 2-year-old Peppin Merino ewes were analysed. Repeatability and heritability of number of lambs born and weaned were low. Heritability of number of lambs born was significantly different from zero (0.20 ± 0.10). Phenotypic and genetic correlations between the fertility traits and greasy wool weight, all measured at approximately 15 months of age, were calculated. Phenotypic correlations between number of lambs born or weaned and greasy wool weight were negative and significant. The phenotypic correlation between number of lambs weaned and clean wool weight was negative and significant. Significant negative genetic correlations were found between number of lambs born and both greasy wool weight and clean wool weight. Genetic correlations between number of lambs weaned and the fleece and body traits had very large standard errors. The results were used to estimate correlated responses in fertility resulting from selection for greasy wool weight, clean wool weight, and body weight of –0.08i, –0.13i, and 0.03i respectively.

The effects of inbreeding, maternal handicap, and range in age on 10 fleece and body characteristics in Merino rams and ewes

Estimates have been made of the influence on 10 fleece and body characteristics of dam's phenotype, range in age of offspring, inbreeding of offspring and dam, type of birth of offspring, and age of dam. The data came from rams 10–11 months old and ewes 15–16 months old, which had previously been shorn as weaners; the animals belong to an unselected control flock run at Cunnamulla, south-western Queensland. The dam's phenotype showed a high positive relationship with that of her offspring in all 10 characteristics, the values of the regression coefficients confirming the levels of heritability previously estimated on the same flock but without removing all the effects included in the present analysis. Younger animals in a group had lower greasy and clean wool weights and body weights, even at 15–16 months, but the effects were slight, except for body weight. For each 1% increase in the offspring's own level of inbreeding, the regression coefficients for rams and ewes respectively were -0.042 and –0,051 lb for greasy wool weight, –0.025 and –0.025 1b for clean wool weight, and –0.431 and –0.541 1b for body weight. These figures represent a decrease of 5–10% in clean wool weight and 8–10% in body weight for the progeny of half-sib matings. Inbreeding of the dam had a negligible effect on the characteristics examined. Animals born in multiple births in this environment suffer penalties which were still evident up to 15–16 months of age, resulting in both sexes in lower wool and body weights, lower wrinkle scores, fewer fibres per unit skin area, and fewer crimps per inch of staple. Fibre diameter was slightly higher for the multiple birth animals, but �he signs for the effects on other characteristics differed between sexes. The handicaps for rams and ewes respectively were 9 and 5% for clean wool weight and 7 and 5% for body weight. Dams were separated into four age groups (2, 3, 4–7, and 8–10 years). Greasy and clean wool weights and wrinkle score rose for offspring of both sexes to a peak at 4–7-year-old dams, then fell slightly. Body weight reached a peak at 3 years for rams and 4–7 years for ewes, while fibre diameter and staple length reached a peak at 3 years for ewes and 4–7 years for rams. In no case was the fall for the older dam age groups sufficient to invalidate the usual practice of adjusting only the progeny of 2-year-old dams. Other characteristics showed no consistent pattern.

Vital statistics for an experimental flock of Merino sheep. III. Factors affecting wool and body characteristics, including the effect of age of ewe and its possible interaction with method of selection

Estimates were made of the effects of the following factors on 10 fleece and body characteristics measured on breeding ewes aged 1½ to 10½ years in three mating groups over a period of 15 years: age of ewe, single or twin birth, age of dam, the ewe's own lambing performance, the year in which measurements were made, and the year in which each set of ewes was born. Two groups (S and MS) were under selection for high clean wool weight at 15–16 months, with a ceiling on wrinkle score and fibre diameter, while the third (C) was a random control. Changes with age were present in all characteristics and were similar in the three groups. The finding that selection on wool weight at an early age had no effect on subsequent age changes in any characteristic is of considerable importance. Greasy and clean wool weight reached a maximum at 34 years, then declined by 0.3–0.2 1b per year. Percentage clean yield, fibre diameter, body weight, and wrinkle score had maxima at 5½ to 6½ years. Staple length fell consistently by approximately 0.2 cm per year, while face cover rose consistently but slightly. Crimp number rose, fell, and rose again, while fibre number rose, fell, and remained constant from 4½ years. The chief source of increase in wool weight from l½ to 3½ years was an increase in the total number of fibres. The chief source of the subsequent fall was a decrease in fibre volume, with a minor contribution from a fall in total fibre number after 6½ years. Twin-born ewes cut 0.21 lb (4.2% of the mean) less clean wool per year over their lifetime than single-born ewes, while the progeny of 2-year-old ewes cut 0.32 lb (6.4%) less than the progeny of adults. The main source of lower weight in each case was a lower total fibre number. Pregnancy lowered clean wool weight more than lactation, the separate effects being 0.87 and 0.38 lb respectively (17.4 and 7.7% of the mean) and the combined effect 1.25 1b or 25.1%. Pregnancy lowered total fibre number but lactation had no further effect. Mean clean wool weights over all ages in the C group varied from year to year, the range being from 1.08 lb (21.6%)below the mean to 0.97 lb (19.4%) above. Differences in total fibre number contributed between one-third and two-thirds of the variation. Ewes born in consecutive years in the S and MS groups showed marked upward trends in clean wool weight, fibre number, and staple length, with a marked downward trend in crimp number and a slight upward trend in body weight. These trends demonstrate direct and correlated responses to the strong selection for high clean wool weight at 15–16 months of age, and the associated slight selection against fibre diameter and wrinkle score. The mean annual increases in clean wool weight were 0.15 and 0.11 Ib (3.0 and 2.2%) in the S and MS groups, approximately 40% of the increase arising from increased total fibre number and 40% from increased staple length. The effects of age and lambing performance can be used to predict productivity in flocks of differing age structures. As the casting age rises to 54 years changes in productivity are negligible. With a rise in casting age to 7½ years the average clean wool weight of the flock would fall by 0.14 lb, with a slight decrease in staple length and crimp number. These changes need to be balanced against any increased lambing percentage or decreased annual genetic gain due to increased generation interval. Comparison with other available figures indicates that age changes may vary from one area to another.

Genetic and phenotypic parameters for body weight and greasy fleece weight at weaning in Australian Merino sheep

Genetic and phenotypic parameters for body weight and greasy fleece weight at weaning were estimated in a flock of Australian Merinos. Maternal handicaps were found to be more severe at weaning than at the older age of 15–16 months. Lambs born to 2-year-old ewes were 2–3 lb lighter in body weight at weaning and 0.2 lb lighter in greasy fleece weight than the offspring of adult ewes. Twin lambs were on the average 6–7 lb lighter than singles and cut 0.5 lb less greasy wool. Greasy fleece weight at weaning was found to be fairly highly heritable but only moderately repeatable. The repeatability and heritability of weaning body weight were both low. The genetic correlations estimated here were associated with appreciable sampling errors, but the estimates strongly suggested high and positive correlations between measurements at weaning and at 15–16 months for both traits. A general consideration of the relative efficiency of direct versus indirect selection, based on the information obtained in this study, leads to the conclusion that for greater genetic gains, mass selection for greasy wool weight and body weight at weaning should be carried out on measurements at 15–16 months of age, rather than at weaning.