Heavier Fleeces Research Articles

Productivity and Reproductive Performance of Mixed-Age Ewes across 20 Years of Selection for Ultrafine Wool in Uruguay

This study reports the phenotypic trends for wool, growth, and reproductive traits in mixed-age ewes after twenty years of genetic selection. Data were obtained from the Merino nucleus flock in Uruguay between 1999 and 2020. Overall, the aim of this selection flock was to reduce the fiber diameter (FD) and increase both the clean fleece weight (CFW) and live weight (LW). Data on ewe wool traits, LW, body condition score (BCS), the total number of lambs weaned (TLW), and the total LW of lambs weaned (TWW) across all lambing opportunities (1–8 mating seasons) were analyzed. Between 1292 and 2063 ewes were measured, depending on the trait considered. Ewe FD decreased by approximately 3 µm (19–16 µm), whereas greasy fleece weight (GFW) increased by 0.2 kg. This improvement in wool traits was accompanied by increases in LW at mating (3 kg), decreases in BCS at mating (approximately by 1 unit), and a small positive change in TWW across years. This study demonstrated that increasing farmer income by selecting for finer wool, heavier fleeces, and heavier animals can be obtained without compromising ewe lifetime reproduction.

A comparison of transcriptomic patterns measured in the skin of Chinese fine and coarse wool sheep breeds

We characterised wool traits, and skin gene expression profiles of fine wool Super Merino (SM) and coarse wool Small Tail Han (STH) sheep. SM sheep had a significantly higher total density of wool follicles, heavier fleeces, finer fibre diameter, and increased crimp frequency, staple length and wool grease (lanolin) production. We found 435 genes were expressed at significantly different levels in the skin of the two breeds (127 genes more highly in SM and 308 genes more highly in STH sheep). Classification of the genes more highly expressed in SM sheep revealed numerous lipid metabolic genes as well as genes encoding keratins, keratin-associated proteins, and wool follicle stem cell markers. In contrast, mammalian epidermal development complex genes and other genes associated with skin cornification and muscle function were more highly expressed in STH sheep. Genes identified in this study may be further evaluated for inclusion in breeding programs, or as targets for therapeutic or genetic interventions, aimed at altering wool quality or yield. Expression of the lipid metabolic genes in the skin of sheep may be used as a novel trait with the potential to alter the content or properties of lanolin or the fleece.

Correlated responses to selection for or against facial eczema susceptibility in Romney sheep in New Zealand

Genetic selection for or against susceptibility to facial eczema (FE) in Romney sheep began in 1975, with the establishment of a resistant (R) selection flock, a susceptible (S) selection flock, and later (in 1982) a control (C) flock. For all but the initial years, rams were identified by performance testing with a sporidesmin challenge, then ranked on relative elevation of the liver enzyme, gamma glutamyltransferase (GGT), measured in serum. A different dose rate of sporidesmin was used for performance testing in the R and the S flocks, with a balanced half of the C‐flock animals being tested at each dose rate. Results are reported here up to the 1997‐born lamb crop. Mixed‐model animal‐model methods were used to determine the direct responses to selection, expressing results as breeding values for loge GGT. Correlated responses were monitored in lambs for weights, fleece weight, and survival, and in ewes for reproductive traits. Up to 1997, a 9‐fold difference in GGT concentration, 3 weeks after challenge, was achieved between the R and S lines. Selection line differences in correlated traits were significant (P < 0.01) for weaning and January weights (with the R line 5–6% lighter than the S line), whilst the R line yearlings produced 8% heavier fleeces (P < 0.05). Ewe reproductive differences among lines were small, and nonsignificant for the overall trait (numbers of lambs weaned per ewe mated), but there were significant ram differences in fertility among lines, with highest fertility in the R line. Using a multi‐variate restricted maximum likelihood analysis, genetic correlations of lamb production traits with loge GGT were consistent in sign with the selection‐line responses, i.e., for animals which were more resistant (with lower GGT), both weaning and autumn weights decreased slightly, and both yearling weight and fleece weight increased slightly.

Effects of a controlled-release albendazole capsule on parasitism and production from grazing Merino ewes and lambs.

Effects of a controlled-release albendazole capsule (CRC) on nematode parasitism and production of Merino ewes and lambs were investigated in a replicated grazing experiment between August 1986 and July 1989. The experiment was conducted on a site where the naturally occurring parasites were benzimidazole-resistant, with double the recommended dose of oxfendazole reducing faecal egg counts of Trichostrongylus colubriformis by less than 50%. Two CRC treatments were compared with a minimal treatment control and the widely-used strategic control program, Wormkill. Egg counts and worm burdens of major parasite species of ewes and of lambs before and after weaning were significantly reduced by use of the CRC in ewes before lambing or in lambs at weaning. These parasitological effects were reflected in increased productivity of CRC ewes and lambs. Ewes given CRCs lost less weight and grew more wool during lactation than ewes given Wormkill or control treatments, while their lambs gained more weight and had heavier fleeces than lambs from Wormkill or control treatments. Where lambs were weaned by removing ewes from the lambing paddock, administration of the CRC at weaning to lambs whose dams had also been treated with the CRC did not result in improved production when compared with lambs from ewes dosed with CRCs and treated after weaning according to the Wormkill program. Some possible uses for the CRC in ewes and lambs were identified.

Comparison of a modified cryptorchid treatment and castration: effect on growth, wool production, posthitis, testosterone production and development of masculine characteristics

Male lambs born to Merino, Polwarth and Merino x Polwarth ewes were used to study a technique for manipulating testicular size. Of these lambs, 82 were castrated at marking (wethers). For the remaining 100 the testicular parenchyma was removed at marking and then, at a subsequent date, the scrotal sac and any large testicles were removed (modified cryptorchids). Cryptorchids were significantly (P&lt;0.05) heavier than wethers throughout the study and produced significantly (P&lt;0.05) heavier fleeces (4.3 � 0.08 v. 4.0 � 0.06 kg). Bin class, as an indicator of wool quality, was not significantly different between the 2 groups. At all times of the year, cryptorchids had a significantly lower prevalence (P&lt;0.001) and severity of posthitis. Posthitis increased in spring and decreased in summer. There was significantly (P&lt;0.001) more horn development in the cryptorchids, and Merino-sired animals had more horn development than those sired by Polwarth rams. The basal level of testosterone in the wethers was 0.08 � 0.07 ng/mL averaged over 3 successive blood samples, compared to the cryptorchids at 0.95 � 0.16 ng/mL with an asymmetric distribution. The rank correlation between average testosterone levels and testicle score was significant (P&lt;0.05) with a coefficient of 0.54. The rank correlations between testosterone levels and fleeceweight, liveweight or horn score were not significant (P&gt;0.05).

The performance of Merino ewes and lambs grazing two cultivars of Trifolium subterraneum at Kybybolite, South Australia

Two cultivars of subterranean clover, Trikkala and Mt Barker, were continuously grazed by Merino ewes and lambs at 3 stocking rates (8, 13, 18 ewes/ha) from 1976 to 1981. The sheep were assessed for liveweight, fleeceweight, fibre diameter, staple length, wool yield and lambing performance including lambing, marking and weaning percentage. From September 1978 onward, ewes grazing Trikkala pastures were consistently heavier than those grazing Mt Barker pastures, and they produced heavier fleeces in 1978 and 1980, with a 3 and 9% greater total wool production. The heavier fleeces of 1980 were associated with a larger fibre diameter. There were no cultivar differences in lambing performance. Cultivar treatment had no effect on lamb birthweight, but in 1980 the Trikkala lambs were, on average, 3.5 kg heavier at weaning. These lambs also produced heavier fleeces than lambs on the Mt Barker pastures. Higher stocking rates produced decreases in all of the animal performance variables measured. The results of this study suggest that improved livestock performance may only occur if animals are grazed on higher performing cultivars for at least 3 years.

Breed and sex differences among equally mature sheep and goats 6. Breed correlations for body composition and food conversion efficiency

ABSTRACTBreed means are given for 40 traits relating to food conversion efficiency and body composition at the same stage of maturity in seven breeds of sheep and a feral goat breed. In terms of breed means, food intake and food conversion efficiency were genetically correlated, as were most traits associated with fatness or leanness.Highly inter-correlated measures of breed fatness were proportion of fat in the carcass, proportion of total carcass fat found in the rib plus loin, the fat : muscle ratio and the lipid concentration in the dry matter of all tissues except bone. Dressing proportion was highly correlated with all these measures of fatness.Breeds with a high proportion of subcutaneous fat did not necessarily have a low proportion of intra-abdominal fat. A low proportion of carcass fat in the rib plus loin was associated with a high proportion in the shoulder (inter-breed correlation —0·7): both were measures of leanness. Muscle : bone ratio was not correlated with fatness or leanness. Slower maturing, larger breeds had slightly more bone, less fat and more lean in their higher-priced cuts. Breeds with heavier fleeces were fatter (0·7). The food conversion efficiency of a breed was largely independent of its body composition.

Effect of dietary calcium and zinc levels on weight gain and blood and tissue mineral concentrations of growing Columbia- and Suffolk-sired lambs.

One hundred and sixty Columbia- and Suffolk-cross intact male and female growing lambs (8 wk of age) were used in an 84-d feeding trial to determine the effect of two levels dietary Ca and Zn on weight gain, feed utilization and several blood and tissue traits. Two levels of Ca (.5 and .8%) and two levels of Zn (20 and 100 ppm) were fed in a 2 X 2 factorial arrangement of dietary treatments. There was no effect of diet on performance or on blood traits. Columbia lambs had heavier fleeces at slaughter than Suffolks (P less than .01) and males had heavier fleeces than females (P less than .01). Based on the similarity in performance among lambs fed the four diets differing in Ca and Zn level, it is concluded that a dietary Ca level of .5% and a Zn level of 19 to 26 ppm is adequate for normal weight gain, feed utilization, liver and humerus ash concentrations and blood plasma concentrations of Ca, P, Zn, total protein, albumin, alkaline phosphatase and blood hemoglobin and hematocrit. Further, it appears that an elevated level of dietary Ca does not precipitate a clinical Zn deficiency in the growing lamb, in contrast to the general observation in growing swine.

Frequency of anthelmintic drenching of lambs in Waikato

Abstract Experiments in 1972 in Waikato with anthelmintics on lambs compared six drenches at monthly intervals from January to June inclusive with a drench in March, April, and May, and with no drenching. Drenching improved live-weight gains in winter and resulted in heavier fleeces at spring shearing, lowered incidence of acquired faults in wool, and heavier shorn body weights. After shearing, undrenched lambs showed compensatory growth, but it was insufficient to compensate fully for the earlier retardation, when final weighings were made in January and February. Six drenches were more effective than three, from a slight advantage in winter to more pronounced effects in wool weights and shorn body weights at October shearing. At the final weighings the beneficial effects from six drenches were more marked than from three. Wool- and body-weight increases from more frequent drenching would not necessarily have been financially beneficial.

Effect of time of joining and rate of stocking on the production of Corriedale ewes in southern Victoria. 4. Production of ewes born in July and September and effect of inclusion of Phalaris tuberosa in annual pasture

The production of two groups of 56 ewes born either in the month of July or September in 1968,1969 or 1970 (a total of 336 ewes) was compared until November 1972. From weaning (1 2 weeks) to approximately 15 months of age the ewes were grazed on two types of pasture (with and without Phalaris tuberosa) at two rates of stocking (8 and 11 ewes ha -1) and thereafter ewes born in the same year grazed common pasture. Ewes lambed in August, the first lambing being at two years of age. Throughout the experiment ewes born in July remained heavier and produced heavier fleeces and heavier lambs than ewes born in September. In the first lambing (maiden ewes only) 20 per cent more lambs were weaned from ewes born in July than from ewes born in September but at later lambings differences in reproductive performance were small. Liveweight gains of ewes grazing pastures containing phalaris were 1 to 2 kg greater between November and February than those grazing pasture without phalaris. At their first lambing, ewes that had been grazing phalaris at the rate of 8 ewes ha-1 produced fewer lambs than the corresponding group grazing pasture without phalaris. Losses in production due to lambing ewes in July rather than September as previously reported are unlikely to be offset by production differences of their offspring.

OPEN-VS. CLOSE-FACED SHROPSHIRES

In 1948 the Shropshire ewe flocks at the Central Experimental Farm, Ottawa, Ontario, and Experimental Farm, Nappan, Nova Scotia, were divided on the basis of face cover into two lots of approximately 20 each. The lots with least face cover were bred to British type, open-faced rams; the lots with most face cover to close-faced, or American type rams. Each lot was bred to at least one ram, with the rams being changed, in so far as possible, each year. In the 7-year period, 11 rams of the open-faced type, and 13 of the close-faced type, were used at the two Farms. Three of the open-faced type were used at both Farms. Average weights of the ewes in the Ottawa flock were equal at time of division.The open-faced type sired lambs were superior to the close-faced in birth weight, 14-day weight, 28-day weight, weaning weight, yearling weight, market weight, and age at marketing.Average weight of both types of ewes increased during the test period, but the open-faced, British type group increased faster than the close-faced, American type.There were no differences in fleece count in the two types at either Farm; but the open-faced type ewes had slightly heavier fleeces, this being significant in the Nappan flock only.Within the limits of the flocks at these two Farms, the superiority of the open-faced, British type of Shropshire is illustrated. However, this type is considerably larger than the more common close-faced, American type, and at least part of the advantage shown may be due to "grading-up" to this larger type. Heterosis, resulting from such wide out-crossing, also may be a contributing factor.

Effects of Some Environmental Factors on Yearling Traits of Columbia and Targhee Ewes

The effects of age of dam, type of birth, year of birth, age at shearing and percent inbreeding on staple length, grease fleece weight, body weight, type, condition, face covering and neck folds were studied on 406 Columbia and 290 Targhee yearling ewes at the U. S. Sheep Experiment Station, Dubois, Idaho. The ewes were born during the years 1941 to 1944. The effect of the environmental factors was greatest on fleece weight and body weight and least on face covering and neck folds. Year of birth was the most important environmental source of variation followed by type of birth, age at shearing, and percent inbreeding. Age of dam was the least important source of variation of Columbia and Targhee yearling traits. Single ewes had heavier bodies and fleeces, longer staple and better type and condition than twins. Daughters of mature dams had heavier fleeces and bodies than those of 2-year-old dams. Fleece and body weights, staple length, type and condition improved with age at shearing and became poorer with inbreeding.