The relationship between greasy fleece weight and clean fleece weight in the South Australian Merino

1961 ◽  
Vol 1 (1) ◽  
pp. 34
Author(s):  
GH Ford

The correlation between clean fleece weight and greasy fleece weight in South Australian strain Merino hoggets of both sexes in three widely different seasons was found to be Rams, 0.841, 0.890, 0.701 and Ewes, 0.846, 0.850 and 0.839. A covariance analysis of clean and greasy fleece weights showed no significant differences between slopes of individual sires, but significant differences between sire group means, indicating genetic variability for these two traits. It is concluded that the correlations are high enough to make selection for clean fleece weight by partial culling on the basis of greasy fleece weight, followed by scouring of midside samples of the fleece from the top sheep for greasy fleece weight, as advocated by Beattie (1956), practicable. The use of the clean fleece weight, greasy fleece weight relationship will rarely be sufficient on its own to formulate a selection plan. The conditions for the use of other aids to estimate clean fleece weight, such as the Neale squeeze machine, are discussed.

1958 ◽  
Vol 38 (1) ◽  
pp. 53-60
Author(s):  
S. B. Slen ◽  
E. C. Banky ◽  
H. F. Peters

The relationship of shearling and second-year clean fleece weight to total wool production, i.e., first 5 years of life, was analysed in three breeds of range sheep (Canadian Corriedale, Rambouillet, and Romnelet) to determine its usefulness in selection for increased wool production.A correlation of +.67 (p <.01) between shearling clean fleece weight and the sum of the four mature fleece weights was obtained in the three breeds studied. When the first mature weight (second fleece) was correlated with the total weight of the three subsequent fleeces, the correlation was increased significantly (p <.01). Consequently, the second fleece appeared to be a more reliable estimate of lifetime production than shearling weight. No breed differences in these correlations were found when lifetime production was compared to shearling or to second-year fleece weights. The regression coefficients of lifetime production on shearling fleece weight showed that a shearling ewe which produced 1.0 lb. of clean wool above the average produced approximately 3.0 lb. more than the average during her productive life.Shearling fleece weight was found to represent 83, 77, and 80 per cent of the maximum mature fleece weight in the Canadian Corriedale, Rambouillet, and Romnelet, respectively. No breed differences were observed in this relationship.The repeatability of annual clean fleece weight was found to be.93,.83, and.76 for the Rambouillet, Romnelet, and Canadian Corriedale, respectively.


1982 ◽  
Vol 33 (2) ◽  
pp. 363 ◽  
Author(s):  
IP Gregory

Genetic, phenotypic and environmental correlations were estimated between 23 quantitative and qualitative wool and body traits of South Australian Merino sheep. Clean fleece weight was significantly correlated genetically with greasy fleece weight (0.62), yield (0.47), staple length (0.41), crimps per inch (-0.34), secondary/primary follicle ratio (0.37) and skin thickness (0.39). No significant half-sib genetic correlation was found between clean fleece weight and fibre diameter and the dam-offspring correlation was quite low, although significant (0.16, P < 0.05). This indicates that selection for clean fleece weight should not lead to any great increase in fibre diameter. Skin thickness is discussed as a possible early indicator of clean fleece weight.


1955 ◽  
Vol 6 (6) ◽  
pp. 873 ◽  
Author(s):  
FHW Morley

Genetic and phenotypic relationships among subjectively graded characteristics were examined in a flock of Merino sheep a t Trangie Agricultural Experiment Station. Estimates of heritability were: wool handle, 0.30; wool colour, 0.63; wool character, 0.38; back wool, 0.00; hocks, 0.14; face cover, 0.38. The genetic correlation between face cover and fleece weights suggested that selection for fleece weight would increase "wool-blindness", with possible diminution of reproductive efficiency. Selection for wools of good character (well-defined crimp) would improve softness and would not decrease fleece weight. The conclusion emerging from this and previous studies is that intense selection for high fleece weight will be rewarded by substantial increases, and will be offset only partly by adverse changes in a few of the several characters investigated.


2019 ◽  
Vol 59 (1) ◽  
pp. 35
Author(s):  
S. F. Walkom ◽  
A. N. Thompson ◽  
E. Bowen ◽  
D. J. Brown

There is little evidence to show that mortality rates during the period after weaning are improving over time in Australian sheep. The average mortality rate of Merino lambs during the post-weaning period has been estimated to be 5.2%. The present study explored the potential for producers to breed for improved survival rates during the post-weaning period and the potential impact this would have on key production traits. A total of 122526 weaner survival (mortality) records were obtained from 18 Merino flocks, between 1989 and 2014, encompassing a wide variety of Australian Merino sheep types and production systems. The heritability of weaner survival from a sire model was estimated to be 0.07 ± 0.01 and was significantly greater than zero. The survival of lambs post-weaning was significantly influenced by weaning weight, with higher survival rates observed in the heavier lambs. The phenotypic relationship with weight indicates that selection for heavier weaning and post-weaning weights, and in turn larger growth rates, will improve survival rates. There is genetic variation in weaner survival not explained by the relationship with weaning weight. Weight-corrected weaner survival was antagonistically genetically correlated with fleece weight. Due to these antagonistic genetic relationships selection based on popular MERINOSELECT indexes is leading to a very small reduction in the survival rate of lambs after weaning through to the post-weaning stage. To prevent a decline in weaner survival, producers are advised to record weaner survival and include it in their breeding objective.


2002 ◽  
Vol 53 (3) ◽  
pp. 271 ◽  
Author(s):  
S. W. P. Cloete ◽  
J. C. Greeff ◽  
R. P. Lewer

(Co)variance estimates for hogget liveweight, greasy fleece weight, clean fleece weight, clean yield, fibre diameter, and the coefficient of variation of fibre diameter were obtained for a Western Australian Merino resource flock. The flock encompassed 16 medium wool bloodlines and data were available for the period 1982–93. Direct additive genetic variances (h2) — expressed as a ratio of the total phenotypic variance within bloodlines — were estimated at 0.52 for hogget liveweight, 0.44 for greasy fleece weight, 0.42 for clean fleece weight, 0.63 for clean yield, 0.71 for fibre diameter, and 0.62 for coefficient of variation of fibre diameter. Maternal genetic variance estimates were significant (P < 0.05) only in hogget liveweight and fibre diameter, but components within bloodlines were low (0.05 for liveweight and 0.02 for fibre diameter). Direct within-bloodline genetic correlations of hogget liveweight as well as greasy and clean fleece weight with fibre diameter were positive (0.17, 0.31, and 0.31, respectively), suggesting that selection for bigger and heavier cutting sheep would generally lead to a broader fibre diameter. Liveweight was unrelated to clean yield and negatively related to coefficient of variation of fibre diameter (–0.17). Greasy fleece weight was negatively related to clean yield (–0.20). The genetic correlation of clean fleece weight with clean yield was positive (0.37). Wool quantity was, in general, positively related to coefficient of variation of fibre diameter, although the estimated genetic correlations were low (0.12 for greasy fleece weight and 0.07 for clean fleece weight). The genetic correlation between fibre diameter and coefficient of variation of fibre diameter was negative, and fairly low (–0.10). These results are discussed with reference to sheep breeding.


1967 ◽  
Vol 20 (5) ◽  
pp. 959 ◽  
Author(s):  
DW Cooper ◽  
LF Bailey ◽  
O Mayo

Population data for the transferrin varil;mts in the South Australian and Camden Park strains of the Australian Merino are reported. In all, five variants designated A, B, C, D, and E were distinguished. The relationship between these variants and those reported in previous investigations of the Merino and other breeds has been determined. In two out of the six samples there were significant departures from Hardy-Weinberg expectations. It was observed that closed flocks with small effective population size, Camden Park and one South Australian (Roseworthy) flock had fewer than five variants, the number generally found in all strains of the Australian Merino so far examined. For the Roseworthy material it was possible to demonstrate that the parent population, Anama, had the five variants. Further, the two Roseworthy flocks derived from the Anama stock had significantly different gene frequencies from that flock.


1970 ◽  
Vol 21 (5) ◽  
pp. 837 ◽  
Author(s):  
N Jackson ◽  
JW James

Data from two-tooth rams and ewes representing seven Australian Merino studs were analysed to provide estimates of between-stud genetic variances and between-stud genetic correlations for 20 wool and body traits. The estimates were used to compare two methods of choosing foundation animals for a new stud: selection within one stud or selection within each of several studs. Where only one trait was considered in selection, and provided that accurate estimates of stud mean breeding values were available, selection from a single stud was superior, although there were some differences between traits in the degree of superiority. Where more than one trait was considered the conclusion depended on the relative magnitudes and signs of the between and within-stud genetic and phenotypic correlations. In the particular case of selection for high clean fleece weight and fine fibre diameter, a strong unfavourable between-stud genetic correlation shifted the emphasis more toward selection from several studs, but selection from a single stud was still superior when accurate estimates of stud mean breeding values for clean fleece weight were available. When response to subsequent selection, as well as immediate gain in choice of founders, was considered, the conclusions were reversed. For a single trait, selection from several studs was always superior in the long term (three or more generations), and also in the short term when accurate estimates of stud mean breeding values were not available.


1965 ◽  
Vol 16 (6) ◽  
pp. 997 ◽  
Author(s):  
SSY Young ◽  
GH Brown ◽  
Turner H Newton ◽  
CHS Dolling

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.


Author(s):  
Tatiani De Azevedo Lobo ◽  
Marli M. Moraes Da Costa

Resumo: O presente ensaio busca apresentar e fomentar algumas questões pertinentes ao debate contemporâneo sobre a pobreza, demonstrando a importância do tema no cenário mundial. Para tanto, inicialmente discorre-se sobre a construção histórico-social da pobreza e suas características contemporâneas. Com efeito, aponta-se a limitação dos fatores tradicionalmente apresentados como causadores da pobreza, como cultura, genética, geografia etc. Além disso, apresentam-se as formas atuais de monitorar o fenômeno, como o coeficiente de Gini e o IDH. Posteriormente, aborda-se a distribuição mundial da pobreza. Nesse ponto, colaciona-se que a pobreza é um problema mundial. No entanto, é perceptível que o Sul ainda concentra maior número de indivíduos pobres do que o Norte. Na esteira dos últimos dados da pesquisa realizada pelas Nações Unidas, houve uma nítida ascensão do Sul, especialmente nos indicadores sociais ligados à educação. A seguir, trata-se do capital social e da Teoria das Capacidades, apresentando-se novas abordagens da pobreza. Assim, o capital social trata de uma ideia utilizada para verificar a rede de relacionamento dos indivíduos. Já a Teoria das Capacidades está ligada com a ideia de oportunidade da liberdade. Por fim, estuda-se as políticas públicas, bem como seu aspecto fragmentário. Conclui-se, assim, sobre a necessidade de implementação de políticas públicas elaboradas sob a égide de novos paradigmas, a fim de possibilitar o tratamento específico do fenômeno da pobreza, conforme as peculiaridades de cada local. Para tanto foi utilizado neste trabalho o método de abordagem hipotético-dedutivo, o método de procedimento monográfico e a técnica de pesquisa, operacionalizados por meio do emprego de vasta pesquisa bibliográfica. Abstract: This essay seeks to provide and foster some relevant to the contemporary debate on poverty issues, demonstrating the importance of the issue on the world stage. For this purpose, initially spoke about the historical and social construction of poverty and its contemporary features. Indeed, he pointed out the limitation of the factors traditionally presented as the cause of poverty, as a culture, genetics, geography, etc. Furthermore, we presented the current ways of monitoring the phenomenon, such as the Gini coefficient and the HDI. Subsequently addressed the global distribution of poverty. At this point, if collated that poverty is a worldwide problem. However, it is apparent that the South still more concentrated than the poor North individuals. In the wake of recent data from research conducted by the United Nations, there was a sharp rise in the South, especially in social indicators related to education. Next, we treated the capital and the Theory of Capabilities, presenting new approaches to poverty. Thus, social capital is an idea used to verify the relationship network of individuals. Already Capabilities Theory is linked with the idea of freedom of opportunity. Finally, we studied public policy, as well as its fragmentary appearance. Thus, it is concluded on the need to implement public policies prepared under the aegis of new paradigms to enable specific treatment of the phenomenon of poverty, according to the peculiarities of each site. For that was used in this work the method of hypothetical-deductive approach, the method of procedure and the monographic research technique, operationalized through the use of extensive academic research.


Sign in / Sign up

Export Citation Format

Share Document