Research Article

Genetic analysis of fleece and post-weaning body weight traits in Makuie sheep

Published: February 20, 2014
Genet. Mol. Res. 13 (1) : 1079-1087 DOI: 10.4238/2014.February.20.9

Abstract

Estimation of genetic parameters is the most important component of an organized selection program. With respect to economic traits, such as wool and mutton traits, production costs can be reduced through a suitable selection program focused on genetic improvement. This study aimed to evaluate genetic parameters of fleece and post-weaning growth traits in sheep. Greasy fleece weight at 6, 16, 28, 40, and 52 months of age (GFW1, GFW2, GFW3, GFW4, and GFW5) represented characteristics of wool quantity. Staple length at shoulder, side, and rump (SL1, SL2, and SL3), fiber diameter, and percentage of true wool (TW%) were used as characteristics of wool quality. Live body weight at 6, 9, and 12 months of age (BW6, BW9, and BW12) reflected post-weaning growth characteristics. These data were collected over 23 years, from 1989 to 2012, at the Makuie Sheep Breeding and Raising Station (MSBS). Estimations were calculated using the derivative-free restricted maximum likelihood (DFREML) model. Direct heritability estimates, based on single-trait analyses, ranged from 0.10 (GFW1) to 0.80 (TW%). Additive genetic correlations among the traits ranged from highly negative (-0.46) to highly positive (0.99). The log likelihood ratio test (LRT) was used for selection of the most appropriate model. Based on the LRT, direct additive genetic and maternal permanent environmental effects were considered as the main sources of variation in the studied traits.

Estimation of genetic parameters is the most important component of an organized selection program. With respect to economic traits, such as wool and mutton traits, production costs can be reduced through a suitable selection program focused on genetic improvement. This study aimed to evaluate genetic parameters of fleece and post-weaning growth traits in sheep. Greasy fleece weight at 6, 16, 28, 40, and 52 months of age (GFW1, GFW2, GFW3, GFW4, and GFW5) represented characteristics of wool quantity. Staple length at shoulder, side, and rump (SL1, SL2, and SL3), fiber diameter, and percentage of true wool (TW%) were used as characteristics of wool quality. Live body weight at 6, 9, and 12 months of age (BW6, BW9, and BW12) reflected post-weaning growth characteristics. These data were collected over 23 years, from 1989 to 2012, at the Makuie Sheep Breeding and Raising Station (MSBS). Estimations were calculated using the derivative-free restricted maximum likelihood (DFREML) model. Direct heritability estimates, based on single-trait analyses, ranged from 0.10 (GFW1) to 0.80 (TW%). Additive genetic correlations among the traits ranged from highly negative (-0.46) to highly positive (0.99). The log likelihood ratio test (LRT) was used for selection of the most appropriate model. Based on the LRT, direct additive genetic and maternal permanent environmental effects were considered as the main sources of variation in the studied traits.

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