PHENOTYPIC CHANGES OF FAT IN LORI-BAKHTIARI FAT-TAILED SHEEP
Mohammad Ali Talebi
Department of Animal Science, Agriculture and Natural Resources Research Center, Sharekord, Iran
maitalebi@yahoo.com
The data set used in this study was body weight at 6 months of age (BW6M), fat-tailed weight (EFTW) and hypodermic needle measure of soft tissue at 12‑13th rib, 120 mm from the midline (GR) of 2391 lambs at 6 months of age recorded over a 8-year period (2003 to 2011) from a Lori-Bakhtiari research flock in the Chaharmahal and Bak¬htiari province, Iran. The flock is managed under a semi-migratory or village system. SAS procedures were used for the statistical analysis. Average of BW6M, EFTW and needle soft tissue depth measured in live lambs (NGR) estimated at the age of six months in lambs were 43.30, 2.73 kg and 7.36 mm, respectively. During the selection program for reducing fat, 4.45 percent of the fat-tailed decreased. Fat-tailed weight per kg of the body weight decreased from 78 g to 52 g in the end of the program. The effects of sex, year of birth, type of birth and rearing type were significant for the BW6M and EFTW traits. The phenotypic trends for EFTW and NGR regressed in the year of birth with constant weight were ‑140 g/year and ‑0.37 mm/year, respectively. The phenotypic trend for the BW6M was positive (0.744 kg/year). Consequently, the phenotypic progress is possible for decreasing fat without decreasing body weight, too.
Keywords: fat; phenotypic trend; Lori-Bakhtiari; sheep
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