Abstract
Live animal selection programs that favor animals with a minimum amount of carcass fat are used for improving breeding flocks of sheep. To predict carcass characteristics of live sheep using body measurements in breeding flocks, 200 male and female lambs of two fat-tailed Iranian sheep breeds (Moghani and Makui) were used. Depth of soft tissue over the 12th rib of the live animals was measured with ultrasound (ULGR) and with hypodermic needle (NGR). The height at withers (HW), body length (BL), circumference of heart girth (CH) and width of hooks (WH), were measured. All animals were slaughtered; carcasses were cut into joints and dissected. Breed had a significant effect on all of the live measurements. The Moghani breed showed a higher value for HW, CH, ULGR and NGR, compared to that of Makui. Except for soft tissue depths; ULGR, NGR and GR, the male lambs showed higher values in live and carcass measurements than females. Percentages of carcass, total fat and intermuscular fat in females were higher than that of male lambs. In spite of the higher amount of subcutaneous and intermuscular fat in female (which is usually used for their physiological need, such as pregnancy and lactation), the male lambs had a heavier fat-tail than females. There was a wide range of variation of percentage of total carcass fat and total chemical fat content of carcass in the two breeds. Eventually this wide variation could be use by animal breeders for selection of animals with a lesser amount of carcass fat. Live weight of lambs showed a relatively low correlation with percentage of carcass lean, total fat and subcutaneous and intermuscular fat. Total lean meat was predicted with relatively high coefficients of determination in the two breeds (R 2 =0.61 and 0.89, respectively). Live weight and carcass traits were predicted using simple measurements, but with R 2 ranging from 0.53 to 0.93. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 5 : 693-699)
Highlights
Live weight (Simm et al, 1990; Cameron and Bracken, 1992)
Live animal selection programs including the animals with a minimum amount of carcass fat is to be used for improving achieving that objective (Osfoori and Fesus, 1996; Bourden, 2000)
Exogenous sheep are not fat-tailed so the depth of soft tissue measured could be attributed to subcutaneous fat that is more abundant in exogenous sheep
Summary
Some equations have been presented by using this technique can be used for evaluation of fat content of lambs of New Zealand mixed sheep breeds (Ramsey et al, 1991). Stanford et al 1995 used 1,162 lambs at live weights ranging from 32.5 to 70.5 kg and age ranging 3 to 15 months. The purpose of the present study was to evaluate several methods of predicting carcass characteristics of live sheep using body measurements in breeding flocks. Live animal selection programs including the animals with a minimum amount of carcass fat is to be used for improving achieving that objective (Osfoori and Fesus, 1996; Bourden, 2000)
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