Twenty-five male Shugor, 25 female Shugor, 25 male Watish and 25 female Watish lambs, individually fed for 57 days, were used to study post-weaning growth performance and carcass composition of these breed types when subjected to a period of intensive feeding.
Means and standard error of means of daily gain on experiment were 191·0±5·81, 166·0±5·81, 150·0±5·81 and 134·0±5·81 g for Shugor males, Watish males, Shugor females and Watish females, respectively. The means and S.E. for feed conversion ratio (FCR) were 5·79±0·190, 7·30±0·190, 7·47±0·190 and 8·00±0·190 in the same order. Shugor and male lambs had better gain (P < 0·001) and FCR (P < 0·01)than Watish and female lambs respectively.
Shugor had heavier slaughter weight and cold carcass weight than Watish (P < 0·01). Males were superior to females in slaughter weight, carcass weight and dressing percentage (P < 0·01). No difference was detected in lean, fat or bone percentage between breed type or sex (P < 0·05). Males had larger muscle area (P < 0·001) than females. On the other hand, females had more percentage kidney knob and channel fat (P < 0·001) and thicker fat depth (P <0·01) than males. Shugor were superior (P < 0·01) in fat depth to Watish.
Percentage non-carcass components showed that females had more percentage omental and mesenteric fat (P < 0·001) and percentage full stomach (P < 0·01). Breed type and sex showed significant effect (P < 0·001) on percentage liver.
In linear measurements, Shugor had greater carcass length and femur length (P < 0·01). Males had bigger circumference of buttocks and chest depth (P < 0·001).
For carcass joints as a percentage of side weight, the only clear effect of breed type was on percentage loin (P < 0·05). Males had bigger percentage middle neck (P < 0·001) and shoulder and percentage scrag (P < 0·01) than females, whereas females had higher percentage loin and chump.
Heritability estimates of some carcass traits, admittedly based on limited numbers, ranged from 0·32 (S.E. 0·183) for leg to 0·18 (S.E. 0·180) for loin weights. Linear carcass measurements showed low heritability of around 0·10 (S.E. 0·160).