Forty-five local Omani ram, wether and ewe lambs were reared from birth until slaughter at 18, 28 or 38 kg live weight (five of each ‘sex’ at each weight group) on an ad libitum concentrate diet and Rhodesgrass hay.

Ram lambs grew faster from birth and reached predetermined slaughter weights earlier than wether and ewe lambs. At 28 kg live weight, ram lambs had: heavier heads, feet, reticulo-rumens and livers; higher muscle and bone and lower fat proportions in the carcass; lower muscle: bone and higher muscle: fat ratios; higher proportions of carcass but lower non-carcass fat than had wether and ewe lambs. The head, feet, alimentary tract, liver and heart of Omani sheep grew at a lower rate; the skin grew at a similar rate and the carcass grew at a rate faster than empty body weight (EBW). Relative to EBW, muscle grew at a similar rate, fat faster and bone slower. Both carcass and non-carcass fats grew at a rate higher than that of the growth of EBW, with non-carcass fat growing at a higher rate than that of carcass fat. The growth rate of omental fat was the fastest followed by kidney, mesenteric, subcutaneous, tail, scrotal, intermuscular and pelvic fats respectively.

This study demonstrated that Omani sheep have good potential for growth if they are managed and fed satisfactorily. Omani sheep are early maturing for which reason it is recommended that they be slaughtered at lighter weights to avoid higher fat content in the carcass. Castration in Omani sheep is not recommended for production of meat lambs under intensive systems as it resulted in reduced growth rates and deposition of excess fat at lower slaughter weights.

Distribution of tissue weight in the musculature and skeleton was studied in ram, wether and ewe Omani sheep raised under an intensive management system and slaughtered over the range 18 to 38 kg live weight. Ram lambs had higher muscle weight in the forequarters than wether and ewe lambs whereas the latter ‘sexes’ had heavier hindquarters and slightly more muscle in the muscle groups of proximal hind- and forelimbs and those surrounding the spinal column. Some of the neck region muscles, e.g. m. splenius and m. longissimus capitis et atlantis, were more developed in ram than in wether and ewe lambs. The proportions in the side muscle weight of some muscles (mainly in the hindquarter) decreased with increased slaughter weight whereas others (mainly in forequarter) increased, with the majority of the muscles showing no significant slaughter weight effects. The magnitude of change in proportions of individual muscles with increased slaughter weight was small and unlikely to have a commercial impact on meat production from Omani sheep.

As a proportion of total carcass bone, the axial skeleton and the hindlimb decreased with increased slaughter weight whereas the forelimb did not show a significant change. Ram lambs had heavier individual bones than wether and ewe lambs and higher proportions of the axial skeleton and lower proportions of the hindlimb than wethers at 28 kg live weight. There were few differences between the various ‘sexes’ in length, width or circumference of bones. Except for the 12th rib, individual bones, in all sexes, grew at a rate lower than empty body weight.

It is suggested that future improvement of Omani sheep should take into consideration the high proportion of bone in the carcass of these animals as well as the relatively higher proportion of bone in the limbs than in the axial skeleton.