Growth and carcass composition of ram and wether lambs fed at two levels of nutrition

This experiment examined the effects of two levels of nutrition on growth rate and fat deposition in the subcutaneous, kidney plus channel, omental and mesenteric depots of ram and wether second-cross lambs. Growth rates to slaughter were higher (P< 0.001) in lambs fed at the higher level of nutrition (170 ¦ 5 v. 88 ¦ 3 g/day; mean ¦ s.e.). There was no difference in growth rates between ram and wether lambs at the levels of nutrition imposed. The level of nutrition did not influence fat depots when the comparison was made at the same carcass weight. Ram lambs had less subcutaneous fat than did wethers, the difference increasing (P = 0.06) at heavier carcass weights (1 00 v. 20 1 g increase in subcutaneous fat/kg increase in carcass weight, for rams and wethers respectively). A similar trend was evident in GR tissue depth; consequently, the distribution of fat scores of wether carcasses was closer to the high (fat) end of the range than was the distribution for ram carcasses (P < 0.05). The levels of total solvent-extractable fat in the carcass did not differ between sexes or levels of nutrition.