Effect of testicular status and feeding diets containing palm by-products on growth and composition of the rack cut in Omani sheep

Abstract

Thirty local Omani male sheep, 10 each of intact, cryptorchid, and castrated were fed two diets which contained 40% of either ground palm fronds or Rhodesgrass hay. Each diet contained 38% barley grain and 11.3% soybean and had a 15% CP. Feed intakes, average daily gain and feed conversion ratio (FCR) were computed. Animals were slaughtered at an average body weight of 28 kg. Animals fed diets based on ground palm frond had a slower ( P<0.05) growth rate (122 g/d) and needed more feed/kg body weight (7.19) than those fed diets based on Rhodesgrass hay (154 g/d; 6.09 FCR). Intact and cryptorchid sheep had higher ( P<0.05) average daily gains than the castrates (155, 150 and 109 g/d, respectively) whereas the intact had higher FCR than castrated sheep (5.99 and 7.46). Intact and cryptorchid sheep had higher slaughter weight (28.9, 29.3 kg), empty body weight (24.0, 24.0 kg), hot carcass weight (12.6, 12.9 kg), cold carcass weight (12.3, 12.2 kg) and backfat thickness (4.01, 4.55 mm) than castrates (24.2 kg, 19.9 kg, 10.7 kg, 10.3 kg and 2.82 mm, respectively). Animals fed Rhodesgrass-based diet had heavier EBW (23.8 kg), hot carcass weight (13.0 kg), cold carcass weight (12.6 kg) and higher dressing out percentage (45.9%) than those fed diet based on palm frond (21.4 kg, 11.2 kg, 10.8 kg and 41.9%). Intact and cryptorchid lambs had lower proportions of feet and heart in their EBW than the castrates. Lambs fed palm frond-based diet had higher proportions of head, gut fill but lower proportions of liver, kidney plus pelvic fat than those fed Rhodesgrass-based diet. There were no major effects of either testicular status or diet on weight of wholesale cuts, physical or chemical composition of the rack cut. This study indicated that while palm fronds may not equal Rhodesgrass in feeding value for native sheep, it may still offer a source of roughage for feeding local ruminants given the costs of irrigated forage in Oman.