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The present study evaluated the effect of replacing elephant grass (EG) with moist pineapple by-product silage (PS) on the apparent digestibility, consumption of digestible nutrients and performance of 25 castrated male lambs Santa Ines crossbreds. The lambs had an initial body weight of 20.2 ± 3.5 kg and were housed in individual pens in a completely randomised design with five treatments (replacement of EG by PS at five proportions of 0, 25, 50, 75 and 100 %) and five replicates during 74 days. There was no significant effect of PS replacement proportions on the intake of dry matter (DM), organic matter (OM), total carbohydrates (TC), non-fibrous carbohydrates or total digestible nutrients (TDN). The consumption of crude protein (CP) decreased linearly with the inclusion of PS in the diets. The digestibility of DM, OM and TCs as well as levels of TDN increased linearly with the addition of PS. The use of PS in the diets had no significant effect on the digestibility of CP and neutral detergent fibre corrected for ashes and protein (NDFom(n)). These results demonstrated that there was no difference in the performance of animals fed diets with or without PS.

On a fattening diet in which final molasses supplied from 68 to 76 % of the metabolizable energy and napier grass some 10 %, the treatments in a 2 x 2 x 3 factorial design were breed (Brahman or Brown Swiss x Brahman), source of supplementary protein (fish meal or poultry waste) and protein level (low, medium or high-replacing urea). Mean daily gains to 404 kg live weight were better for the crossbreds (0-89 compared with 0-77 kg), as was conversion rate in terms of Meal ME per kg gain (25-6 compared with 29-5); fish meal improved gains by 44 % and conversion rate by 39 % as compared with poultry waste when the two supplements were fed at levels designed to equate N intakes from this source. The superiority of the crossbreds was only apparent on the fish meal diets where they averaged 1*19 compared with 0-94 kg/day for the Brahmans. Daily N x 6-25 intakes decreased from 3-8 g/kg live weight on the low level of poultry waste to 2-9 on the high level due to low palatability of this material. On this treatment (poultry waste), daily gain (kg) was significantly related (6 = 0-119+0-031; P<0-01) to N X 6 -2 5 intake (g) per unit live weight (kg). Commercial half carcass dissection showed the crossbreds to have significantly more edible meat, more bone and less excess fat than Brahmans. Protein source had no effect on carcass composition.

The effect of pineapple by-product silage as a substitute for elephant grass on carcass yield, commercial cuts and non-carcass components was evaluated in 25 castrated male Santa Inês feedlot finishing lambs. The lambs had an initial body weight of 18.0±3.4 kg, and they were fed four pineapple by-product silage concentrations (0, 25, 50, 75 and 100%) distributed in a completely randomized design with five treatments and five repetitions. Lambs were slaughtered at a body weight of 30 kg. The hot carcass weight and hot carcass yield were recorded and chilled at 4°C for 24 h. The quantitative parameters of the carcass, the wholesale cuts expressed in kg and percentage, and non-carcass components were determined. Carcasses were divided into seven commercial cuts. The hot and cold carcass yields significantly increased when elephant grass was replaced with pineapple by-product silage in the diets. The weight of the false rib and loin cuts increased linearly when pineapple byproduct silage was added to the diets (P< 0.05). No significant differences were observed in the weights of the other cuts (P>0.05). The average weights of the non-carcass components were not affected by the addition of pineapple by-product silage, except for gastrointestinal tract (GIT) content, which decreased linearly, and omental-mesenteric, perirenal and internal fat depots, which increased linearly with the addition of pineapple by-product silage to the diets. The use of pineapple by-product silage as a substitute for elephant grass in growing lamb diets is recommended because it did not negatively affect the carcass characteristics, commercial cut yields or non-carcass components.

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