Abstract
The objective of this study was to evaluate the effect of the levels of replacement of ground corn by forage cactus meal in the diet on the muscularity and adiposity of carcass of Santa Inês lambs finished at feedlot. This study was carried out at Estação Experimental de Pendência, belonging to Empresa de Pesquisa Agropecuária da Paraíba S.A. (EMEPA-PB). Forty male Santa Inês lambs in feedlot were used in the experiment. Treatments were randomly assigned to the animals according to a completely randomized design, with four treatments, that consisted of growing substitution levels of ground corn for forage cactus meal: 0, 33, 66 and 100% of substitution and ten replications (lambs). Animals were slaughtered and carcasses cooled for 24 hours for later assessment of conformation, morphometry, loin eye-muscle area, fatness, perirenal fat, marbling and subcutaneous fat thickness. Legs were separated for dissection of muscle, bone, subcutaneous fat, intermuscle fat and total fat, which were weighed for the determination of the muscle:bone and muscle:fat relation and the relative weight of tissue components. Averages were submitted to variance and regression analyses at a 5% level of probability. Diets had no effect on carcass conformation. However, a negative linear effect on weights and yields of fats was observed with the increased levels of forage cactus meal in the diet, and the opposite was observed in the muscle yield behavior. Forage cactus meal is biologically as efficient as ground corn, because it increases the muscularity and reduces the adiposity of the carcass of Santa Inês lambs in feedlot.
Highlights
Feedlot is an alternative to improve the reduced weight of lambs bred in the caatinga
Forty 90-day-old Santa Inês lambs, with a 15.52 kg average live weight were distributed in four groups, fed on growing levels of replacement of ground corn by forage cactus meal (0, 33, 66 and100%) in the diet concentrate
The similarity between carcass conformation suggests that the replacement of ground corn by forage cactus meal, regardless of the level, did not affect the muscle ratio of the carcasses
Summary
Feedlot is an alternative to improve the reduced weight of lambs bred in the caatinga. Santello et al (2006) affirmed that the cost analysis is not favorable to the finishing of feedlot of lambs, and that one of the factors contributing to the increase in costs is the use of corn as the main source of energy. There is great fluctuation in the price of corn during the year because of its use in human and animal food, which stimulates the search for cheaper food alternatives, inexpensive sources of energy available in the region (Melo et al, 2003). Veras et al (2005) studied the effect of replacing a ground corn diet with a forage cactus meal diet on the performance traits of Santa Inês lambs. The evaluation of the final product must include some carcass traits, especially muscularity and adiposity (Cezar & Sousa, 2007), to meet customer demands
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