Physical and chemical characterization of lamb meat from different genotypes submitted to diet with different fibre contents

The objective of the study was to evaluate the effect of genotype and the dietary fibre concentration in the chemical composition and physical properties of lamb meat. Samples from 54 animals from Morada Nova and Santa Inês native breeds and Dorpper × Santa Inês half-breed were analyzed, which received two diets, one with 41.7% and another with 33.6% fibre content, until reaching the average slaughter weight of 30 kg. The design used was fully randomized 3 × 2 factorial, three genotypes and two diets with nine replicates. Colour and pH in Semimembranosus muscle were determined, together with the analyses of the water retention capacity, loss of weight due to cooking, shearing force, and chemical composition in Longissimus dorsi muscle. The factor genotype influenced the chemical composition of meat, with Santa Inês lamb and crossbreed showing the highest protein percentages. The diet with 33.6% fibre content provided meat with higher moisture percentage and lower protein value, and the loss of weight due to cooking and shearing force parameters did not interfere in other variables. In addition, lambs receiving higher fibre content diet produced meat with lower shear force values, having indicated to be more tenderness. Despite these variations, the meat of lambs from all genotypes and under the diets evaluated can be considered of good quality.