Genetic type, sex, age at slaughter and feeding system effects on carcass and cut composition in lambs

Abstract

The aim of this research was to estimate the effects of grading up of Gentile di Puglia with Ile de France on carcass traits and the composition of cuts in lambs slaughtered at 35 and 54 days of age. Data was collected on 223 lambs of both sexes, single birth, belonging to the genetic types Ile de France (IF), Gentile di Puglia (GP) and the result of grading up of the latter with Ile de France rams (F1 and F2). About half of the subjects were fed with maternal milk (natural feeding) while the others were fed on a milk replacer (artificial feeding). The lambs of both groups were randomly allocated in two slaughter age subgroups: 35 and 56 days. The results of statistical analysis showed that the considered factors of variation significantly influences the weight of the carcass, the percentage of cuts and their composition. Most of the variation was due to the age and to the feeding system. The F2 lambs on average had the heaviest carcass and sides, the GP had the highest percentage of fore quarter while the IF had the highest percentage of back quarter. Furthermore F1 lambs did not show any heterotic effect compared with both parental breeds, while F2 breeds showed better performance. The carcass of the males resulted heavier than the females, with a lower percentage of dissectible fat at the neck, brisket, shoulder and leg and a higher percentage of meat in the shoulder cut. The lambs slaughtered at 35 days of age showed a higher incidence of kidney, shoulder and leg weight, while at 56 days furnished a higher percentage of kidney fat, brisket and loin weight. The artificially fed lambs furnished a lighter carcass and neck and shoulder cuts than naturally fed lambs, less kidney fat and a higher percentage of kidney, rib and loin weight. The employment of artificial feeding permitted a higher percentage of lean and less dissectible fat as well as a higher lean/bone ratio. These results show that Ile de France rams crossbreed with Gentile di Puglia determine good productive performance if the lambs derive from the F2 crossbreed and are artificially fed and slaughtered at 56 days of age.