Effects of grass and concentrate feed on growth performances of rumbi lamb and meat fat composition

Abstract

This study aims to evaluate and compare the effect of grass and standard feed on lamb zoo technical parameters and meat fatty acid (FA) composition. 36 lambs of Rumbi breed were used in this trial, of which 24 lambs were organized in 2 groups (n=12) grazing on pasture at Semi-Arid (SA) and Wet (W) areas in west of Algeria during 100days. The third group was bred indoors by Concentrate feed (C). At the end of the experiment, lambs from group C were heavier (48.04 vs 28.13 and 24.23kg pre-slaughter). After slaughter, carcasses from SA and W groups were leaner (14.38 and 11.63 vs 23.93kg after cooling). Samples of longissimus dorsi (LD) were removed and analyzed. The results showed much fat in meat from group C (16.44 vs 6.87 and 5.89%)(P<0.001). The percentages of polyunsaturated fatty acids (PUFA) in meat from grazing lamb were higher (7.01 and 8.71 vs 5.05%)(P<0.05). All PUFA n-3 in meat from pasture have promoted significant amounts (2.07 and 2.67 vs 0.41%)(P<0.001),most importantly in terms of C18:3n-3 (ALA) (1.16 and 1.42 vs 0.2%)(P<0.001) while there was no significance for C18:2 n-6 (LA) (3.40 and 3.94 vs 3.40%). However the LA/ALA and n-6/n-3 ratios were much desirable for health in grazing lamb meat respectively (4.01 and 2.90 vs 14.31)(P<0.001), (2.86 and 2.25 vs 12.08)(P<0.001). Based on these results and from a fattening perspective, grazing is declared to be a husbandry system economically sustainable. Itneeds a promotion to seek new opportunities for the production of the main organic food such as light lamb.