The use of glycerine in rations for light lamb during the fattening period

One hundred and two Ripollesa weaned lambs (15 ± 1.7 kg BW; 45 ± 7.9 days of age) from two different lambing periods (Period 1 n = 39 and Period 2 n = 63) were used to study three different diets that included 0 g/kg, 50 g/kg or 100 g/kg glycerine in the concentrate. Lambs were fed concentrate (180 g/kg CP, 18.7 MJ of GE/kg DM) and barley straw ad libitum until the slaughter weight (25 SEM = 1.4 kg BW). Lambs were distributed in 9 pens per period in groups of 4 or 5 lambs (Period 1) and 7 lambs (Period 2) according to their weaning BW and age, and BW and concentrate and straw intakes as well as water consumption were measured weekly. Blood samples to determine glucose and insulin concentrations were obtained at 2 and 4 wk of the study, and carcass weight was recorded at the slaughterhouse. At slaughterhouse a sample of rumen mucosa of the caudal sac of the ventral zone was obtained to determine the number of rumen papillae, and a sample of the Longissimus dorsi from ten female lambs per treatment was obtained to analyse fatty acid profile of the meat. None of the parameters measured in lambs were affected by the glycerine content of concentrates. The only differences observed were in meat fatty acid composition. The C12 (P=0.08) and C17 (P=0.06) tended to be greater in lambs fed concentrates with glycerine than without glycerine. In contrast, total amount of C18:1 cis in muscle tended (P=0.10) to be greater in lambs consuming a concentrate without glycerine than in lambs receiving concentrates with glycerine. Glycerine can be included as an ingredient in lamb diets during their fattening period without impairing the growth of lambs, without reducing concentrate or straw intake, and without affecting blood metabolites, rumen papillae development, and the main fatty acids of L. dorsi muscle.