EFFECT OF BETAINE ON FAT-CONTENT IN GROWING LAMBS

A total of 48 weaned Manchego breed lambs (same number of males and fe males) with ail initial live weight of 11.5 kg were randomly distribut ed into four pens to study the effect of betaine supplementation in a 2x2 factorial design with dietary betaine and sex as main effects, Wea ned males and females were fed on a starter diet for 3 weeks (aprox 20 kg live weight) and then were changed to a finisher diet for another 3 weeks. Within each feeding period, the starter and finisher diets co ntaining 0 or 2 g kg(-1) betaine were fed to each group of males and f emales lambs. No effect of betaine was observed on weight gain and fin al body weight of lambs. The evolution over time of ultrasonic determi nation of subcutaneous fat thickness (FT) showed a significant lower F T from near week four of experiment to slaughter in lambs receiving th e diet enriched in betaine (P<0.0001). No effect of sex was observed o n FT. Measurement of longissimus dorsi muscle area showed no effect of sex or diet. Muscle area and FT measured on the carcass showed simila r results, A lower concentration of neutral lipid in intramuscular fat of lambs Fed diets enriched in betaine than in those fed the basal di et, was also observed (P=0.0211), which suggest a generalized effect o f betaine lowering animal fat in all lamb tissues, No effect of diet o r sex was observed on polar lipid concentration in muscle. No effect o n individual fatty acids was observed in any case, but lambs fed diets enriched in betaine had slightly lower concentration of (n-6) fatty a cids (P=0.0479) and higher concentration of monounsaturated fatty acid s (P=0.0478) in neutral lipids of intramuscular fat. (C) 1998 Elsevier Science B,V.