Effects of milk replacer supplementation with Conjugated Linoleic Acid and Live Weight at Slaughter on growth and carcass and meat quality of kids

Abstract

The objective of present research was to determine effects of Conjugated Linoleic Acid (CLA) inclusion in milk replacer on artificial rearing of kids. CLA was fed to newborn kids as 1.2% of the diet. A commercial CLA preparation (CLA 60) containing 60% CLA isomers was included at 2% to provide 1.2% CLA in the diet. The inclusion of CLA in diet was initiated at 2 days of life and fed until slaughter. Growth, carcass and meat quality data were collected and analyzed. Treatment groups included two control diets, one slaughtered at 6 kg (C6) Live Weight at Slaughter (LWS) and another one slaughtered at 10 kg LWS (C 10) and 2 CLA supplementation at 1.2% of the diet for 6 (CLA6) and 10 (CLA10) kg LWS. Average Daily Gain (ADG) was significantly (p<0.05) affected by the inclusion of CLA in the milk replacer. CLA 1.2%+milk replacer fed kids grew at 156 g d(-1) while CLA 0%+milk replacer kids grew at 130.98 g d(-1). Commercial Carcass Yield (CCY) and Net Carcass Yield (NCY) were affected by CLA, where kids CLA fed (CLA6 and CLA10) presented lower CCY and NCY than control kids. The statistical differences were slightly higher rising to p<0.05 in CCY and lower in NCY. An increase in LWS had a statistical effect on CCY and NCY, because older kids presented higher carcass yield values. A statistical interaction was observed in CCY and NCY parameters between two fixed effects, however C6 and CLA6 kids presented more differences in carcass yield than C10 and CLA10. These results may suggest a relationship between CLA feed and early abomasum development, however the empty gastro-intestinal tract was heavier in CLA6 and CLA10 than in control kids (p = 0.03). CLA in milk replacer tends to increase the total fat in the shoulder cut (p = 0.073) but no other effects are shown. There were significant differences among LWS for the percentage contribution, increasing subcutaneous and intermuscular fat, total fat and muscle and decreasing bone to carcass side weight. pH values were statistically affected by CLA inclusion in the milk replacer, but a high interaction between CLA and LWS was observed in pH(u). Initial and final pH in the Longisimus toracis et lumborum and semimembranosus muscles was higher in CLA6 than C6 but these differences did not show in 10 kg LWS kids. The L, Croma and Hue values were unaffected by CLA addition in milk replacer. The L and Hue value was slightly higher in C6 than in CLA6 for the Longissimus toracis et lumborum and Semimembranosus muscles.