Effect of various levels of supplementation with sodium bicarbonate on feed intake and animal performance in fattening lambs

Forty-eight male Merino lambs with an average initial age of 6-7 weeks and 15.7 kg of body weight were used to evaluate the effects of either adding increasing amounts of sodium bicarbonate to the concentrate or the free access to this buffering salt on feed intake and animal performance. Animals were allocated into six experimental groups, receiving concentrate and barley straw ad libitum. The control group (B0) received concentrate without sodium bicarbonate. Another group (Bfree) received the same diet and sodium bicarbonate ad libitum. The other groups were fed concentrates with different levels of inclusion of sodium bicarbonate: 10 (B1), 20 (B2), 30 (B3) and 40 (B4) g bicarbonate/kg concentrate. Animals were slaughtered after a 45-day fattening period. Hot and cold carcass weights were recorded. There were no differences among dietary treatments in barley straw intake. However, concentrate intake tended to be higher (P = 0.09) for B2, B3 and B4 as a unique group when compared to B0. A tendency (P = 0.05) for a B0 vs. B2+B3+B4 comparison was observed for organic matter intake per unit of weight gain. There were not significant effects on cold carcass weight, chilling losses or dressing percentage. Ad libitum sodium bicarbonate intake fluctuated within a wide range, the mean consumption being 47g per kg of concentrate intake, without any consistent effect on any of the parameters measured, probably due to both an excess of additive intake and the intermittent pattern of ingestion of the salt. Our results show that supplementing sodium bicarbonate in the concentrate at levels ranging from 20 to 40 g/kg may improve feed intake and animal performance of fattening lambs fed high concentrate diets, and the optimal supplementation rate seems to be situated around 20 g/kg.