Effect of Sodium Bicarbonate Supplementation on Fatty Acid Composition of Lambs Fed Concentrate Diets at Different Ambient Temperature Levels

The objective of this study was to evaluate the effect of ambient temperature and sodium bicarbonate (NaHCO3) supplementation in diets for growing lambs on meat fatty acids composition. A slaughter study was carried out on 12 male Black Belly Barbados lambs randomly drawn from a prior growth trial (245 days). The lambs were divided into four equal groups and allotted in a 2×2 factorial design. The lambs were allotted at random to two dietary treatments of a basal diet (35: 65 roughage: concentrate) or basal diet supplemented with 4% NaHCO3 at different ambient temperatures (20 and 30°C) in an environment controlled chamber for 10 days. Lambs were slaughtered for carcass evaluation at about 262 days of age (245 days of growth trial, 7 days adaptation and 10 days of experimental period). Samples for fatty acids analysis were taken from the leg muscles and longissimus dorsi region (between the 12 and 13 rib). Ambient temperature influenced (p<0.05, p<0.01, p<0.001and p<0.05) C18:2t isomers, C20:4, C20:3 n-6 and C20:4 n-6 levels on the longissimus dorsi muscle, with higher C20:3 n-6 (p<0.001) but lower C20:4 n-6 (p<0.05) levels in lambs under the higher ambient temperature. The fatty acids C18:1c, C18:2t and C20:5 levels on the leg muscle were also significantly influenced (p<0.01, p<0.001 and p<0.01 resp.) by dietary treatments with higher levels in lambs fed NaHCO3 diet. These results indicated that NaHCO3 supplementation at low ambient temperatures significantly decreased fatty acids levels.