Effect of Sodium Bicarbonate Supplementation on Carcass Characteristics of Lambs Fed Concentrate Diets at Different Ambient Temperature Levels

The objective of this study was to investigate the influence of ambient temperatures on carcass characteristics of lambs fed concentrate diets with or without $NaHCO_3$ supplementation. A slaughter study was carried on 12 male Black Belly Barbados lambs randomly drawn from a growth trial (35 weeks). The lambs were divided into four equal groups and allotted in a $2{\times}2$ 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% $NaHCO_3$ at different ambient temperatures ($20^{\circ}C$ and $30^{\circ}C$) 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). Ambient temperature had significant (p<0.05, p<0.05, p<0.01, and p<0.001) effects on meat color from the ribeye area (REA), fat, leg and longissimus dorsi muscles with higher values recorded for lambs in the lower temperature group than those from the higher ambient temperature group. Significant differences (p<0.05) in shear force value ($kg/cm^2$) recorded on the leg muscles showed higher values (5.32 vs 4.16) in lambs under the lower ambient temperature group compared to the other group. Dietary treatments had significant (p<0.01, p<0.01, and p<0.05) effects on meat color from the REA, fat, and REA fat depth ($cm^2$) with higher values recorded for lambs in the $NaHCO_3$ supplementation group than the non supplemented group. Similarly, dietary treatments had significant differences (p<0.05) in shear force value ($kg/cm^2$) of the leg muscles with the $NaHCO_3$ groups recording higher (5.30 vs 4.60) values than those from the other group. Neither ambient temperature nor dietary treatments had any significant (p>0.05) effects on pH, and water holding capacity on both muscles. These results indicated that $NaHCO_3$ supplementation at low ambient temperatures had caused an increase in carcass characteristics leading to significant effect on meat quality.