Slaughter Parameters of Broiler Chickens at Different Levels and Ratios of Lysine and Threonine in the Compound Feed

Abstract

The article highlights the results of the study of the influence of different levels and ratios between lysine and threonine in compound feed of broiler chickens on slaughter indicators. The experiment was conducted by the group method on 600 heads of broiler chickens of the "Cobb-500" cross, which were divided into 6 groups of 100 heads each. In the combined feed of chickens of the first three groups against the background of the basic level of lysine, the level of threonine was increased. In the feed of the birds of the other 3 groups, the level of threonine was increased against the background of the increased level of lysine. It was established that the highest indicators of meat productivity in broiler chickens were established for the content of lysine and threonine in compound feed, respectively, in the first growing period (age 1–10 days) – 1.24 and 0.83%; in the second growing period (age 11–22 days) – 1.14 and 0.78% and in the third growing period (age 23–42 days) – 1.09 and 0.70%. When using compound feed with an effective content of lysine and threonine, pre-slaughter live weight increases by 0.65% (р<0.05); weight of semi-carcasses - by 2.12% (р<0.05); the mass of the cartridge carcass - by 3.85% (р<0.05); pectoral muscle mass - by 12.27% (р<0.05); muscle mass of the pelvic limbs - by 12.77% (р<0.05); yield of semi-carcasses - by 1.25% (р<0.05); cartridge carcass yield - by 2.50% (р<0.05); output of pectoral muscles – by 2.34% (p<0.05) and output of pelvic limb muscles – by 1.93% (p<0.05). No antagonism between lysine and threonine has been established. Neither an increase in the content of lysine nor threonine caused a decrease in productivity or other negative consequences. The influence of the lysine-threonine ratio on the meat productivity of chickens has not been established. Productivity increased regardless of the ratio, with an increase in the content of both amino acids in the compound feed. However, the highest meat productivity was noted for the ratio of lysine to threonine in compound feed, in the first period of growing - 0.67: 1; in the second - 0.68: 1 and in the third - 0.70: 1.