Goat kid slaughter value and muscle quality after dietary supplementation with an alfalfa protein–xanthophyll concentrate
Abstract. The objective of this study was to determine the effect on goat kids of supplementation with protein–xanthophyll concentrate (PX) obtained from alfalfa (Medicago sativa). Assessments were made on carcass dressing percentage and the lipid profiles of muscle tissue. When the animals reached 30 days old (the start of the fattening period), they were allocated to two feeding groups: a control group (K), which received a standard concentrate diet, and an experimental group (D), which was fed a modified control diet where 3 % of the soybean meal was replaced with an alfalfa protein–xanthophyll preparation (PX). For the rest of the study the kids had ad libitum access to dam milk, hay and their respective diets. After 90 days of rearing (from the end of the fattening period up to when the kids were approximately 120 days of age), five (male) kids were randomly selected from each group and slaughtered. Overall, PX supplementation in goat kids does not affect any parameters of fattening, such as slaughter weight, daily weight gains or dressing percentage. However, beneficial effects of feeding with PX concentrate were found in a higher loin percentage and improved tissue composition resulting from lower fat tissue content. Moreover the PX dietary supplement improved the chemical composition of the muscle tissue by increasing the content of protein and unsaturated fatty acids. Taken together, our results suggest that supplementing the fattening diet for goat kids with the PX preparation did not affect the quantitative parameters of fattening but had a positive influence on the quality of carcass composition.