Fast-growing chickens fed with lucerne protein-xanthophyll concentrate: growth performance, slaughter yield and bone quality

The aim of this study was to determine the effect of addition of lucerne protein-xanthophyll concentrate (LPC) on physicochemical, morphometric and strength characteristics of bone tissue as well as growth performance and selected slaughter parameters in broiler chickens. One hundred fifty broilers were assigned to three treatment groups, each group was replicated five times (10 birds in each). The control group (C) was fed a standard feed mixture without the experimental additive. The soyabean meal in the experimental diets was replaced with LPC in an amount of 1.5% (group 1.5% LPC) or 3.0% (group 3% LPC). In comparison with group C, the LPC doses increased chicken body weight on day 21 of rearing, reduced the mortality rate by 50%, increased pectoral muscle weight and reduced the content of abdominal fat by 42.5% and 51.5%, respectively. Addition of 3% of LPC increased the chilled carcass weight by 13.2% and slaughter yield by 2.98%, as compared with group C. The greatest length and the largest circumference of tibia and the highest values of the secondary moment of inertia (lx) and mean relative wall thickness (MRWT) of femur and tibia were noted in the LPC-treated chickens. The obtained results indicate that the LPC supplementation enhanced bone mechanical strength resulting from the increase in the geometric parameters (lx and MRWT) as well as the cortical layer thickness. The bones were characterized by higher flexibility and breaking strength. The increased content of Ca and Zn and the higher value of the bone density index indicate normal bone mineralization.