Effect of dietary whole cottonseed and crude protein level on blood parameters and performance of fattening lambs

Abstract

In this investigation effects of whole cottonseed and dietary crude protein level on dry matter intake, live weight gain, feed conversion and carcass quality and quantity of lambs were studied. Treatment diets were different in crude protein (CP) level and amount of whole cottonseed (WCS). The compositions of diets given to the different treatments were as follow: (1) control (without WCS), 14% CP and 2.44% ether extract (E.E.); (2) 20% WCS, 14% CP, 6% E.E.; (3) 20% WCS, 12% CP, 5.8% E.E. All diets contained 49% of forage and 51% of concentrate. Twenty four male lambs were allocated to three treatments as completely randomized design. All three groups were fed a control diet for 21 days prior to the start of the 90-day experimental period. Thereafter, one group (control) continued to receive the same diet while other groups received the diets 2 and 3. At the end of the experiment, all the animals were slaughtered on the same day. Feeding 20% of WCS significantly ( P < 0.05) decreased the final weight, live daily gain, feed conversion, the weight of warm and cold carcass, liver, lung, shoulder, loin, leg, lean meat, empty forestomach, and eye muscle area (cm 2), but increased the blood cholesterol and HDL. The lambs fed diet containing WCS and 12% crude protein had significantly ( P < 0.05) lower blood urea and LDL concentration than that of lambs fed diet containing WCS and 14% crude protein. These results suggest that in feeding fattening lambs with WCS the proportion of WCS in the diet should be lower than 20%. However, when using 20% whole cottonseed, the dietary crude protein level should be reduced about 2%.