Effect of protein nutrition between 5.5 and 20 kg on the on the subsequent performance and carcass quality of pigs.

Abstract

EFFECT OF PROTEIN NUTRITION BETWEEN 5.5 AND 20 KG ON THE SUBSEQUENT PERFORMANCE AND CARCASS QUALITY OF PIGS R.G. CAMPBELL* and R.S. BIDEN** Between 5 and 20 - 25 kg liveweight pigs -are generally offered diets with high levels of protein to promote rapid growth. However, little emphasis is given to the effect that nutrition, during this early period of development, may have on the pig's subsequent performance and carcass quality. A number of research workers, amongst them Elsley a963), Nielsen @964)and Zimmerman and Khajahern @975)have shown, however, that pigs subjected to nutritional restriction up to 20 kg liveweight often exhibit compensatory growth responses during subsequent development. Our experiment studied how pig performance and carcass quality subsequent to 20 kg liveweight was influenced by protein nutrition between 5.5 and 20 kg liveweight, A total of 30 male pigs weaned at 20 days of age were used in the experiment. Between 5.5 and 20 kg, they were offered diets with a single level of DE and' 16.4, 19.2 or'21.9% crude protein. All,diets were offered ad libitum and four pigs from each treatment were mslaughtered at 20 kg liveweight and their carcass characteristics compared. The remaining pigs were transferred to a diet with 19.7% crude protein fed e in restricted amounts until 70 kg liveweight, when all pigs were slaughtered and their carcasses compared. Between 5.5 and 20 kg liveweight pigs offered 19.2 and 21.9% crude protein diets grew faster and more efficiently (P < 0.05) than pigs offered the diet with 16.4% crude protein. The proportion of protein and ether extractable material in the empty carcass at 20 kg liveweight increased and decreased respectively with each increase in dietary protein. However, subsequent to 20 kg liveweight the pigs previously offered the 16.4% crude protein diet tended to exhibit the fastest growth and between 20 and 45 kg liveweight had a significantly (P < 0.05) lower food conversion ratio than pigs previously offered the two higher protein diets. Compared over the entire production period (5.5 to 70 kg) there were no differences in growth rate or food conversion between treatments. Likewise there were no significant differences between treatments for carcass composition on any of the carcass quality parameters measured at 70 kg liveweight. The lack of any differences in the overall performance (5.5 to 70 kg) on carcass quality at 70 kg liveweight between pigs offered diets with adequate or inadequate protein for optimum performance between 5.5 and 20 kg suggests the present practice of feeding young pigs high protein diets to produce maximum growth to 20 - 25 kg liveweight may be unnecessarily expensive. ELSLEY, F.W.H. (1963). J. Agric. Sci. Camb. 61: 243. == NIELSEN, H.E. (1964). Anim. Prod. 9: 301. ZIMMERMAN, Dr'R. and KHAJAHERN, S. (1575). J, Anim. Sci. 36: cc 189. . ** Animal Research Institute, Department of Agriculture, Werribee, 3030. Present ly located at School of Agriculture, University of Melbourne, Parkvil le, 3052, 156.