A response surface approach to examining the use of separated milk and wheat by growing pigs

Abstract

Response surfaces were examined relating inputs of separated milk and wheat to liveweight gain, efficiency of feed conversion, and carcase composition of pigs growing to pork or bacon weights. Twenty-eight different dietary treatments were examined in eight separate experiments. Diets ranged from all separated milk to all wheat, and in each experiment levels of feeding ranged from two to five per cent of body weight. A total of 128 individually fed pigs were used. As levels of feeding increased, daily gains increased, dissectible lean decreased, but there was no consistent effect on efficiency of feed conversion. The exception was where the quality and quantity of protein ingested limited growth rate, and under these circumstances feed efficiency tended to worsen. Desirable production factors were not necessarily associated with any one treatment. Although high daily gains meant that pigs were marketed earlier, carcases produced in this way were fat and not as valuable as those pigs grown more slowly. It was concluded that the response surface approach offers a method of examining a wide range of inputoutput relationships with a minimum expenditure of research facilities.