INGREDIENT AND PROCESSING INTERRELATIONSHIPS IN SWINE FEEDS: II. EFFECTS OF ANTIBIOTICS, PROTEIN SOURCE AND PELLETING ON THE RESPONSES TO THE INCLUSION OF WHEAT BRAN

This is the second in a series of reports on the growth, feed intake and digestibility responses of growing swine (50 to 110 pounds) involved in a 2 × 2 × 2 × 2 factorial test of the effects of wheat bran, pelleting, antibiotics and type of protein in the ration. Discussion in this paper was restricted to those factors affecting the responses to the inclusion of wheat bran.With approximately isocaloric diets the inclusion of 10 per cent bran resulted in a general increase of 6 per cent in feed intake (P = <.01) and 8 per cent in digestibility of protein. The greatest effects were obtained with antibiotic-free, animal protein-free, meal-type rations in which the inclusion of bran resulted in 18 per cent more feed and 28 per cent more digestible energy being consumed.The effect of bran on energy digestibility was small relative to its effect on protein. It is postulated that differences in the rates and site of absorption of starch and protein components may be related to the efficacy of bran in the digestive tract.The similarity observed between the effects of bran and antibiotics is discussed in relation to possible deficiencies of B-vitamins and amino acids.