Lactose and Whey U T I L I Z a T I O N by Rats and Swine I

The growth rate and feed efficiency of pigs fed a diet containing 10% dried whey and 20% alfalfa was less than with either treatment alone, suggesting a possible antagonism between alfalfa and whey. A digestibility trial with rats indicated that feeding lactose, a major constituent of whey, reduced the digestibility of alfalfa fiber and purified cellulose. In another rat experiment, the feeding of 10 or 20% lactose did not influence growth performance but with 30% lactose growth rate was significantly reduced (P<0.05). At each lactose level, either 10% cellulose, 30% alfalfa or no added fiber were used. There was a significant (P<0.05) fiber source X lactose level interaction, due to a better growth at the 30% lactose level with no added fiber. Examination of the effects of various materials on the interaction between lysine and lactose in heat-treated diets indicated that in contrast to earlier work, alfalfa did not stimulate lysine-lactose interactions (browning reaction). Possible explanations for this are discussed. Torula yeast, ascorbic acid and diammonium citrate additions improved growth, while citric acid, benzoic acid and diammonium phosphate were not effective. A comparison of various fat sources indicated that in general browning was more severe when unsaturated fats were used.