Rumen microbial population, movement of ingesta from the rumen, and water intake of steers fed apple pomace diets.

The effects of apple pomace diets on rumen microbial population, movement of ingesta from the rumen, and water intake were studied in two trials with beef steers. Trial 1 was a 5 • 5 Latin square in which five ruminal fistulated steers were fed either corn silage plus cottonseed meal (CSM), apple pomace plus CSM, apple pomace plus urea, apple pomace plus urea and starch, or apple pomace plus urea and straw. Apple pomace dyed with Sudan IV was used as a measure of pomace particle depletion from the rumen, and PEG was used to measure ruminal liquid washout rate. Total ruminal ingesta volume and PEG liquid volume were not affected by diet. Both tungstic acid precipitable nitrogen (TAPN) and total bacterial numbers were similar when steers were fed either corn silage plus CSM or apple pomace plus CSM diets, but were higher for these diets than for the apple pomace diets that contained urea. Neither apple pomace, urea, nor straw affected rumen microbial morphology or protozoal numbers. Starch tended to increase the proportion of Gram-positive cocci in ruminal ingesta. Dye deplet ion from the rumen was not affected by treatment. However, liquid washout rate from the tureen tended to be greater when apple pomace diets were fed, particularly from 1 to 4 hr after the apple pomace plus urea and the apple pomace plus urea and starch diets were fed. The washout rates obtained when the apple pomace plus urea and straw diet was fed more closely resembled the washout rates when the apple pomace plus CSM diet was fed. Trial 2 was a 3 x 3 Latin square in which three steers were fed either corn silage plus CSM, apple pomace plus CSM, or apple pomace plus urea. The results of this trial suggested increased water consumption concurrent with greater ruminal liquid washout rate in steers fed apple pomace diets. (