| Abstrakt: |
Horses and rabbits were fed high (casein or soybean meal) and low (corn gluten meal or gelatin) quality protein diets in 10 conventional metabolism trials. In eight trials, the diets were fed ad libitum whereas they were pair-fed in two trials.Both immature rabbits and mature horses and rabbits were sensitive to protein quality—the main effect being on voluntary food intake. Both herbivores consumed significantly more high than low quality protein diets. Consequently, digestible energy intake, nitrogen balance, apparent biological value and weight gain were greater in all trials on the high quality protein diets. Coprophagy improved the apparent biological value of gelatin more than casein. However, the improvement did not make it equal to that of casein. It also significantly increased digestible energy intake, energy and protein digestion, nitrogen retention and body weight gain. The data suggest that microorganisms of the lower tract improve the biological value of low quality protein, but that the microbial protein thus formed may be poorly digested and absorbed from the lower tract. |
