Effects of animal or plant protein diets on cecal fermentation in guinea pigs (Cavia porcellus), rats (Rattus norvegicus) and chicks (Gallus gallus domesticus)

Monogastric herbivores such as the guinea pig depend on energy supply from enteric fermentation as short-chain fatty acids (SCFA) corresponding to 30- 40% of their maintenance energy requirements. They evolved specific digesti ve system to adapt their indigenous microflora to plant polysaccharides fer mentation. No information has been available about the adaptability of micr obial fermentation in hindgut of the monogastric herbivorous to an animal p rotein diet. We investigated if the guinea pig can fully retrieve energy of an animal protein diet by hindgut fermentation compared with a plant prote in diet. For comparison, we also studied two omnivores. End products of in vitro cecal fermentation (SCFA, ammonia and gases) were measured to judge h ow well an animal protein diet could be fermented. The animal protein diet resulted in the less intensive fermentation with increased feed intake and volume of cecal contents than the plant protein diet only in guinea pigs. T his may be due to a limited capacity of the hindgut microflora to adapt to the substrate rich in animal protein. We also found that chick cecal conten ts produced methane at higher emission rate than ruminants. (C) 2000 Elsevi er Science Inc. All rights reserved.