Last update: November 22, 2010 12:37:34 PM E-mail Print

 

A comparison of rumen fermentation patterns in sheep and goats on a variety of diets

 

P. G. Marais1 &  J. A. Roux2

 

1Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg, 5900, Eastern Cape, South Africa

2Cradock experimental Station, P O Box 284, Cradock, 5880, Eeastern Cape, South Africa

 


 

The aim of this study was to widen the range of observations from poor to good quality diets, with the hypothesis being that interspecies differences in apparent digestibility of nutrients do occur. The in vivo digestibility, the rate of fermentation and passage and the rumen fermentation pattern was compared in Merino wethers, Dorper wethers, castrated Angora goats and castrated Boer goats on a 100% lucerne, 75% lucerne and 25% wheat straw, 50% lucerne and 50% wheat straw and 25% lucerne and 75% wheat straw diets. The animals were all stallfed with a pelleted diet. The nylon bag technique was used to estimate the extent and fractional rate of degradation of the specific diet in the rumen. The fractional outflow rate of particles was determined with chromium as a marker. Significant interspecies differences in the nutrients digestibilities were found. Values of potential and effective degradability and rates of degradation differ between breeds. Also, the calculated values of the fractional rate of passage of the digesta out of the rumen differ significantly between species on the low quality diet. On the low quality diet the values of the ammonia-N concentrations were higher in goats than in sheep. These results do not support the observations that allow conclusions, that sheep and goats,  have a similar capacity to digest forages of medium to good nutritional quality. Therefore, that extrapolation of feed energy values from one to other animal species could not be validated.