Adding bentonite to sorghum grain-based supplements has no effect on cow milk production

Abstract

Summary. Twenty-four Holstein–Friesian cows were used in an experiment comparing milk production from cows offered rolled sorghum grain either alone at 8 or 10 kg/head. day of air-dried grain or with 4% sodium bentonite. The design was a 4 × 4 latin square with a 1 week adjustment period and a 3 week treatment period. This design was used to highlight the effects of high levels of grain feeding and changing that level of grain or grain–bentonite every 4 weeks. Cows grazed either ryegrass (Lolium multiflorum cv. Tetila) or oats (Avena sativa cv. Cluan) during the day and a mixed ration based on maize silage, lucerne hay, and meat and bone meal at night.

There was no significant effect of treatments on milk yield or composition. Cows fed bentonite had a higher (P<0.05) rumen pH, tended to eat less grain sorghum and have lower concentrations of rumen ammonia and faecal starch. Faecal crude protein tended to increase with the use of bentonite indicating cows may have substituted pasture or mixed ration for grain and maintained a more stable rumen fermentation.