The effect of supplements of sucrose and of glucose monohydrate on the milk production and live weight of dairy cows

Abstract

SUMMARYThree experiments on the effects of sugars on milk production and live weight of cows are described. Two experiments each with twelve cows were of latin square design with 5-week periods. The third was a continuous treatment experiment of 11 weeks duration with twenty cows. All the animals were in mid-lactation. Performance on the basal diet of hay and concentrates was compared to that when the basal diet was supplemented with 10·7 Meal digestible energy daily in the form of sucrose or glucose monohydrate or concentrates.Additional concentrates regularly increased milk yield, live-weight gain, solids-not-fat content of the milk, and yields of solids-not-fat and milk fat. Fat content of the milk was not affected.Sucrose had a small beneficial effect on milk yield; the effect of glucose monohydrate on yield was small and indecisive. Sucrose depressed milk fat percentage; the effect of glucose on milk fat percentage varied between experiments. Both sugars increased solids-not-fat content of the milk, solids-not-fat yield, and rate of live-weight gain.Over the longer treatment period in the third experiment milk fat content tended to recover partially for both sugar-supplemented rations. The effects on yield of milk and of milk fat did not alter. The effects on live-weight gain were established more decisively and the final order of the size of the beneficial effect of the supplements was: concentrates, glucose monohydrate, sucrose.At the end of the third experiment rumen, contents from all cows were sampled by stomach tube. The concentrates supplement had no effect on the proportions of volatile fatty acids. Both sugars depressed the proportion of acetic acid and increased the proportions of propionic, butyric and valeric acids. In all cases except that of butyric acid, where the reverse occurred, the effect of sucrose was greater than that of glucose monohydrate.