The effect of level of feeding on persistency of milk yield of Ayrshire cows

SUMMARY 1. Twenty-four Ayrshire cows were used in a changeover experiment to investigate the effects on milk yield of offering concentrates at three rates of feeding (220, 250 and 290 g SE/kg milk) and two nutrient densities (63·5 and 72·5 SE). Nutrient density had no effect on milk yield but there was a positive relationship between rate of feeding and persistency. 2. A regression equation relating log10 (—log 10 persistency) to the rate of feeding (g SE/kg milk) was fitted to the data and accounted for 92·3 % of the variation between treatments.