Studies on the nutrition of ruminants 4. The use of ground straw of different particle sizes for cattle from twelve weeks of age

SUMMARY Twenty-four Friesian calves were fed from twelve weeks of age on six diets containing 15 or 30% ground barley straw, the straw being ground through screens of and in. From twelve weeks to seven months of age (120–250 kg) the calves had mean growth rates of 1·15 kg/day with a feed conversion ratio of 4·15: 1. From seven to eleven months of age (250–380 kg) the corresponding figures were 1·16 kg/day and 5·53: 1, and in the final fattening period of 11–14 months (380–500 kg), 0·92 kg/day and 8·19: 1. These differences between stages of fattening were highly significant. There were no differences in performance due to the particle size of the straw or to the proportion of straw in the diet.