The herbage intake of cattle grazing lucerne and cocksfoot pastures

Abstract

1. From 1955 to 1957 a cattle grazing experiment was carried out on lucerne and cocksfoot pastures. Hereford-cross steers were used. Results obtained on the assessment of herbage intake either by the use of chromic oxide and faecal index methods or by herbage sampling are presented here.2. Except in 1955, when techniques were being developed, the digestibility of the herbage on offer to the bullocks was estimated by cold storing herbage, cut with an Allen Autoscythe and later feeding it to sheep in indoor digestion trials. The in vitro digestibility of herbage samples cut in 1955 and 1956 was also determined.3. In 1956 the mean intake of organic matter (lb.) per 100 lb. live weight by faecal methods was 2·38, 2·07, 2·20 and 2·29 on pastures of lucerne, cocksfoot, lucerne/cocksfoot (broadcast) and lucerne/cocksfoot (alternate 1 ft. drills), respectively, and 1·99, 1·76, 2·02 and 1·97, respectively, in 1957.4. In 1956 the mean intake of organic matter (lb.) per 100 lb. live weight by herbage sampling methods was 2·14, 1·70, 2·11 and 1·99 on the same pastures of lucerne, cocksfoot, lucerne/cocksfoot (broadcast) and lucerne/cocksfoot (drills), respectively, and 2·49, 1·32, 2·35 and 2·03, respectively, in 1957. The modified Tarpen trimmer, cutting to within 1 in. of the ground was used for sampling in 1956 and the Allen Autoscythe cutting to within 2 or 3 in. of ground level in 1957.5. Detailed botanical separation of herbage samples showed that the bullocks were selecting the more digestible parts of the plants; the top 4 in. of lucerne and the ends of leaves and stems of cocksfoot. This and other factors which could affect the estimates of digestibility of herbage eaten by the cattle are discussed together with possible sources of error in the herbage sampling methods.