More frequent allocation of herbage does not improve the milk production of dairy cows in early lactation

Abstract

Two experiments were conducted to test the hypothesis that offering a given daily allowance of herbage as smaller feeds more frequently than once per day will increase daily herbage intake and milk yield.

In experiment 1 (spring 1995), cows in early lactation were offered either 40 or 65 kg DM/cow.day allowance of herbage as either 1 feed or as 6 equal feeds. The latter cows received a fresh strip of herbage at 0600, 0900, 1100, 1330, 1800 and 2000 hours. The experiment lasted 28 days with treatment effects being measured from days 15 to 28. There were no significant differences in herbage intake (15.6 v. 15.9 kg DM/cow.day), grazing time (9.4 v. 9.5 h/cow.day), milk production (25.4 v. 25.2 L/cow.day) or milk composition between the 1-feed treatment and 6-feed treatment, respectively, during the final 2 weeks of the experiment. Increasing herbage allowance increased (P<0.001) herbage intake. Liveweight loss during the experiment was less (P<0.05) for 6-feed cows than 1-feed cows.

A similar experiment was conducted in 1996 (experiment 2); however, all cows were offered a single herbage allowance of 50 kg DM/cow.day. The frequencies of feeding were the same as in experiment 1 except that a new strip of herbage was offered to the 6-feed cows at 0800, 1130, 1700, 2030, 2400 and 0330 hours. The experiment comprised 2 intensive measurement periods, the first in weeks 1 and 2 (period 1) and the second in weeks 4 and 5 (period 2). Herbage intake did not differ between treatments averaging 15.2 and 16.3 kg DM/cow.day for the 1-feedtreatment and 6-feed treatment respectively. Milk yield declined from 27.1 L/cow.day in period l to 25.6 L/cow.day in period 2 and was lower for the 6-feed treatment than for the 1-feed treatment 25.7 and 26.7 L/cow.day, respectively. Offering fresh herbage to the 6-feed cows between 2000 and 0600 hours decreased the proportion of daylight hours these cows spent grazing but did not change total grazing time.

Despite the adoption of extreme grazing management procedures in the experiments reported in this paper, we were unable to increase herbage intake or milk production of dairy cows in early lactation. It would appear that farmers have little opportunity to increase herbage intake in early lactation by increasing the frequency of allocation of pasture