Effects of grass pasture and concentrate-based feeding systems for spring-calving dairy cows in early spring on performance during lactation

The effect of offering a total mixed ration of silage and concentrate (proportionately 0·44 silage) system [in-door feeding system (IF)] was compared with grazing at a high daily herbage allowance with a low level of concentrate supplementation [early grazing system (EG)] in early spring on the performance of spring-calving dairy cows in Ireland. Sixty-four spring-calving Holstein-Friesian dairy cows (mean calving date, 2 February) were allocated to one of two systems between 16 February and 4 April 2004. An equal number of primiparous and multiparous cows were assigned to each system. The dairy cows on the IF system were housed for a 7-week period and offered a diet of 10·9 kg DM cow^-1 d^-1 (s.d. 2·3) of concentrate, the remainder of the diet was 8·6 kg DM cow-¹ d^-1 (s.d. 1·9) of grass silage. The dairy cows on the EG system were offered a mean daily herbage allowance of 15·1 kg DM cow^-1 d ^-1 (s.d. 3·7) and were supplemented with 3·0 kg DM cow^-1 d^-1 (s.d. 1·0) of concentrate. There was no difference in milk yield between the two systems but the cows in the EG system had a higher milk protein concentration (2·9 g kg^-1) and a higher milk protein yield than in the IF system. Milk fat concentration was higher for cows in the IF than EG system (3·0 g kg^-1). There was no difference in total daily dry-matter intake between the systems, measured in week 6 of the study. Mean live weight of the cows in the IF system was greater than in the EG system. The results of the study suggest that a slightly greater performance can be achieved by a system offering a high daily herbage allowance to spring-calving dairy cows in early lactation compared with a system offering a total mixed ration containing a high proportion of concentrate with grass silage.