Development of an Intensive Dairy Calf-to-Beef System and Associated Grassland Management.

Abstract

Over the years, beef production systems have been intensified and de-intensified in response to national and European Union policy changes. In the mid 1990s, a millennium target was set to produce 1000kg of beef carcass per ha in a dairy calf-to-beef system. This was in anticipation of possible future decoupling of premia from animals and the evolution of a production environment favourable to intensification. Results from a dairy calf-to-beef system for the years 1994 to 1997 are included in an earlier report (Keane and O’Riordan, 1998). This report presents the results of three production cycles of a two-year-old system (1996- 1998, 1997-1999 and 1998-2000) together with the findings from a comparison of three systems of grazing management. In cycle 1, Standard and Improved management options were compared. The differences between the two were that under Improved management, the yearlings were put to pasture about 3 weeks earlier than normal and they grazed the silage area until Standard turnout time, there were double the number of grazing paddocks in the rotation, and the animals remained at pasture later in autumn. Stocking rate was 2.76 animal units (yearling + calf) per ha. In cycles 2 and 3, stocking rate was 3.0 animal units per ha. Spring-born Charolais x Friesian steers were used in all cycles. Improved management increased liveweight gain of yearlings particularly in the early part of the grazing season but the Standard management animals exhibited compensatory growth subsequently which continued throughout finishing so that by slaughter there were no differences between the two management systems. In cycles 1, 2 and 3, total fertiliser N inputs were 217, 230 and 264 kg/ha, total silage yields conserved were 1.8, 1.6 and 1.7 t dry matter per animal unit, total lifetime concentrate inputs were 1057, 1042 and 1118 kg per animal and total number of days from arrival to slaughter were 736, 738 and 769, respectively. For cycles 1, 2 and 3, mean slaughter weights were 665, 660 and 644 kg, mean carcass weights were 360, 356 and 346 kg, mean carcass conformation scores were 2.77, 2.75 and 2.75 and mean carcass fat scores were 4.16, 4.19 and 4.15, respectively. Slaughter weight and carcass weight outputs per ha were 1833, 1980 and 1932 kg, and 992, 1068 and 1038 kg for cycles 1, 2 and 3, respectively, indicating achievement of the millennium target of 1000 kg/ha carcass output. Three systems of grazing management namely leader/follower, calves and yearlings mixed, and calves and yearlings grazed separately, were compared. Mean liveweight gains for the grazing season as a whole for the treatments as listed were 891, 948 and 1076 (s.e.d. 35.5) g/day for the yearlings, and 744, 702 and 671 (s.e.d 13.5) g/day for the calves. Leader/follower calves were 39 and 51 kg, respectively heavier than the mixed and separate calves at housing as weanlings. The corresponding values at turnout the following spring and at housing as yearlings were 42 and 52 kg, and 22 and 39 kg, respectively. There was no evidence of compensatory growth during the winter but some compensation did occur during the following grazing season. Having calves graze ahead of yearlings in the leader/follower system reduced housing weight of the latter by 18 and 34 kg compared with the mixed and separate treatments, respectively. There was no compensation during the following (finishing) winter at the end of which the corresponding slaughter weight differences were 19 and 36 kg resulting carcass weight differences of 12 and 21 kg. In the current policy environment where the optimum economic stocking rate is well below that which is technically possible and where it is no longer necessary to simultaneously optimise output per animal and output per ha, the challenge is to devise grazing strategies which maximise the performance of both calves and yearlings during the grazing season.