Abstract

Over three dairy seasons (1993/94-1994/95) the input of additional N fertiliser (149 kg N/ha) and dairy meal (570 kg meal/cow) was evaluated in dairy farm systems with calving commencing on 20 June. Four farm systems were evaluated: Control LS (no extra N fertiliser, stocking rate, 3.6 cows/ha), NLS (21 kg N/ha after every grazing September to January, 3.6 cows/ha), NHS (N fertiliser same as NLS, 4.2 cows/ha) and NMHS (N fertiliser same as NLS, dairy meal fed at 0.5-3.0 kg/cow/day depending on pasture availability, 4.2 cows/ha). Each farmlet received a base application of 100 kg N/ha; 40 kg N/ha in March and 60 kg N/ha in July. The additional 146 kg N/ha increased (P<0.01) milksolids production by 107 kg/ha, or an additional 0.73 kg MS/kg of N fertiliser applied. The increased milksolids resulted mainly from increased pasture conserved (average of 192 kg DM/cow) which when fed out in summer/early autumn resulted in an increased lactation length of 17 days. A comparison of the NHS and the NMHS treatments showed that the feeding of dairy meal (ME, 13.7 MJ/kg DM and 11.1% crude protein) increased (P<0.01) milksolids production by 77 kg/cow. An increase of 136 g MS/kg of meal fed. The advantage to meal feeding occurred throughout lactation but more in late lactation where lactation length was extended by 35 days. The greater proportion of the response to additional feed inputs from an increase in lactation length rather than an increase in production/cow/day.

NA, Thomson, RJ Johnson, J Clough, and DA McCallum

Proceedings of the New Zealand Society of Animal Production, Volume 57, , 172-175, 1997