Abstract #482
Section: Production, Management and the Environment (orals)
Session: Production, Management, and the Environment 3
Format: Oral
Day/Time: Wednesday 10:45 AM–11:00 AM
Location: Room 264
Session: Production, Management, and the Environment 3
Format: Oral
Day/Time: Wednesday 10:45 AM–11:00 AM
Location: Room 264
# 482
The effect of milk predicted transmitting ability and concentrate supplementation level on milk production and composition in late-lactation spring-calving grazing dairy cows.
M. J. Doran*1, M. B. Lynch1, F. J. Mulligan2, A. G. Fahey1, E. L. Brady2, C. Grace1, K. M. Pierce1, 1School of Agriculture and Food Science, University College Dublin Lyons Farm, Naas, Co. Kildare, Ireland, 2School of Veterinary Medicine, University College Dublin, Veterinary Science Centre, Belfield, Dublin, Ireland.
Key Words: dairy cow, late lactation, grazing
The effect of milk predicted transmitting ability and concentrate supplementation level on milk production and composition in late-lactation spring-calving grazing dairy cows.
M. J. Doran*1, M. B. Lynch1, F. J. Mulligan2, A. G. Fahey1, E. L. Brady2, C. Grace1, K. M. Pierce1, 1School of Agriculture and Food Science, University College Dublin Lyons Farm, Naas, Co. Kildare, Ireland, 2School of Veterinary Medicine, University College Dublin, Veterinary Science Centre, Belfield, Dublin, Ireland.
In Ireland, spring calving grazing systems utilize CS mainly in the spring and autumn when there is a shortage of grass. Studies show there is a better response to CS in cows with a higher genetic merit for milk production. The objective of this study was to investigate the effect of PTA, CS level and their interaction on milk production and composition in late lactation (+200 DIM) spring calving grazing dairy cows. A factorial experiment, with 2 milk PTA groups (high (+191 kg) versus low (−53 kg)) and 2 CS levels (0 (GO) versus 2.7 kg dry matter (DM) CS) was carried out over a 51-d period. Forty-eight Holstein Friesian (24 low milk (LM) and 24 high milk (HM) PTA) dairy cows were blocked on parity and balanced on DIM, BCS and Economic Breeding Index. Cows within PTA groups were randomly assigned to one of 2 CS levels, resulting in 4 treatment groups (n = 12): 1) LM PTA offered GO (LG); 2) LM PTA plus 2.7 kg DM CS (LC); 3) HM PTA offered GO (HG) and 4) HM PTA plus 2.7 kg DM CS (HC). All cows were grazing full time and were offered 17 kg DM grass/cow per d. HC had higher milk yield (+3.53 kg, P < 0.05), fat kg (+0.14 kg, P < 0.05) and lactose kg (+0.17 kg, P < 0.05) compared with H0. HC tended to have higher milk yield (+3.06 kg, P = 0.09) and lactose kg (+0.14 kg, P = 0.09) compared with LC. HM PTA increased milk yield (+2.13 kg, P < 0.05) and lactose kg (+0.10 kg, P < 0.05), while CS increased milk yield (+2.68 kg, P < 0.01), fat kg (+0.10 kg, P < 0.01), protein kg (+0.08 kg, P < 0.05), casein kg (+0.06 kg, P < 0.05), fat and protein (milk solids) kg (+0.18 kg, P < 0.05) and lactose kg (+0.13 kg, P < 0.01). However, HM PTA reduced fat (−0.21%, P < 0.05), protein (−0.16%, P = 0.02) and casein % (−0.14% P < 0.05), while CS decreased protein (−0.14%, P < 0.05) and increased lactose % (+0.08%, P = 0.01). HM PTA cows had a higher response to CS compared with LM PTA cows (1.31 versus 0.67 kg milk/kg DM CS). In conclusion, HM PTA increased milk yield and lactose kg but decreased composition. HM PTA cows had a better response to CS than LM PTA cows.
Key Words: dairy cow, late lactation, grazing
