Publicaties

Consequences of extending the voluntary waiting period for insemination on reproductive performance in dairy cows

Ma, J.; Burgers, E.E.A.; Kok, A.; Goselink, R.M.A.; Lam, T.J.G.M.; Kemp, B.; Knegsel, A.T.M. van

Samenvatting

The aim of the study was to evaluate the effect of extended voluntary waiting period (VWP) on ovarian cyclicity and reproductive performance of dairy cows. Holstein-Friesian dairy cows (N = 154) were blocked and randomly assigned to one of 3 groups with different VWP (50, 125 or 200 d: VWP-50, VWP-125 or VWP-200). Milk samples were collected 3 times a week and analysed for progesterone concentration. Ovarian cycles were classified as: normal (18–24 days), short (<18 days) or prolonged (>24 days). For cows that became pregnant within 100 days after VWP, a VWP-200 d was related with fewer days until pregnancy after end of the VWP (19.4 d) compared with VWP-50 or VWP-125 (35.5, 37.3 d respectively). During 100 days (−50 until 50 d) around the end of VWP, cows in VWP-200 had a greater percentage of normal cycles (91.9 vs 58.0 %, P < 0.01) and a lower percentage of prolonged cycles (6.0 vs 32.7 %, P = 0.01) compared with cows in VWP-50. In the 4 weeks around the end of the VWP, cows in VWP-125 and VWP-200 had a lower milk yield compared with cows in VWP-50 (32.0, 27.5 vs 37.4 kg/d, P < 0.01). Inseminations continued until 300 days in milk, resulting in fewer pregnant cows for longer VWPs. In conclusion, extending the VWP from 50 to 125 or 200 days resulted in a greater percentage of cows with normal ovarian cycles and a lower milk yield around the end of VWP. Moreover, VWP-200 reduced days open after the end of the VWP, compared with VWP-50.