Effect of restricting silage feeding prepartum on time of calving, dystocia and stillbirth in Holstein-Friesian cows

A study was carried out to investigate the effect of restricting silage feeding on time of calving and calving performance in Holstein-Frlesian cows. In the treatment group (n=1,248 cows, 12 herds) silage feeding commenced in the evening (17:00 to 20:00h), after a period of restricted access (2 to 10h) while In the control group ad-libitum access to silage was provided over the 24h period (n=1,193 cows, 12 herds). Daytime and nighttime calvings were defined as calvings occurring between the hours of 06:30 and 00:29 and between 00:30 and 06:29, respectively. Restricting access to silage resulted in less calvings at night compared to cows with ad-libitum access to silage (18 vs 22%, P<0.05). Cows with restricted access to silage had a higher percentage of difficult calvings (11 vs 7%, P<0.001) and stillbirths (7 vs 5%, P<0.05) compared to cows in the control group. The percentage of calvings at night was lower (13%) when access to silage was restricted for 10h compared to 2, 4 or 6h (22, 18, 25%, respectively) (P<0.001). Calf sire breed, calf gender or cow parity did not influence time of calving. In conclusion, offering silage to pregnant Holsteln-Frieslan cows In the evening, after a period of restricted access, reduced the incidence of nighttime calvings, but increased the incidence of dystocia and stillbirth.