Abstract

Changes in cow genetics and systems of farming have had large effects on the reproductive performance of dairy cows. The objective of this study was to determine if grain supplementation modified the previously identified effects of Holstein-Friesian (HF) strain on the postpartum anoestrus interval (PPAI). Thirty multiparous Overseas (OS) HF and 30 New Zealand-HF cows from a 1990s strain (NZ) were offered unrestricted access to fresh pasture and randomly allocated to three levels of a maize and barley-based concentrate supplementation (0, 3 or 6 kg DM/day). Postpartum anovulatory interval (PPAI) was not significantly affected by either strain or diet, and there was no significant strain x diet interaction. Results suggest that the nutritional requirements necessary for multiparous NZ or OS HF cows to resume oestrous cycles before 40 days postpartum can be achieved when offered unrestricted access to high quality pasture. In this circumstance, additional concentrate feeding did not alter the length of the postpartum anoestrous interval.

LM, Chagas, PJS Gore, AJ Sheahan, JM Lee, KA Watkins, PW Aspin, and JR Roche

Proceedings of the New Zealand Society of Animal Production, Volume 66, Napier, 339-343, 2006