Quantifying the effect of the InCalf Farmer Action Group on seasonal-calving pasture-based dairy farms in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
Dairy herd reproductive performance is purportedly in decline in New Zealand and internationally. The aetiology is multifactorial and complex and a broad range of hypotheses for this decline have been proposed, including cow and herd factors. An effective dairy industry needs optimal reproductive performance to maintain cattle welfare and a competitive advantage in the international marketplace. Six key herd-level management factors were identified as being associated with the reproductive performance in Australian seasonal-calving pasture-based dairy herds. A reproductive extension programme was built around these findings designed to enable farmers to improve reproductive performance on farm (InCalf). In 2008, the New Zealand dairy industry adapted InCalf for New Zealand conditions and made it available to dairy farmers and rural professionals. Coinciding with this programme development, the New Zealand dairy industry also set a national target of a herd-level average of 78% of cows pregnant by day 42 of the seasonal breeding period (6 week in-calf rate) by 2016. The last benchmarking of reproductive performance in the New Zealand dairy herd was undertaken in 1999-2000 and the first aim of this thesis was to estimate the current national-level for reproductive performance. Secondly, the effectiveness of farmer participation in the InCalf extension programme was quantified using a randomised controlled study.
This study found a 67% mean 6 week in-calf rate over both 2009/10 and 2010/11 study years amongst those herds allocated to a control group, reflecting similar findings to the previous benchmarking study. Although this finding suggests that overall reproductive performance has remained similar over the decade, conception to first mating (first service conception rate) has declined by 5% to 48% while the rate of breeding in the first 21 days of mating (3 week submission rate) has remained similar at 81% suggesting that the submission rate in the second 21 days of breeding has improved to account for the decline in first service conception rate. Change in behaviour in key management factors is needed in order to improve 6 week in-calf rate. Baseline interviews with farmers found general satisfaction with reproductive performance. This is a potential barrier to improvement, since dissatisfaction is needed to create the tension for change hypothesised to drive behavioural change.
This randomised controlled study found that farmer participation in regional InCalf extension programmes resulted in an average 2% improvement in reproductive performance during the year
of the intervention over herds where farmers did not participate (p = 0.05). The greatest effect was seen in the lowest performing herds and these should become the focus of future extension.
Herds participating in the InCalf extension programme had a significant improvement in heifer live-weight, premating mean body condition score and oestrus detection over herds that did not participate (p <0.05). No significant difference was found in the distribution of calvings, anoestrous cow management or bull management. Improvements in the InCalf programme to achieve behaviour change for those management factors where the current InCalf has not proved effective may lift performance and further work is needed to evaluate the extent of the effect of participation on attitude change.
The industry must now decide if this is sufficient improvement in reproductive performance to invest further in this model of extension and whether to improve it using the recommendations from this thesis.
Appendix 2 removed for copyright reasons: Brownlie, T.S., Weir, A.M., Tarbotton, I., Morton, J.M.,
Heuer, C., & McDougall, S. (2011). Reproductive management of dairy herds in New Zealand: Attitudes,
priorities and constraints perceived by farmers managing seasonal-calving, pasture-based herds in
four regions. New Zealand Veterinary Journal, 59(1), 28-39. doi:10.1080/00480169.2011.547167