title: A randomised controlled study to assess the effects of an extension programme on the 6 week in-calf rate of seasonal calving, pasture-based dairy herds in New Zealand.
abstract: The aim of this study was to quantify the effect of participation by New Zealand dairy farmers in a year-long extension programme designed to improve herd reproductive performance. This was estimated by comparing, over two successive years, the proportions of cows becoming pregnant during the first 6 weeks of the seasonal breeding programme (6 week in-calf rate) in herds involved in a full participation group (treatment), with herds in an actively monitored control group or a passively monitored control group. Possible interactions between treatment and various biophysical and socio-demographic factors were also assessed. Multivariable modelling was used to determine the effect of treatment on 6 week in-calf rate, adjusting for design factors (study year and region). It was estimated that the 6 week in-calf rate was 68% (95% confidence interval 65-67%) in the treatment group of farms that participated in the extension programme compared with 66% (95% confidence interval 67-69%) in the actively monitored control group of farms that did not participate in the extension programme (P= 0.05); thus the risk difference was 2.0% (95% confidence interval 0.0-3.9%). No significant interactions were found between treatment and region, study year or any of the biophysical and socio-demographic variables on the 6 week in-calf rate (P > 0.05). There was no significant difference in the 6 week in-calf rate between the actively and passively monitored control groups (P= 0.56). It was concluded that enrolment in the extension programme improved the 6 week in-calf rate, and that the treatment effect was not modified substantially by region, study year or any of the biophysical and socio-demographic variables assessed.
authors.affiliation: Cognosco, Anexa Animal Health, PO Box 21, Morrinsville 3300, New Zealand; Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand. Electronic address: tbrownlie@lic.co.nz.
authors.forename: Tom S
authors.initials: TS
authors.lastname: Brownlie
authors.affiliation: Jemora, PO Box 2277, Geelong, Victoria 3220, Australia.
authors.forename: John M
authors.initials: JM
authors.lastname: Morton
authors.affiliation: Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
authors.forename: Cord
authors.initials: C
authors.lastname: Heuer
authors.affiliation: Cognosco, Anexa Animal Health, PO Box 21, Morrinsville 3300, New Zealand.
authors.forename: Scott
authors.initials: S
authors.lastname: McDougall
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying / Q000379:methods*; D005260:Female; D009520:New Zealand; D012098:Reproduction; D012621:Seasons
keywords: Dairy cattle; Extension programme; Randomised control trial; Reproduction