The use of hormones to treat dairy cattle reproductive diseases: An integrated epidemiological and socio-economic analysis

To sustain optimal production levels in dairy cows, reproductive performance is an important factor. Nevertheless, reproductive diseases commonly occur on dairy farms, posing an impact to reproductive performance, cow productivity, and farm profitability. To mitigate those reproductive diseases, hormonal treatments can be used. However, the use of hormones in dairy farming does generate societal concerns, particularly regarding the demand to reduce medicine use and to produce naturally. Hence, the aim of this thesis was to support decision-making on the use of reproductive hormones to treat reproductive diseases in Dutch dairy farms, through an integrated epidemiological and socio-economic analysis. Therefore, four sub-objectives were specified to reach the aim of this thesis: 1) to investigate the herd level association of reproductive hormone use with reproductive performance in Dutch dairy herds, 2) to determine and associate dairy farmers’ knowledge and attitude regarding the use of reproductive hormones with their hormone use behaviour, 3) to estimate the costs of reproductive disorders, including dystocia, post-partum puerperal disorders and post-partum ovarian disorders, in dairy farms, and 4) to compare the economic impact of reproductive management programs applying systematic hormonal treatments to individual cows with a reproductive management program applying cow-specific hormonal treatments based on a veterinary diagnosis. Results showed that at herd level, an increased hormone use was associated with a better reproductive performance in terms of shorter calving interval and calving to first insemination interval but with an extra number of inseminations per cow. Farmers’ knowledge and a stronger farmers’ attitude on benefits of using hormones and on following the hormonal treatment protocol were positively associated with a higher hormone use., while a stronger farmers’ attitude towards non-hormonal fertility management was associated with a lower hormone use. Additionally, by taking into account their complex interrelations, the mean annual cost of dairy cow reproductive diseases was €100/cow/year. At herd level, the highest mean annual cost was observed for acute metritis at €30/cow/year, while the lowest mean annual cost was observed for dystocia at €4/cow/year. In terms of cost per case, the highest cost was observed for acute metritis (€257/case) while the lowest cost was observed for cystic ovarian disease (€58/case). Furthermore, reproductive management programs where hormones were systematically used gave economic advantages over the reproductive management program in which hormones are administered to individual cows based on a veterinary diagnosis during a fertility check. In conclusion, in comparison with the current use of hormones in the Netherlands, an increased use of reproductive hormones improves cow reproductive performance, increases milk production, and reduces culling rates, thereby offering economic benefits to dairy farmers. However, a farmer’s decision to use more hormones must be balanced with their preference to implement non-hormonal fertility management. Moreover, these decisions should also meet societal concerns regarding the use of hormones and their preference for natural dairy production practices. Therefore, in order to balance economic and ethical considerations regarding reproductive management in dairy herds, fertility guidelines should align the use of hormones in reproductive programs with societal demands.