Introducing hormone-free insemination in dairy sheep farms challenges their feeding system design

Abstract

International audienceHormone-free (HF) reproduction management in dairy sheep farming is a way to address current societal demands However, we must be prepared for the collateral impacts to be expected in the rest of the farming system components.Indeed, the efficiency of related HF practices (e.g. using male effect for oestrus induction and synchronisation) is more uncertain than that of hormonal treatment (HO). Direct consequences, on the feeding system design, will thus reflecta higher variability of physiological stages present in the flock throughout the year. This work aims to simulate the impact of a HF reproduction including artificial insemination (AI) on the distribution of productive performances andnutritional requirements of a conventional dairy sheep flock, using a dynamic agent-based model. Six reproductive management scenarios, for managing the same flock (n=597 Lacaune ewes), in the Mediterranean Roquefort Basin,were simulated and compared over one full and representative production season i.e.: HO+AI in mid-May (Early); HO+AI in July (SumLate); HO+AI in November (AutLate); as well as their HF version (i.e. HF-Early; HF-SumLateand HF-AutLate, respectively). In all HF scenarios, a reduction in the number of ewes lambing and in the annual milk production (-1 to -8%) was observed, which was accompanied by a subsequent decrease of the flock’s annualnutritional requirements (-2 to -7%). The HF scenarios also resulted in a staggering of lambing occurrences which led to a shift in the peaks of milk production and, consequently, in the nutritional requirements during the productionseason. In conclusion, transitioning to HF reproduction management, while preserving AI, would imply an increase in the workload, a prolongation of the programmed milking period, and an essential readjustment of the feedingmanagement strategy of the flock with regard to farm’s feed resources availability. Our simulation results are used to support discussions within the dairy sheep industry looking for sustainable alternatives to using hormones