Lucerne with a high coumestrol content is not a suitable feed for ewes just before and during the early breeding period

Abstract

Abstract The objective was to determine whether grazing lucerne for 7 days before breeding and for the first 7 days of breeding affected the reproductive performance of ewes with different body condition scores (average of 3.2 versus 3.7). This was compared with grazing a grass-based sward with a high proportion of dead herbage that was available at the time of breeding in a summer dry region (Wairarapa) in autumn 2016. The lucerne contained large amounts of fungal infected stem and dead herbage, which induced high levels of coumestrol (107 ± 15 mg/kg DM). By the end of the feeding period the grass and lucerne on offer were both of low quality (7.8 MJ ME/kg DM). Ewes that grazed lucerne for 7 days before breeding and for the first 7 days of the breeding period produced 18 fewer (P<0.05) foetuses per 100 ewes joined, compared with ewes grazing grass. These findings indicate there was no benefit of grazing ewes on lucerne with a high level of coumestrol under summer drought conditions compared with grazing poor quality grass. Keywords: alfalfa, coumestrol, drought, flushing, nutrition, oestrogen, reproduction