An update on the nutrition of dairy sheep grazing Mediterranean pastures

Abstract

In the light of recent findings in sheep nutrition and feeding behaviour, the diets of grazing dairy sheep should be based on forages encompassing a variety of complementary nutritional values and containing moderate levels of diverse plant secondary metabolites, until recently regarded as “anti-nutritional”. In lactating sheep, pastures of tannin-containing legumes like sulla ( Hedysarum coronarium) and chicory ( Cichorium intybus) can be integrated with annual grasses for establishing artificial pastures under rainfed conditions. Diets based on these forages, while ensuring high milking performance, can mitigate the unbalance of CP to energy ratio of grazing sheep. By grazing sulla and Italian ryegrass (50:50 by area) as spatially adjacent monocultures or in timely sequence (complementary grazing) sheep eat more and perform better than by grazing the ryegrass pasture only. Concentrate supplementation of lactating sheep should be preferably based on sources rich in digestible plant fiber (soyhulls or beet pulps), particularly from mid-lactation onwards and when supplementation levels are high. Milk urea concentration is confirmed as a useful monitoring tool to balance protein nutrition and curb the waste of N at animal and system level. Finally, challenging tasks for future research on dairy sheep grazing management and nutrition are on-farm application of recent technological advances, such as image-based estimation of pasture biomass and quality, evaluation of sheep dietary quality by faecal Near Infrared Reflectance Spectrometry, and establishment of remote control systems.