Vicia sativa as a grazed forage for lactating ewes in a temperate grassland production system

Abstract

AbstractHere, we present research to overcome a current limitation of temperate grassland systems to provide home‐grown, early season protein for lactating ewes—a period of high protein demand in these systems. Traditionally used as a forage crop, there is renewed interest in common vetch (Vicia sativa) due to its ability to grow during low temperatures over‐winter compared to other legumes. We hypothesised that vetch would support the sustainable development of lamb production by reducing reliance on purchased protein typically used in grass‐only systems. A grazing study determined the performance of early lactation ewes and their twin lambs grazing either an Italian ryegrass (IRG) sward or a vetch/IRG (V/IRG) mix over a six‐week period. The experiment comprised replicate plots of two treatments, with 8 ewes, each rearing twin lambs, grazing each plot. Plots were divided into sub‐plots using electric fencing and rotationally grazed. Findings showed i) ewes selectively grazed vetch as evidenced by a drop in vetch percentage by, on average, 10% units between the start and end of grazing; ii) vetch re‐grew when rotationally grazed with a 21– 28‐d rest period, with vetch percentage of the sward increasing 10% units; and iii) grazing lactating ewes on V/IRG improved combined ewe and lamb weights by five weeks post‐lambing but longer term effects were limited by vetch availability. Furthermore, there was a tendency for lamb live‐weight gains to be higher for lambs whose dams grazed on vetch/IRG compared to IRG swards (573 versus 563 g ewe−1 d−1, respectively, p = 0.056). As the need for alternatives to imported protein feed increases, this research demonstrates how vegetative common vetch, as part of a mixed sward, has the potential to provide a home‐produced winter‐grown protein feed in temperate grasslands.