Prevention of high ewe losses in ewes grazing wheat in southern NSW: a producer survey

Anecdotal reports exist of high livestock losses in southern NSW associated with grazing reproducing ewes on dual-purpose wheat. A study was conducted to identify causes of high ewe losses in ewes grazing dual-purpose wheat during late-pregnancy and lambing, and the factors associated with these high ewe losses.Forty three sheep producers in the south-eastern Riverina area of NSW were surveyed using a semi-structure interview format regarding their experiences with grazing late-pregnant and lambing ewes on dual-purpose wheat in a season between 2005 and 2010. Producers were grouped as either 'control' (n=23) if they identified that ewe losses were not above normal levels, or 'case' (n=20) if they nominated that ewe deaths were higher than normal or a spike in ewe deaths had occurred associated with grazing dual-purpose wheat on their farm. Data from control and case groups were compared using a Chi square or Student T-test.Mean ewe losses in the case group were significantly higher than in the control group (8.6 ± 5.9% v. 1.8 ± 1.7%; P<0.001).B Mineral supplement including this mineral was supplied to ewes during the specified grazing periodThe results indicate that metabolic diseases were a key cause of ewe deaths where abnormally high ewe mortalities have occurred on dual-purpose wheat. Ca and Mg concentrations in wheat forage may be below the requirements of reproducing ewes (McGrath et al. 2011), and deficiencies in these minerals may cause metabolic diseases (Freer et al. 2007), which may explain the high ewe mortality rates reported in case flocks. The results suggest that supplying a mineral supplement that includes Mg, Na and/or Ca to reproducing ewes grazing wheat pasture may assist to prevent high ewe mortalities given that a higher proportion of producers in the control group supplemented ewes with these minerals when grazing wheat (Table 1). Supplying roughage (hay or straw) to grazing sheep did not appear important in disease prevention given there was