Factors involved in high ewe losses in winter lambing flocks grazing dual-purpose wheat in southern New South Wales: a producer survey

Abstract

A comparative survey was undertaken with 43 sheep producers in southern New South Wales using a semi-structured interview to investigate factors associated with high ewe mortality rates in winter lambing flocks grazing dual-purpose wheat. Participants were classified as either control (n = 23), who had not observed abnormally high ewe deaths, or case (n = 20), who had observed abnormally high ewe mortality rates when sheep grazed dual-purpose wheat. Ewe losses associated with grazing wheat were higher in the case group compared with the control group (8.6 vs 1.8%; P < 0.001) and there was also more deaths attributed to metabolic disease (3.4 vs 0.6%; P < 0.05). A higher proportion of control respondents had provided magnesium or sodium supplementation to ewes grazing wheat (P < 0.05). The body condition score of ewes entering the grazing period was significantly higher in the control group (3.2 vs 2.8; P < 0.05). The proportion of respondents who fed roughage to ewes grazing wheat did not differ significantly between control and case groups (48 vs 35%). A higher proportion of respondents in the case group had supplied grain to ewes (25 vs 0%; P < 0.05), which may have been associated with the lower body condition of sheep in these flocks compared with the control group. It was concluded that supplying ad libitum access to mineral supplements that include magnesium, sodium and possibly calcium, and maintaining adequate body condition score can reduce the risk of high ewe mortality rates when reproducing ewes graze dual-purpose wheat.

Reproductive Performance of Triplet-Bearing Ewes on Commercial Farms and Research Priorities Identified by Sheep Producers to Improve the Survival of Triplet-Bearing Ewes and Their Lambs

“…Subclinical deficiencies in calcium and magnesium may increase the risk of dystocia and related issues, including hypothermia in lambs and poor ewe-lamb behaviour [ 34 ]. Providing lambing ewes with ad libitum access to mineral supplements containing magnesium, sodium and calcium has been reported to reduce the risk of ewe mortality when grazing cereal crops [ 36 ]. However, the impact of subclinical mineral deficiencies on lamb mortality and the benefits of mineral supplementation remains unclear.…”

Performance of confined and grazing lambs fed diets with different mineral-concentrate supplements

“…Thus, the response to supplementation of the minerals could also be due to the interrelationships between nutrients such as between protein and energy (Anderson et al, 2013;McGrath et al, 2013). Furthermore, the concentrations of the minerals in the diet are regulated in the body of the animal by homeostatic mechanisms and remain within small ranges to achieve a well-balanced steady state.…”

Identifying high-value tactical livestock decisions on a mixed enterprise farm in a variable environment

“…Furthermore, much of this work was conducted over a decade ago and farming systems and technologies have evolved significantly since then. Research on livestock management has either assumed that every year is the same (Kopke et al 2008;Bathgate et al 2009;Young et al 2010Young et al , 2020Young et al , 2022 or when year-to-year variation has been included, management has not been optimised and, frequently, the tactical-management options have been over-simplified (McGrath et al 2016;Godfrey et al 2019). For example, supplements are always fed to sheep once they reach a threshold-condition score, rather than considering the marginal costs and benefits of the supplementary feed.…”