Udder defects negatively impact lamb production in non-dairy pasture-based ewes

Introduction: In pasture-based sheep production systems total weight of lamb weaned impacts flock profitability, thus farmers aim to optimise lamb survival and growth to weaning. Initially, lambs depend solely on their dams for milk for survival and growth, andudder defects can negatively impact this.
Research objective: We aimed to investigate associations between lamb survival and growth to weaning and ewe udder scores measured at pre-mating, pre-lambing, docking (tailing) and weaning.
Methods: We enrolled 1000 ewes from a commercial sheep flock,and over 2-years, assessed their udders at four key management times. We also matched newborn lambs with their dams and recorded lamb survival and growth rate parameters to weaning in each year.Results: The prevalence of ewes with abnormal udder palpations ranged from 2.7% to 7.7%, and pre-mating udder palpations were predictive of total lamb weaned. Lambs born to ewes with lumps or hard udders had 4.9 and 3.0 increased odds of mortality, while lambs that were born to ewes with udder defects and survived had significantly lower growth rates to weaning. Ewes with normal udders premating weaned an estimated mean of 42.2 kg and 45.4 kg in year 1 and year 2, while ewes with abnormal udders weaned 25.8% lesslamb (p < 0.0001) and 33.2% less lamb (p < 0.0001) in the first and second year of the study respectively.
Conclusion: Combined, this suggests farmers could use udder palpation prior to mating as a tool to identify and prioritise culling of ewes with palpable udder defects, as these ewes are predicted to havelower lamb production.

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