The Energetics Research Group has made a range of exciting discoveries this year. Highlighted below are two projects that span both applied and fundamental ecophysiology themes.
The behavioural and physiological response of dairy cows to regrouping practises
Catherine Hambly and her team worked with the dairy industry to tackle how common husbandry practises can drive both behavioural and physiological changes in cows. Regrouping is a husbandry practice where the individual members of groups housed together, or in a specific location, are changed typically with the goal of improving milk production. Here, the team explored if regrouping had an impact on stress, behaviour and milk production in cows during their first pregnancy (primiparous) and after multiple pregnancies (multiparous).
Post-regrouping, primiparous cows spent less time with other cows and had decreased milk and oxytocin levels compared to multiparous cows. Interestingly post-regrouping all cows reduced milk fat%, had increased activity and decreased rumination but there was no impact on cortisol. Overall, the study shows that the practice of regrouping has a greater impact on primiparous cows.
Read full article in the journal “animal" here: Behavioural variability, physical activity, rumination time, and milk characteristics of dairy cattle in response to regrouping
Why do we age?
A team lead by Sharon Mitchell and John Speakman tested fundamental ideas on why we age. One of the most popular theories on ageing is the Disposable Soma Theory (DST). Reproduction is an extremely energetically expensive period of life, and the DST proposes a trade-off between reproduction and maintenance. The team tested the DST in breeding mice, using virgin female pairs as controls. There was an immediate higher mortality as a direct consequence of reproduction, but there was no evidence of a residual effect on survival once breeding females ceased reproducing. Overall, the results did not support the fundamental Disposable Soma Theory of ageing.
Read the full article in the journal “PNAS” here: Reproduction has immediate effects on female mortality, but no discernible lasting physiological impacts: A test of the disposable soma theory
