Long term genetic selection for reproductive success affects neonatal lamb vitality across cold stress conditions

Adverse weather conditions are important contributors to mortality in new-born lambs. Previous studies have shown variation between lambs in their ability to cope with circumstances of cold stress, and genetic selection could be a viable option for improving animal robustness. The Elsenburg Merino f...

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Bibliographic Details
Published in:Journal of thermal biology 2021-05, Vol.98, p.102908-102908, Article 102908
Main Authors: Nel, Cornelius L., Cloete, Schalk W.P., Kruger, Annelie C.M., Dzama, Kennedy
Format: Article
Language:English
Subjects:
Adaptation
Breeding success
Chill index
Cold
Divergence
Genetic analysis
Heat loss
Lamb survival
Lamb viability
Mortality
Neonates
Parturition
Rainfall
Selection
Sheep
Weaning
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Summary:Adverse weather conditions are important contributors to mortality in new-born lambs. Previous studies have shown variation between lambs in their ability to cope with circumstances of cold stress, and genetic selection could be a viable option for improving animal robustness. The Elsenburg Merino flock was divergently selected on number of lambs weaned (NLW). This resulted in divergent responses in reproduction and lamb survival. This study evaluated lamb vitality and mortality of positively selected H-Line relative to the negatively selected L-Line in response to cold stress. Traits included lamb rectal temperature (RT), surface temperature (ST), shiver score (SS), lamb vigor score (LVS), breaths per minute (BPM), mortality to three days of age (M3) and to weaning (TM). Cold stress was described by a chill index derived from daily rainfall, wind speed and ambient temperature, and represented as the mean of the one (CI), two (CI-2) or three (CI-3) days since parturition. Overall, H-Line lambs had a higher neonatal RT and were less likely to succumb than L-Line contemporaries. In a significant (P 
ISSN:0306-4565
1879-0992
DOI:10.1016/j.jtherbio.2021.102908