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Individual adaptive responses of meat ewes facing an abrupt nutritional challenge after lambing
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Edité par CCSD ; Wageningen Academic Publishers -
Session 65 - Théâtre 2. International audience. Simulating a climate change event, responses of Mediterranean meat ewes when facing an abrupt nutritional challenge (NC; i.e. fed with cereal straw of very low nutritional value only) were studied at a very sensitive physiological stage (i.e. just after lambing). Forty Romane ewes were chosen at early-mid pregnancy (around 2 mo) according to parity (20 primiparous, PRIM; 20 multiparous, MULT); feed efficiency genetic line [residual feed intake (RFI); inefficient, RFI-, n= 10 per parity; efficient, RFI+, n= 10 per parity); litter size (i.e. bearing twins, diagnosed by ultrasonography); and BW and body condition score (BCS) [initial BW and BCS (mean ±SD): 51.6±7.41 kg; 2.5±0.20, respectively; representing average BW and BCS of their parity in the flock]. Effects on intake, ewes’ BW and BCS, subcutaneous back-fat thickness (BFT), energy metabolism [plasma NEFA, β-OHB, glucose, urea, tri-iodothyronine (T3)], and lambs’ growth were examined before, during and after NC. Individuals’ profiles of the response-recovery of each ewe to NC were described using a piecewise mixed-effects model and clustered using principal components analysis and Euclidean distance. MULT presented sharper β-OHB recovery from NC than PRIM (P≤0.05). Parity or genetic line did not affect the other evaluated traits. Clusters of individuals’ response-recovery to NC suggested three different adaptive strategies to NC (i.e. adaptation on acquisition, allocation or trade-off between acquisition and allocation of energy. Interestingly, ewes’ response-recovery to NC demonstrated also to be related to lamb average daily gain (ADG, g/d), especially plasma β-OHB and NEFA (r≥0.50). Results provide new insights in how such short and abrupt NC affect some key physiological parameters, and to what extent the impacts of NC and the ewes’ potential response-recovery are influenced by the individual nature of the animals (i.e. observed inter-individual differences in the responses). This work was financed by the PRIMA ADAPTHERD project (https://www.adapt-herd.eu/).
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