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* INRA, UMR1079 SENAH, F-35000 Rennes, France
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Agrocampus Rennes, UMR1079, F-35000 Rennes, France
Nutreco Agriculture Research and Development, 5832 AE Boxmeer, The Netherlands
Marie-Christine.Salaun{at}rennes.inra.fr
Abstract
Voluntary feed intake in sows after parturition may be related to the capacity of the sow to cope with the numerous changes occurring around farrowing. This experiment was undertaken to investigate whether the feed intake during lactation was related to the reactivity of the sow during gestation and plasma Trp and cortisol concentrations. On d 58 of pregnancy, 37 sows were individually placed in a novel environment, and their behavior was observed during the 5-min open-field test. This test allowed the selection of 12 reactive (R) and 8 non-reactive (NR) sows for the study. Sows were fed 3 kg of a standard gestation diet/d before farrowing and a standard lactation diet ad libitum thereafter. The behavioral reactivity of sows when a human touched their neck in the farrowing crate was evaluated on d 72 of gestation and their behavior during farrowing was analyzed. Sows were catheterized on d 70 of gestation and blood samples were taken after an overnight fast on d 37 before farrowing, daily during the week before and the week after parturition, and on d 14 and 21 of lactation for plasma Trp and cortisol determination. The NR sows were less reactive to human contact (P = 0.02), had a shorter farrowing duration (P = 0.02), and tended to have a shorter birth interval between piglets (P = 0.09) than the R sows. Feed intake was greater for the NR sows than for the R sows during wk 1 of lactation (P = 0.02), as well as during the whole lactation (P = 0.03). Plasma cortisol concentration increased the day after farrowing (P = 0.01) and returned to basal concentration within 4 d postpartum. No relationship was observed between sow behavior and plasma concentration of cortisol. For both groups of sows, plasma concentrations of Trp between d 2 and 4 postpartum were lower than during gestation (P < 0.05). The NR sows had lower plasma Trp concentrations than the R sows during wk 1 of lactation (P = 0.02). A low reactivity during gestation was associated with behavior of the sow that was favorable to piglet survival during farrowing, high feed intake, and low plasma Trp concentration during wk 1 of lactation. Further research is needed to elucidate whether Trp or Trp metabolites are related to reactivity and ADFI of the reproducing sow.
Key Words: feed intake lactation reactivity sow tryptophan
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