This study evaluated the effect of full physical boar exposure at different stages of lactation Received 3 June 2014 on the incidence of lactation oestrus in both primiparous and multiparous sows. A total of 38 primiparous (PP) and 80 multiparous (MP) sows (parity 2–6; 3.170.18) of Large White
Landrace genetics were individually housed in conventional farrowing crates from 1 week before expected farrowing until weaning on day 27.570.08 post-parturition. The experi ment was designed as a 2 4 factorial, incorporating the two sow parity groups, and boar Full physical boar exposure day 10 (n¼10), day 14 (n¼9), day 18 (n¼9) and weaning (n¼10); MP sows boar exposure Multiparous starting on day 10 (n¼20), day 14 (n¼20), day 18 (n¼20) and weaning (n¼20) ). According
Primiparous to treatment, sows were taken daily to a detection mating area where they received 20 min of boar exposure and were artificially inseminated at the first observed oestrus. A significant effect of replicate on the incidence of lactation oestrus was found; specifically, the proportion of sows expressing a lactation oestrus was lower in replicate 4 (autumn) than in the other three replicates (winter/spring; 0.15 versus 0.51; Po0.01). In replicate 1–3, a significantly higher proportion of MP compared to PP sows experienced a lactation oestrus (0.63 versus 0.36; Po0.05). Lactation oestrus expression was lower for MP sows starting boar exposure on day 14 compared to day 18 post-partum (0.38 versus 0.79, respectively; Po0.05), but was similar for days 10 and 18 of lactation (0.69 versus 0.79, respectively; Po0.05). Commencing boar exposure on day 18 as opposed to day 10 post-partum significantly reduced the interval from boar exposure to lactation oestrus expression (4.570.8 versus 7.770.8 days, respectively; Po0.05). Therefore, full physical boar exposure stimulated a high proportion of lactation oestrus in multiparous sows; however, season impacted this expression, and first parity sows are less likely than multiparous sows to express a lactation oestrus. In conclusion, there appears to be no benefit in commencing boar exposure before day 18 post-partum to stimulate a lactation oestrus
This study evaluated the effect of full physical boar exposure at different stages of lactation Received 3 June 2014 on the incidence of lactation oestrus in both primiparous and multiparous sows. A total of 38 primiparous (PP) and 80 multiparous (MP) sows (parity 2–6; 3.170.18) of Large WhiteLandrace genetics were individually housed in conventional farrowing crates from 1 week before expected farrowing until weaning on day 27.570.08 post-parturition. The experi ment was designed as a 2 4 factorial, incorporating the two sow parity groups, and boar Full physical boar exposure day 10 (n¼10), day 14 (n¼9), day 18 (n¼9) and weaning (n¼10); MP sows boar exposure Multiparous starting on day 10 (n¼20), day 14 (n¼20), day 18 (n¼20) and weaning (n¼20) ). AccordingPrimiparous to treatment, sows were taken daily to a detection mating area where they received 20 min of boar exposure and were artificially inseminated at the first observed oestrus. A significant effect of replicate on the incidence of lactation oestrus was found; specifically, the proportion of sows expressing a lactation oestrus was lower in replicate 4 (autumn) than in the other three replicates (winter/spring; 0.15 versus 0.51; Po0.01). In replicate 1–3, a significantly higher proportion of MP compared to PP sows experienced a lactation oestrus (0.63 versus 0.36; Po0.05). Lactation oestrus expression was lower for MP sows starting boar exposure on day 14 compared to day 18 post-partum (0.38 versus 0.79, respectively; Po0.05), but was similar for days 10 and 18 of lactation (0.69 versus 0.79, respectively; Po0.05). Commencing boar exposure on day 18 as opposed to day 10 post-partum significantly reduced the interval from boar exposure to lactation oestrus expression (4.570.8 versus 7.770.8 days, respectively; Po0.05). Therefore, full physical boar exposure stimulated a high proportion of lactation oestrus in multiparous sows; however, season impacted this expression, and first parity sows are less likely than multiparous sows to express a lactation oestrus. In conclusion, there appears to be no benefit in commencing boar exposure before day 18 post-partum to stimulate a lactation oestrus
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