Synchronising Ovulation Improved Litter Size

CANADA - Synchronising ovulation in weaned sows led to more piglets born and fewer inseminations were required than for an untreated control group, according to researchers in Ontario and Alberta.
calendar icon 17 May 2010
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Dr Louisa Zak of Bioniche Animal Health in Belleville, Ontario, and colleagues there and at the University on Alberta have investigated synchronising ovulation with porcine luteinising hormone for weaned sows with a fixed-time insemination protocol. Their paper is published in the latest issue of Journal of Swine Health and Production.

The authors explain that the objective of the trial was to determine reproductive performance of weaned sows inseminated twice at fixed times after controlling time of ovulation with porcine luteinising hormone (pLH) administered at onset of behavioural oestrus.

Multiparous sows were randomly assigned to treatment at weaning. From weaning, twice-daily boar exposure facilitated oestrus detection. Untreated control sows (n=150; controls) were artificially inseminated at least twice. Treated sows (n=168; LUT) received 5mg pLH intramuscularly concomitant with the first detection of standing heat. To coincide with the normal working day, sows in oestrus in the morning were inseminated at 24 and 30 hours (am and pm), while sows in oestrus in the afternoon were inseminated at 24 and 42 hours (pm and am), after pLH administration.

For multiparous sows bred on days 4 to 6 after weaning, total litter size was greater in LUT than the controls (12.88 and 11.80, respectively; P<0.01). However, adjusted farrowing rate was unaffected by treatment (LUT, 87.28 per cent; controls 83.20 per cent; P>0.05).

Neither variable was affected by day of breeding or a treatment × day interaction (P>0.05).

Fewer inseminations (P<0.001) were performed in LUT (2.00) than the controls (2.13).

Zak and co-authors concluded that double insemination of multiparous sows, timed to coincide with optimal sow fertility, may improve litter size.


Zak L.J., J. Patterson, J. Hancock, D. Hockley, D. Rogan and G.R. Foxcrof. 2010. Benefits of synchronizing ovulation with porcine luteinizing hormone in a fixed-time insemination protocol in weaned multiparous sows. Journal of Swine Health and Production, 18(3): 125-131.

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