Home > Pork CRC Supported Research Identifies Gilts and Sows at Risk of LPL

Pork CRC Supported Research Identifies Gilts and Sows at Risk of LPL

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During the seasonal infertility period (summer and early autumn), sow farrowing rate typically drops by 5-10% and about half of the pregnancy loss occurs after the usual five week pregnancy check, making it difficult for producers to predict or maintain production volume and income.

A published Pork CRC supported research at the University of Sydney indicated that parity (number of pregnancies), wean to service interval (WSI), lactation length and litter size weaned were risk factors for late pregnancy loss (LPL) in sows. 

Researcher Michael Bertoldo said the aim of his research was to identify gilts and sows at-risk of LPL.

“We looked at mating records for 10,122 sows and 3900 gilts from three farming groups in different parts of Australia, identified sows with LPL and compared their immediate past farrowing performance with those that farrowed,” he said.

“For gilts, the effect of age at first service on LPL was a risk factor on only one farm. On two farms we found that as sow parity, or the number of pregnancies a sow has had, increased, so too did the incidence of LPL.” 

Bertoldo noted that longer lactations appeared to protect against LPL by allowing more complete repair of the reproductive tract and hormones to return to normal levels.

“Perhaps related to this, we found that as WSI increased, the chance of LPL also rose. This is consistent with previous research suggesting longer lactations reduce WSI and increase subsequent litter size and farrowing rate. 

“Our data is new in that we are the first group to specifically relate this to LPL during seasonal infertility. Our analysis also indicated a different effect of WSI across parities, with no effect for first parity sows,” he said.

“Interestingly, we found that sows weaning seven piglets had the highest risk of LPL and sows weaning more than 13 piglets had the lowest, suggesting lactation pressure had no impact on LPL in the subsequent mating.” 

In the next stage of the Pork CRC project, the University of Sydney team, which also includes Chris Grupen, Peter Thomson, Gareth Evans and Trish Holyoake, will conduct more detailed on-farm studies to identify environmental and management risk factors for seasonal infertility.

Bertoldo suggested producers should consider the project’s results in conjunction with analysis of available data from their own farms. 

“Decisions regarding early culling of older sows, increasing lactation length, gilt management and fostering should only be made after advice from your consultant.

“Good reproductive records and accurate pregnancy diagnosis are essential to assist decision making on gilt and sow management during the seasonal infertility period, the severity of which varies from farm to farm,” Bertoldo said.

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