Making More Milk

For piglets, entering the nursery is like the first day of school: controlled chaos.

In order to thrive in that environment, they must maximize their milk intake during lactation. Yet as litters get larger, sows lack enough milk to feed every piglet sufficiently. Thankfully for producers, the SIP-sponsored project “Developing a feeding strategy for the transition period to maximize sow milk yield” is yielding results.

While previous studies stimulated mammary development by adding lysine – an essential amino acid that aids in growth and health - to sow diets in late gestation, more milk is needed to support growing litter sizes. By combining two different treatments, researchers on this project aimed to further enhance milk yield and piglet growth.

“In the past, we have found that one treatment – adding lysine to the diet - would increase mammary development in late gestation, and a second one – increasing prolactin concentrations in blood - boosted milk yield during lactation,” says Dr. Chantal Farmer, research scientist with Agriculture and Agri-Food Canada (AAFC) at the Sherbrooke R & D Centre.

Prolactin is a hormone that is most important for mammary development and enhancing milk yield in sows. It is also essential for both the onset and the maintenance of lactation.

“With this project, we put the two treatments together to see if the effect would be greater than just improving mammary development in gestation.”

In research, as in life, things don’t always go as planned.

“Surprisingly, adding lysine alone to sow diets did not elevate sow milk yield, nor did the use of prolactin. As a result, the study could not determine if there is a synergy between feeding supplementary lysine in late gestation and increasing prolactin concentrations during lactation to raise sow milk yield.”

Even so, the reasons behind the results are valuable for informing future studies.

“The lack of effect of dietary lysine in late gestation on milk yield could have been due to an inadequate litter size (12 piglets), whereby the nursing demand was not large enough to maximize milk yield. Hence, sows may not have shown their full potential.”

The presence of prolactin should have increased milk yield by itself, but unfortunately it didn’t with this study. When Dr. Farmer compared the results to those of her previous project, where prolactin did boost milk production, she saw two key distinctions: The earlier project used only multiparous animals (having given birth to multiple litters), which benefit more from prolactin, instead of primiparous sows (that gave birth only once), as in the current study.

“Also, in the earlier project, treated sows had an increased feed intake of 7-9%. In our study, no such increase occurred.”

With those distinctions in mind, Dr. Farmer plans to adjust her approach in subsequent studies. This includes using treatments where all the animals are of the same type – multiparous or primiparous – and ensuring that feed intake during lactation is not limited.

Over the next two years of this project, researchers will examine the effect of combining two treatments in late gestation on mammary development. Additional lysine in the diet will be combined with increased concentrations of insulin-like growth factor-1 (IGF-1). The latter is a growth factor produced by the liver that causes bones and muscles to grow and that was also shown to stimulate mammary development in gilts.

“We want to determine whether there is a maximum threshold for mammary tissue growth, beyond which you simply can’t push that growth any further. By the spring of 2026, I will have the answer for gilts in late gestation.”

In another part of the study, the team will compare the impact of added lysine in late gestation with the use of a feed additive called NuPro®, a concentrated, natural source of highly digestible and functional nutrients. Rich in nucleotides (organic molecules that serve as the building block for nucleic acids like DNA), NuPro® has been shown to elevate growth and lifetime performance in a range of livestock, including pigs.

As they proceed, researchers are keeping their eyes squarely on the prize for industry.

“We have seen in other studies that increased lysine at the end of gestation boosts milk production in primiparous sows, and that is a major benefit for producers. Going forward, we must still determine if adding another treatment can be advantageous. In a couple of months, once we’ve compiled new data on mammary development in late gestation, we should have some valuable insights.”