Pig Knowledge Centre

Essential role of the sow: production of milk

Editor’s note: Dr. Chantal Farmer, research scientist at Agriculture and Agri-Food Canada at the Sherbrooke R&D Center in Quebec, Canada, recently spoke at the global event, LifeStart: Nourishing Animal & Business Potential. The event was hosted online by Trouw Nutrition, and more than 1,100 people from 66 counties participated. Dr. Farmer spoke to attendees about colostrum’s role for the newborn piglet and factors that impact colostrum yield.

“One of the essential roles of the sow is milk production for piglets. Sows produce more milk than cows on a per kilogram basis of body weight,” said Farmer. “If she’s producing lots of milk, what's the problem? The problem is that the sow is not producing enough milk to sustain maximum growth of her piglets.”

If you take a baby pig, and on top of the milk it's consuming, you take a bottle to provide the piglet with artificial milk, the piglet will grow more. Farmer says this tells us the piglet has the capacity to grow beyond the milk the dam is providing.

“There has been an increase in milk yield over time, but it's remained pretty stable since 1998,” explained Farmer. “At the same time, we have had great success in increasing litter size. We have a new situation of hyperprolificity. So, we have to make sure that these piglets get enough milk because the amount of milk ingested per piglet has actually decreased due to the larger litter size that we are seeing.”

How can we increase sow milk yield? There are many sow factors affecting milk yield:

  • Genetics
  • Breed
  • Parity
  • Litter size
  • Stage of lactation
  • Suckling interval

Environmental factors affecting sow milk yield:

  • Photoperiod (day length)
  • Ambient temperature (heat stress)
  • Continuous high noise – can negatively impact nursing behavior
  • Hormones
  • Nutrition

One factor that has not been considered until about 10 to 15 years ago is mammary development. In 1991, it was determined that the number of milk-secreting cells that are present in the mammary tissue at the onset of lactation is a major factor limiting milk yield.

“It makes a lot of sense and is important - the more cells you have that can synthesize milk, the greater your capacity to produce larger quantities of milk,” said Farmer. “Also, there's a correlation between the size of a mammary gland and its milk yield, which was measured by the weight of the piglet nursing that teat.”

That earlier study concluded that replacement gilts should be managed to enhance their mammary development. But how do we do that? Dr Farmer addresses a component of this topic.

First, identify when mammary gland development takes place in pigs. At birth, piglets have a very poorly developed mammary duct system, then there are three stages of rapid mammary development.

  • Pre-puberty - starting at 90 days of age to puberty
  • Last third of gestation - starting at 90 days of gestation to farrowing
  • Lactation

“It’s very important to understand that it's only during the periods where you do have mammary development, that it’s possible to do anything to try to stimulate it,” she said. “I always say three times zero gives you zero. There's no sense trying to use hormones or nutrition to stimulate mammary development when there is none to start with. Again, there are many factors that can influence mammary development, physiological status of the animal, hormones, nutrition, management, sucking intensity. Let’s look at two projects dealing with one aspect, which is that of suckling intensity or use of a teat.”

The first study addresses the question: what is the possible impact of non-use of a teat in first lactation on its milk yield in the next lactation?

The study was conducted by Dr. Farmer and her team to block either the same teats during parities one and two or different teats during parities one and two. So that in the second parity, piglets suckled either teats that were used before or not used before.

In lactation one, the sows had an average of 14 functional teats. The rear teats were always blocked because they're difficult for piglets to access. Of the other available teats, two were blocked on one side, and two were blocked on the other side. Then, the team considered position and side of the glands when blocking them.

In parity two, the team either blocked the same teats, so piglets were nursing a gland that had been used before, or they blocked different teats, so the piglets were nursing from glands that were not used in the previous lactation. In the second lactation, six piglets per litter were used because there were six available teats. Piglets of similar weight were used.

The results in parity 2, when looking at the weight of the piglets, show no difference on Day 2. Dr. Farmer says this is good as it’s the beginning of the trial. However, as the study continues, the difference between the weights of the piglets keeps getting bigger. By Day 56, there’s 1.12 kilograms more in terms of body weight of piglets that are suckling a teat that has been used before.

“The study tells us that yes, it is important to have a teat suckled in the first lactation if you want that teat to produce more milk in the second lactation,” she explained. “Interestingly, if you look at the difference in weight gain of the piglet between Days 2 and 4, and remember farrowing was on Day 1, so that's as of 24 hours after farrowing, you already see a significant increase in gain and body weight gain of these piglets. What is it suggesting? That colostrum yield is also improved. So, use of a teat increases milk yield, but it may very well also increase the amount of colostrum.”

This leads to the second question. What is the minimum time that a teat must be suckled in first lactation to avoid decreasing its milk yield in second lactation?

In the second study Farmer conducted, in the first parity sows were divided into three groups, according to lactation length – 2 days, 7 days and 21 days. For second parity, all had a 21-day lactation. Twelve piglets were included for the 12 teats, and piglets were weighed on a regular basis. Looking at the weight of the piglets, the results showed no difference based on length of lactation. “The results tell us it doesn't matter if we go above 2 days, 7 days or 21 days during the first lactation, the length of time the teat is used doesn't bring much more improvement,” she said. “But two days is the minimum amount of time that the teat needs to be used in first parity for it to have an adequate milk yield in the next parity.”

To watch Dr. Chantal Farmer’s full presentation, go here.

Or to read more from Dr. Farmer’s presentation, click here to learn about the essential role of colostrum for piglet performance.

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