Farm managers continue to seek optimum performance from sows that are considerably more prolific than their predecessors. Banff Pork Seminar brought three speakers to conduct a seminar on helping those high-performance sows live up to their genetic potential.
Opening the session was Prof. Billy Flowers of North Carolina State University, Banff Pork’s 2014 George Foxcroft Lecturer.
“The way I look at sow longevity, I really break it down into a development period and a functional period,” said Flowers.
Comparing sows to high-performance vehicles, he said development of the gilt determines what sort of engine she will have while the way she is managed from birth will determine how well that engine works.
Gilts that are heavier at birth will, in general, perform better and mature faster. Therefore, how the sow is managed during gestation will play a large role in how well her offspring will perform as an adult, said Flowers.
The longevity of gilts selected for the breeding shed will then rest largely in how they are managed through to their first and second parities, including the culling process. Flowers cited incidents in which autopsies performed on culled gilts showed that healthy animals with well-developed ovaries were incorrectly culled because of some other problem in the barn, such as a failure to detect estrous.
Flowers encouraged producers to inspect the internal organs of slaughtered gilts to see if they are culling healthy breeders and if they should be doing something differently in the barn.
Comparing longevity rates in two different herds with the same genetic makeup, Flowers said he found some key differences in management practices between the barn with the higher sow longevity and the lower longevity barn.
“What’s really interesting to me is, (the high-longevity barn) specialize the gilts – they look at the gilts differently than the sows. The high longevity farm dedicates one person to take care of what they call the new girls.”
Another significant factor was in the boars used for gilt stimulation and heat checking. While the low-longevity barn used an immature boar that was not collected, the barn with the greater success used mature boars that were collected regularly.
Flowers said he also found that the sows on the high-longevity barn were handled differently and, as a result, were more comfortable with human contact.
Their comfort levels were measured using a Hemsworth test, in which a handler goes into the pen with an animal to see whether it approaches or moves away.
Flowers believes that the reason the high-longevity sows are calmer around people is partly because they are moved by hand rather than with boards and paddles.
“So, what does all this mean?”
Flowers said producers need to think about the way replacement gilts are developed in the fetal stage, and then work on management practices as the young animals are being prepared for breeding.
“The comprehensive test on how well you’ve done is how early (the gilt) reaches puberty,” said Flowers.
Chantal Farmer, a biologist with Agriculture and Agri-Food Canada in Sherbrooke, Que., walked producers through the basics of mammary development and milk production in hyper-prolific sows.
Having enough milk in the first days of life is the most important factor in piglet growth and development, said Farmer. Because of their larger litters, hyper-prolific sows may not produce enough milk to get all of their piglets off to a good start, she says.
“You will have more milk if the litter is bigger, but the increasing litter size still means less milk for each pig,” she said.
Genetics, nutrition, body condition and how the sow is developed and managed – including the number of piglets suckled in her first lactation – are all factors in milk production.
Farmer cited research showing that suckling in the first parity will determine how well each teat functions for the life of the sow.
A teat that is not suckled in the first parity will never produce as well as those that are suckled, she said. Additionally, where new pigs are introduced to a lactating sow, teats that are not used for a short period of time will return to production, but will not produce as much milk in future lactations, she said.
That loss of milk production needs to be considered when introducing piglets to nurse sows, said Farmer.
She also advised producers to keep suckling intervals as short as possible to encourage maximum production from the sow, noting that each teat reaches maximum production about 35 minutes after suckling.
Mammary glands develop during three stages: Within 90 days before puberty, during the last third of gestation and during lactation.
How the gilt is managed through puberty to the end of her first lactation, including nutrition and hormones, will set the stage for the amount of milk she will produce in future litters, including the number and size of milk-secreting cells, said Farmer.
While prolactin is recognized as an essential hormone for stimulating milk production, more research is needed to find ways to improve milk production as much as possible in hyper-prolific sows, she said.
Reproduction physiologist Mark Wilson from Zinpro gave further insight on management strategies for retaining sows in the breeding shed.
Sow longevity may have a much bigger financial impact than what may be recognized, Wilson said in his presentation.
He set a target of 43 per cent as the optimal replacement rate.
“If we go below 40 per cent, what happens to you is you cannot maintain your parity profiles. You do not bring in enough gilts to keep it flowing,” said Wilson.
The barn’s profits, in general, come from the proportion of sows in the herd that are at their second and third parity, he said.
Gilt selection, lameness and milk production are all factors for producers to consider when assessing strategies in their sow herds, said Wilson.
Gilts should be carefully culled for reproduction and lameness issues, without losing too many animals without good reason. Losing large numbers of gilts before they even farrow is expensive, said Wilson.
“Listen to Billy Flowers when he tells you that heat-check boar is really important.”
Pointing to Farmer’s presentation, he said body condition should be maintained at a fairly even level because big weight swings equate to poor performance.
Wilson also pointed out that, because their pigs tend to be smaller and more susceptible to disease, having a large proportion of gilts in the barn will reduce production rates overall.
The barn has a good chance to increase overall birth rates and quality with an optimum rate of gilts litters, he said.
“To me, birth rate and weaning rate is still an important payback. The real impact from longevity . . . really may be the impact on the offspring. What are the differences if we change these replacement rates?” said Wilson.
Details of the discussions are available in proceedings from the 2014 Banff Pork Seminar, in the three chapters dedicated to Breakout Session 6: Long Live the Hyper-prolific Sow. •
— By Brenda Kossowan