Nutrition: Does multiple feeding help group-housed sows?

Monday, December 10, 2007

When Kansas State University researchers tested this theory, they found little difference from normal feeding routines, though previous research suggests it has benefits in the dog days of summer
by JANICE MURPHY

In the modern swine industry, change continues to be the norm. While sows are individually housed in gestation stalls in many commercial swine facilities, animal welfare concerns have recently led to a shift toward group housing.

This trend has been fuelled by ballots cast in Arizona and Florida, where gestation stalls have been banned, as well as decisions by Smithfield Foods and Maple Leaf Foods to make the move to group housing.

The perception is that group housing allows for increased freedom of movement and social interaction and, as a result, is more welfare-friendly than housing sows in stalls. Group housing is also thought to decrease chronic stress in sows and speed up the farrowing process, most likely due to the increased level of activity compared to sows confined to stalls.

Unfortunately, not all sows will thrive in a group housing situation. Just like children in a schoolyard, there is always the chance of running into a bully. The opportunity for social interaction can lead to aggressive behaviour between sows, allowing dominant sows at the top of the pecking order to consume more feed at the expense of sows at the bottom. The result is most likely fear and distress on the part of the less dominant sow.

To complicate matters, the conventional North American sow diet is a concentrated blend of nutrients, lacking bulky ingredients, and although it is sufficient to support good health and performance, it might not promote a feeling of satiety. Also, sows normally eat as a group, but the amount of floor space available for feeding in a group pen often decreases as the number of sows increase, limiting the potential for this to happen.

There have been many attempts at figuring out how best to feed gestating sows in group housing situations, including feeding stalls within a pen, electronic sow feeders, trickle feeding and ad libitum feeding of high-fibre diets. A recent approach used on some farms is multiple feedings (five or six meals) spread throughout the day. The theory behind this is that offering feed more frequently may allow the more dominant sows to eat their fill early on, giving the timid ones a better chance of catching up later on, thereby reducing variation and any other negative impacts.

Researchers at Kansas State University recently tested this theory. The objective of their research was to determine whether feeding group-housed gestating sows six times per day reduces variation in sow body weight, backfat thickness, aggressiveness, and feet and leg problems compared with feeding twice daily. A total of 496 group-housed gilts and sows were used from a commercial operation in northeast Kansas which typically housed gestating sows and gilts in pens.

The experimental treatments consisted of feeding similar amounts of feed to each sow (2.5 kg) or gilt (2.05 kg) either two or six times daily. The time intervals, which grouped feedings in the morning and afternoon, were chosen based on an earlier researcher's finding that blood glucose and insulin peaked at roughly 30 minutes after consumption of a meal. Based on this information, the researchers suggested that, if the more dominant sows consumed the first meal, they should have a greater sense of satiety by the time the second and third meals occurred.

Gilts and sows were moved into pens one to four days after breeding, with eight sows or 12 gilts assigned to each pen. In this commercial operation, the standard management protocol required moving gilts to a different gestation facility on day 42. In keeping with that protocol, on day 42, two pens of gilts with similar breeding dates and treatment were grouped and moved to another facility with larger pens, where they stayed until farrowing.

Despite the theory behind this feeding strategy for group-housed sows, the results did not show much in the way of significant differences between treatments. Gilts fed six times daily tended to show greater average daily gain (ADG) from day 0 to 42 and a tendency for greater backfat on day 42 (see Table 1). After movement to the larger group, ADG was similar for gilts, regardless of treatment. Gilts fed twice daily had lower body weight variation at day 42 and, similarly, tended to at farrowing as well.

In sows, there were no differences in ADG, backfat or variation in bodyweight (Table 1). There was a trend for sows fed twice a day to farrow more total pigs born, but the number born alive and other reproductive performance results were not different among treatments (Table 2). In gilts, there were no differences in reproductive performance.

The researchers were not surprised by these results, as they speculated that increasing the feeding frequency was not going to dramatically increase stress, which could hurt reproductive performance.

Sows fed twice daily had more skin and vulva lesions, as well as a small increase in feet and leg and hoof problems (Table 3). In gilts, there were no differences in skin and vulva lesions, or feet and leg scores. Lower skin and vulva lesions are an indication that fewer fights and injuries occurred in the sows fed six times per day. However, the differences between treatments were relatively small and the researchers were confident that this most likely resulted from a stable pen environment and established pecking order after mixing.

Based on these results, the researchers concluded that there were few differences among sows or gilts fed either two or six times daily. Increasing the feeding frequency does not appear to have a negative or positive impact on the performance or welfare of group-housed gilts and sows, suggesting that either feeding method would be suitable.

It is interesting to note that increased feeding frequency yielded some advantages in the dog days of summer. Previous research has shown that, when producers switch from feeding two to three times per day, most experience a 10 to 15 percent increase in sow feed intake. Some farms in North Carolina have been reported to feed four or more times per day in the summer.

Their reason for using this strategy is related to the normal increase in body temperature that occurs after a sow consumes a meal. In theory, since there is less food to be digested, there will not be as big an increase in a sow's body temperature after she eats a smaller meal. Consequently, this could translate into an advantage for sows whose body temperatures already may be in the upper end of the thermo-neutral range due to high environmental temperatures. BP

Janice Murphy is a former swine nutritionist with the Ontario Ministry of Agriculture, Food and Rural Affairs, who now lives and works in Prince Edward Island.

Sources:
Schneider, J. D., Tokach, M. D., Dritz, S. S., Nelssen, J. L., DeRouchey, J. M. and Goodband, R. D. 2007. Feeding schedule for group housed sows - Effects of feeding schedule on body condition, aggressiveness, and reproductive failure in group housed sows. J. Anim Sci. first published on September 4, 2007 as doi:10.2527/jas.2007-0345.
Rozeboom, K. and Rozeboom, D. 2001. Managing Today's Reproductive Female. Proceedings of the London Swine Conference - The Pork Industry and Public Issues. April 5-6, 2001.