Pigs weighing less than 2.2 lb. at birth are a growing concern as pork producers strive to wean more pigs per sow per year. Although it is normal to have a small percentage (approximately 15%) of lightweight pigs born, these pigs are more difficult to manage.
Production records managed by Innovative Swine Solutions, Carthage, IL, indicate that preweaning death loss of pigs weighing less than 1.98 lb. can be 67% or higher, and for pigs born weighing 1.98 to 2.51 lb. at birth, mortalities can run as high as 25%. Therefore, it is essential to understand methods to reduce the percentage of lightweight pigs at birth and/or to improve the survivability of these small pigs.
Low-birth-weight pigs can be caused by a variety of reasons, such as the gestation feeding program, litter size and sow parity.
In a study conducted by Innovative Swine Solutions, the value of increasing daily feed levels to gestating females was evaluated to determine the impact on piglet birth weight. Gestating gilts were sorted into three groups based on body condition at 100 days of gestation, then assigned to one of three levels of feed.
One group remained on their daily feed allotment of 4.93 lb. and served as a control group. Another group received an additional 1.98 lb./day, and the third group received 3.96 lb. more feed per day. Therefore, in this trial, gilts’ total daily feed allowance was 4.93, 6.49 and 8.49 lb., respectively, for 12 days.
At farrowing, individual pig weight and total born information were collected. Pigs from control group gilts averaged 2.89 lb. at birth (Figure 1). The average birth weight of gilts fed 6.49 or 8.49 lb./day was 3.05 or 3.16 lb., respectively. Litters in both groups receiving more feed had fewer lightweight pigs.
In another study, conducted by APC, Inc. and Innovative Swine Solutions, a total of 640 sows were fed either a diet with 0 or 0.5% spray-dried plasma protein from Day 14 of gestation to parturition. Piglet birth weights in gilt litters were more uniform when fed the plasma-supplemented diet, and the weaning weights of piglets from Parity 1, 3 and 4 litters were improved (12.54 vs. 13.20 lb.). Although birth weight was not significantly improved, the weight distribution was skewed to the right in favor of the group receiving blood plasma.
Colostrum intake for all pigs is essential, but it is even more critical for low-birth-weight pigs. Research conducted by Jeff Vallet at the USDA Meat Animal Research Center in Clay Center, NE, has shown an interaction of colostrum intake and birth weight on survivability. By running an immunocrit on blood drawn from day-old pigs, producers can begin to evaluate whether pigs have received adequate colostrum intake. (See related article on page 15).
Management practices can be put in place to improve the survivability of low-birth-weight pigs. One method for improving colostrum intake is to split-suckle litters at the time of birth. Piglets should be adequately dried and placed into a warm area or box shortly after birth. As farrowing progresses, a portion of the newborns can be allowed to nurse and then returned to the box so the remaining pigs have an equal opportunity to nurse. Generally, the lightweight pigs should remain with the sow at all times to ensure adequate time to nurse and receive colostrum.
Some producers have found it worthwhile to create “nurse moms” to improve small piglet survivability. Placing lightweight pigs on a Parity 2 or older female with proper teat size and placement may improve the chances that pigs receive adequate milk.
Some producers have had good success with placing lightweight pigs in rescue decks and providing energy supplementation. But it is important to remember that colostrum intake is essential for piglet survivability before any of these management practices can be of value.
The impact of lightweight pigs extends beyond the farrowing room. Generally, they do not perform as well throughout the nursery period. Research conducted at the University of Illinois demonstrated that even with supplemental milk during lactation, piglet birth weight was more influential on postweaning growth performance.
It is important for producers to continue to improve birth weights and reduce birth weight variation through nutritional programs.
Laura Greiner is director of swine nutrition and research at Innovative Swine Solutions, Carthage, IL.