When it comes to litters, size matters. The number of pigs born per litter has a direct correlation on total pigs marketed. But there’s more to the story: For pigs to meet their full potential, adequate birth weights also are an important factor.
“No matter the genetics, the management or the facilities, birth weight plays a big factor in a pig’s lifetime productivity,” says Gawain Willis, director of nutrition services for Purina Animal Nutrition LLC.
Willis explains that measuring birth weights is especially important as genetics allow sows to produce larger litters. Unfortunately, this trend also can result in lower birth weights. In fact, research shows the average birth weight of each pig drops an average of 0.10 pound for each additional pig in the litter.
“As the industry evolves and larger litters become more common, producers must pay close attention to birth weights in their farrowing units,” he says.
“In our research, birth weights played a significant role in pre-weaning mortality rates,” adds Willis, citing research studies at the company’s animal nutrition center.
“Almost all of our pre-weaning mortality occurred in the smaller birth weights. Growth rates, feed efficiency and piglet vitality also were noticeably improved with higher birth weights.”
In the trials, heavier-born pigs were able to get off to the proper start and also reached weaning and market weights more quickly; with 2.8 lbs. higher weaning weights. In terms of finishing, pigs born between 3.1 and 3.5 lbs. reached a marketable weight of 270 lbs. seven days sooner than pigs with birth weights of 1.6 to 2 lbs.
Kansas State University researchers say increases in litter size have raised concern over the impact that the increase may have on piglet birth weight and performance.* However, they say, there is little data available that adequately describes these relationships and their effects on subsequent performance. Their research indicates that low-birth-weight pigs, especially those weighing 2.3 lbs. or less at birth, had poorer growth performance and higher mortality preweaning.
“Although larger litters had a greater number of low-birth-weight pigs, these litters also produced a greater number of live pigs with a birth weight greater than 2.3 lbs.,” the researchers wrote. “In addition to increasing litter size, maximizing the reproductive and economic efficiency of swine requires identifying methods to improve birth weight and performance of the lightest pigs born.”
Increased nutrients through gestation and lactation are one major factor required to allow sows to produce heavier litters. Willis explains that higher-producing sows often require increased nutrients to achieve long-term production or they may fall out of the herd too soon.
Genetics and management play important roles too, and day-one care can benefit not only the larger pigs, but can help smaller pigs survive and thrive.
*Editor’s note: The research referenced was from the paper, Effects of Piglet Birth Weight and Litter Size on the Preweaning Growth Performance of Pigs on a Commercial Farm, by: 1 J. R. Bergstrom, M. L. Potter2 , M. D. Tokach, S. C. Henry3 , S. S. Dritz2 , J. L. Nelssen, R. D. Goodband, and J. M. DeRouchey.