Launching Gilts for Longevity
Bill Raufer
| Monday, February 11, 2002
Special attention to the replacement gilt offers immediate and long-term benefits, says R. Dean Boyd, technology director for the Hanor Company, which has 100,000 sows in several states.
To start, he says, keeping first-litter gilts in a separate group – rather than housing them with older sows – pays off in the gilts' lifetime performance. It also benefits their pigs all the way to market.
"Gilt development is among the more disappointing aspects of pork production," says Boyd. "There's much room for improvement industry-wide. And we need to start when the replacement gilt is young – at about 50 pounds."
Paying increased attention to gilt development, he strongly believes, can positively impact a sow's lifetime productivity. Early health acclimatization by exposing gilts to pathogens present in the herd also can benefit her long term. Boyd recommends exposing gilts to first-litter or older cull sows once they reach 50 to 60 pounds up to breeding.
Separating out replacement gilts, beginning at 50 pounds, makes it possible to tailor their nutrition and management in each stage. Segregating pigs from first-litter gilts' in the nursery and finishing stages also offers worthwhile advantages all the way to market. Boyd cites the following benefits:
- It recognizes that a first-litter gilt's pigs have lower levels of immunity to diseases received from their mothers through colostrum and maybe even milk. Keeping them separate avoids exposure to diseases carried by older sows' piglets.
- Segregated rearing makes strategic medication and vaccination of first-litter pigs possible and more practical.
Boyd advocates strategic vaccinations early in the pig's life and emphasizes that the vaccines should match the herd's health history and challenges. Vaccinations should begin by the time gilts reach 100 pounds or soon thereafter. "A veterinarian familiar with the operation can work out a program using vaccines that will be effective against pathogens present in the herd," he notes.
Feeding the growing gilt
Boyd recommends feeding gilts a ration designed to promote structural integrity by developing strong bones and cartilage while achieving minimal body weight prior to breeding.
"A ration normally fed to grow market hogs is not adequate in critical nutrients, such as calcium, phosphorous and vitamin D," he says. "Replacement gilts need about 15 percent more of those elements than hogs destined for market. Gilts should be full-fed a properly fortified development ration."
Gestation feeding
To continue developing a bred gilt to achieve her full productivity potential, Boyd advocates four-phase feeding:
1. After the first breeding or semen insemination, limit daily feed intake to 4 pounds or slightly less for a period of 3 to 5 days.
2. Then feed 5 pounds per day until the 90th day of pregnancy.
3. Increase daily feed intake to 6.5 pounds to promote fetal growth and mammary development
4. Two or three days prior to the farrowing date, reduce daily feed intake to 5 pounds.
"Throughout the development stage," Boyd stresses, "always remember that you want to build the young
female's structural integrity, increase her body protein and fat. Of course, we never want the gilt to get too fat."
Lactation feeding
The new mother must receive adequate nutrients to meet her milk production needs and to increase the size of her second litter, Boyd stresses.
"The feeding strategy during lactation should be to maximize consumption. Nutrients are secondary to feeding method, which is by far more important," he says. "A swine nutritionist can set the nutrient level after intake is estimated by matching pig weight to nutrients needed to support the gain."
Among the most critical nutrients to monitor are lysine, calcium and phosphorus. A nursing gilt can require as much as 65 grams to 70 grams per day of dietary lysine.
Preserving body protein during lactation is important to shorten weaning-to-estrus intervals. It also affects the size of subsequent litters. With first-litter gilts, loss of body protein and/or fat during lactation can delay the female from returning to heat up to 12 to 15 days post-weaning. "Obviously," Boyd notes, "this can severely disrupt a desired farrowing schedule."
He further points out that as the number of pigs in a gilt's first litter increases, so does the likelihood of her second litter being smaller by one or two piglets. This is another good reason for paying close attention to her ration and feed intake.
"Ration content is always important, but it is secondary to feed intake with first-time mothers," he emphasizes. "That means ensuring that feeders and the feeding method are not limiting consumption."
Boyd also recommends twice-a-day feeding of first-time nursing mothers.
Weaning
This is the time to assess lactation-feeding effectiveness and to set objectives for rebuilding the gilt's body reserves. Limiting backfat loss to 2 mm from farrowing to weaning is evidence of proper feeding management.
After a first-litter gilt's pigs are weaned, Boyd recommends feeding her a gestation ration two or three times a day until she is re-bred.
"This helps improve feed intake, which tends to be low for several days after weaning. It can provide an energy level that stimulates reproductive hormone secretion, which is vitally important for second-litter size," he notes.
With adequate feed intake, a high percentage of gilts exhibit estrus within 10 days of weaning. "Prompt conception prevents the possibility of needless culling due to presumed reproductive failure," says Boyd.
Adding this word of caution, he points out that scenario is different with more mature sows in relatively good body condition. "High-level feeding has no beneficial effect on them," he says.
Joining the sow herd
After the first-litter gilt's piglets are weaned and she is re-bred, she can be put on the same gestation ration as the rest of the sow herd.
"Close attention to a lifetime program of structural and immune-system development – beginning by about 50 pounds – will result in gilts achieving their potential, litter after litter," concludes Boyd.
