The key to reducing the number of lightweight pigs at weaning is to increase average weaning weights.
That may sound like a no-brainer. But according to Mike Tokach, many producers find it's no small task to achieve that uniformity. Normal weaning weight variation is depicted in Figure 1. (Data for Figure 1 and Table 1 was generated from farms with weaning ages of 14-23 days on average.)
For starters, some producers go about fixing that litter weight variation in the wrong way, says the Kansas State University extension swine specialist.
Management techniques like split weaning or split nursing are common approaches. Split weaning or bump weaning refers to weaning off the big pigs or moving them to a nurse sow for a few days to give the smallest pigs in the litter access to the udder for a few extra days. This technique can increase weight gains on those small pigs. But the technique does not work effectively unless pigs are weaned on two or more days each week on the farm.
In reality, by weaning big pigs off a week early, you create two problems. First, those big pigs are too young to wean. Second, it creates too large of an age range in the litter at weaning.
"For example, if the maximum weaning age is 21 days, the average is 18 days and you wean some early, they will only be 8 to 14 days old, creating a weaning age spread of over 10 days," he explains.
For split nursing, the largest half of the litter is taken off the sow for a two-hour period within the first 24 hours after birth, to provide weaker pigs with extra access to sow's milk. Research has shown that split nursing reduces variation.
But a closer look at the data shows that a 0.5 lb. increase in pig weaning weight will provide similar benefits in reducing the number of lightweight pigs in a litter as split nursing.
Tokach observes, "We have had more success in reducing the number of lightweight pigs by concentrating on increasing weaning weight instead of just increasing the weight of the smallest pigs in the litter."
Therefore, adding weaning weight should be the goal of management in striving for even-sized litters, he notes. As shown in Table 1, the heavier the average weaning weight of the litter, the less overall weight variation and lightweight pigs, stresses Tokach.
Lactation Feeding The key to adding weight to the litter is adopting a proper lactation feeding scheme, he continues.
Most of all, employees must have a commitment to keeping feed in the sow feeder at all times. Sows should be fed multiple times a day and those not eating should be promptly investigated.
Tokach says there are three reasons lactation feed intake is a problem:
1. Producers are concerned with sows going off feed, so they limit consumption in early lactation to prevent dips in feed intake.
2. Sows are often not fed correctly during gestation, causing lower lactation feed intake.
3. Many producers use feed intake cards as a crutch. This allows them to believe feed intake is higher than actual feed disappearance.
To make sure feed is always available, lactating sows should be fed three or four times a day, says Tokach. He suggests using the following example as a means of achieving maximum sow feed intake.
Morning feeding: All sows are fed one scoop (4 lb.) if a small amount of feed is left in the feeder, two scoops if the feeder is empty.
Late morning feeding: A second feeding late morning or just after lunch follows the same routine as the morning feeding. If no feed has been eaten since the morning feeding, the sow is checked out immediately to determine if she has a fever, retained pig or other obvious reasons for being off feed.
Evening feeding: Do the same for the evening feeding. But use some judgment if there is some feed left in the feeder. Sows that have had good appetites all days but have some feed left in the feeder should receive two scoops of feed. Sows that have cleaned up their feed and appear to be reaching the peak of their appetite should receive one scoop of feed.
Again, if the feed has not been touched since the last feeding, the sow should be checked to find out the reason.