More and more U.S. pork producers are moving away from individual gestation stalls to housing gilts and sows in groups. However, producers face the challenge of being able to monitor how much feed each female consumes and how efficiently they are using that feed. To keep tabs on feed intake, producers have started to install electronic sow feeding systems. Though in a group setting, each female enters a feeding station by herself, a gate locks behind her. Each female has a transponder in her ear tag, and this transponder triggers the computer-controlled feeder to dispense the specific amount of feed for the individual. Unless a computer glitch occurs, or a transponder is lost, the systems work as they should.
Progressive producers desire as much data on each female as possible, and researchers at Kansas State University decided to take a look at feed efficiency by stage of gestation for the sows and gilts. “To our knowledge, no one has ever looked at gestation feed efficiency by stage of gestation in a large group housing set-up, and we thought it would help with determining nutrient requirements and feeding recommendations,” says Bob Goodband, Kansas State University animal science professor. “As the swine industry transitions to group housing, computerized feeding programs will offer opportunities to really fine-tune gestation feeding programs for sows.”
Two Kansas State University graduate students – Lori Thomas and Carine Vier – went to a hog farm using ESF to study gestational feed efficiency, as well as to examine the importance of training gilts and sows to use such systems before they are bred and begin gestation. The studies followed 300 gilts and 550 sows.
Producers who have used ESF systems have learned, as did the Kansas State researchers, that there is a learning curve for the humans using the system, but also for the pigs. “The training process is very, very important, and not only is it a long procedure, but we found that you still may not get all sows or gilts to eat as much as we would like them to the first few days after they are moved into their pens,” Goodband says.
The cooperating farm had a training protocol in place, with three stages. Once gilts left isolation they were moved to gilt development into a grower pen for a 10-week period (age 11 weeks to 21 weeks old) for a pre-training stage. They then enter a gilt training pen for a two-week training stage, before reaching the post-training stage where gilts would go to the ESF pens or would be moved to crates for insemination.
The pre-training is a very important stage as developing gilts are exposed to the process of going through an automatic chute “that would get them accustomed to what they will see later on as they go through gestation in the ESF pens,” Goodband says. “They need to learn that they will need to go through a device in order to eat.”
Feed efficiency evaluation
Once properly trained, it is up to the sows/gilts and the system itself to reach ultimate efficiency. One of the goals for Thomas and Vier was to get a better understanding of gestation feed intake patterns and to use that information to then model the changes in protein and lipid deposition and the products in conceptus and how they change in relation to nutrient and feed allowance during gestation.
The cooperating farm has six ESF feeding stations per pen, and researchers were hoping to use the technology to identify patterns of feed intake and record the growth of the animals. Each female has a radio-frequency identification tag, identifying which specific animal has just entered the feeding station, and a predetermined amount of feed would be dropped – 4.4 pounds per day for gilts or 5 pounds per day for sows. Upon finishing eating, the female then passes through an alley to walk over a scale, and a weight is registered for each female. During the training process, Thomas stopped each female pig on the scale, to be certain of getting a “starting” weight for each individual.
Researchers found that a sow may go through an ESF system three to six times a day, even though they may not get feed each time, “but they’ll still go through hoping there will be some food there for them,” Goodband says.
One thing that surprised the researchers was that the sows and gilts did not eat their full feed allocation or gain much weight in the first 10 days in the pen. After the first 10 days, each sow and gilt generally consumed her whole ration.
“We found significant changes in average daily weight gain following the initial 10 days in the pen. Thereafter, females were consistently eating and gaining for the remainder of gestation,” says Thomas, the graduate student in charge of the study. “Our results, I think, share a very important message that even with a good training program, gilts and sows appear to struggle within those first few days of introduction into the gestation pen. It doesn’t take long before they become adjusted and are up to full feed, but it is important for producers to be aware of this.”
“The question we’re hoping to answer is, ‘Will these changes in initial feed intake affect subsequent reproductive performance?’” she says, adding that the research team is planning further studies this spring to look at nutrient requirements during gestation.
Goodband says the slow start of average daily gain in gestation held fairly consistent when comparing Parity 1, Parity 2 and Parity 3+ sows and gilts. After the first period, ADG was consistent during the rest of the periods in gestation. (See Figure 1)
From an actual feed intake perspective, multi-parous sows and second parity gilts are eating about 95% of their allocated feed during the first 10 days of gestation. Gilts on the other hand, are only consuming 90% of their allocated feed, and Goodband rationalizes that may be due to the challenges of learning the ESF training process.
Researchers found that the older the female, the more comfortable they become throughout the gestation period in the ESF system, as where the Parity 1 females may need a little coaxing as they reenter the ESF system.
While data show pigs will learn the ESF system, Goodband says it’s important to focus on the lower feed intake during the early stage of gestation and how that may be influencing subsequent litter performance.
As expected, when feed intake is down the first 10-15 days of gestation, so is feed efficiency, as Goodband says the females ate enough of their allocated feed to stay above their maintenance level, but not enough to gain weight.
“The take-home message,” Goodband says, “is that ESF systems provide great opportunities for modeling to determine the rate at which a sow adds lean muscle and fat that we can then tie back into a nutrition program on changing the amount of feed and different nutrition levels.”
“There is a lot of excitement on the data that have been generated and will continue to be generated from this system and many other similar systems,” he adds. “Improving our knowledge of the pregnant sow and how to properly meet her nutrient requirements in gestation, to have her enter into the farrowing house ready to farrow and successfully nurse a vigorous litter of piglets is a goal we hope to achieve.”
Helping a pregnant female to meet her nutrient requirements in an ESF system will also involve overcoming the challenges that she faces each time she reenters the ESF system.
The studies were supported by a USDA National Institute of Food and Agriculture grant and PIC, Hendersonville, Tenn.