Feeding: In search of the ideal back fat range

Saturday, October 3, 2015

The Learn family farm uses a three-stage feeding program to attain a back fat level of 16-20 millimetres, which they believe reduces feed waste, leads to fewer obese sows birthing and better feeding of the babies. And their production numbers back them up

by DON STONEMAN

When Graham Learn and his brother Adam came into Richmar Farms, the family pork-producing business near Tillsonburg with their father Richard and a newly-built barn in 2006, they brought some fresh ideas with them, including batch farrowing. (See "Batch farrowing attracts growing interest in Ontario," Better Pork, August 2015.) But that wasn't the only innovation that came along.

Graham Learn is keen on a three-stage feeding system which, he says, maximizes the gains from his prolific sow genetics and also reduces sow feed wastage. After piglets are weaned, sows are individually scaled and bred in the dry sow barn and also measured for millimetres of back fat, using a Renco laser probe. "It is a little bit more work," Graham Learn allows, and the management technique isn't widely used.

Feed company Shur-Gain uses a version of this, sampling a number of sows in a herd several times a year in a feed program whose goal is the elimination of "outliers" that are overfed, says Jeff MacDougald, Shur-Gain's swine business unit manager, based in St. Marys.

The program aims to have sows with back fat in the 16-20 millimetre range. The benefits are reducing wasted feed to over-conditioned sows, fewer problems with obese sows birthing and better feeding of the babies because properly conditioned sows will continue to eat well during lactation, whereas overfed sows do not. Learn has taken that system further by scaling and probing every sow in the 350-sow herd after weaning, when she is rebred.

This feeding approach has been around for a bit more than 10 years, says Ontario agriculture ministry veterinarian Tim Blackwell. It is based on the fact that, with new, more muscular genetics, a "big" sow may not have as much fat cover as that same size, shape or dimension of sow would have had 20 years ago, when she could only look big if she had some fat cover. The ultrasound probing can distinguish between fat and muscle, and the theory is that a sow with little back fat gets fed more than a sow with adequate back fat, maybe 17 to 20 millimetres.

"It sounds good," says Blackwell, "but I have not seen data confirming that this approach actually leads to increased reproductive performance, but perhaps such data does exist."

Learn agrees that appearances are deceiving and weighing or scaling sows alone won't  determine if they are carrying enough fat to take them through a lactation.

For the first 35 days after weaning at the Learn farm, sows are on an individual feeding program based on their body weight (heavier sows require more feed for maintenance), their back fat and the number of parities they have achieved. The cheapest weight to put on a market hog is up to weaning weight, Learn explains, so the mother has to milk well.

To achieve that level of back fat, feeding has to be ramped up early in gestation, while the embryos sows carry are still small. Moreover, gilts and sows that are well fed earlier in their lives are more likely to achieve greater lifetime productivity with more litters. Thin sows tend to be culled early for shoulder lesions and don't reach their potential as income earners.

Feeding canisters are set for individual animals. They are calibrated regularly because the feed density changes depending upon the weight of corn in the ration, Learn says. Sows that didn't milk down as well don't get as much feed as those that lost 10-15 millimetres of back fat.

In the system the Learns use, after 35 days post-breeding each sow is fed the same amount. In the last 15 days of the gestation, the daily ration is "bumped up" a kilogram, Graham Learn says, as sows' physical resources go into growing the gestating piglets. (See chart on page 10.)

Back fat target
The Learns aim for 16-18 millimetres of back fat on sows going into the farrowing room. "We are more concerned with the physical condition of the sows going into the farrowing room and, in turn, their ability to nurse the litter and still be in good condition at weaning," writes Allison Learn, Graham's wife, in an email. For biosecurity purposes Allison manages the finishing barn and also handles the farm financial records. "And, of course, don't over-feed a sow that is already over-conditioned or, on the other hand, don't ship underweight cull sows. We don't do a second back fat measurement to gauge success, but are happy with the physical condition of the sows at the end of their gestation."

There is no perfect amount of back fat, Graham Learn says, but typically sows after weaning carry between 10 and 20 millimetres of back fat, depending upon how well they milked. The first 35 days after weaning are the most crucial in getting that sow back into the best shape possible for the next farrowing. After 35 days, her body has to ramp up to produce those pigs and she is putting the extra feed into the baby pigs rather than into herself.

"You can get away with that for the first three parities, but then her milk capacity goes down. Her babies don't get as much milk and she doesn't breed back for the next three parities," Learn says.

The Learns consider their feeding program and management in general to be successful. Through their gilt supplier, Topigs, Richmar Farms information is mined by Swine Management Services (SMS), a bench marking company located in Fremont, Neb. Based on 1.7 million farrowings, the Richmar operation is in the 98th percentile from gilt to parity three.

"Sow retention after parity three is quite high, too," Graham Learn says.  "There is a chart I employ that uses the back fat and the weight to give me the feed per day. The canisters can ration feed daily in increments from 2.3 to seven kilograms."

Learn is part of a local benchmarking group of eight producers and uses the lowest amount of tonnage of dry sow and lactation sow feed for that group. The mill on the Learns' farm makes two tonnes in 20 to 30 minutes; about 175 tonnes a month.

Graham's brother, Adam, is in charge of cropping and the farm grows 275 acres of corn, 50 acres of wheat and 275 acres of soybeans. The corn is dried and stored on the farm. Some additional corn is purchased. There are commodity bins for corn, liquid fat, soybean meal, distillers dried grains and wheat shorts.

Shur-Gain's Jeff MacDougald says Graham Learn used to be a Shur Gain Feed customer and was set up with a program four or five years ago.

In many cases, Shur-Gain will measure the sows for producers. Producers who have their own probe will follow up independently. "It's kind of like taking a snapshot of the herd. We sample the herd three or four times a year, ideally sampling 15 sows post-weaning and about to go into farrowing, as well as 28 days prior," MacDougald says.

This is part of Shur-Gain's national sow feeding Mission program, which has had limited uptake in its six years of existence. "There isn't as much demand as we would like," MacDougald admits. It is more heavily used in Quebec, where there is more integration of systems.

Better use of feed
The value of the program is seen mostly in the sow herd through better feed utilization. And, through that, there is efficiency in management and in farrowing. Obese sows going into farrowing have a greater risk of stillborns. So, with better conditioned sows, stillborn numbers are reduced.

There's no particular size of herd that benefits, MacDougald says, though the improvement is most noticeable in large herds. For farmers weaning 1,000 pigs a year, "it saves maybe $1,000 a year, multiples of that with more pigs fed. In larger systems, there are more opportunities to control feed wastage." MacDougald sees benefits with both overfed and underfed sows.

He also sees more problems with overfat sows than with thin ones, though the problems may not be the same on both sides of the border. "Over-conditioned sows used to be the main concern on many swine farms but, in recent years, thin sows have become a more prevalent problem," says a 2007 document from Kansas State University entitled "Breeding Herd Recommendations for Swine." (www.bookstore.ksre.ksu.edu/pubs/MF2302.pdf)

The document notes: "There is some disagreement, however, on whether the ideal back fat level at farrowing should be 16-18 millimetres or 18-21 millimetres. The most important point is to have as few sows as possible under 15 millimetres or over 24 millimetres of last rib fat depth at farrowing."

There is no disagreement, however, that the Learn sow herd has good production numbers. At the end of 2014, average born alive per litter was 13.4 — steady upward progress from 11.7 in 2010.

Non-productive sow days are 34. By day seven, 95.8 per cent of sows are bred. Total feed cost last year, sow and nursery, was $26.06. Feed quantity per breeding female was 1,011 kilograms, the lowest in the eight-producer benchmarking group in which Learn participates. Total kilograms of piglets weaned per crate per year was 1,023 — the highest in the group. BP