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 Knowledge for the CommonWealth

Swine Industry News And Notes

Livestock Update, August 1998

C. M. Wood, Animal and Poultry Sciences, Virginia Tech


The following questions have come up during the World Pork Expo, around Virginia, and in national publications. Hopefully the discussion will provide some food for thought, debate, and potential solutions to problems faced by your producers.

My packer still says my pigs need to be leaner, even though I've tried feeding high-protein feed, and I buy my boars from someone who gets premiums for his pigs. What else can I do?

One possibility is to actually depopulate and repopulate with new genetics. It may sound crazy with hog prices as low as they are, but in many cases seedstock also are lower priced at this point in the cycle. Boars provide half the genetics; the other half come from the sows. Sometimes a fresh start on the maternal side can be beneficial.

Is it really worth paying all that money for elite boars?

How much you can afford to pay depends on what you are trying to accomplish. If you need big genetic changes quickly, then elite boars can make sense. For example, if your sow herd has excellent maternal performance, but market hogs are being discounted for too much fat, then spending the money for an extremely lean elite boar may very well be worthwhile. On the other hand, an elite boar may not solve the problem. Do a check on management, herd health, and nutrition before spending a large sum on genetics.

I've been told that I should feed high-protein feed to get the benefit of improved genetics. But that costs more money. Can I justify that in today's market?

You need to evaluate your market hogs to make sure they have the genetic potential to utilize the higher-protein feed. You can get the detailed procedures from a feed company, your extension agent or specialist, or from publications like the NSIF Guidelines. Essentially, it entails feeding two groups of pigs with similar genetics two different feeds: a "regular" ration, and a high-protein ration. Then compare the lean gain of the two, using information from your packer's kill sheet, and your farm records. If the pigs on the high-protein feed perform better and bring enough premiums to justify the expense, then feed all your pigs that ration. If not, then you are probably justified in feeding the regular ration. Don't forget to repeat the comparison any time major changes occur on your farm.

Everyone's talking about pork quality traits, but I get paid on grade and yield. Should I invest in breeding stock with quality trait information?

A tricky question. Seedstock suppliers need to be seriously considering "Yes" to this question. Commercial farms have a bit longer time frame, but it is probably just a matter of time before packers figure out a way to measure these traits at line speed. So IF you can find breeding stock that will meet current packer specifications AND have desirable quality traits, go for it. Otherwise, keep looking and listening.

How do I sort through all these acronyms (EPD, SPI, TSI, etc.)?

They can be confusing. Just as consumers are advised to read the label when purchasing groceries, producers in the market for improved genetics need to be familiar with these and other abbreviations. Most sire summaries and other genetic evaluations come with an explanation. It pays to read that carefully before making buying decisions. If an explanation is not provided, don't be shy about asking for one.

EPD stands for Expected Progeny Differences, and provides exactly what that says: the expected difference between this animal's offspring and the average of its breed or line. Or if you want to compare two individuals in the same breed or line, you can subtract the lower EPD from the higher one and get the expected difference between offspring of those two individuals.

SPI stands for Sow Productivity Index. It was originally developed to rank sows on litter size and milking ability, and can still be used on farms for that purpose. With improvements in genetic evaluation programs, the SPI can now be used to predict daughter performance in those two traits as well, which is why sire evaluations often contain an SPI column. A simple spreadsheet program is all that is needed to calculate the index on the farm. A number of software companies have incorporated SPI calculations, as well. To use SPI correctly, it is very important that sows be grouped carefully: similar genetic background, farrowing in similar facilities, in the same time frame.

TSI is Terminal Sire Index. As you might expect, it is used to rank animals on terminal sire traits like growth, efficiency, and backfat. Again, most sire summaries include a TSI.

Indexes like the SPI and TSI are convenient, but may not meet your particular needs. If you need an animal just to improve litter size, for example, then the EPD for litter size would give you more information than either the SPI or TSI.

My packer wants hogs that are heavy, but still wants them lean. I can get them lean, or I can get them heavy, but how do I get them both?

Animals typically deposit lean early, then increase fat deposition as they top out on their growth curves. The growth curve is determined to a great extent by genetics, so you need to find a good source of later maturing pigs that can stay lean longer. They are out there; it's a matter of finding the ones that fit your operation. Then feeding them correctly can help, too. If they have the genetic potential to be heavy and lean, they probably also need a higher level of protein in the diet for a longer period of time (see the question above). Finally, remember that gilts will stay lean longer than barrows, so split-sex feeding might be a possibility as well.

I've managed to get consistent premium payments on my market hogs, but now I'm starting to notice that my litter size average is down a bit. Am I doing something wrong in the breeding barn?

Actually, what you may be seeing is a natural consequence of paying attention to one trait at the expense of ignoring another. Maternal traits and carcass traits tend to be antagonistic, which means that as one improves the other deteriorates. From a genetic standpoint, the thing to do is make sure that you pay some attention to litter size in your selection decisions, and purchasing decisions. Taking another look at your crossbreeding program is also a good idea: are you getting full benefit from hybrid vigor?

At the same time, don't rule out management. Make sure you are managing your pigs according to their genetic potential. Do they need a bit more TLC? Is the nutrition right in the breeding herd and farrowing barn? Some research is showing that high-lean sows need more protein in a more concentrated ration in the farrowing barn, for example. Are you paying as much attention to the breeding barn as you used to, or have you been concentrating so hard on the finishing barn that the breeding herd got the short end of the stick?

You've got the problem half solved because you have the records. More attention to the breeding barn will probably lead you to the answers you need.

I want to use a rota-terminal crossbreeding system to produce my own replacement gilts. How many of my sows should I breed to maternal boars, and how many to terminal sires?

A good rule of thumb is to breed the top 25% of your sows to maternal boars, cull the bottom 20%, and breed everything else to the best terminal sires you can afford.

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