Whether you're interested in new swine nutrition, production or genetics research, the Midwest Animal Science meeting this spring addressed it all. Here's a look at some of what’s happening on the research front.

Giving Immune Systems A Boost
Protecting a pig’s immune system is tough duty, especially right after they have been weaned. But additional research shows that adding spray-dried plasma to a weaned pig’s diet can help relieve stress and prevent illness.

In the early 1990’s, spray-dried plasma products derived from livestock began to surface as a dietary option for early weaned pigs. Today most young pig diets include this product.

“We already knew that spray-dried plasma can enhance a young pig’s growth and performance, especially in a typical production environment,” says Jeff Carroll, with USDA’s Agricultural Research Service. “Growth and performance gains may be due to spray-dried plasma’s ability to improve the health status of the weaned pig. Previous studies revealed that spray-dried plasma altered the pig’s intestinal health, therefore, we believed it might provide protection against normal pathogens or bacteria found in a typical production environment.”

By determining how this protein works, researchers from ARS, University of Missouri and Endogen, teamed up to study the immune systems of young pigs that have been fed spray-dried plasma.

Researchers weaned 20, two-week-old pigs and fed 10 of them diets consisting of 7 percent spray-dried plasma for a week. Then they injected all the pigs with lipopolysaccha ride (LPS) from killed bacteria to simulate an infection by a live organism, and measured pig response in terms of the hormones and other chemicals they produced. Researchers specifically focused on hormones associated with stress and immune responses.

Results indicate that pigs fed the spray-dried plasma had a more positive response to the LPS challenge, notes Carroll. “The pigs seemed to be protected from everyday challenges, then when they were injected with LPS, their immune systems over-responded. This greater immune system response is typical of animals that have not been previously exposed to bacterial challenges.”

The researchers’ overall goal is to find cost-effective ways for you to produce healthier pigs that eat well, gain weight quickly and produce large amounts of pork from each pound of feed.

Therefore, it seems that the added benefits of feeding spray-dried plasma, such as increased gain and improved feed efficiency, may be associated with its ability to protect the pig from the normal bacterial challenges they encounter daily in a typical production setting.

Wean-to-Finish Pigs Give Top Performance
Is a wean-to-finish system really that much better than conventional production? Opinions vary, but test results are leaning in favor of wean-to-finish systems.

A team of researchers from the University of Nebraska and South Dakota State University, along with a consulting swine veterinarian, investigated the effects of three weaned pig management systems on performance from weaning to slaughter. The three systems were:

1 Wean to finish: Pigs were weaned into fully slatted finishing pens stocked at 7.5 square feet per pig from weaning age to slaughter weight.

2 Double stock: Pigs were weaned into fully slatted finishing pens at twice the density, 3.75 square feet per pig. Eight weeks after weaning, the pigs were randomly divided into two groups, with one group remaining in the same pen. The other group moved to another pen in the same facility. Pigs then were finished at 7.5 square feet per pig.

3. Nursery moved to a finisher: Pigs were weaned into a nursery and stocked at 3.75 square feet per pig. Eight weeks after weaning, they moved to the same finisher as the wean-to-finish pigs and were double stocked. They were then finished at 7.5 square feet per pig.

All pens used in the study had a single, two-hole, wean-to-finish dry feeder and one cup drinker per 15 pigs. While there were health-related problems in trials 1 and 2 due to porcine respiratory and reproductive syndrome, researchers say it did not affect the overall trial results.

At the end of eight weeks, wean-to-finish pigs were heavier than the double-stocked pigs with the nursery-to-finisher pigs falling in between (see chart). The heavier weight was due to a difference in feed intake between the wean-to-finish and double-stocked treatments. There was no effect of nursery phase treatment on feed efficiency or on the grow/finish production phase.

The research suggests that performance gains associated with wean-to-finish systems occur during the first eight weeks after weaning. Results also show that you can expect improved performance even when health challenges occur in a wean-to-finish production system.

Can Hoops Compete With Confinement?

Finishing pigs raised in hoop structures in the Midwest encounter seasonal affects. Pig performance of hoop-reared pigs was better in the summer, but poorer in the winter than their counterparts raised in confinement, according to researchers at Iowa State University.

At the end of the summer research trial, the average market weight and overall weight gain of the hoop- and confinement-raised pigs was similar (see table). Pigs raised in hoop structures grew faster and reached market weight five days earlier than the confinement pigs. There was no difference in average daily feed intake, but average daily gain was 4 percent higher for the hoop pigs than the confinement pigs. Plus, the hoop-reared pigs had a lower feed-to-gain ratio than pigs in confinement.

The Hoop structures produced pigs that were 5 percent more efficient than pigs in confinement. The pigs were in good health and had only a 2 percent mortality rate. The confinement system produced a 4.5 percent mortality rate. In all, 451 pigs were used for each hoop trial, and 132 pigs for each confinement study.

For the winter trial, the hoop and confinement pigs started off at the same weights, but by market time, the hoop-raised pigs were slightly heavier. However those pigs were on feed about 12 days longer than the confinement-reared pigs. The hoop pigs ate about 5 percent more feed than the confinement pigs, but grew about 5 percent slower. Also the hoop structures produced higher pig mortality and percentage of light pigs (weighing less than 220 pounds) at market than confinement buildings during the winter.

Researchers determined there is a seasonal effect on pigs in the naturally ventilated hoop structures. In the summer trial, the hoop pigs ate less feed, grew faster and were more efficient than the confinement pigs.

However, in the winter trial, pigs raised in the hoop buildings ate more, grew slower and were less efficient than pigs in confinement. The winter cold caused the hoop-reared pigs to consume extra feed and use it to maintain body temperature.

Overall, pig performance was similar when the data was simulated for an entire year, with confinement pigs producing more consistent results throughout the different seasons.

While these trials show that pig performance in hoops and confinement facilities is similar, the jury is still out on the economics.