NCSU Extension Swine Husbandry 1996

August, 1996 . Volume 19, Number 7


Although corn is the standard grain for feeding hogs, there is, from time to time, considerable interest in alternative grains. The current price of corn has, for example, stimulated much discussion of alternative feed grains.

One of these alternative grains is barley. Dr. Allen Harper, Extension Swine Specialist at Virginia Tech, recently published an in-depth review of using barley as a swine feed. This publication is "Potential for Greater Use of Virginia Barley in Swine Feeding" and was printed as Tidewater-AREC Information Series No. 367. In this review Dr. Harper discusses the common questions asked when one is considering barley as a feed grain. These questions address nutritional composition, variety and regional differences, test-weight, example diet formulations, feeding test results, and processing and physical form of barley diets. The following paragraphs, taken directly from the publication, summarizes the merits of barley as a feed ingredient for pigs:

"The principle disadvantage associated with barley as a swine feed grain has been known for many years; that is: moderately lower metabolizable energy content in association with a higher fiber content relative to other grains such as corn, wheat and grain sorghum. This fact, coupled with relatively consistent supplies of corn has resulted in only modest use of barley in U.S. swine feed formulations. To some degree corn has become such a standard feed grain for swine that U.S. feed formulators may feel reluctant to consider barley as a worthwhile component in least-cost diet formulations. Indeed one group of swine researchers indicate that barley "suffers from a strange enigma" in that it is widely grown but is not a familiar ingredient with many animal nutritionists.

"To its credit, barley has some significant advantages. Total protein, total lysine and available lysine content of barley is higher than that found in corn. This allows reduction of expensive protein supplement in formulations which can reduce total diet cost and increase the relative value of barley. Furthermore, barley is often competitively priced with other grains when considered on an available energy and protein basis.

"Other recent developments have the potential to make barley more competitive in the feed ingredient market. First, crop breeders have developed some high yielding, high test weight feed barleys for the mid-Atlantic region. This is significant because feeding data clearly shows that higher test weight barleys have greater feeding value for swine. Secondly, the changing structure of the swine industry has resulted in a greater proportion of swine feed being prepared at large centralized feed mills. These mills are adept in producing feeds from a varied and complex set of ingredients including feed grade fats and multiple grains and by-products. The elevated energy density of feed grade fats along with grain blending offers a means to compensate for the reduced energy content of barley. Furthermore, pelleting of swine feeds at centralized mills has become routine and feeding trials clearly indicated improved feeding value of barley with pelleting. Other feed processing methods such as extrusion and expansion offer more potential to improve the feeding value of barley, but these processes require further development for widespread use.

"Ultimately, the value of barley in the swine feed ingredient marketplace will be determined by least-cost formulation systems that consider the cost of competing grains, protein supplements and feed grade fat sources. As the price of competing grains and protein supplements increase, the value of barley will increase. As the price of feed grade fats decreases, the value of barley will increase because, within limits, adding dietary fat can compensate for the reduced energy level of barley."

Copies of this publication can be obtained from the author, Dr. Allen Harper, at Tidewater Agricultural Research and Extension Center, 6321 Holland Road, Suffolk, VA 23437.

Charles Stanislaw


Feed intake of lactating sows has been studied extensively in research settings but until recently little had been reported about the factors affecting lactation feed consumption on commercial farms. A group of researchers at the University of Minnesota have published an article in the Journal of Animal Science (74:1202) that "is an effort to bridge the gap between University research farm studies and what is occurring on commercial farms". This study characterized feed consumption and temporal patterns of feed intake in lactating sows on commercial farms and identified factors influencing average daily feed intake.

The farms enrolled in this study were from Southern Minnesota and Northern Iowa and records were collected using PigChamp® for a one year period. Producers recorded twice daily the amount of feed provided to each lactating sow. Farm workers were trained to measure feed using a scoop and accuracy of this measure was checked four times per year. The observed measurement errors for producer recording of feed intake were within ± 5%. Daily high and low temperatures in the farrowing room and backfat thickness one week before farrowing were also measured.

Drops in feed intake were found to be associated with greater feed intake during early lactation. It was also reported that day of peak feed intake is associated with average daily feed intake. Sows having earlier peak feed intakes have higher average daily feed intakes.

The following factors affected feed intake on the commercial farms:

This study indicates that producers can manage sows to improve feed intake during lactation by appropriate gestation feeding and the avoidance of elevated ambient temperature during lactation. Other factors such as lactation length and parity distribution should also be considered when designing management programs to maximize lactational feed intake of sows.

Todd See


In the race to design and produce the ideal pig, artificial insemination (AI) is a widely used shortcut. More and more producers are buying boar semen to introduce new genetics, as well as to cut herd exposure to contagious diseases. However, recent checkoff-funded research indicates that boar semen may carry and transmit the PRRS (porcine reproductive and respiratory syndrome) virus, according to David Benfield, professor in the Department of Veterinary Science at South Dakota Sate University (SDSU) in Brookings.

"Epidemiological and experimental information now indicates that acute and chronically infected boar studs are potential sources for the introduction of PRRS into 'native' or PRRS-negative herds," he said. In response to the SDSU discovery, Benfield and Jan Christopher-Hennings, assistant professor in the Department of Veterinary Science, developed a lab test, a polymerase chain reaction (PCR) assay, that identifies the PRRS viruses in boar semen. The simple, economical test ($60) can be done at SDSU or at the University of Minnesota to screen semen from potential AI boars. In the past, the only available swine bioassay took three to four weeks and cost $300.

"For the most part AI is much safer than buying and transporting a boar which may shed PRRS virus from other portals," Benfield said. But to increase the safety of your herd when using AI, Benfield recommends the following steps:

  1. If you buy semen from boars known to be seronegative, don't worry.
  2. If you buy from a mixed stud (some seropositive and some seronegative) have the supplier submit three successive PCR assays of the boars.
  3. If you want to be more thorough, make serological tests your starting point.
  4. For further insurance, go to a PCR assay that can also accurately determine the time, from six to 92 days, that a particular boar is shedding infective viruses. "The cost of the test may seem high, but when you consider the potential impact of a PRRS outbreak, it's cheap insurance," he said.
  5. Don't use semen from a seropositive boar in seronegative sows or gilts. "If this needs to be done, consider vaccinating the susceptible gilt pool prior to the use of such semen," he said.

Questions? Contact Benfield or Christopher-Hennings at 605-388-5171.

July/August 1996


Lean pigs could become even leaner if producers just paid more attention to the amount of phosphorus they feed their hogs. Research at Iowa State University indicates that farmers raising hogs with high-lean potential can significantly increase muscle and reduce backfat by boosting phosphorus levels in swine rations. "The results were quite dramatic and much larger than we originally thought," says Tim Stahly, professor of animal science at ISU.

In the study, Stahly selected 7 sets of 6 litter-mate barrows according to lean-gain potential. Pigs capable of 0.8 lb/day muscle growth were considered high-lean pigs, while pigs with 0.7 lb/day muscle growth were considered moderate-lean pigs. The pigs were all fed different amounts of phosphorus. They were slaughtered at 240 lbs and their carcasses were evaluated for muscle content.

Stahly found that the growth rates of the pigs from 40 lbs to 240 lbs were similar, regardless of lean-gain potential, however the high-lean pigs required less feed per unit of body growth and had higher estimated muscle growth per day.

The ISU study verified that phosphorus requirements differed among hogs, depending on their potential for lean gain, and phosphorus requirement changed as pigs grew. As the phosphorus level increases, there is a four-fold improvement in average daily gain, feed conversion and daily muscle gain. As a result, Stahly says new phosphorus recommendations for optimum lean gain have been developed.

Vol. 6, No. 3


Updated national averages and quartile breaks for Fat-Free Lean Index (FFLI), Standard Reference Backfat (BF) and Hot Carcass Weight (HCW) were announced at the recent World Pork Expo. The data shown in the table below represent 1995 averages and were derived from data reported by packers as part of the Uniform Lean Information Project.

Some highlights are:

The distributions (as seen in the quartile breaks) remained stable for both FFLI and BF but reduced for HCW. The last effect is no surprise given the price discounts packers have placed on under-weight hogs.

Item 4th 3rd Avg. 2nd 1st
FFLI Less than 43.7 43.7-46.3 46.3 46.3-48.9 Greater than 48.8
BF Greater than 1.2 1.0-1.2 1.0 0.8-1.0 Less than 0.8
HCW Less than 171 171-181 181 181-191 Greater than 191

Steve Meyer


Reducing the variation in the number of pigs weaned each week and analyzing production records can help pork producers use their facilities more efficiently. A certain amount of variation in weaning numbers from week to week is inevitable. However, successful managers understand and manage the sources of variation.

"The key to efficient use of the facilities is to minimize variability," says Will Marsh, University of Minnesota College of Veterinary Medicine. "The best place to start is to strictly monitor the number of sows and gilts bred each week, making adjustments for anticipated seasonal fluctuations in farrowing rates and pre-weaning mortality."

To remodel facilities, Marsh recommends using existing records to analyze variation over time and estimate the amount of inherent variation in the production system. Producers should use this information to operate at a level of expected overflow at which the producers and pigs will be comfortable.

Vol. 6, No. 3

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Last modified August 7, 2000.