NCSU Extension Swine Husbandry 1996

March, 1996 . Volume 19, Number 2


The February 1996 issue of SWINE NEWS had a discussion on the effects of weaning age on pigs/sow/year. In that discussion, data was presented that showed a gradual reduction in pigs per litter as lactation length decreased. This becomes significant with management practices such as SEW that requires weaning at less than 21 days. The beneficial effects of SEW on improving health and performance of pigs is very well documented. However, producers should be aware of some of the possible negative side effects on sow productivity. According to Dr. Joe Crenshaw, manager of swine research for MoorMan's (MOORMAN'S Feed Facts, January, 1996), the magnitude of these side effects of early weaning on sow productivity tends to be variable. These effects of various weaning ages on sow productivity are summarized by Dr Crenshaw in Table 1. He states that individual producers should utilize their own production records to determine the most profitable early weaning age for their operation.

Table 1. Effect of Reduction in Weaning Age on Sow Productivity Traits 1

Trait Weaning Age (days) Change from 21-Day Weaning
Farrowing rate 14-18

-3.0% (ie. 86% to 83%)


Litter size at birth 10
-0.43 pigs
-0.40 pigs
-0.20 pigs
-0.20 pigs
-0.15 pigs
Pigs weaned 12
+0.60 pigs
+0.40 pigs
Litter/sow/year 17 +0.08 litters
Pigs weaned/sow/year 17 +0.5 pigs
Sow feed/year 17 -100.0 lb
Return to estrus 12
+1.6 days
+1.0 days
+1.3 days
1Compilation of numerous research trials cited in research journals and industry magazines.
*Separate trials using 13-day weaning age.

Charles Stanislaw


Although other programs may be facing cuts, the congressional appropriation for the pseudorabies eradication effort appears safe.

In both the Senate and House budgets, funding for PRV eradication is set at approximately $8.5 million for the 1996 fiscal year, matching the appropriation for FY '95.

PRV Progress
Nov-Dec 1995


Another milestone has been passed in the National Pseudorabies Eradication Program. By the end of October, the number of infected herds nationally had fallen to 3,876, dipping below 4,000 for the first time.

The number of quarantined herds dropped by 353 during September and october, an 8.4 percent decrease, and the national herd infection rate fell below two percent for the first time.

Iowa alone saw its herd count drop by 210 during the two months. Also, two states - Delaware and Vermont - advanced to Stage V, or free, status in October to create another milestone of sorts. Seventeen states are now in Stage V and Dr. Arnold Taft of the USDA's Animal and Plant Health Inspection Service says that is significant. "We now have more states in Stage V than in any other stage," Taft explains. "That's the first time that column has been the longest. "

In addition to Delaware and Vermont, three other states advanced in status in October. New Hampshire, Rhode Island and West Virginia all moved up to Stage IV.

(Stage status and number of infected herds)

State Stage 6-30-95 8-31-95 10-31-95 Trend % Infected
Alabama III 0 2 1 -1 0.05%
Arizona III 1 1 0 -1 0%
Arkansas III 1 1 1 -- 0.03%
California III 3 3 3 -- 0.07%
Colorado IV 0 0 0 -- 0%
Delaware V 0 0 0 -- 0%
Florida II 13 22 29 +7 0.76%
Georgia III 4 2 0 -2 0%
Hawaii III 0 0 0 -- 0%
Illinois II 118 111 100 -11 0.9%
Indiana III 22 20 17 -3 0.16%
Indiana II 341 327 301 -26 2.7%
Iowa II 2,625 2,453 2,243 -210 7.7%
Kansas II 3 2 1 -1 0.02%
Kentucky III 0 0 0 -- 0%
Louisiana III 0 0 0 -- 0%
Maryland IV 0 0 0 -- 0%
Massachusetts III 2 1 1 -- 0.125%
Michigan II 147 135 122 -13 2.4%
Michigan III 6 6 3 -3 0.06%
Minnesota III 57 46 44 -2 0.3%
Minnesota II 407 374 336 -38 2.4%
Missouri III 22 21 16 -5 0.15%
Nebraska II 114 98 68 -30 0.62%
Nebraska III 29 25 23 -2 0.2%
New Hampshire IV 0 0 0 -- 0%
New Jersey III 5 5 5 -- 0.7%
North Carolina II 460 467 455 -12 6.5%
North Carolina III 38 30 32 +2 0.46%
Ohio III 1 0 0 -- 0%
Oklahoma III 0 0 1 +1 0.03%
Pennsylvania II 62 57 54 -3 0.95%
Rhode Island IV 0 0 0 -- 0%
South Carolina V 0 0 1a +1 0.04%
South Dakota III 19 16 15 -1 0.24%
Tennessee III 1 1 1 -- 0.02%
Texas IV 0 0 3b +3 0.04%
Vermont V 0 0 0 -- 0%
Virginia IV 0 0 0 -- 0%
West Virginia IV 0 0 0 -- 0%
Wisconsin III 2 3 0 -3 0%
Wisconsin IV 0 0 0 -- 0%
TOTAL 4,503 4,229 3,876 -353 1.9%
States not listed are in Stage V of the eradication program.
Bold states had no reported cases of PRV for at least six months.
a Imported pigs in a feedlot. South Carolina's status not affected.
bImported feeder animals and feral pigs. Texas status not affected.

PRV Progress
Nov-Dec 1995


Following up on a resolution passed at the Livestock Conservation Institute Annual Meeting, the PRV Committee of the United States Animal Health Association has recommended to USDA additional options in the program standards regarding testing for maintenance of qualified negative or qualified negative vaccinated herd status.

The recommendation provides two options for monthly testing of herds to maintain status:

  1. A test of 7 percent of the breeding animals in the herd, plus a test of offspring 4-to-6 months old equal to 2 percent of the breeding animals in the herd every 30 days.
  2. On approval of the state veterinarian, herds in Stage III, IV or V states or areas may maintain status on the basis of a monthly negative official random sample test (95-5) in each separate population of sows on a premises. Also required are negative tests on 50 offsprings 4-to-6 months of age if offspring are on the same premises as the breeding herd.

The quarterly testing option remains for maintenance of status. It was rewritten to require a test of 20 percent of the breeding animals in the herd, plus a test of offspring 4-to-6 months old equal to six percent of the breeding animals, to be done every 80 to 105 days.

The random sample testing option recommended by the PRV Committee is similar to that proposed at the LCI Annual Meeting. It calls for using what is called a "95-5" sampling method. With this method, a maximum of 59 head are tested each month. This gives 95 percent confidence of detecting at least one positive animal if the disease prevalence is five percent or higher. The "95-5" method is seen as a way to eliminate excess testing while still getting reliable results.

Among the proponents of the "95-5" method is Dr. Jerry Torrison of Franklin, KY's Pig Improvement Company. "I think it's a very good addition to the program standards," Torrison says. "It can reduce excess testing without sacrificing sensitivity, and it will allow the possibility of working more closely with the regulatory community with those larger units."

In other action at the USAHA Annual Meeting, the PRV committee called on the USDA's Animal and Plant Health Inspection Service to coordinate the development and implementation of a national premises identification system for identifying cull sows and boars.

The resolution, proposed by leaders of the National Pork producers Council calls on APHIS to make changes in regulations, notices and memoranda to allow the system to proceed by April 1, 1996. Identification of cull sows and boars back to the farm of origin is vital to a successful slaughter surveillance program, one of the keys to finding infected herds in the final stages of the eradication effort.

PRV Progress
Nov-Dec 1995


A satellite conference on Practical Solutions to Odor Problems is scheduled for March 13th from 6 to 8 p.m. This two conference sponsored by National Pork Producers Council, PORK 96 and Pioneer Hi-Bred International will cover:

A special feature of the satellite conference will be prerecorded segments showing successful environmental management methods currently being used by pork producers across the country. Insight into the latest odor research being conducted will be presented through prerecorded interviews with some of the nationžs leading environmental scientists.

During the final 30 minutes of the telecast, you may call in your questions to a panel of swine odor specialists. The panel will consist of specialists in the areas of facilities, manure storage, manure application, and on-farm management practices.

To register call 1-800-344-4040 or contact your local extension office. The cost is $15.00 and includes a workbook to use and to follow along with the telecast.

Todd See


The N.C. General Assembly passed Senate Bill 974 in 1995 requiring people who land apply animal waste to be certified by January 1, 1997. This legislation gave the responsibility for the development of this program to the Department of Environment, Health and Natural Resources (DEHNR), in cooperation with the Cooperative Extension Service. For this legislation an animal waste management system is defined as a system that is designed to manage and that actually serves more than 250 swine.

Each applicant for this training will complete six hours of instruction on the operation of animal waste management systems and will be issued a certificate by DEHNR as an operator upon passing an examination and paying a $10.00 fee. Certification will be renewed annually for a $10.00 fee for a period of five years at which time training and examination must be competed again.

Training programs will be offered by the Cooperative Extension Service starting in the Spring of 1996. More information on training times and dates will be available from your county extension office.

Todd See

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Last modified August 7, 2000.