National Swine Registry

International Marketing

Resource Center

Proper Care and Adjustment of Imported Boars
Wayne L. Singleton, Ph.D., Purdue University
Download article as a pdf

The National Swine Registry asked Dr. Wayne Singleton, reproduction management extension specialist with Purdue University, West Lafayette, Indiana, to address some of the most frequently asked questions pertaining to management tips and suggestions regarding the proper care and adjustment for imported boars from the United States. Here are his responses:

Once a boar arrives in the new country, what are some methods to help the boars to recuperate from the trip? Provide clean, comfortable housing conditions and, if possible, hand feed a ration similar that was used during the quarantine period and provide plenty of fresh water. Allow at least 20 square feet of dry, draft-free, well-ventilated sleeping area per animal. Be patient and let the boars rest and acclimate to their new surroundings. Consider providing moderate exercise within a few days after arrival.

How should the boar be introduced from quarantine to the herd or AI stud? Basically follow the above recommendations. Once the boar is eating and drinking well, and assuming that he is old enough, he should be ready for training. Be sure to follow the recommended vaccination and acclimation protocols as recommended by your veterinarian.

When should I start to train the boar and what are the potential problems I should expect? First, remember that the trip, isolation periods and various veterinary procedures are more stressful to some animals than others. Assuming that the boars are well acclimated to their new surroundings and they are about 8 months of age, training for natural service or semen collection can begin. Because some boars may have had several injections and frequent blood samples taken, they may be shy with people. In order to gain their confidence, spend some time each day with these boars. For natural service boars, expose them to an estrus gilt for a test mating and provide assistance if needed. For AI boars, provide short training sessions with the collection dummy. Some boars may require more patience and time than others. If possible, determine the number of sperm cells and the percent normal sperm in these early ejaculates. This information should be helpful in determining when the boar can be put into service. Certain problems, such as the presence of abnormal sperm cells, may be related to various stresses encountered during the importation process. Continue to collect and evaluate semen about every two weeks.

When can the mating or collection frequency be increased? From 8 ½ to about 12 months of age, young natural-service boars can be mated once daily or up to five times per week. Young AI boars can be collected twice per week, however a less frequent collection schedule (i.e. every 10 days) will allow for greater sperm reserves to accumulate and therefore a greater number of sperm will be harvested in the ejaculate.

What temperature should boars be kept to avoid heat stress and once a boar is heat stressed how do I bring the boar back into full semen production? In warmer climates, it is very important to allow ample time for the animals to acclimate to higher temperatures and to provide an environment near 21 C. At temperatures above 27 C, sperm production and semen quality may decline. The pattern of this decline and subsequent recovery period is dependent upon the level and length of the elevated temperatures.

What are some common signs of heat stress? Symptoms of heat stress vary among individual boars and severity of the elevated temperature conditions. Animals may go off feed, become lethargic, have lower libido levels, have lowered semen quality and have increased respiration rates. The normal respiration rate of resting boar at 21 C is less than 30 breaths per minute. At 40 breaths per minute, the boar would be at risk, and at 60 or more per minute, he would be suffering. Since the cycle of sperm production requires up to 50 days, semen quality may be depressed for several weeks after the end of the high-temperature period.

What type of body condition should I try to keep the boar as they grow and mature? For optimum sperm production boars need to be in a weight-gaining condition. A young boar weighing 125kg should be gaining about 0.4 kg/day while a more mature boar weighing 200kg should gain about 0.3 kg per day. A 16 percent or 17 percent protein diet should be adequate for most boars. For AI boars consider a ration that is specifically formulated to support maximum sperm output.

Following the suggestions above will help to ensure that newly imported boars will acclimate to their new environment and contribute to the new herd’s genetic-improvement program.

U.S. purebred breeders are the correct choice for genetics that balance performance, reproduction and meat-quality traits in a profitable package for the swine industry.