Improving reproductive efficiency | TSLN.com

Improving reproductive efficiency

Dave Barz, DVM

For the April 10, 2010 edition of Tri-State Livestock News.

Now that April is here, we definitely feel that spring has arrived. Soon we will be taking our cow-calf pairs to pasture. Once there it will be breeding season. Now is a great time to do a breeding soundness exam (BSE) on our adult bulls.

Reproduction is the most important economic driver in cow-calf herds. High management strategies require that we settle as many cows as possible during the first heat cycle (21 days). Cow fertility and nutrition are very important in attaining these goals, but bull fertility is also very important.

First you must evaluate your calving records for this spring. You should be able to simply calculate how many calves were born in the first 30 days of the calving season. This allows for variability in gestation lengths and still reflects the first 21 days of the breeding season. As you evaluate these records you may find that your breeding percentages may vary from pasture to pasture. If you have a group with low conception rates, you should scrutinize the bulls in that pasture. Sometimes your dominant bull in the pasture may be below average for fertility. Also examine your records for bulls which were injured or lame during the breeding season. Bulls losing excessive weight may also be a problem. Careful analysis of your records will target bulls to examine more carefully.

Now is a good time to evaluate your bulls. They should be recovering from temperature shock, wind chill, and nutritional inadequacies. A visual physical examination should be part of your BSE. Your bull must have good mobility to travel the miles required during breeding season. Hooves should be in good condition and if needed feet should be trimmed. It is best not to retrain breeding heifers from bulls with hoof abnormalities. It is very important for the bull to have good hind leg conformation to assure he can support his weight on his hind legs during breeding.

The bull should be in adequate body condition (BCS). The testicles need to be palpated. They should be firm, but not hard and equal in size. Many veterinarians measure the scrotal circumference.

Most veterinarians use an elector ejaculator to collect the sample. The skill of the veterinarian is very important in collecting good samples. The use of the electro stimulation is an unnatural act for the bull and requires knowledge and know-how to be done correctly. After several complaints on varying abilities of South Dakota veterinarians, Dr. Sam Holland, then state veterinarian remarked, “BSE is more an art than a science.”

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The penis should be exposed and erect during the BSE. This helps remove bulls which were injured last season. The semen collected is examined for motility under the microscope. It is very important to have the sample stained and examined for abnormal cells. Many times abnormal cells are motile, but unable to fertilize eggs. Bulls with abnormal semen may recover over time, so test now and give the bulls a chance to improve and re-test before breeding season.

The final part of the BSE is the bull’s ability to mount and penetrate females. This is done on the ranch with cows or heifers which are in heat but are going to be culled from the herd. Mature bulls should be aggressive and quickly breed the female. Yearling may require some experience (practice) to successfully breed females. Many of you old hog producers remember training young boars to properly mount and breed.

BSE is important in achieving reproductive efficiencies in your herd. Careful examination of last year’s records thorough physical examinations, a well conducted BSE and careful evaluation of breeding expertise will allow you to select your most productive bulls. Removal of low fertility and outlier bulls will improve your herd’s reproductive efficiency and increase your returns next year.

Now that April is here, we definitely feel that spring has arrived. Soon we will be taking our cow-calf pairs to pasture. Once there it will be breeding season. Now is a great time to do a breeding soundness exam (BSE) on our adult bulls.

Reproduction is the most important economic driver in cow-calf herds. High management strategies require that we settle as many cows as possible during the first heat cycle (21 days). Cow fertility and nutrition are very important in attaining these goals, but bull fertility is also very important.

First you must evaluate your calving records for this spring. You should be able to simply calculate how many calves were born in the first 30 days of the calving season. This allows for variability in gestation lengths and still reflects the first 21 days of the breeding season. As you evaluate these records you may find that your breeding percentages may vary from pasture to pasture. If you have a group with low conception rates, you should scrutinize the bulls in that pasture. Sometimes your dominant bull in the pasture may be below average for fertility. Also examine your records for bulls which were injured or lame during the breeding season. Bulls losing excessive weight may also be a problem. Careful analysis of your records will target bulls to examine more carefully.

Now is a good time to evaluate your bulls. They should be recovering from temperature shock, wind chill, and nutritional inadequacies. A visual physical examination should be part of your BSE. Your bull must have good mobility to travel the miles required during breeding season. Hooves should be in good condition and if needed feet should be trimmed. It is best not to retrain breeding heifers from bulls with hoof abnormalities. It is very important for the bull to have good hind leg conformation to assure he can support his weight on his hind legs during breeding.

The bull should be in adequate body condition (BCS). The testicles need to be palpated. They should be firm, but not hard and equal in size. Many veterinarians measure the scrotal circumference.

Most veterinarians use an elector ejaculator to collect the sample. The skill of the veterinarian is very important in collecting good samples. The use of the electro stimulation is an unnatural act for the bull and requires knowledge and know-how to be done correctly. After several complaints on varying abilities of South Dakota veterinarians, Dr. Sam Holland, then state veterinarian remarked, “BSE is more an art than a science.”

The penis should be exposed and erect during the BSE. This helps remove bulls which were injured last season. The semen collected is examined for motility under the microscope. It is very important to have the sample stained and examined for abnormal cells. Many times abnormal cells are motile, but unable to fertilize eggs. Bulls with abnormal semen may recover over time, so test now and give the bulls a chance to improve and re-test before breeding season.

The final part of the BSE is the bull’s ability to mount and penetrate females. This is done on the ranch with cows or heifers which are in heat but are going to be culled from the herd. Mature bulls should be aggressive and quickly breed the female. Yearling may require some experience (practice) to successfully breed females. Many of you old hog producers remember training young boars to properly mount and breed.

BSE is important in achieving reproductive efficiencies in your herd. Careful examination of last year’s records thorough physical examinations, a well conducted BSE and careful evaluation of breeding expertise will allow you to select your most productive bulls. Removal of low fertility and outlier bulls will improve your herd’s reproductive efficiency and increase your returns next year.

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