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Cow Tales: Breeding soundness exams

Kenny Barrett Jr., DVM, MS
For the May 14, 2011 edition of Tri-State Livestock News.

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Spring is a busy time of year. There is a mix of cattle work and field preparations that should have been done last week. But ranchers need to pause and consider their bull pen well in advance of the breeding season.

Bulls are easily overlooked as they are normally tucked away for the winter and calving season. One important cattle management tool is to ensure the bulls are in good health and able to breed cows well before the breeding season. A breeding soundness examination is a comprehensive evaluation of a bull and his predicted fertility. Evaluating herd bulls about sixty days prior to turn out can help ensure each herd has an adequate number of capable bulls. Sixty days allows producers adequate time to schedule subsequent reevaluations and purchase any necessary replacement animals.

A breeding soundness exam consists of two main parts: the physical exam and a reproductive evaluation. Each bull needs to be evaluated for body condition, structural soundness and overall health. Bulls that lack condition and are generally unthrifty will have decreased sperm production and are less likely to settle a large number of cows on the first cycle.

Likewise, breeding animals need to be able to cover the breeding pasture to find the cows in heat. Lame bulls are likely to experience some difficulty attending to their romantic needs. Most lameness occurs in the foot and includes infectious diseases like footrot as well as genetic defects such as corkscrew claw. Aberrations that decrease the number of females becoming pregnant within the first cycle decreases calf crop uniformity, weaning weight and percentage of pregnant females at the end of the breeding season.

The reproductive examination consists of palpating the reproductive organs, evaluating penis function, and a microscopic evaluation of the semen. Rectal palpation allows examination of the seminal vesicles, size and shape of the pelvis, inguinal rings, and other lesser reproductive structures. The seminal vesicles produce assessory fluid for the ejaculate, but can become infected, negatively impacting fertility. The scrotum needs to have a normal shape and size. A larger scrotum is associated with earlier puberty in female offspring. Additionally, larger testes have a greater capacity to produce sperm and should be able to service more cows in a shorter time period. Unusually sized or asymmetrical testes can be an indication of testicular disease. More importantly, the testes need to move freely within the scrotum to allow for normal thermoregulation or temperature control.

Electroejaculators are commonly used to cause ejaculation for semen evaluation. Commercial units consist of a probe with electrodes that stimulate the appropriate nerves. Other methods used include manual massage of the ampulla, or less commonly, the use of an artificial vagina. Electroejaculators commonly cause extension and erection allowing for a visual exam of the penis. Reproductive warts frequently hemorrhage during copulation, leading to decreased viability of the sperm and should be removed. Other defects such as persistent frenulum, prepucial injury, abscess, etc., can be diagnosed at this time.

Collected semen is microscopically evaluated for motility and morphology. Motility is an estimate of the proportion of sperm exhibiting forward movement. Those exhibiting backwards or drunken movement should not be counted. It is the most subjective measurement in the breeding soundness examination and is greatly influenced by environmental temperature. Morphology is the microscopic appearance of the individual sperm. Here a veterinarian is looking for bent or coiled tails, midpiece defects, and abnormalities of the acrosome and head, just to name a few. If the number of normal motile sperm falls below a specified threshold, the bull is deferred or fails the breeding soundness exam. It is important to note that young animals may fail their initial exam but may pass subsequent exams with increased maturity. Older herd bulls are less likely to pass subsequent examinations.

A breeding soundness exam is a comprehensive evaluation of a bull and his predicted ability to settle cows in a timely fashion. However, producers need to remain vigilant during the breeding season to detect lame and/or injured animals that cannot breed females. Additionally, it should be noted that bulls can pass a breeding soundness exam and fail to settle an adequate number of cows due to poor libido. Additionally, venereal diseases are not routinely tested for unless specified. These animals can harbor a venereal disease that reduces fertility or causes abortion and still pass their exam. Cattlemen need to work with their veterinarian to determine their risks.

Breeding soundness examinations are a form of reproductive insurance to help ensure bulls are able to breed cows in an efficient manner. Infertility causes a longer calving season, decreased calf crop uniformity, lighter weaning weights and more open cows.

Spring is a busy time of year. There is a mix of cattle work and field preparations that should have been done last week. But ranchers need to pause and consider their bull pen well in advance of the breeding season.

Bulls are easily overlooked as they are normally tucked away for the winter and calving season. One important cattle management tool is to ensure the bulls are in good health and able to breed cows well before the breeding season. A breeding soundness examination is a comprehensive evaluation of a bull and his predicted fertility. Evaluating herd bulls about sixty days prior to turn out can help ensure each herd has an adequate number of capable bulls. Sixty days allows producers adequate time to schedule subsequent reevaluations and purchase any necessary replacement animals.

A breeding soundness exam consists of two main parts: the physical exam and a reproductive evaluation. Each bull needs to be evaluated for body condition, structural soundness and overall health. Bulls that lack condition and are generally unthrifty will have decreased sperm production and are less likely to settle a large number of cows on the first cycle.

Likewise, breeding animals need to be able to cover the breeding pasture to find the cows in heat. Lame bulls are likely to experience some difficulty attending to their romantic needs. Most lameness occurs in the foot and includes infectious diseases like footrot as well as genetic defects such as corkscrew claw. Aberrations that decrease the number of females becoming pregnant within the first cycle decreases calf crop uniformity, weaning weight and percentage of pregnant females at the end of the breeding season.

The reproductive examination consists of palpating the reproductive organs, evaluating penis function, and a microscopic evaluation of the semen. Rectal palpation allows examination of the seminal vesicles, size and shape of the pelvis, inguinal rings, and other lesser reproductive structures. The seminal vesicles produce assessory fluid for the ejaculate, but can become infected, negatively impacting fertility. The scrotum needs to have a normal shape and size. A larger scrotum is associated with earlier puberty in female offspring. Additionally, larger testes have a greater capacity to produce sperm and should be able to service more cows in a shorter time period. Unusually sized or asymmetrical testes can be an indication of testicular disease. More importantly, the testes need to move freely within the scrotum to allow for normal thermoregulation or temperature control.

Electroejaculators are commonly used to cause ejaculation for semen evaluation. Commercial units consist of a probe with electrodes that stimulate the appropriate nerves. Other methods used include manual massage of the ampulla, or less commonly, the use of an artificial vagina. Electroejaculators commonly cause extension and erection allowing for a visual exam of the penis. Reproductive warts frequently hemorrhage during copulation, leading to decreased viability of the sperm and should be removed. Other defects such as persistent frenulum, prepucial injury, abscess, etc., can be diagnosed at this time.

Collected semen is microscopically evaluated for motility and morphology. Motility is an estimate of the proportion of sperm exhibiting forward movement. Those exhibiting backwards or drunken movement should not be counted. It is the most subjective measurement in the breeding soundness examination and is greatly influenced by environmental temperature. Morphology is the microscopic appearance of the individual sperm. Here a veterinarian is looking for bent or coiled tails, midpiece defects, and abnormalities of the acrosome and head, just to name a few. If the number of normal motile sperm falls below a specified threshold, the bull is deferred or fails the breeding soundness exam. It is important to note that young animals may fail their initial exam but may pass subsequent exams with increased maturity. Older herd bulls are less likely to pass subsequent examinations.

A breeding soundness exam is a comprehensive evaluation of a bull and his predicted ability to settle cows in a timely fashion. However, producers need to remain vigilant during the breeding season to detect lame and/or injured animals that cannot breed females. Additionally, it should be noted that bulls can pass a breeding soundness exam and fail to settle an adequate number of cows due to poor libido. Additionally, venereal diseases are not routinely tested for unless specified. These animals can harbor a venereal disease that reduces fertility or causes abortion and still pass their exam. Cattlemen need to work with their veterinarian to determine their risks.

Breeding soundness examinations are a form of reproductive insurance to help ensure bulls are able to breed cows in an efficient manner. Infertility causes a longer calving season, decreased calf crop uniformity, lighter weaning weights and more open cows.

Spring is a busy time of year. There is a mix of cattle work and field preparations that should have been done last week. But ranchers need to pause and consider their bull pen well in advance of the breeding season.

Bulls are easily overlooked as they are normally tucked away for the winter and calving season. One important cattle management tool is to ensure the bulls are in good health and able to breed cows well before the breeding season. A breeding soundness examination is a comprehensive evaluation of a bull and his predicted fertility. Evaluating herd bulls about sixty days prior to turn out can help ensure each herd has an adequate number of capable bulls. Sixty days allows producers adequate time to schedule subsequent reevaluations and purchase any necessary replacement animals.

A breeding soundness exam consists of two main parts: the physical exam and a reproductive evaluation. Each bull needs to be evaluated for body condition, structural soundness and overall health. Bulls that lack condition and are generally unthrifty will have decreased sperm production and are less likely to settle a large number of cows on the first cycle.

Likewise, breeding animals need to be able to cover the breeding pasture to find the cows in heat. Lame bulls are likely to experience some difficulty attending to their romantic needs. Most lameness occurs in the foot and includes infectious diseases like footrot as well as genetic defects such as corkscrew claw. Aberrations that decrease the number of females becoming pregnant within the first cycle decreases calf crop uniformity, weaning weight and percentage of pregnant females at the end of the breeding season.

The reproductive examination consists of palpating the reproductive organs, evaluating penis function, and a microscopic evaluation of the semen. Rectal palpation allows examination of the seminal vesicles, size and shape of the pelvis, inguinal rings, and other lesser reproductive structures. The seminal vesicles produce assessory fluid for the ejaculate, but can become infected, negatively impacting fertility. The scrotum needs to have a normal shape and size. A larger scrotum is associated with earlier puberty in female offspring. Additionally, larger testes have a greater capacity to produce sperm and should be able to service more cows in a shorter time period. Unusually sized or asymmetrical testes can be an indication of testicular disease. More importantly, the testes need to move freely within the scrotum to allow for normal thermoregulation or temperature control.

Electroejaculators are commonly used to cause ejaculation for semen evaluation. Commercial units consist of a probe with electrodes that stimulate the appropriate nerves. Other methods used include manual massage of the ampulla, or less commonly, the use of an artificial vagina. Electroejaculators commonly cause extension and erection allowing for a visual exam of the penis. Reproductive warts frequently hemorrhage during copulation, leading to decreased viability of the sperm and should be removed. Other defects such as persistent frenulum, prepucial injury, abscess, etc., can be diagnosed at this time.

Collected semen is microscopically evaluated for motility and morphology. Motility is an estimate of the proportion of sperm exhibiting forward movement. Those exhibiting backwards or drunken movement should not be counted. It is the most subjective measurement in the breeding soundness examination and is greatly influenced by environmental temperature. Morphology is the microscopic appearance of the individual sperm. Here a veterinarian is looking for bent or coiled tails, midpiece defects, and abnormalities of the acrosome and head, just to name a few. If the number of normal motile sperm falls below a specified threshold, the bull is deferred or fails the breeding soundness exam. It is important to note that young animals may fail their initial exam but may pass subsequent exams with increased maturity. Older herd bulls are less likely to pass subsequent examinations.

A breeding soundness exam is a comprehensive evaluation of a bull and his predicted ability to settle cows in a timely fashion. However, producers need to remain vigilant during the breeding season to detect lame and/or injured animals that cannot breed females. Additionally, it should be noted that bulls can pass a breeding soundness exam and fail to settle an adequate number of cows due to poor libido. Additionally, venereal diseases are not routinely tested for unless specified. These animals can harbor a venereal disease that reduces fertility or causes abortion and still pass their exam. Cattlemen need to work with their veterinarian to determine their risks.

Breeding soundness examinations are a form of reproductive insurance to help ensure bulls are able to breed cows in an efficient manner. Infertility causes a longer calving season, decreased calf crop uniformity, lighter weaning weights and more open cows.


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