Many producers with herds that calve in the spring will be corralling cows this fall to wean the calves. A long list of management practices can be carried out at fall workings in September, October or November. These include pregnancy examinations, body condition scoring, culling, deworming and vaccinations. I would like to describe to you a management practice that can help your herds reach a high level of reproductive performance: Breeding season evaluation.
This is a correlation of herd reproduction management with performance. Performance is determined from data collected by the herd's veterinarian at pregnancy diagnosis. Ranchers can use this tool to follow the reproductive performance of their herds from year to year or to identify reasons for low reproductive performance.
Reproductive management of the herd is made up of a profile for each breeding group that includes pasture location, breeding dates, number, age and breed of females, and bull-to-female ratio. Reproductive performance is measured by the overall pregnancy rate of each group and pregnancy pattern (pregnancy or conception rate per 21-day breeding period) based on rectal palpation by the herd's veterinarian.
When most people think of reproductive performance, pregnancy rate jumps into their minds. What percentage of cows became pregnant?
Pregnancy pattern is another outcome of a herd's reproductive program and has almost as much impact on profit as pregnancy rate. Two herds with the same overall pregnancy rate could have very different profits due to different pregnancy patterns. The calving pattern -- percent of herd calving each 21-day period of the calving season -- reflects the pregnancy pattern.
Our field studies on calf growth rates indicate that most beef calves in Texas grow 1.8 to 2.2 pounds daily. The average calf born each 21-day calving period will weigh 38 to 46 pounds more at weaning than the average calf born the next 21-day calving period. At a sale price of $1.10 per pound there is a difference of $42 to $51 per calf at weaning. There could be an increased income of $5,000 for moving the calving pattern back 1 heat cycle (21 days) in a 100-cow herd or $20,000 in a 400-cow herd. Herds with four- to six-month breeding seasons may have opportunities to make greater changes in their calving patterns, resulting in higher improvements in income.
Veterinarians use pregnancy patterns to help identify the reason(s) for low reproductive performance in beef herds.
The three main causes are inadequate nutrition (poor body condition), infertile bulls, and infectious diseases. The optimum pregnancy pattern is 62 percent, 24 percent, and 9 percent of cows conceiving in the first, second, and third 21-day period of the breeding season. This high level of performance will be possible only in very well managed herds in good rainfall years.
A spread-out pattern of pregnancies with no peak at the beginning of the breeding season can result from inadequate nutrition or sub-fertile bulls. A single-sire breeding group that has good conception rates the first two or three breeding periods followed by poor conception rates or no more pregnancies indicates an injury or illness of the bull.
Infectious diseases can result in very erratic pregnancy rates per 21-day breeding period or good performance at the beginning of the breeding season that goes down due to spread of the disease as the breeding season progresses or even goes down and then comes up toward the end of a breeding season four to six months long.
Median calving date is another very useful measure of beef herd reproductive performance. It is highly correlated to reproductive efficiency. The median calving date is the date that 50 percentage of the cow herd has calved. It can be calculated by a rancher free of charge. The year to year median calving date can help measure the impact of management changes to improve reproductive performance. The amount of movement of the median calving date toward the start of the calving season indicates amount of success of management changes.
In addition, median calving date can be used to help calculate the benefit: cost ratio of the management changes. For example, if median calving date is moved five days back in a herd weaning 200 calves that gained 2 pounds per day and sell at $1.10 per pound, the benefit of management changes would be $2,200.
Of course, things are not quite that simple. Weather is a huge factor in beef cattle production in Texas and always must be considered when evaluating year-to-year production. If those results were realized in a good-rainfall year that followed a drought year, they could simply be caused by improved rainfall, while those results in a drought year would be a huge success.
Fall workings for beef herds are just around the corner. In addition to overall pregnancy rates, pregnancy patterns and median calving dates are valuable tools to evaluate the reproductive performance of beef herds. They can be used to compare the performance of different breeding groups within a herd as well as the performance of herds year to year.
Good fertility is critical to the profitability of beef herds. Your veterinarian is the most qualified person to give you advice on how to optimize reproductive performance in your herd.
*Dr. Steve Wikse is a retired professor of large-animal clinical sciences in the Texas A&M College of Veterinary Medicine.
Timing of pregnancy affects the bottom line
By STEVE WIKSE, DVM
Many producers with herds that calve in the spring will be corralling cows this fall to wean the calves. A long list of management practices can be carried out at fall workings in September, October or November. These include pregnancy examinations, body condition scoring, culling, deworming and vaccinations. I would like to describe to you a management practice that can help your herds reach a high level of reproductive performance: Breeding season evaluation.
This is a correlation of herd reproduction management with performance. Performance is determined from data collected by the herd's veterinarian at pregnancy diagnosis. Ranchers can use this tool to follow the reproductive performance of their herds from year to year or to identify reasons for low reproductive performance.
Reproductive management of the herd is made up of a profile for each breeding group that includes pasture location, breeding dates, number, age and breed of females, and bull-to-female ratio. Reproductive performance is measured by the overall pregnancy rate of each group and pregnancy pattern (pregnancy or conception rate per 21-day breeding period) based on rectal palpation by the herd's veterinarian.
When most people think of reproductive performance, pregnancy rate jumps into their minds. What percentage of cows became pregnant?
Pregnancy pattern is another outcome of a herd's reproductive program and has almost as much impact on profit as pregnancy rate. Two herds with the same overall pregnancy rate could have very different profits due to different pregnancy patterns. The calving pattern -- percent of herd calving each 21-day period of the calving season -- reflects the pregnancy pattern.
Our field studies on calf growth rates indicate that most beef calves in Texas grow 1.8 to 2.2 pounds daily. The average calf born each 21-day calving period will weigh 38 to 46 pounds more at weaning than the average calf born the next 21-day calving period. At a sale price of $1.10 per pound there is a difference of $42 to $51 per calf at weaning. There could be an increased income of $5,000 for moving the calving pattern back 1 heat cycle (21 days) in a 100-cow herd or $20,000 in a 400-cow herd. Herds with four- to six-month breeding seasons may have opportunities to make greater changes in their calving patterns, resulting in higher improvements in income.
Veterinarians use pregnancy patterns to help identify the reason(s) for low reproductive performance in beef herds.
The three main causes are inadequate nutrition (poor body condition), infertile bulls, and infectious diseases. The optimum pregnancy pattern is 62 percent, 24 percent, and 9 percent of cows conceiving in the first, second, and third 21-day period of the breeding season. This high level of performance will be possible only in very well managed herds in good rainfall years.
A spread-out pattern of pregnancies with no peak at the beginning of the breeding season can result from inadequate nutrition or sub-fertile bulls. A single-sire breeding group that has good conception rates the first two or three breeding periods followed by poor conception rates or no more pregnancies indicates an injury or illness of the bull.
Infectious diseases can result in very erratic pregnancy rates per 21-day breeding period or good performance at the beginning of the breeding season that goes down due to spread of the disease as the breeding season progresses or even goes down and then comes up toward the end of a breeding season four to six months long.
Median calving date is another very useful measure of beef herd reproductive performance. It is highly correlated to reproductive efficiency. The median calving date is the date that 50 percentage of the cow herd has calved. It can be calculated by a rancher free of charge. The year to year median calving date can help measure the impact of management changes to improve reproductive performance. The amount of movement of the median calving date toward the start of the calving season indicates amount of success of management changes.
In addition, median calving date can be used to help calculate the benefit: cost ratio of the management changes. For example, if median calving date is moved five days back in a herd weaning 200 calves that gained 2 pounds per day and sell at $1.10 per pound, the benefit of management changes would be $2,200.
Of course, things are not quite that simple. Weather is a huge factor in beef cattle production in Texas and always must be considered when evaluating year-to-year production. If those results were realized in a good-rainfall year that followed a drought year, they could simply be caused by improved rainfall, while those results in a drought year would be a huge success.
Fall workings for beef herds are just around the corner. In addition to overall pregnancy rates, pregnancy patterns and median calving dates are valuable tools to evaluate the reproductive performance of beef herds. They can be used to compare the performance of different breeding groups within a herd as well as the performance of herds year to year.
Good fertility is critical to the profitability of beef herds. Your veterinarian is the most qualified person to give you advice on how to optimize reproductive performance in your herd.
* Dr. Steve Wikse is a retired professor of large-animal clinical sciences in the Texas A&M College of Veterinary Medicine.