Vet’s Voice: Heifer breeding considerations | TSLN.com

Vet’s Voice: Heifer breeding considerations

Dave Barz, DVM

Estrous synchronization programs offer a good way to achieve a high percentage of pregnant females with less labor. The success of heifer genetics and breeding can affect the herd’s profitability for eight to fourteen years. That is why it is important to develop a workable protocol for the herd and not just make “spur of the moment” decisions. Have goals for the herd and the replacement program – which is the largest herd expense after feed.

In the past, we were taught heifers needed to be 65 percent of their mature bodyweight before breeding. With the increase in feed prices, research has shown heifers at 55 percent of their mature bodyweight seem to be as effective on first cycle breeding, with more longevity as well. I still prefer heifers closer to the 65 percent figure, but excessive flesh is not needed to make the mark. Extra flesh (fat) may even impede synchronization, and possibly summer fertility as the heifers lose weight on pasture.

Initial heifer selection and preparation are very important to the herd’s breeding success. It is important to choose heifers from bloodlines that have proved to be reproductively efficient (calve early every year) and feed efficient (easy keepers). Next evaluate calf records and determine growth rates of the heifers. Once selected, we recommend producers begin a vaccination programs with live virus vaccines, which provides immunity diseases in the area at least 30 days before breeding begins.

We pelvic measure and freeze brand many heifers in our area. We believe pelvic measurement is a way to remove the bottom 5-10 percent of heifers. We do not believe it eliminates problems at calving time, though. It is a way to remove heifers that do not have an adjusted yearling area of 144 centimeters, or larger. At this size, a heifer should be able to deliver a 70-pound calf.

Many producers breed their heifers three weeks before the cowherd. In an attempt to get these girls bred, many try to stimulate this first heat with a progesterone product. We have know for years that MGA, a progestin, will keep heifers out of estrus in the feedlot. Studies have shown that feeding MGA for a short period of time will stimulate heifers to cycle when feeding is discontinued. The first heat, several days after feeding has stopped, is not considered highly fertile and thus skipped and the second heat is used.

MGA is fed at a rate of 0.5 mg for 14 days. When the MGA is discontinued, some producers will add a battery of bulls about 7 days later for 30 days. Other producers begin a synchronized breeding program by injection a prostaglandin 19 days after discontinuing MGA. With proper timing, producers may get a 65 percent conception rate to artificial insemination. The major drawback to the MGA feeding is proper mixing. (Each animal needs to receive its proper dosage in the feed bunk) and MGA retention (fat animals may retain the chemical in fat cells and there will not be good response when the feed supplement is removed).

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For producers who prefer, or are unable to make the MGA program work, there is another option. The CIDR, which stands for controlled internal drug release, is a vaginal implant which is impregnated with progesterone. The CIDR is inserted for 14 days and then removed. Bulls may be turned in, or a prostaglandin injection administered 16 days later for a timed breeding program. We have producers using both programs with good success.

Although it cannot be recommended, it has been reported that cows also respond to MGA feeding to stimulate heats without harming lactation. We feel if cows need to be stimulated, an injection of GnRH (gonadotropin-releasing hormone) or the 14-day CIDR program works well for bull breeding programs. Timed artificial insemination (AI) programs in cows utilize these same products at more specific times. Check with your veterinarian or AI technician for details.

The financial future of your cow herd hinges on their reproductive efficiency. Visit with your veterinarian extension specialist or AI technician to devise a protocol which best fits your production model. Careful planning and attention to detail will raise your herd reproduction programs profitability while decreasing your time and labor investments.

Estrous synchronization programs offer a good way to achieve a high percentage of pregnant females with less labor. The success of heifer genetics and breeding can affect the herd’s profitability for eight to fourteen years. That is why it is important to develop a workable protocol for the herd and not just make “spur of the moment” decisions. Have goals for the herd and the replacement program – which is the largest herd expense after feed.

In the past, we were taught heifers needed to be 65 percent of their mature bodyweight before breeding. With the increase in feed prices, research has shown heifers at 55 percent of their mature bodyweight seem to be as effective on first cycle breeding, with more longevity as well. I still prefer heifers closer to the 65 percent figure, but excessive flesh is not needed to make the mark. Extra flesh (fat) may even impede synchronization, and possibly summer fertility as the heifers lose weight on pasture.

Initial heifer selection and preparation are very important to the herd’s breeding success. It is important to choose heifers from bloodlines that have proved to be reproductively efficient (calve early every year) and feed efficient (easy keepers). Next evaluate calf records and determine growth rates of the heifers. Once selected, we recommend producers begin a vaccination programs with live virus vaccines, which provides immunity diseases in the area at least 30 days before breeding begins.

We pelvic measure and freeze brand many heifers in our area. We believe pelvic measurement is a way to remove the bottom 5-10 percent of heifers. We do not believe it eliminates problems at calving time, though. It is a way to remove heifers that do not have an adjusted yearling area of 144 centimeters, or larger. At this size, a heifer should be able to deliver a 70-pound calf.

Many producers breed their heifers three weeks before the cowherd. In an attempt to get these girls bred, many try to stimulate this first heat with a progesterone product. We have know for years that MGA, a progestin, will keep heifers out of estrus in the feedlot. Studies have shown that feeding MGA for a short period of time will stimulate heifers to cycle when feeding is discontinued. The first heat, several days after feeding has stopped, is not considered highly fertile and thus skipped and the second heat is used.

MGA is fed at a rate of 0.5 mg for 14 days. When the MGA is discontinued, some producers will add a battery of bulls about 7 days later for 30 days. Other producers begin a synchronized breeding program by injection a prostaglandin 19 days after discontinuing MGA. With proper timing, producers may get a 65 percent conception rate to artificial insemination. The major drawback to the MGA feeding is proper mixing. (Each animal needs to receive its proper dosage in the feed bunk) and MGA retention (fat animals may retain the chemical in fat cells and there will not be good response when the feed supplement is removed).

For producers who prefer, or are unable to make the MGA program work, there is another option. The CIDR, which stands for controlled internal drug release, is a vaginal implant which is impregnated with progesterone. The CIDR is inserted for 14 days and then removed. Bulls may be turned in, or a prostaglandin injection administered 16 days later for a timed breeding program. We have producers using both programs with good success.

Although it cannot be recommended, it has been reported that cows also respond to MGA feeding to stimulate heats without harming lactation. We feel if cows need to be stimulated, an injection of GnRH (gonadotropin-releasing hormone) or the 14-day CIDR program works well for bull breeding programs. Timed artificial insemination (AI) programs in cows utilize these same products at more specific times. Check with your veterinarian or AI technician for details.

The financial future of your cow herd hinges on their reproductive efficiency. Visit with your veterinarian extension specialist or AI technician to devise a protocol which best fits your production model. Careful planning and attention to detail will raise your herd reproduction programs profitability while decreasing your time and labor investments.

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