Most artificial insemination (AI) programs rely heavily on a wide array of available estrous synchronization (ES) programs. But success can vary widely, so it's critically important producers know which factors can negatively impact their AI programs — and how to manage them.
“The key to ES in cows and heifers is knowing the six basic factors that can hurt success, and understanding that management can overcome most of them,” explains University of Minnesota's Cliff Lamb.
- Age differences in females
Two-year-old cows have more difficulty initiating estrus than older cows, even when they calve earlier than older cows.
“Younger cows have greater energy needs due to lactation, and because they're still growing,” Lamb says. “Both of those needs take priority over her ability to begin her postpartum estrous cycles.”
Because older cows have no growth requirements, nutrients are more likely to be prioritized for milk production and initiation of estrous cycles, he says. Because of this priority system, young growing cows need more energy and higher-quality nutrients, especially in the weeks leading up to and immediately post-calving.
Thus, producers need to manage young cows and older cows differently. Lamb says, “If you provide younger cows with better care, you'll have much better results when you synchronize and AI them later.”
- Days since calving
As a general rule, the longer between calving and ES, the better the breeding results. ES shouldn't occur less than 45 days after the birth of the calf, Lamb says.
For ES to work, producers must know when their cows calved, whether she had a difficult birth and the birth weight of all calves. That's why good records are important to ES success.
“Producers should target starting their ES protocols when cows are greater than 45 days from calving,” Lamb says. “However, if a specific cow had calving difficulties or a large calf, wait a few extra weeks. Without accurate records, these decisions can be extremely subjective.”
Using ES, producers can expect more females to be in simultaneous heat. Thus, adequate facilities to handle the larger cattle numbers are needed.
ES programs also require females to be handled more frequently in chutes for injections. Thus, working facilities need to be able to accommodate the extra work.
“Not only are reliable holding and sorting pens needed, but you should have a solid alley and chute system,” Lamb says. “Anticipating the increase in facility use will certainly contribute to a successful ES program.”
Heat detection is important to ES program success. That requires a commitment to having people on location checking for heat.
“An observer needs to know exactly how cows act in heat,” Lamb says. “This is where a program often fails. A producer might feel he has more important things to do, but abandoning heat checks or entrusting them to an incompetent worker results in poor estrus response or poor conception rates.”
- Herd health and nutrition
To improve AI results, use a veterinarian-approved vaccination program for breeding animals, Lamb stresses. Nutrition programs also need continuous year-long monitoring, not only to ensure adequate feed and water are available, but that mineral and protein needs are met.
This article is provided by the National Association of Animal Breeders. Learn more at www.NAAB-CSS.org, or call 573/445-4406.