Vet's Perspective

Opinion
Jun 21, 2013
by WLJ

Managing first calf heifers, young cows

All of our herd must be in optimal shape in order to attain prime breeding potential, but first timer heifers may have special needs.

In order to create “reproduction momentum” in your herd, body condition scoring becomes paramount. A perfect world would allow for all cattle to breed and re-breed in an efficient, timely manner ever year.

Benefits abound with early calving heifers as well, the first one being that early calves will weigh more than late calves at sale time. An early calving cycle is more apt to keep in sync and prevent late calving delays as well.

Puberty must also occur early if a heifer is to be expected to conceive early in the breeding season.

When nutrition is consistent and bull fertility is not compromised, most mature cows will tend to calve near the same date every year. A good amount of effort should be centered on a heifer’s first breeding season. Many producers focus on a goal of approximately 80 percent of their females to be cycling before the start of breeding season. Most estimates average that 65 percent of matings between fertile bulls and females actually result in a detectable pregnancy. Some experts recommend that heifers calve two cycles prior to mature cows, as heifers typically require approximately 30 to 40 more days to produce another fertile cycle post-calving.

A successful pregnancy typically does not occur on the first cycle after calving or even the first cycle during puberty. It is optimal to have heifers and cows go into the breeding season already cycling before exposure to bulls. According to analysts at Kansas State University, “in order to have approximately 65 percent of cows calving in the first 21 days of the calving season, essentially all of the cows need to be cycling by the end of that first 21 days of the breeding season.” This means that cows entering another season must have their calves at least 80 to 100 days before the start of the following season.

The type of nutrition being offered to heifers is also a critical point. Young females require about the same poundage of protein and energy as mature cows; however, the ratio of protein and energy within a diet must be higher for younger animals as they tend to not consume as much feed. Research out of Nebraska University demonstrated a 17 percent decrease in feed intake for first calf heifers during the last three weeks before calving. One way to alleviate this issue is to manage young females separately from mature cows during the last month of gestation, when possible.

Nutritionists recommend that heifers receive a ration that is approximately 11 percent crude protein and 62 percent total digestible nutrients when post-calving. Ideally, heifers should be at 65 percent of mature cow body weight during their first breeding season. Management decisions should always keep in mind that calves are ensured adequate nutrition (even if it is forage alone) up to the animals’ puberty so that weight gains remain constant. Likewise, heifers and cows should be placed at approximately a “6” on the “1 to 9” body condition score, at the time of calving so as to avoid post-calving disease and complications.

Prior to the breeding season, heifers should be examined as to physical maturity and cycling. One to two months before the season, a reproductive examination involving rectal palpation can be helpful in identifying heifers with ovarian follicles present or absent, as well as body weight and pelvic area measurements.

Estrous synchronization is also a valuable tool to aid conception in mature cows as well as heifers. The average age of puberty in beef heifers is approximately 11.5 to 14 months of age. Adequate management ideally strives for 80 percent of the heifers to be cycling in order to have a successful breeding season. A first calf heifer can usually be expected to require 100 days (or slightly less) in order to resume another fertile cycle after calving.

For more information, please consult your farm nutritionist and veterinarian; they are always happy to help! — Dr. Genevieve Grammer [Dr. Genevieve Grammer is a mixed-species veterinarian practicing in eastern Colorado. Please direct correspondence to drgigi19@gmail.com].

{rating_box}