January important to heifer growth

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Dr. Les Anderson, UK Beef Extension Specialist, stresses that January is an important “check-point” in spring heifer development programs. The key to proper heifer development lies in understanding the factors that influence conception in yearling heifers.

One key factor regulating heifer fertility is age at puberty. Most producers do not consider age at puberty of their heifers to be a major problem, yet few know how many heifers are actually cyclic at the beginning of the breeding season.

A Nebraska study demonstrated that the proportion of heifers that were pubertal on the first day of the breeding season varied greatly over five consecutive years in a single herd. The percentage of heifers that were pubertal on the first day of the breeding season ranged from only 21 percent to as high as 64 percent over the five-year period.

For maximum fertility and reproductive performance, heifers must have had at least one estrus before the beginning of the breeding season. Our goal then, is to incorporate reproductive management techniques to reduce the age of puberty, increase fertility, and shorten the interval to conception.

One of the largest factors regulating puberty in the heifer is weight. For puberty to occur, heifers must weigh at least 65 percent of their mature weight. This weight is referred to as their target weight. Most heifer development programs require that heifers reach their target weight, approximately 65 percent of their expected mature weight, by the onset of their first breeding season. Because fertility increases until the third estrus after puberty, heifers should reach their target weight at least 30 days before the start of the breeding season (target date).

January is the time to determine if your heifers are “on track.” Most yearling heifers will need to reach 700-800 pounds (their projected target weight) by mid-April to ensure high fertility assuming that the heifer breeding season starts about mid-May.

Weigh your heifers to determine how much they have left to gain to reach their target weight. If the heifers weighed on average 600 pounds and their target weight is 750 pounds, then they will need to gain 150 pounds or 1.5-1.6 pounds each day to reach their target weight by mid-April. Heifers should reach a BCS of 5.0-5.5 by their target date.

The next important phase in heifer development occurs one month prior to the start of the breeding season. At this time, heifers should be vaccinated (Vibrio fetus, Leptospirosis, and the respiratory disease complex which includes PI3, BRSV, BVD and IBR; modified-live vaccine is preferred), dewormed, and pelvic area measurements should be obtained. Heifers with small pelvic areas and especially large heifers will small pelvic areas tend to have greater difficulty calving.

Consider estrus synchronization and/or AI. Estrous synchronization and AI have many advantages: higher pregnancy rates, heavier, more uniform calves at weaning, and increased production and labor efficiency. The greatest advantage of AI is the ability to use superior, more predictable sires.

Proper heifer development is one of the key components to profitability in a beef cattle operation. Understanding the principles of heifer development can enable producers to incorporate management techniques to improve the efficiency of your operation.

For more information, please contact the Carroll County Cooperative Extension Service at (502) 732-7030.

Dates of interest

Jan. 30 – Carroll County District Board meeting, 6 p.m., Carroll County Extension Office.

Feb. 6 – Beef Quality and Care Assurance Certification: Genetics, 6:30 p.m., Carroll County Extension Office. Cost: $5 for class only or $10 for class and farm sign.

Feb. 15 – Deadline to turn in CAIP receipts to Shelia Banks at the Conservation District Office. If you are in need of the education requirement, please contact me ASAP.

Christin Herbst is the Carroll County Extension agent for agriculture and natural resources. Call her at (502) 732-7030 or send e-mail to Christin.Herbst@uky.edu.