A session addressing heifer development and management strategies is the second webinar in the five-part webinar series on Managing Replacement Heifers for the Future. An important component to profitability of a cow-calf operation is the cost of developing heifers. Replacement heifer selection and development involves a suite of decisions, including selecting the right genetics, evaluating structure and temperament, and designing an appropriate nutritional strategy. Maximum lifetime productivity is obtained when heifers calve by 24 months of age. Additionally, heifers that calve earlier in their first calving season tend to stay in the herd longer.

The main goal of a heifer development program is to have heifers reach puberty before their first breeding season, allowing them to breed early in the season. Age at puberty is related to weight, therefore, feeding heifers to reach an adequate weight for puberty is critical. Expected weight at puberty differs by breed and depends upon mature cow size and relative breed leanness. Heifers of breeds with heavier mature weight tend to reach puberty at older ages and heavier weights.

The greatest single cost in developing heifers is feed during the period from weaning to breeding and a variety of strategies can be used to optimize cost of production during this period. Since pre-weaning rate of gain has been shown to strongly influence age at puberty post-weaning nutritional management programs need to start by considering the nutritional status of heifer calves at weaning. Heifers should be managed to make the best use of available feed and labor resources. They can be fed diets that provide a steady rate of gain from weaning to breeding or other strategies can be used to take advantage of low cost feeds early in their development, followed by diets that allow faster rates of gain in the last 60 to 90 days before breeding. These programs might include pasture or range grazing during fall and winter with some supplementation provided when needed.

Guidelines have historically suggested that beef heifers should reach 65% of mature body weight by first breeding. These guidelines were set to allow heifers to reach puberty in advance of first breeding for improved conception rates and for heifers to be in good nutritional condition during their first pregnancy. Recent research suggests that development of beef heifers to about 55-60% of mature body weight at breeding may provide economic benefit in comparison to the previously recommended 65% of mature weight, provided a good nutritional program is used after breeding. A recent study from Nebraska reported $38 in cost savings per pregnant heifer when wintered on corn residue compared with those developed to a heavier weight in the drylot. However, some studies in which heifers have been bred at 55% of mature body weight have reported lower pregnancy rates or fewer heifers bred in the first 21 days of the breeding season compared to raising heifers to 65% of mature weight at breeding. Because lifetime cow productivity is positively related to heifers breeding within the first 21 days of the breeding season, any effect of a development program on time of conception is an important management consideration.

Raising heifers to 55% of mature weight has sometimes shown favorable economics when cost per pregnant heifer is considered. This arises when accounting for decreased feed costs along with the sale value of an open heifer, which can lower the cost per pregnant heifer when compared to feeding for more rapid rates of gain and higher pregnancy rates. However variations in the sale value of open heifers will cause this to change from year to year.

Perhaps more important than whether the heifer reaches 55 or 65% of mature weight by first breeding, is the goal of reaching 85% of mature weight by first calving. Because the heifer is still growing between first breeding and first calving, her nutrient requirements continue to be high. Adequate nutrition needs to be provided to allow for both pregnancy and growth.

More information on the many facets of heifer development will be discussed during the “Managing Replacement Heifers for the Future” webinar series starting January 14, 2015. The series will run Jan. 14, 21, 28, Feb. 11, and Feb.18 All sessions will start at 12:30 p.m. CST and run for one hour.

The January 21 session will have more information on nutrition and heifer development programs.

Event Information & Registration

For more information regarding heifer development management and strategies, contact Dr. Elaine Grings at 605.688.5455 or Dr. Julie Walker at 605.688.5458.

- See more at: http://igrow.org/livestock/beef/developing-beef-heifers-for-the-long-hau...