| HEIFER DEVELOPMENT GUIDELINES The guidelines presented are based on general management and development recommendations published by the Texas Agricultural Extension Service in publication B-1213 titled “Management of Replacement Heifers for a High Reproductive and Calving Rate”. In addition recommendations on records and general selection aspects are contained in “Guidelines for Uniform Beef Improvement Programs” published by the Beef Improvement Federation (BIF). The most appropriate approach to effective heifer development in a planned program concept is to age associate the necessary records and performance practices relative to the developing heifer with both age and weight references. This will start with the identification and singular handling of the heifer at weaning time (1) followed by the postweaning growth period to target yearling puberty weight (2) then the breeding season of 60 days followed by pregnancy determination (3) followed by the post-breeding management recommendations (4). 1. Heifer Selection at Weaning · Only heifers of known genetic composition should be selected based on controlling mating type. This allows various types of crossbred and straightbred heifers to be recommended but does not allow heifers from unknown cows or cattle of mixed breeding without a defined mating plan. · Cattlemen are recommended to carefully follow the selection of genetic potential to match the production environment. This is attached in Table 1 as published by the BIF in matching, which breeds types and genetic traits should generally be considered. It is the responsibility of each cattleman to make this assessment based on the production environment to be most cost effective. · Select weaning age heifers ( in a 90-day maximum age range in a contemporary group) that are born in the first half of the calving season (older heifers). These heifers should be heavier than average or no heifers below a 90-index rank of weaning weight should be retained. A general guideline to desired weight should be based on expected mature cow size. A frame score based on hip height at any defined age is a good indicator of potential mature size. Generally heifers of Frame 3 or less are Small and reflect a mature cow size at 1,050 pounds or below. Frame score 4 and 5 heifers relate to a 1,050-1,250 mature size and are Medium. Large frame heifers score from 6-7 and relate to 1,250 -1,350 pounds at maturity. Heifers scoring 8 or greater are X-Large and will be greater than 1,350 in mature size. The better weaning weight related to mature cow size is about 45% of the mature cow size. If Small cow are preferred, then . 45*1050= 472.5 pounds or the average weaning weight should be close to this number. It is recommended to ratio the actual heifer’s weaning weight to this guideline and it will define how far below or above an individual heifer record relates. · Cull all structurally unsound, nervous or unruly heifers and avoid any attempt to select on visual characteristics or femininity. 2. Postweaning Management · Based on expected mature cow size from frame scores, calculate the targeted yearling breeding weight needed as 65% of the mature cow size. For example, Small heifers at 1,050 pounds mature weight should weight 682.5 pounds at 14 months of age. The breeding age is expected to be at 14-15 months in a 60-day breeding season (recommended breeding seasons May - June and/or mid Nov.-mid Jan). This will relate to calving at 23.5 to 24.5 months of age or slightly earlier if gestation is shorter due to use of early maturing breed of bulls. · Calculate the needed average daily gain (ADG) between the actual weaning weight and target breeding weight for a breed-contemporary heifer group. Assuming a 7-month weaning age and a 14- month breeding age then the producer has a 7-month period to make the needed gain. If a group averages 475 pounds at weaning and needed to weigh 682.5 at breeding then the gain needed is 207.5 pounds over 7-months or 210 days. The calculated ADG is 207.5/210 or 1.0 pounds per day. Since heifers can grow slowly with the time allotted or be fed supplemental feed or grazed on improved pastures based on forage management programs, there is great flexibility available on how to grow heifers. The emphasis is to recommend only forage programs with protein or protein-energy supplements at low daily intake levels of roughly 2 pounds per day or less on lower quality forages. If grain supplementation is required due to forage failure, it is recommended to be fed at 1-% bodyweight with the remainder of the diet from stored forages or in the form of a high fiber product. Considering that postweaning heifers can gain in excess of 2.0 pounds per day, confined feeding programs can be short and concentrated. 3. Breeding Management · Plan the 60-day breeding season at 14-15 months of age. Bulls used should be selected for low birth weights (EPD) or for Calving Ease Scores. Most commercial cattlemen should use early-maturing breeds of bulls of smaller mature size on heifers to avoid dystocia (calving difficulty). Natural service sires should be younger bulls to avoid major size differences in the actual mating that might injury heifers. It is generally recommended not to use bulls that are heavier than 1.8 times the mature size of cows. If Small cows are expected (1,050 pounds at maturity) then the maximum sized mature bull should not exceed 1,890 pounds. However, use of relatively smaller mature-sized bulls is recommended. · Prior to the breeding season heifers should be observed for estrous activity and supplementation considered insuring heifers are gaining prior to and in the breeding season. · Use of AI can be helpful and estrous synchronization considered for timed group mating of a breed- age contemporary group. · Any unthrifty, injured or ill heifers should be removed or culled prior to the breeding season. · The recommended Body Condition Score (BCS) should be 5,6 or 7 or relate to actual fatness of .2, . 3 or .4 inches of fat over the rib measured by ultrasound. 4. Postbreeding Management · Pregnancy testing of exposed heifers should be completed 60 days postbreeding or at 17 months of age. · Open heifers should be removed and marketed at palpation time. · Heifers should be managed to achieve a minimum of 85% of their estimated mature size based on frame score at calving. Assuming a mature size of Medium (1,150 pounds), then the 23-24 month old heifer should weigh roughly 975 pounds. If her breeding weight was at 65% of mature size (1150*.65= 747.5 pounds), then the bred heifer must gain about 225 pounds in 180 days. The ADG minimum is 225/180 or 1.25. This should be based on a combination of weight and fatness. Here again the acceptable BCS should be from 5-7 at all times during the development periods. Upon attaining a group of breed-age developed bred heifers, these cattle can be sold at anytime desired. Generally producers should avoid selling last trimester-bred heifers (greater than 7 months bred). Those held beyond this pregnancy stage should be calved and sold as pairs. Again it is recommended to sell pairs when calves are a minimum of 45 days of age. This allows sufficient time to rebreed and insures the calf has a proper start early in life. Probably the most critical aspect in brood cow development is getting the first-calf heifer to rebreed on time. Cattlemen should separate first-calf heifers and carefully monitor gains and development. Supplemental feeding or access to the best forages is needed on these lactating young cows. Most research indicates a 75% conception rate in first-calf heifers is likely. Continued management and monitoring of BCS is crucial in improving on rebreeding rate. First -calf heifers should be placed in the herd with older brood cows when palpated safe in calf with the second calf or at weaning time. Prepared as a general guide for the Texas Forage and Grasslands Council to assist in the development of a commercial heifer development program emphasizing maximum utilization of forages and to assist beef producers of all herd sizes to effectively develop and market quality replacement beef heifers. |