| Heifers- The Future of the Ranch |
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| The Cattle Show |
| Written by Bryan McMurry, PH,D. |
 The future of any cowherd is heavily dependent upon a good heifer development program. By developing a strategy for where we want the cow/calf operation to go, we ensure the heifers' long-term profitability. It is today's replacement heifers that will take us there. Start with the end in mind.As with any business, a strategy is only viable if it can be tactically supported and executed by the organization. It doesn't make sense to try and pull a sow through a knothole. We must select females to fit the environment and bulls to fit the market. Cows that do not fit the production environment are less profitable and require additional, often costly, inputs. The two factors to consider while selecting females are biological type, as it relates to mature size, and breed type or genetic make up. We cannot manage what we do not measure. The most valuable piece of equipment on the ranch is a good set of cattle scales, especially if it is under the chute. The most important criterion by which an individual cow is measured is her productivity relative to her weight per year; 50% of the cows’ weight weaned every year. Mature size, in this case body weight at maturity, is the starting point for heifer development. Once we determine the "ideal" mature weight for the herd in a given environment and select the heifers most likely to fit that environment, we are ready to tackle the heifer development program. Mature body weight drives the calculation of the target metrics for our heifer development program, the weight at breeding and calving. If we are retaining heifers from the herd then the heifer development program starts at weaning. We begin with a 30 to 45- day preconditioning program to get the cattle through the stresses of weaning, vaccinated and started on a track for optimal weight-gain performance. This portion of the program can either be more extensive, utilizing as much grazed forage as possible and appropriate supplementation to achieve the targeted gain, or intensive, where we confine the heifers in a dry lot and feed them a palatable, high roughage diet. Because internal and external parasites are a constant irritant and rob nutrients, a good parasite prevention program is essential. During this preconditioning period we should craft a diet that can ramp up performance levels on the front end of the heifers' development offering a little more latitude in management by being a little ahead of the curve rather than behind it. After weighing the heifers at weaning, we establish the target breeding dates and weights to get the heifers on a rate of weight gain to meet the specific target weight. The targeted breeding weight is 2/3's of the expected mature weight, a weight that signifies the heifer has reached its reproductive maturity to insure an active and fertile estrus. For example, if the heifer's expected mature weight is 1200 lbs., it needs to be a minimum of 800 lbs. by breeding time to achieve a high rate of breeding success. (1200 lbs. X .67= 800 lbs.) Next, we determine the breeding date in order to calculate the average targeted daily gain from weaning to breeding. Typically, the objective for heifers is to calve as two-year-olds one heat cycle (21 days) ahead of the cowherd, or at 23 months of age. Since the gestation length of nine months is known, the initial heifer breeding age becomes standardized at 14 months. As it normally takes on average one additional heat cycle for heifers to rebreed after their first calf, heifers calving the first time at 23 months of age will be ready at 24 months of age to rebreed with the rest of the cowherd. We then take our average age and weight at weaning and calculate the average daily gain needed to reach the ideal breeding weight. Example: Weaning weight and age: 550 lbs., 7 months. Ideal breeding weight and age: 800 lbs., 14 months. Gain needed: 800-550 lbs. = 250 lbs. Days to breeding: (14 months- 7 months) X 30 days= 210 days. ADG to reach breeding weight: 250 lbs. / 210 days = 1.2 lbs. of weight gain per day. Normally we wean calves when the forage quantity and quality is in a state of decline. Generally, these conditions will not support the level of gain needed to reach the target breeding weight and it becomes extremely valuable to understand the quality of the forage from a protein and energy perspective so we can strategically supplement the heifers. Since we know the weight of the heifers and the intended gain, we can then use our nutritional models to estimate the forage intake and determine the apparent deficiencies relative to the nutritional requirements. In many cases, the deficiencies exist simply because the young heifers cannot consume enough of the lower quality forage to meet their requirement. For example, let's say the heifer requires 1.3 lbs. of protein per day in her total diet. From the forage supply we establish that given the amount and quality of forage the heifer will consume (dry matter intake), she will receive about 0.9 pounds of protein a day. This leaves a 0.4 lb. protein "gap", which must come from a supplemental source (1.3 lbs.-0.9 lbs.). Based on the protein content of the chosen supplement, we calculate the daily amount. In this case, if we had a high protein supplement (38 to 40% range) we would provide about one lb. per head per day to meet the heifers' protein requirement. As mineral deficiencies are also likely to occur during this low vegetation season, the heifers, like the cowherd, should be on a good quality, year-round, free-choice mineral program to insure the mineral requirements are met for optimum gains and fertility. This way, when she joins the cowherd, she will be accustomed to consuming the mineral. Purchasing cheap, low quality minerals may eventually cost more in terms of lower conception rates, breeding performance and higher calf mortality. Energy is calculated by using metabolizeable energy (ME). The TDN, Total Digestible Nutrients, measurement of energy has been used for years with reasonable results, however ME has proven a more accurate method for measuring energy in grazing diets. Similar to the protein supplements can be designed; however, most quality feed manufacturers have a repertoire of products that will fit the nutrient requirement and management considerations. The supplementation can be delivered in cubes, pellets, blocks, or liquid. We may even make use of some home-raised ingredients for supplementation, such as corn, barley, oats, or other by-products available from the milling industry. In a dry lot situation we would design a high roughage diet to achieve our target gain. We recommend consulting someone with a strong beef cattle nutrition background to evaluate the forage supplementation strategy and use of by-products. The better animal nutrition companies have qualified representatives that will sample and evaluate forage, provide a diet strategy and a supplementation solution for developing heifers. It is important to weigh the heifers about 60 days before breeding season to determine if they are on track to meet expected performance and make adjustments in the nutrition program if the heifers are behind schedule. Since heifers are smaller in frame structure and body weight when they calve (about 80% of mature weight), it is important to target relatively small birth weights when considering the selection of a sire. The best way to insure low birth weight offspring is choose sires with low relative birth weights when considering the selection of a sire. The best way to insure low birth weight offspring is to choose sires with low relative birth weights and the sires' birth weight EPD's. After breeding, the next target is the optimum weight at first calving, which is 80-85% of the expected mature weight (1220 lbs. X .85 = 1020 lbs.). If we achieved the breeding weight of 800 lbs., then we only need to put on 220 lbs., (1020-800) in 270 days [(23-14 months) X 30 days], which is about .8 lbs. per day. With adequate forage and high quality minerals, this daily target will be relatively easy; however, as the pastures begin to mature, protein and energy supplementation is needed to maintain the gain and reach the target calving weight. During the heifers' nutrient intake to account for the developing fetus and associated tissues. Approximately 0.5 lbs. per day gain is attributed to the fetus in developing fetus heifers. We will supplement these heifers the same way as we did prior to breeding, by performing similar calculations to determine nutrient gaps and feeding rate. Raising heifers in an environment that is as close to that of the cowherd is the best-case scenario, but we cannot "rough" them along and expect satisfactory results. If heifer development falls short by not reaching target weights then we will likely experience delayed estrous, late or underweight breeding, causing late or difficult calving. Heifer management is an extremely important component of a cow/calf production system. By providing heifers with a good start, they have the opportunity to be productive and profitable cows throughout their lifetime. |
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