September 2017 Articles

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Managing First-Calf Heifers

Managing First-Calf Heifers Source: Pasture to Market, LSU Ag Center A heifer’s worth today is equal to all her future earning (calf sales and salvage value), minus her annual expenses. Therefore, assuming a 1200 lb. cow with a life span of 8 years weaning a 550 lb. calf each year: Þ $6,238.32 (calf sales 550 lbs. X $141.78/cwt. X 8 yrs.) + $885 (salvage value 1200 lbs. X $73.69/cwt.) = $7,123.32 - $4,480 ($560 annual expense) = $2,643.32 (this is what she’s worth….not necessarily what one is willing to pay) · Unless she’s trained to do circus tricks, there are only two ways she is going to earn a living: produce beef or become beef. · If she is going to make a career of producing beef, it is important that she wean a calf each year, and the odds of her coming up short on the rent are greatest when it is time for her to conceive her second calf. · When a cow doesn’t rebreed, the cost of keeping her for a year must be absorbed by the females that do wean a calf. If she conceives late in the breeding season (2nd estrous), her calf will lose 21 days of growth against a common weaning date. Either way, she’s not living up to her profit potential. · The first step towards doing her job year-in and year-out is that she must become pregnant again within 82 days of calving. (365 days in a year - 283 days average gestation period = 82 days to rebreed) Managing First-Calf Heifers · Rebreeding is a first-calf heifer’s lowest priority. She will use nutrients to stay alive first and to provide milk for her calf second. Þ Only after she reaches her genetic maximum for milk production and meets her requirements for maintenance and growth will she repartition energy for reproduction. When the body detects low energy levels, it shuts down the production of reproductive hormones. Þ She will not cycle again until blood energy levels are high enough to meet all her requirements. Low energy levels as a result of poor body condition at calving are generally the cause of re-breeding failure. · Compounding the low energy problem is the fact that she just overcame the greatest physiological stresses of her life; fetal development, parturition, lactation and reproductive tract repair require a lot of energy! · All 2-year-olds and some 3-year-olds are still growing themselves while providing milk for their calves. In the case of 2-year-olds, these young mothers are losing their baby teeth and are not yet good foragers. Therefore, many go into the breeding season with reduced intake. · As intake falls short of the incredibly high energy requirements, she compensates by mobilizing the energy stored in fat. Over several weeks, a noticeable change in her appearance occurs. This change can be quantified by utilizing body condition scores (BCS). Nutritional Management— Pre-Breeding · Heifers should be bred at an estimated 65% to 70% of her mature body weight (You’ve heard it before….I’ll say it again….scales are very important on a cow/calf operation). · Example: Þ Group A heifers expected to weigh 1,200 pounds as mature cows, and should weigh 780 to 840 pounds at breeding. Þ The group is weaned on August 1st and will be bred on March 25th, leaving 237 days to reach the target weight. Determine the average daily gain (ADG) required over the 237 day period to reach target weight: * Heifers weaned at 550 pounds with a target weight of 810 pounds will need to gain a total of 260 pounds in 237 days. That results in an ADG of 1.10 pounds. This is easily obtained with diet consisting of 9% crude protein (CP) and 60% total digestible nutrients (TDN) @ 15 lbs. of dry matter intake (DMI). · Weight gain should be monitored every 30-60 days to make sure the heifers are gaining on schedule, and make adjustments to the feeding program. Nutritional Management— Gestation · Heifers should be at an estimated 85% to 90% of their expected mature body wt. at calving. · Example: Þ Group A heifers are expected to weigh 1,200 pounds as mature cows, and should weigh 1,050 lbs. at calving. Þ The group is bred on March 25th at a weight of 810 pounds and are expected to calve on January 1st (283 day gestation), they must gain 240 pounds resulting in an ADG of 1.18 pounds. If we maintain a diet consisting of 9% CP and 60% TDN @ 19 lbs. of DMI, we should be able to achieve this weight gain goal. Separate heifers in good body condition (BCS 6) from those in poorer condition (BCS 3 and 4). Overfeeding can be avoided while allowing those that are thinner to add condition, increasing their potential milk production & re-breeding percentages.
Nutritional Management — Post-calving · At the beginning of calving, heifers should be at a BCS of 6. · Continue to provide adequate forage or feed resources consisting of 11% CP and 64% TDN @ 25 lbs. of DMI for the first 90 days after calving. · Females that calve in thin body condition but regain weight and condition going into the breeding season do not re-breed at the same rate as those that calve with a minimum BCS of 6 and maintain it through the breeding season. · Once a heifer has calved in a poor BCS (3 or 4), it is virtually impossible to feed her enough early in lactation to get her to increase BCS and to produce milk while continuing to grow. It is easier to increase body condition before calving. Take home points: · A bad idea….in an attempt to decrease calving problems, some producers allow heifers to lose body condition and calve at a BCS of less than 5 so the calf’s birth weight will be lower. Producers should remember that heifers are still growing, have maintenance needs, have to battle environmental stresses and must produce milk for the first time. Therefore, there is no validity to holding back feed from heifers to make their calves smaller at birth. · Reducing calving difficulty (dystocia) is an important strategy in maintaining rebreeding rates. Cattle suffering from dystocia experience 16% lower pregnancy rates during the next breeding season. Many calving problems can be eliminated if heifers are bred to low birth weight bulls and are 85% to 90% of their expected mature weight at first calving. · Weaning calves at 4-5 months of age (early weaning), or earlier if cows are in dire straits nutritionally (i.e., drought) may provide young cows with 30-45 days of additional rest before their second calving. Very early weaning, 40 to 80 days of age, should be a last-ditch effort to keep the heifers in the herd. However, this decision creates an entirely different set of calf-management issues. · Sometimes just reducing the calf’s reliance on mama can be enough of a nudge for rebreeding. Removing calves for 48 hours has been shown to improve conception rates of moderately (BCS 5) conditioned cows by 4% - 8%. Short-term calf removal can be used at the first of the breeding season, in the middle or at both points in time. · Creep-feeding or creep-grazing calves is another method to reduce the nutritional demands on first-calf heifers, enabling her to use more energy for rebreeding. Creep gates should be constructed so only calves have access to the feed/pasture. The mamas also like the high quality feed/pasture and will go to great lengths to get it. · Remember, cows continue to grow until they are 4-5 years old. Nationwide, almost as many 3-year-olds come up open as 2-year-olds, so both groups should be managed with equal intensity and, if possible, as a single unit. Þ Managing 2 and 3-year-olds together is better than mixing 3-year-olds with the mature cows because the younger cows frequently get pushed away from high quality forage/feed, which keeps them from paying their rent. In Conclusion: 1. Graze first-calf heifers and mature cows separately. Consider grazing first-calf heifers with 3-year-olds or virgin replacement heifers. 2. During gestation, supplement first-calf heifers with grains (such as corn or DDG) to obtain 85% - 90% of mature body weight at calving. Research at the LSU AgCenter’s Hill Farm Research Station has shown that energy supplementation during late gestation has a greater effect on subsequent BCS and body weight change compared with protein supplementation.— Evaluating the effects of late gestation supplementation on timed –artificial insemination pregnancy rates and body composition in beef cattle; R. S. Walker ,D. LaMay , and B. Buttrey 3. Keep a close eye on BCS. First-calf heifers should have a BCS of 6 at calving. If first-calf heifers begin to lose too much condition after calving, consider weaning calves early or offering creep feed/grazing. — Jason E. Holmes, LSU AgCenter