The opportunity for profit in cow-calf production begins with a successful breeding season. Females that conceive early in the breeding season will calve early and wean older, heavier calves. They will also return to estrus sooner giving them the maximum opportunity to rebreed again within a specified period resulting in more efficient management of the cowherd. As breeding season draws near, consider each of these four important components of rebreeding success.

Nutrition
Nutrition is one of the most important factors influencing reproductive performance. You may find yourself faced with tough decisions when it comes to nutrition, but the worst decision you can make is to underfeed your cowherd. Underfeeding during early lactation will decrease a cow's milk production and increase the time from calving to first estrus, which will delay breeding.

When acquiring supplemental feed, it's important to consider how long supplemental feed will be required, what your cows have been eating, what supplies are available, and what will deliver the best return on investment.

"Assuming cows have been on a forage based diet throughout the winter, consider buying more forage-based supplements that will maximize the utilization of the forage," says Twig Marston, beef specialist at Kansas State University. "Buy low- and medium-quality forages, and supplement with protein to increase their digestibility and intake. The protein supplements that first come to mind are grain and oilseed byproducts, as well as commercial supplements.

"Grain feeding will be of limited effectiveness if grain is fed only for a duration of 30 days or less," adds Dr. Marston. This is because the rumen takes time to adjust to the grain diet and then back to a grass diet. The yo-yo effect on the rumen microbial population will most likely limit animal performance.

Feed to meet biological priorities
Once a cow has calved she must recover from the stress of calving, produce adequate levels of milk and conceive within a period of 82 days. Energy and nutrition are utilized in progressive stages in the female. Energy is first used for maintenance, then growth, followed by lactation and then reproduction. The requirements of the preceding stages must be met before energy is used for the next function. Failure to provide energy and nutrition that exceeds the demands of all her body functions will result in failure to conceive. Reproductive performance is the first to suffer and last to recover.

Evaluate body condition as a tool
Body condition is a useful indicator of nutrition. If cows are thin at calving, getting them bred in a timely manner is increasingly difficult. Likewise, cows that maintain adequate condition at calving but are then stressed post-calving will lengthen the postpartum period.

"It's important to not let nutrition slide in either case," says Bob Larson, extension veterinarian at the University of Missouri.

A management tool used by many producers and researchers to monitor the effectiveness of nutritional programs is body-condition scoring (BCS). Though the concept is not new, BCS simply puts a quantitative number on a procedure many cow-calf producers have followed for years when determining the body fat reserves of their cows. Assigning a BCS score also allows producers to sort cows according to nutritional needs, thereby improving the efficiency of their nutrition programs. This is possible because of the strong link between body condition and weight change.

Body-condition scores involve the assigning of a score between 1 and 9. Cows in BCS 1 are severely emaciated while cows with a BCS 9 are considered very obese to the point of impairing mobility. Optimum scoring range is a BCS 5 for cows, meaning they are in moderate condition with slight evidence of ribs showing. First-calf heifers should have a BCS 6, which is indicated by a smooth appearance, evidence of fat deposits in the brisket and a smooth, round look to the ribs. First-calf heifers need more condition because they are still growing while lactating and trying to rebreed. For more information on body-condition scores talk to your veterinarian or livestock specialist, or go to www.drovers.com

Weather increases energy demands
Weather conditions also can impact forage intake by disrupting grazing patterns. While cold weather generally increases intake, windy or wet weather will reduce grazing time and intake. Typical ratios may be low in energy during extremely cold weather and allowances should be made for the additional requirement.

The only adjustment in cow rations necessitated by weather is to increase maintenance energy. Protein, mineral and vitamin requirements are not changed by weather stress. The general rule of thumb is to increase winter ration energy 1 percent for each degree (F) below the lower critical temperature.

Calculate cost of supplements
Both underfeeding and overfeeding supplements can be expensive. Analyze the major roughage for nutrient content then supplement to provide a balanced ration. To determine the cost of protein, divide the ton cost of a feedstuff by 2000 and then multiply it by the percent crude protein on a per pound basis for comparison. Feed ingredients that are high in crude protein may carry a hefty price tag, and comparing cost on a per pound basis is the best way to determine value.

Stage of production
There are a lot of demands placed on a cow that has just calved. In addition to the initiation and maintenance of lactation, the cow must repair her reproductive tract and resume normal estrous cycles. A cow should produce a calf every 365 days. To do that she must be bred within 83 days after calving. It takes an average of 40 days from calving before the uterus is in condition for pregnancy, which leaves only two heat periods for her to rebreed.

Resumption of normal estrous cycles and uterine involution are independent functions that must occur simultaneously if pregnancy is to occur. Two significant events must take place during the postpartum period in order for a cow to cycle and conceive again, according to Dr. Larson. First, the uterus must return to a pre-pregnancy state known as involution. Second, the hormones that control the estrous cycle must resume normal function and signal the ovaries to resume fertile ovulation.

Herd Health
In addition to nutrition, a sound herd health program is an essential part of any reproductive management system. Cattle are susceptible to a variety of diseases that are detrimental to reproduction. In addition to disease, parasites damage internal organs of their host, cause the loss of appetite and weight loss. Under the guidance of your veterinarian, map out vaccination and parasite control programs that maximize protection and minimize costs.

Genetics
Though they vary by breed, the heritability of fertility traits is considered to be quite low. Because of this low heritability, fertility is affected to a higher degree by management. This means that sub-par fertility can often be overcome with high nutrition and care. That is not to say, however, that genetic selection for fertility is not important. Neglecting genetic potential for fertility will eventually lead to higher nutrient demands by the replacements in your cow herd, and that extra feed for less efficient cows can add up in a hurry.

Genetic selection for milk production also has a long-term effect on conception rates. As milk production and calf growth increases due to genetic trait selection, reproductive efficiency decreases. Therefore, to maximize profits, the right balance between growth performance and reproductive performance must be met.