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  4. 1997
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The Concept of Entropy

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Many years ago (too many), I first heard about a concept called entropy. This occurred during a lecture in a freshman chemistry class. The professor explained how all things tend to move toward disorder (or chaos) unless energy (effort) is exerted to re-establish order. He further explained that the universe is much like a dorm room in that it will continue to become increasingly messy unless energy is expended to clean it up.

At the time, I thought this concept was interesting but of no real practical value. I have since come to realize that I was very wrong. Chaos exists everywhere, and some of the best examples are on farms and ranches. Controlling chaos in cow-calf operations not only requires expenditure of energy (management), but also careful planning as to how this energy will be used. Order first must be established during the planning process.

It is extremely important that producers place emphasis on "first things first". There is one key cattle management practice that must be dealt with before others can be applied. When this is missing, all other management practices become virtually useless. This "key practice" is the establishment and maintenance of a controlled calving season. By controlled calving, I mean calving the entire cow herd within a 45 to 90-day period each year. When this is lacking, the producer cannot adequately or economically feed his cattle, market his calves, manage grazing, or even prevent disease.

Disorder caused by uncontrolled breeding and calving is difficult to correct. Both physical effort and economic inputs are needed. Careful thought and planning are needed before any action is taken. First, identify the most desirable time to breed and calve. This decision should be based on analysis of forage type, managerial ability and, of course, economics. The following gives some general guidelines to help you make this decision.

Early Spring Calving. Early spring calving is very desirable in areas that are dominated by summer grasses. In the southern plains, we usually observe an abundance of very high quality forage in late spring and early summer (May - June). This is an ideal time to breed. Cows tend to gain body weight and condition during this period making it much easier to achieve high conception rates. Some protection from inclement weather during the early phase of calving may be needed.

Late Spring Calving. Some producers delay calving until spring grasses emerge. In this case, calving occurs during April, May, and possibly June. Though this practice reduces winter feeding, there are some notable negatives. Because forage quality declines during breeding, (July-August), conception rates in a late spring calving program may be affected.

Heat stress may also affect semen quality (fertility) of bulls and possibly embryonic survival in the cow. Also, because calf age is important, a major factor determining weaning weight, calves will be lighter at weaning. Though late spring calving will no doubt reduce wintering costs, this must be weighed against the risk of declines in reproductive efficiency and reduced weaning weights.

Fall Calving. Fall calving creates some unique opportunities for producers. Unfortunately, it also causes some management problems. Because fall calves are usually 6-8 months of age by early May, they can be used to increase grazing pressure during the time of peak forage production, remaining on cows until 9 months of age. Breeding in fall calving herds must be done during the winter months; so, excellent nutritional management is needed to maintain reproductive efficiency. As a rule of thumb, we like to see a cool-season perennial forage base (fescue, etc.) on farms with fall calving herds.

Moving calving seasons can be difficult. First, examine your current calving distribution. Remember it is virtually impossible to make an entire herd calve earlier. On average, the gestation length of a cow is about 285 days. It also takes 80 days or more after calving before most cows re-breed. So, we are fortunate to get a cow to calve every 365 days and it is much more difficult to get her to calve earlier. Like most management activities, creating a defined calving season requires effort and some capital over the short run. But if a controlled calving season is not in place, improvement on other fronts will be very difficult if not impossible.