Performance of beef steers and heifers of varying initial weights fed alike during wintering period

The topography of Tennessee varies from flat delta, to rolling hills, and to mountain areas. Much of the land is suitable for the production of various roughages for livestock production, Tennessee livestock producers utilize this land and roughages for the production of over a half million beef calves annually. Ruminant animals are efficient converters of roughages to usable energy. This is done by a unique stomach which has four distinct compartments—rumen, reticulum, omasum, and the abomasum. Bacteria, protozoa, and yeast present in the rumino-reticulum area are able to attack and breakdown to usable organic acids and/or sugars, the cellulose and pentosans which form a large per cent of the cell walls of the stems and leaves of plants. By this process the ruminant animal takes products unsuitable for human consumption and converts them into edible products for humans. Extensive research has been conducted to determine the feeding value for cattle of different plant materials available in various areas. Many different methods of storing, curing, cutting, and feeding have been studied and compared. Studies have been conducted to determine the differences between cattle of different breeds, sex, and weight in beef production programs. Very little attention has been given to the weight of the animal at the start of the wintering period in evaluating roughages for wintering beef animals. Initial weight may be an important factor to consider in the wintering phase, as many of the physiological functions of the beef animal are influenced by weight or size. With the rapid increase in feeder calf sales in Tennessee, it is important to know what affect weight may have on wintering performance in a beef production program. Buyers purchasing calves from feeder calf sales usually do not know previous environmental conditions or genetic potential of the animals. They buy on the basis of weight, sex, breed, and grade. When working with biological material, there is inherent variability among individuals treated alike. This complicates plant and animal research. The objective of this test was to determine the effects of weight, sex, and season of birth on the wintering performance of beef calves fed a predominately roughage ration (corn silage) with limited concentrates and to evaluate the variability of animals treated alike.