Evaluation of factors affecting litter and pig performance traits

Profit from a swine enterprise is dependent on the level of performance in the swine herd. Some of the factors affecting profit are size of litter farrowed, pig survival rate and gain from birth to market, Tennessee swine producers follow many practices in relation to breed and age of their breeding stock. Some producers depend largely on mature sows, whereas others use gilts almost exclusively. On most Tennessee farms both gilts and mature sows are used to produce pigs; however, the proportion of gilts to sows a producer keeps varies from farm to farm. Most swine producers do not have a definite plan for maintaining their sow herd, and there may be a large variation in the number of breeding sows and gilts on the same farm from year to year. Usually, farmers select herd replacements as needed with little regard to any systematic breeding program. Some producers practice a program of farrowing gilts at about one year of age and market these gilts when their first litters are weaned. Replacement gilts are selected from the market hogs to produce the next year's pigs. Under this system many gilts are sold for slaughter before they reach the peak of performance. On the average, the gross return from six market hogs is required to pay for the costs of carrying a sow and litter. A study of the various factors which affect performance traits of economic importance to swine producers can aid in the establishment of sound production programs. The objectives of this study were; (1) to. determine the effects of year, season of birth, age of dam, breed of dam and breed of pig on litter and pig performance traits; (2) to compare certain performance traits of straight and crossbred pigs; and (3) to evaluate the effects of various two and three breed rotational crosses on litter and pig performance traits.