Evaluation of Micro Plus, a Fermentation Product in Diets of Growing-Finishing Pigs

Materials and Methods The fermentation product was evaluated at concentrations of 0, .1, and .15% in corn-soybean meal diets (Table 1) fed to pigs from 62.2 to 240.2 lb. body weight. These corn-soybean meal diets previously have been demonstrated to allow rapid rates of body weight gain in pigs of the breeding (Yorkshire x Landrace and Hampshire x Duroc used in this research. The diets contained .85, .78, and .70% lysine for pigs in body weight ranges from 60 to 120, 120 to 180, and 180 to 240 lb., respectively. Each treatment was fed to six pens of pigs and each pen contained six pigs. Within a block of three pens, the sex ratio was constant. Pigs were randomly allotted on the basis of initial weight and sex to pens within blocks, with a restriction that littermates not appear in the same pen. Treatments were randomly allotted to contiguous pens within blocks. A pen of pigs was the experimental unit for statistical analysis as a randomized block design. Pigs were housed in partially slotted, concrete floor pens containing a nipple drinker and a stainless steel selffeeder. Up to 120 lb. body weight, pigs were housed in pens that allowed 5 ft./pig and subsequently were housed in pens that allowed 8 ft./pig. The experiment was conducted from November 15, 1994, to February 28, 1995. A minimum temperature of 551⁄4F was maintained in the environmentally controlled rooms. Pigs were weighed individually and pen feed intake data were collected first at two-week intervals, then at one-week intervals when approaching body weights for designated diet changes, and upon reaching a final weight of 240 lb. Pigs were individually removed from the experiment the week they reached a minimum of 233 lb. body weight. After 50% of the pigs (three pigs) were removed, the remaining pigs were terminated on the weekly weigh day that their average body weight reached a minimum of 233 lb. Backfat depth off-center at the tenth rib was measured by ultrasound on each pig at its termination day. Backfat (BF) was then adjusted to a constant body weight of 240 lb. using a formula from Guidelines for Uniform Swine Improvement Programs, (1987) NSIF: Adjusted BF = actual BF, in + (240 actual weight, lb.) * actual BF/(actual weight 25). Five pigs were removed from the experiment as a result of an outbreak of pneumonia. Growth data for pigs removed were included in the data set up to the weight day in which their growth rate was obviously affected by disease. Likewise, feed intake data for pens from which pigs were removed were adjusted by removing a feed charge for the removed animals. Feed charges were based on body weight and a calculation of maintenance energy requirement of 110 kcal./day x body weight kg.