Laboratory and field evaluation of commercial feed preservatives in the diet of nursery pigs

A two-part study was conducted to compare the effectiveness of 10 neutralized preservatives as inhibitors of microbial activity on cracked shelled corn at two moisture levels (15 and 18%) and to evaluate the performance of nursery pigs fed diets containing the two most effective preservatives selected from part one of this study. In part one, for each of the three replications (15 d), moisture content of the cracked corn was adjusted to 15 and 18%. Preservatives were diluted (1:1) with water and sprayed on 300 g of ground corn. Treated corn was then divided into two equal parts and placed in 500-mL sterilized Erlenmeyer flasks, covered with sterile cotton plugs, and incubated at 31 degrees C. Several preservatives were as effective as propionic acid in inhibiting microbial growth. Liquid Myco Curb (MC) and Sal Curb (SC) inhibited C02 production by 12.7 and 13 d with 15 and 18% moisture corn, respectively. Combining the data for 15 and 18% moisture corn, Sal Curb inhibited microbial growth on corn the longest (12.2 d). The second part of this study consisted of two replicates of a randomized complete block design experiment to evaluate the palatability, ADG, and gain:feed ratio of nursery pigs fed pelleted diets containing 1 kg/t of diet of either MC, SC, or no preservative. Pigs were blocked by sex and weight and randomly assigned to the treatments. Daily feed, weekly feed refusals, and weekly weights were recorded. Pigs consuming the MC-treated diet tended to consume more feed (P < .18) and gain more weight (P < .14) and tended to have greater ADG (P < .14) than pigs fed the SC or the control diet. Gain:feed ratio was similar (P > .87) for SC and MC and higher (P <.07) than the control. Although not significant (P > .05), it seems that MC may have enhanced palatability of the feed and SC improved the efficiency of feed conversion in the nursery pig.