Preservation and Use of Chemically Treated High-Moisture Corn by Weanling Pigs

Abstract

This study was conducted to evaluate (i) application rates and effective preservation time of a buffered C3 (propionic acid, 80%) and C2 (acetic acid, 20%) solution for preservation of high moisture corn (Zea mays L.) stored under aerobic conditions and (ii) the nutritional value of the preserved corn in the diet of growing pigs (Suide suinus). Shelled corn containing 30% moisture was treated with 0.0, 0.5, 1.0, and 1.5% of a chemical preservative (pH 6.1). An additional 1.0 lb of preservative for each 1.0% of moisture above 25% (total of 5 lb) was used per ton of the 30% high moisture corn (all treatments except 0.0%). All treatments were replicated twice and stored aerobically in wooden bins (2 ft by 4 ft by 4 ft) on a concrete floor in a covered shed. Temperature was monitored as an indicator of microbial growth and heat damage. The effective period of preservation for 0.0, 0.5, 1.0, and 1.5% of preservative were <6, 28, 104, and >130 d, respectively, as determined by retarding an increase in temperature, heat damage, and mold growth. The second part of the experiment consisted of two digestion trials to determine the effect of chemically preserved high-moisture corn on dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and digestible energy (DE) in weanling pigs (23.3 ± 3.48 lb). Eighteen pigs (nine/trial) were blocked by weight and randomly assigned to one of the following three dietary treatments. In Treatment 1, dry corn (DC), 14% moisture, was ground through a 1.0-in. screen, mixed with a commercially prepared protein, mineral, and vitamin premix and pelleted. In Treatments 2 and 3, DC was replaced on an equal DM basis with either high-moisture corn (HMC) stored in an airtight silo or with corn from the first part of the experiment, treated with 1.5% preservative (THMC), respectively. Pigs were housed in individual cages. Each digestion trial consisted of at least a 15-d adjustment period, followed by 3 d of total fecal collection. Dry matter intake (1.88 ± 0.20 lb/d) was similar (P > 0.05) among treatments. Percentage of DM and OM digestibles were not affected (P > 0.05) by treatments averaging 86.8% ± 1.8 and 88.3% ± 1.7, respectively; however, CP digestibility (DM basis) was higher (P <0.05) for HMC (86.3%) and THMC (86.0%) vs DC (83.2%). The DE (DM basis) averaged 3408, 3212, and 3176 cal/d for DC, HMC, and THMC, respectively, with no differences (P > 0.05) among treatments. Results indicate that HMC (30% moisture) can be stored aerobically when treated with a neutralized (pH = 6.1) mixture of acetic and propionic acid with no negative effect on its use by weanling pigs.