COMPARISON OF SIX COMMERCIAL HAY PRESERVATIVES UNDER SIMULATED STORAGE CONDITIONS

Abstract

Rehydrated alfalfa (Medicago sativa L.) hay was used to test the effectiveness of six commercial hay additives in the laboratory. The additives were designated B1 (live bacterial culture, protease and cellulose enzymes) P1 (67% propionic acid partly neutralized with ammonia) R2 (25% propionic acid and unspecified amounts of other organic acids and flavorings), S (92% sodium sulphate), P3 (19% propionic acid and unspecified amounts of other organic acids and flavorings) and B2 (12% lactic acid and fermentation extract). The additives were assessed on their ability to prevent deterioration in in vitro digestible organic matter (IVDOM), heating and mould growth, loss of dry matter and associated parameters at hay moistures ranging from 15 to 35% moisture with additive rates specified by the manufacturer. After 21 d of storage and at all moisture levels P1 (1.25% wt wt−1) maintained IVDOM and most other parameters at levels similar (P ≤ 0.05) to an unspoiled Control at 15% moisture. P2 (0.2% wt wt−1) reduced heating and mould growth and maintained IVDOM to the levels of unspoiled hay up to 25% moisture. P3 (0.3% wt wt−1) provided slight improvements in IVDOM up to 25% moisture, but did not prevent heating. S (0.1% wt wt−1) limited dry matter loss at 20% moisture. Alfalfa hays treated with B1 (0.1% wt wt−1) or B2 (80 or 100 mL t−1 of dry matter) were not different from the control hay for any parameters. At 25% moisture B1 and B2 did not affect the growth of anaerobic and aerobic bacteria or moulds while P1 inhibited the growth of moulds and aerobic bacteria. Based primarily on maintaining consistently high IVDOM at ≥ 25% moisture the order of effectiveness was P1 > P2 = P3 > S = B1 = B2. The slight effects of P2 and P3 on IVDOM may not be evident in the field. Key words: Rehydrated alfalfa hay, in vitro digestibility, microbial changes