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The preservation of high-moisture barley and the nutritional evaluation with monogastrics and ruminants Pringle, Dave Bruce


High-moisture barley, preserved either anaerobically, chemically or by drying, was evaluated in a series of digestibility and nitrogen utilization trials with monogastrics and ruminants. In the first of 3 phases, high-moisture barley HMB (17% moisture) from the Peace River region was preserved in experimental silos by: (1) airtight storage, (2) alkali - 3.2 g NaOH/kg HMB (air dry basis) in a 32% w/w solution, (3) acid - 1% mixture of 60:40 acetic-propionic acids and (4) drying - 8 tonnes per hour at 82°C. After 9 months of storage, these treatments were evaluated in a digestibility trial with pigs and a nitrogen balance trial with rats. In the pigs there was no treatment effect on dry matter digestibility, but neutral detergent fibre digestibility was reduced (P < 0.001) in the dried barley. True nitrogen digestibility, with both pigs and rats, was significantly (P < 0.001) reduced by alkali treatment. In the rat trial, alkali-treated barley depressed net protein utilization (NPU) by over 20%. Differences between the non-alkali treatments were small. Digestibility studies with sheep were not carried out on these treatments due to poor palatability results. In the second phase, barley from Lacombe was harvested at 33 and 12% moisture. The HMB (33% moisture) was either stored airtight or artificially dried (ADB) to 88% DM and the field-dried barley (FDB) (12% moisture) was either stored aerobically or reconstituted (RB) to 70% DM and stored airtight. These treatments were evaluated in a nitrogen balance trial with rats and a digestibility, nitrogen-retention trial with sheep. In the rat trial, true nitrogen digestibility was highest (P < 0.001) for HMB while biological valve was higher (P < 0.001) for both of the dry treatments. NPL) tended to be the same for all treatments. In the sheep trial, dry matter digestibility of RB was improved above ADB, but organic matter digestibility of both HMB and RB were greater than that of ADB (P < 0.01). Acid detergent fibre digestibility of HMB was highest (P < 0.001) followed by FDB and RB and then ADB. There was no treatment effect for either nitrogen digestibility or nitrogen retention. Straw from both HMB and FDB was also evaluated in sheep. Apparent dry matter, organic matter and nitrogen digestibility were all significantly (P < 0.001) greater for straw from HMB. The final phase of the study was conducted with barley of an unknown origin. Dry barley was reconstituted to 30% moisture (RB) and portions were treated with 3% NaOH (NaOH-RB) or 1% and 3% anhydrous ammonia (NH3-RB) on a w/w air dry basis. These treatments were again evaluated in a nitrogen balance trial with rats and a digestibility, nitrogen-retention trial with sheep. In the rat trial, true nitrogen digestibility for NaOH-RB was approximately 20% lower than the other treatments. Biological value and NPU were also depressed below all other treatments by NaOH-RB (P < 0.001). NPU for both 1 and 3% NH₃-RB were lower (P < 0.001) than RB after most of the NH₃ was allowed to evaporate for several days. However, there appeared to be no residual effect on protein utilization after the NH₃ was removed completely from the treated barley, as NPU for both 1 and 3% NH₃-RB were not different from RB. Dry matter digestibility was improved by all alkali-treatments (P < 0.001). In the sheep trial, both apparent dry matter digestibility and organic matter digestibility were significantly (P < 0.01) better for only the 3% NH₃-RB as compared to the other treatments. Acid detergent fibre digestibility was lower for 1 and 3% NH₃-RB than RB or NaOH-RB, between which treatments there were no significant differences. NaOH treatment reduced nitrogen digestibility by approximately 20 percentage units, but nitrogen-retention was unchanged between treatments with sheep.

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