PROTEIN PRESERVATION AND RUMINAL DEGRADATION OF ENSILED FORAGE TREATED WITH HEAT, FORMIC-ACID, AMMONIA, OR MICROBIAL INOCULANT

The objectives of this study were to determine whether treatment of fo rage with heat would reduce proteolysis during subsequent fermentation . In Experiment 1, direct-cut barley forage and alfalfa were untreated , microwaved, or steamed and then ensiled in laboratory silos as wilte d forages. Silages of microwaved or steamed forage showed a marked inc rease in N bound to neutral detergent fiber and in the recovery of pro tein; however, alfalfa silages also had high pH values and concentrati ons of butyric acid. In Experiment 2, steam heating was compared with formic acid and NH3 treatments for the prevention of proteolysis in al falfa silages. Silage of steamed alfalfa had a greater amount of N bou nd to neutral detergent fiber and greater recovery of protein than did control silage or silages of forage treated with formic acid or NH3. Silage of steamed forage had lower pH values than did silages of wilte d, direct-cut, or control forage. Microbial inoculant added to steamed forage increased the recovery of protein. Silage of steamed forage ha d less aerobic stability than did silage of direct-cut forage. Ruminal degradability of crude protein (CP) and organic matter of silage from both experiments was evaluated. Degradability of CP was 8 to 26 perce ntage units lower in silages of microwaved or steamed forage in Experi ment 1 than in silage of unheated forage because of slower degradation rates, but all had similar undegraded CP after incubation for 72 h. I n Experiment 2, wilting, steam, formic acid, and NH3 treatments affect ed CP degradability similarly, but CP degradability was decreased when compared with silage of direct-cut forage without treatment.