Four forage sorghum silage additives evaluated

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Four Forage Sorghum Silage Additives Evaluated K. K. Bolsen, J. G. Riley and J. D. Hoover Summary Two trials were conducted to evaluate four forage sorghum silage additives: ammonium iso-butyrate, aureomycin, sodium hydroxide, and a mixture of acetic and propionic acids.A control silage received no additives.
In an animal performance trial, each of the five silages was fed to 15 heifer calves for 112 days.All heifers were full-fed silage plus 4 lb. of rolled milo and 2 lb. of a soybean meal supplement daily.There were no significant differences in gain or feed consumption.Heifers receiving sodium hydroxide silage required more feed per lb. of gain (P<.05) than those receiving ammonium iso-butyrate or organic acid silages.Feed cost per 100 lb.gain was lowest for heifers fed the silage with no additive.
In a digestion trial, each silage was fed to 3 wether lambs in two, 12-day preliminary and 7-day collection periods.Digestion coefficients for dry matter, organic matter, and nitrogen retention were not influenced by silage treatment; however, crude protein digestibilitv was lower (P<.05) for lambs fed the sodium hydroxide silage ration than for lambs fed any of the other four silage rations.
Silage analyses showed pH, ash percentage and butyric acid percentage highest in the sodium hydroxide silage.
These results indicate that feeding values of forage sorghum silage were not significantly improved by any of the four additives.
Many factors affect the fermentation and quality of corn and forage sorghum, the two principal silage crops in Kansas.Five of the factors are plant maturity and moisture content at harvest, fineness of chop, type of storage structure, and anaerobic conditions.Previous research with silage additives has focused on developing acid conditions in the silage or minimizing production of undesirable fermentation end-products.

Introduction
The four additives evaluated in these experiments may inhibit mold growth and alter fermentation or change the chemical structure and nutritive value of the silage.

Experimental Procedure
All forage sorghum used was grown in the same location and was the same variety.It was harvested between September 17 and 24, 1971, to minimize plant maturity differences between the silage treatments.Approximately 50 tons of each silage were ensiled in upright, concrete stave silos (10 ft.x 50 ft.)at about 68% moisture (at harvest).The forage chopper had a 2-inch recutter screen.Trial 2. Fifteen Ramboullet wether lambs averaging 90 lb.were used in a digestion and nitrogen balance trial.Each of the five silage treatments was fed to three lambs in two, 12-day preliminary and 7-day collection periods.The rations contained 78 percent silage and 22 percent soybean meal based supplement (dry matter basis).
During each preliminary period, silage was offered free-choice from day 1 through day 10.Silage voluntary intake was determined for each lamb on days 8, 9, and 10.Chemical analyses of the silages are shown in table 2. Only slight differences were obtained in proximate and structural components among the five silages.Ash content was highest and neutral detergent fiber content lowest in the NaOH silage.Crude protein analysis indicates that only about 20 percent of the nitrogen in the AIB was recovered in the silage after fermentation and storage.AIB contains 84 percent crude protein equivalent so the calculated crude protein in the AIB-treated silage when ensiled was 6.40 percent.Its crude protein content was 5.40 percent when fed.
Acid percentages in the silages after fermentation varied widely.The control and aureomycin-treated silages had similar amounts of acetate, lactate and butyrate.The AIB-treated silage contained 1.46 percent iso-butyrate.The NaOH-treated silage had the highest pH (6.40), traces of lactate.It was also a much darker color (dark brown the highest percentage butyrate, and only to black) than the other four silages.
Performance of heifers in trial 1 is shown in table 3. None of the differences in daily gain or feed consumption differed significantly.Heifers fed AIB and organic acid silage rations tended to gain faster than heifers fed the other three silage rations.NaOH silage was consumed in the largest amounts; but heifers fed this silage required more feed per lb. of gain (P<.05) than those fed AIB or organic acid silages.Also, consumption was more variable between pens of heifers being fed the NaOH silage than those fed the other silages.Heifers fed the control silage ration had the lowest feed costs per 100 lb. of gain.Adding NaOH or the organic acid mixture increased feed costs 18 and 8 percent, respectively.
Results of trial 2 are presented in table 4. Apparent digestion coefficients for dry matter and organic matter were not significantly affected by silage treatment.Crude protein digestibility was significantly lower (p<.05) and percentage of nitrogen retained tended to be lower in lambs fed the NaOH silage ration than in those fed any other ration.Lambs fed NaOH silage consumed 14 to 20 percent more silage dry matter during the preliminary periods than any other group.

Table 1 .
Composition of the Supplement.
a None detected.
c a One heifer died (accidental cause).b Dry matter basis.c