Rosario-López, Carlos A.

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    Efecto de la aplicación de inóculos microbianos sobre las características fermentativas, estabilidad aeróbica y consumo voluntario de ensilaje de gramíneas tropicales naturalizadas
    (2012) Rosario-López, Carlos A.; Rodríguez-Carías, Abner A.; College of Agricultural Sciences; Randel Følling, Paul F.; Jiménez Cabán, Esbal; Latorre Acevedo, José R.; Department of Animal Science; Armstrong, Aristides
    Two experiments were conducted to determine the effects of an additive containing two different microbial inoculants of homo-fermentative and hetero-fermentative lactic acidproducing bacteria (LAPB), on the fermentation characteristics, aerobic stability (AS), and intake by lambs of native tropical grasses (NTG). Both experiments included an “in vitro” and “in vivo” phase. Prior to ensiling, vegetative material was treated or not with the inoculants, applied at 106 cfu/g of fresh material for Commercial Inoculant 1 and 1010 cfu/g of fresh material for Commercial Inoculant 2. To determine fermentation characteristics, treatments were applied to weighted portions of NTG, manually mixed, and packed into PVC laboratory silos. Silages from each treatment were analyzed at seven ensiling periods (0, 4, 7, 14, 21, 28, and 35 days) to determine pH and fermentation products (organic acids and NH3-N). For AS determination, triplicate silos from each treatment were emptied after 35 d of ensiling, placed into styrofoam containers lined with plastic bags, and exposed to air during 5 days. Temperature was monitored every six hours during the five days, by means of thermometers embedded in the surface of the expose silage and pH was determined after 0, 1, 3, and 5 d of aerobic exposure. To determine voluntary intake, NTG were fermented with or without the inoculant of LAPB during 35 days in 55 gallons capacity plastic bags. For each “in vivo” trial, six meat-type crossbred sheep were used, three fed each of two experimental diets, during 5 days. The diets had in common 50% tropical grass hay and 50% NTG fermented with or without with the LAPB and were offered daily at 3% dry matter basis (DMB) of body weight. Experiment 1; the pH of the NTG decreased to final values between 4.38 to 4.39 in the two treatments, thus approaching the ideal level of 4.2 characteristic of a quality silage. Of the organic acids, lactic acid (LA) was the only one that showed initially a significant difference in favor of the control treatment, then descended to final concentrations of less than 0.15% on the DMB (P <0.05); NH3 concentration as well as the ratio ammonia nitrogen/total nitrogen (NNH3/N-Total) remained at very low levels, indicative of little proteolysis. Temperature of the ensiled NTG in AS test, showed minimal increases in both treatments. This indicates a good resistance to aerobic spoilage. However, after the third day of exposure to air, the pH was greater (P <0.05) for LAPB treatment, when compared with the control (4.39 vs. 4.52). Silage dry matter (DM) intake was greater (P> 0.05) in lambs fed NTG inoculated silage than in those receiving the control silage without inoculant (495.2 vs. 316.9 g / d), as was total DM intake (1059 vs. 905 g / d). Experiment 2; silage without inoculant of LAPB, generally showed numerically greater (P> 0.05) concentrations of the organic acids analyzed, its pH was higher (P <0.05) at each observation interval (final values, 5.29 vs. 4.77). Concentrations of NH3 and N-NH3/N-Total ratio fluctuated without significance difference between treatments. In the AS test, the inoculated, silage was better by the criterion of pH (P <0.05), values at 5 days of exposure being 5.32 vs. 5.59, but not with regard to temperature (27.41 vs. 27.22 oC). Lambs fed NTG silage without inoculant consumed numerically more silage DM (525.3 vs. 435.3 g / d) and total DM (1172 vs. 1063 g / d). The addition of neither of the two inoculants of LAPB, achieved great improvement in the fermentation characteristics of NTG, which proved acceptable in control silages. In both experiments, silage with and without inoculants were stable during 5 days under aerobic conditions. There was a positive effect of inoculation with Commercial Inoculant 1 on voluntary intake, in the first experiment but not with the Commercial Inoculant 2 in the second trail.