Abstract

HOLGUIN, Vilma A. et al. Effect of a Pennisetum purpureum and Tithonia diversifolia silage mixture on in vitro ruminal fermentation and methane emission in a RUSITEC system. Rev. mex. de cienc. pecuarias [online]. 2020, vol.11, n.1, pp.19-37.  Epub June 11, 2020. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v11i1.4740.

Livestock diets in the tropics are traditionally based on grass species, with significant consequent nutritional limitations. Balancing the diet requires supplementation with forage species offering high quality protein. An artificial rumen simulation technique system (RUSITEC) was used to digest a mixture of the grass Pennisetum purpureum (PP) and the sunflower Tithonia diversifolia (TD). Evaluations were done of the effects of added lactic acid bacteria on rumen kinetics and methane (CH4) release. Four treatments were analyzed: T1) a control with 100% PP silage with no inoculum; T2) a PP/TD (67:33%) mixture with no inoculum; T3) a PP/TD (67:33%) mixture inoculated with the lactic acid bacteria (LAB) Lactobacillus paracasei T735; and T4) a PP/TD (67:33%) mixture inoculated with the commercial Sil-All®4x4 LAB. Data were analyzed with a completely random design. Ammonium concentration did not differ (P>0.05) between the treatments (T2, T3 and T4) and the control (T1). The T4 treatment lowered volatile fat acids by 57 % compared to the control (P<0.001). Methane release was also lower (P<0.05) in T4 (1.36 mmol/g) than in the control (2.43 mmol/g), although levels were also relatively low in T3. The ciliate protozoa population did not differ among the treatments or with the control (P>0.05). The decrease in methane emission per gram dry matter in the PP/TD silages was probably due to lower fiber degradation levels. This suggests that methane emissions were lower per unit of edible animal protein produced even though the total amount of methane released did not differ.

Keywords : Defaunation; Fiber; Protozoa; Digestion; Silage.

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