Influence of Acacia Mearnsii Fodder on Rumen Digestion and Mitigation of Greenhouse Gas Production

Abstract

In recent years, the worrying generation of GHG from ruminant production has generated widespread interest in exploring nutritional strategies focused on reducing these gases, presenting the use of bioactive compounds (tannins) as an alternative in the diet. The aim of this research was to determine the effect of the addition of different levels of Acacia mearnsii on ruminal degradation, nutrient digestibility, and mitigation of greenhouse gas production. A completely randomized design with four treatments and six repetitions was used. The treatments were: T1, T2, T3, and T4 diets with, respectively, 0%, 20%, 40%, and 60% A. mearnsii. The rumen degradation kinetic and in vitro digestibility, and the production of gas, CH4, and CO2 were evaluated. In situ rumen degradation and in vitro digestibility of DM and OM showed differences between treatments, with T1 being higher (p < 0.05) in the degradation of the soluble fraction (A), potential degradation (A + B), and effective degradation for the different passage rates in percent hour (0.02, 0.05, and 0.08), compared to the other treatments. Rumen pH did not show differences (p > 0.05) between treatments. The lowest (p < 0.05) gas, CH4, and CO2 production was observed in treatments T1 and T2 with an approximate mean of 354.5 mL gas/0.500 g fermented DM, 36.5 mL CH4/0.500 g fermented DM, and 151.5 mL CO2/0.500 g fermented DM, respectively, compared to treatments T3 and T4. Under the conditions of this study, it was concluded that it is possible to replace traditional forages with up to 20% of A. mearnsii, without observing changes in the production of greenhouse gases with respect to the control treatment (0% of A. mearnsii); however, A. mearnsii is not usable because it significantly decreases rumen degradability of DM and OM, which would considerably affect the production in animals.

Rumen Fermentation Profile and Greenhouse Gas Mitigation of Three Forage Species from Agroforestry Systems in Dry and Rainy Seasons

“…The ruminal pH evidenced in the present study (Table 1) is consistent with that reported by Vargas-Ortiz et al [25], who consider positively benefit the activity of microorganisms that degrade cellulose.…”

“…To such an extent that negative effects on productive performance, feed consumption, digestion and animal health have been evidenced. Effects that are probably attributed to: (i) interaction of CT with salivary glycoproteins and subsequent decrease in feed palatability, (ii) greater permanence of feed in the rumen as a consequence of decreased substrate digestibility, (iii) intoxication by the excessive consumption of CT (>55 g CT/kg DM) and (iv) reduced intestinal enzymatic activity of trypsin, amylase and amino acid synthesis [25].…”

Potential Effect of Dietary Supplementation of Tannin-Rich Forage on Mitigation of Greenhouse Gas Production, Defaunation and Rumen Function

“…This is evidenced in the decrease in ruminal degradation and digestion in this study in diets T1 and T2. Vargas-Ortiz et al [ 33 ] and Kozloski et al [ 51 ], also found low digestibility when incorporating CT from A. mearnsii as forage and extract, respectively. The greater in situ degradation and in vitro digestibility of DM, evidenced in the present study, is probably due to the absence (T1: 0%) or low content of tannins in the diet (T2: 3% CT), that is an amount less than 5% of tannins [ 52 , 53 , 54 ].…”

“…Thus, using Acacia mearnsii as forage for ruminants is a valuable alternative due to its wide distribution around the world and its ability to adapt to temperatures between 14.7–27.8 °C, as well as for presenting considerable quantities of bioactive compounds, mainly CT (35% to 45%), due to the antimethanogenic effect that this compound can provide [ 33 ]. Previous research has shown variability in the tannin effects on ruminal fermentation.…”

“…Waghorn et al [ 32 ] showed in their study a higher weight gain and milk production (30% and 11%, respectively) in small ruminants fed tannin rich forages. However, Vargas-Ortiz et al [ 33 ] found negative effects on the degradation and digestibility of DM and OM when incorporating A. mearnsii forage in non-fibrous diets containing Lolium perenne and Medicago sativa . Similarly, Ávila et al [ 34 ] mention the absence of effects on the protozoa population when using extract of A. mearnsii rich in CT in diets high in grain (Tifton 85 hay (60%), ground corn (30.7% to 33.7%) and soybean meal (52.1% to 58.4%)).…”