Reduction of enteric methane emission by using tannin supplementation in grazing goats

Abstract Text: This study aimed providing condensed tannin (Schinopsis quebracho) to reduce methane (CH₄ ) emission and if it keeps through time. 12 Anglo Nubian breed goats were used with an average 56 kg of body weight (BW) in Tanzaniagrass (Panicum maximum) pasture with access to water and mineral salt managed under intermittent stocking with 11 hours of grazing period during 5 days. The treatments were: control (without tannin-WT) and addition of tannin (AT). Condensed tannin contained 70% (± 2) as guarantee level in powder form was fed (at 6:00 PM) once a day individually for each animal orally 0.31 g per kg of metabolic BW (BW^0.75). Tannin was provided for 91 days with three collections of methane with intervals of 30 days and period of feces collection to estimate dry matter (DM) intake. CH₄ emission was estimate by technique tracer gas SF₆ (sulfur hexafluoride). Variables for CH₄ emission were analyzed by SAS software in a completely randomized design with two treatments in a split plot in time with two longitudinal factors (5 days and 3 periods) and 6 replications (animals). F-test (α = 5%) was used for comparisons between treatments and orthogonal polynomial contrast for days and grazing cycles. There was no difference (p> 0.05) between treatments for g CH₄ emission per animal (21.88 ± 0.8 and 20.52 ± 0.8); kg DM intake (43.07 ± 2.1 and 42.73 ± 2.0) and percentage of loss of gross energy intake (14.65 ± 0.7 and 14.54 ± 0.7) respectively for WT and AT. The higher DM intake was observed (P<0.05) in WT (562 ± 9.2 g / day) treatment compared to AT (510 ± 8.7 g / day). CH₄ emission calculated in relation to BW^0.75 resulted in larger (p<0.05) amount in WT (1.13 ± 0.04) than AT (0.96 ± 0.4) group. There was not observed (p>0.05) reducing CH₄ emission per animal through time per CH₄/animal (20.66 g ± 0.8, 1.0 ± 22.51 g and 20.42 g ± 1.2) and per BW^0.75 (1.03 ± 0.04, 07 ± 0.04 and 1.04 ± 0.06) respectively for the period 1, 2 and 3. The similarity in CH₄ production through time is probably due to the amount of tannin provided staying below the required limits for gas reduction and affecting only the fiber digestibility which caused decrease DM intake but no effect on CH₄emission and consequently through time.

Keywords: CH₄; gas emission reduction; tropical pasture