PSXI-5 Impact of Different Vaccine Formulations in Reducing Methane Production in Beef Cattle

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Abstract Ruminants are the main contributor to agricultural emissions of the greenhouse gas methane (CH4), which is one of the main greenhouses causing global warming. The objective of this pilot study was to test the effectiveness of 4 different vaccine formulations (VF) on methane abatement in beef cattle. Two weeks before the start of the trial, steers aged between 9 to 10 months with body weights (236.57 ± 20,61 kg) were trained to use the GreenFeed (C-Lock Inc., Rapid City, SD, USA) system for methane measurement. At the end of the adaptation period, animals that best accepted the GreenFeed system were selected (n = 20) for the experiment. Animals were randomly assigned to one of four different formulations of vaccine treatments as well as a control group. Each treatment group had the following number of steers: Control/Untreated (UTD, n = 4), F1/OVA_ adj (n= 4), F2/Ag1_adj (n= 4), F3/pep1_Ag1_adj (n = 4), F4/pep2_Ag1_adj (n = 4). On day 0, vaccine was administered followed by booster injections on day 20 with 2mL injected intramuscularly in the anterior region of the neck both times. Through jugular venipuncture, blood was collected into a 10 mL vacutainer tube (Becton Drive, Franklin Lakes, NJ) to obtain serum on day 34 post-treatment to determine methanogen-specific IgA and IgG concentration. Rumen fluid (14 mL) was collected on pre-treatment (d0), and post treatments (d 20 and d 34) into a glass jar using an esophageal stomach tube connected to a vacuum and occurred pre-feeding to determine the relative abundance of total archaea and Methanobrevibacter ruminantium. Methane production was sampled on individual animals using the GreenFeed system pre-treatment (d -8 to -1) and post treatment (d 22 to d 29). The GreenFeed system estimates daily methane production (DMP, g/day) by measuring gas concentration for 3 to 5 mins on individual animals. Data were analyzed as one-way ANOVA with Tukey’s HSD post-hoc analysis. Preliminary results showed overall mean methane emission pre-treatment (165.853 ± 2.69 g/d) compared with post-treatment (192.164 ± 2.33 g/d) increased by 16%. However, methane emissions between treatment groups showed statistical difference (P < 0.001) specifically between treatment group F2 and F4. Serum concentration of IgA and IgG, ruminal relative abundance of total archaea and Methanobrevibacter ruminantium did not show significant difference (P > 0.10). From the results, vaccine formulation F2 and F4 showed effects in the methane emission between the treatment groups. Future research will consider increasing the vaccine dosage and analyzing more samples. This project was supported by HelixNano.