The effect of feeding a mix of condensed and hydrolysable tannins to heifers on rumen fermentation patterns, blood urea nitrogen and amino acid profile

Authors: MARSHALL, CAMERON - Lincoln University - New Zealand; Beck, Matthew; GARRETT, K - Lincoln University - New Zealand; CASTILLO, ALEJANDRO - University Of California, Davis; BARRELL, GRAHAM - Lincoln University - New Zealand; AL-MARASHDEH, O - Lincoln University - New Zealand; GREGORINI, P - Lincoln University - New Zealand

Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2022
Publication Date: 7/22/2022
Citation: Marshall, C.J., Beck, M.R., Garrett, K., Castillo, A.R., Barrell, G.K., Al-Marashdeh, O., Gregorini, P. 2022. The effect of feeding a mix of condensed and hydrolysable tannins to heifers on rumen fermentation patterns, blood urea nitrogen and amino acid profile. Livestock Science. 263(2022). Article e105034. https://doi.org/10.1016/j.livsci.2022.105034.
DOI: https://doi.org/10.1016/j.livsci.2022.105034

Interpretive Summary: Agricultural practices that include cattle for meat and dairy have the potential to impact the environment negatively because of the production of methane and excretion of nitrogen in urine. Tannins are a plant secondary compound that form bonds to proteins, thereby reducing the proteins availability for ruminal fermentation, and may reduce environmental impacts associated with methane production and urinary nitrogen excretions. However, still more research is needed to investigate the effects of tannins on ruminal fermentation characteristics, blood urea nitrogen concentration and ruminal microbes. Accordingly, scientists from Lincoln University (New Zealand), University of California-Davis, and ARS (Bushland, Texas) conducted a preliminary study using Holstein-Fresian x Jersey heifers. The heifers were fed ryegrass haylage and 6.6 pounds of soybean meal per day. Heifers then received either an oral drench of water only as a control or an oral drench of tannins dissolved in water at a target rate of 0.15% of dry matter intake. Providing tannins reduced blood urea nitrogen concentration by 13%, shifted rumen fermentation and decreased the relative abundance of methanogenic microbes. All of these results suggest reduced environmental impacts when tannins are provided.

Technical Abstract: The objective of this pilot study was to begin to evaluate the effect of feeding a mix of condensed and hydrolysable tannins to heifers on rumen fermentation patterns, blood urea nitrogen (BUN) and amino acid profile. Four growing Holstein-Friesian × Jersey heifers with a mean live weight of 319.5 ± 8.38 kg and a mean body condition score of 4 ± 0.17 out of 10 were used in a cross-over design. Heifers were either orally administered the mixed tannin treatment at 0.15% of daily DMI or a control dose of water whilst consuming perennial ryegrass baleage and soybean meal for 12 days and then received the other treatment in the following phase. Administration of mixed tannins reduced non-glucogenic volatile fatty acid (VFA) production by 2%, the acetate to propionate (A:P) ratio by 13%, and the relative abundances of specific methanogenic archaea – i.e., Methanobrevibacte and Methanosarcina. The tannin treatment also reduced BUN concentration by 12% in comparison with the control dose of water, which indicates reductions of daily urinary nitrogen excretion and therefore environmental impact. The effects of ingestion of mixed tannins on rumen function in this study would be expected to result in a reduction of both methane and urinary nitrogen excretion and thereby reducing the environmental impact of heifers consuming conventional feeds.