Impact of a tannin extract on digestibility, ruminal fermentation and duodenal flow of amino acids in steers fed maize silage and concentrate containing soybean meal or canola meal as protein source

Abstract

Four Holstein steers (297 ± 56 kg of body weight (BW)) fitted with duodenal cannula and rumen catheter, were housed in metabolism cages and used in a 4 × 4 Latin Square trial to evaluate the effect of both protein source and Acacia mearnsii tannin extract on digestibility, ruminal fermentation, rumen microbial protein synthesis, N utilization and on duodenal flow of individual amino acids. The diet was offered at restricted amount of 25 g of dry matter (DM)/kg BW and consisted of maize silage plus concentrate, in a proportion of 0·7:0·3 (DM basis) respectively. Concentrate was formulated with either soybean meal or canola meal as protein source, with or without 50 g/ kg of A. mearnsii tannin extract (i.e. 15 g/kg of total dietary DM). There was no effect of protein source on most variables. The apparent and true organic matter (OM) digestibilities, as well as neutral detergent fibre (NDF) digestibility were negatively affected by tannin extract inclusion without, however, affecting digestible OM intake. The amount of nitrogen (N) excreted in faeces increased whereas the urinary N excretion decreased in tannin extract treatments. No interaction time × treatment was detected for any rumen variable and no treatment effect was observed for rumen fluid pH and reducing sugars concentration. Rumen fluid concentration of ammonia N was lower for the canola meal plus tannin extract treatment. Rumen concentration of α-amino compounds was not affected by tannin extract but was higher when canola meal was the protein source. The duodenal flow of OM, total N, α-amino N and non-ammonia non-microbial N increased with tannin extract inclusion, whereas the duodenal flow of microbial N was not affected by treatment. For both protein sources, the amount of most individual amino acids flowing to the duodenum increased due to tannin extract addition. In conclusion, the dietary inclusion of 15 g/kg DM of tannin extract from A. mearnsii improved the amino acid supply independently of whether the protein source was canola meal or soybean meal, without affecting the amino acid profile, to steers fed maize silage plus concentrate, with a minor but significant impact on OM digestibility.

Effect of feeding condensed tannins in high protein finishing diets containing corn distillers grains on ruminal fermentation, nutrient digestibility, and route of nitrogen excretion in beef cattle1

“…Feed intake was, however, reduced in the cattle when the CT extract was increased to 3.5% (1.86% CT) of the diet. Likewise, there was no effect of up to 2.7% CT extract (A. mearnsii) on DMI of forage-based diets fed to beef steers (Ávila et al, 2015;Orlandi et al, 2015). Carulla et al (2005) fed CT extract (A. mearnsii) at a higher concentration of 4.1% (2.5% CT) of a forage-based diet to sheep and found a small but significant increase in DMI.…”

“…Condensed tannins (CT) are secondary plant metabolites with complex and diverse chemical structures with a general affinity for binding to protein and to a lesser extent complex carbohydrates (Mueller-Harvey, 2006;Waghorn, 2008). The CT extract of Acacia mearnsii is an industrial tannin that has been investigated for improving N utilization (Ávila et al, 2015;Orlandi et al, 2015) and reducing methane emissions (Carulla et al, 2005;Grainger et al, 2009) in ruminant production. One of the most consistent effects of feeding the CT extract is a reduction in ruminal protein degradation and urinary N excretion.…”

Effect of using Acacia mearnsii tannin extract as a feed additive on nutritional variables and productive performance in dairy cows grazing a temperate pasture

“…For example, the dietary inclusion of 15 or 18 g of TA/kg DM improved the duodenal amino acids supply and decreased the urinary N excretion in steers fed corn silage or oat forage, respectively, plus concentrate (Ávila, Kozloski, Orlandi, Mezzomo, & Stefanello, 2015; Orlandi, Kozloski, Alves, Mesquita, & Ávila, 2015). However, when dairy cows fed ryegrass‐based diets were supplemented with TA at contents ranging from 12.0 to 29.0 g/kg DM, a negative impact on feed intake and milk yield was observed (Grainger et al., 2009; Griffiths, Clark, Clark, & Waghorn, 2013).…”

Red clover silage: an alternative for mitigating the impact of nitrogen excretion in ovine production systems

“…Despite the lower apparent digestibility of DM and OM in the RC diet, the ruminal digestibility of these components (as a proportion of total digestibility), as well as the apparent and ruminal digestibility of fiber, did not differ between the treatments. Conversely, previous studies evaluating the inclusion of condensed tannins (as a modulator of ruminal fermentation) in animal diets reported a reduction in OM and fiber digestibility (Naczk et al, 1994;Ávila et al, 2015). This result evidenced that condensed tannins may also form complexes with bacterial enzymes and/or with polysaccharides such as cellulose and hemicellulose (Priolo et al, 2000), thus reducing fiber degradation.…”