Abstract
Simple SummaryCondensed tannins are plant secondary compounds that can modulate ruminal fermentation by binding to proteins, reducing their ruminal degradation, and also reduce ruminal protozoa, which may improve the efficiency of nitrogen utilization. In this study, we tested increasing levels (0, 5, 10, 15, and 20 g/kg of diet dry matter) of Acacia mearnsii condensed tannins in the diets of Jersey steers. Condensed tannins did not affect intake and ruminal protozoa population, but reduced protein digestibility and decreased ruminal pH and acetate proportion. Overall, the tested doses of condensed tannins extract did not improve ruminal fermentation and nutrient digestibility.The objective of this study was to evaluate the effect of inclusion of condensed tannins (CT) from black wattle (Acacia mearnsii) on feed intake, ruminal protozoa population, ruminal fermentation, and nutrient digestibility in Jersey steers. Five ruminally-cannulated steers were used in a 5 × 5 Latin square design, with five periods of 20 days each (14 days for diet adaptation and six days for sample collection per period). Treatments were composed of dietary inclusion levels of condensed tannins at 0, 5, 10, 15, and 20 g/kg of diet dry matter. Intakes of dry matter, organic matter, ether extract, crude protein, neutral detergent fiber, and total digestible nutrients were not affected by condensed tannins. The ruminal pH was reduced linearly with tannin levels. Ruminal ammonia nitrogen concentration was not affected by tannins. Tannins reduced the molar proportion of acetate and did not affect the ruminal protozoal population, which might be related to the low doses used. Digestibilities of dry matter, organic matter, and neutral detergent fiber were not altered; however, there was a linear reduction in crude protein digestibility. Based on these results, CT extracts from black wattle are not recommended for improving nutrient utilization in steers at the tested levels.
Highlights
Tannins are secondary metabolites synthesized by plants [1] and, for a long time, have been considered antinutritional factors due to their adverse effects on feed intake and nutrient utilization by ruminants; tannins have been recognized as useful additives that can modulate microbial ruminal fermentation [2].Condensed tannins (CT) can bind to proteins and can prevent their rapid ruminal degradation, regulating the rate of nitrogen release in the rumen, increasing the flow of essential amino acids to the small intestine [3]
The objective of this study was to evaluate the effect of inclusion of increasing levels of CT extracted from black wattle (Acacia mearnsii) on feed intake, ruminal fermentation, ruminal protozoa population, and nutrient digestibility in Jersey steers
Intakes of dry matter (DM), organic matter (OM), CP, EE, NDF, Non fiber carbohydrates (NFC), and total digestible nutrient (TDN) were not affected by CT inclusion (Table 3)
Summary
Condensed tannins (CT) can bind to proteins and can prevent their rapid ruminal degradation, regulating the rate of nitrogen release in the rumen, increasing the flow of essential amino acids to the small intestine [3]. These compounds can be complexed with other nutrients, such as carbohydrates and minerals [4,5]. Dickhoefer et al [8] observed a reduction in the acetate to propionate ratio when quebracho tannins (Schinopsis sp.) were fed at 40 and 60 g/kg of diet dry matter (DM). Aguerre et al [9] evaluated levels of 4.5, 9, and 18 g/kg of diet DM and did not find effects on pH, total volatile fatty acids, molar proportions of acetate, propionate, and the acetate propionate ratio, whereas a reduction in ruminal ammonia concentration was observed
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