Short-term use of monensin and tannins as feed additives on digestibility and methanogenesis in cattle

R. Bras. Zootec., 49:e20190098, 2020 https://doi.org/10.37496/rbz4920190098 Ruminants Full-length research article Brazilian Journal of Animal Science e-ISSN 1806-9290 www.rbz.org.br Short-term use of monensin and tannins as feed additives on digestibility and methanogenesis in cattle Flavio Perna Junior1* , Diana Carolina Zapata Vásquez1 , Rodrigo 1 Gardinal , Paula Marques Meyer2 , Alexandre Berndt3 , Rosa Toyoko Shiraishi Friguetto4 , João José Assumpção de Abreu Demarchi5 , Paulo Henrique Mazza Rodrigues1 1 *Corresponding author: Received: May 6, 2019 Accepted: February 19, 2020 How to cite: Perna Junior, F.; Zapata Vásquez, D. C.; Gardinal, R.; Meyer, P. M.; Berndt, A.; Friguetto, R. T. S.; Demarchi, J. J. A. A. and Rodrigues, P. H. M. 2020. Short-term use of monensin and tannins as feed additives on digestibility and methanogenesis in cattle. Revista Brasileira de Zootecnia 49:e20190098. https://doi.org/10.37496/rbz4920190098 Copyright: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Universidade de São Paulo, Faculdade de Medicina Veterinária e Zootecnia, Departamento de Nutrição e Produção Animal, Pirassununga, SP, Brasil. 2 Instituto Brasileiro de Geografia e Estatística, Pirassununga, SP, Brasil. 3 Embrapa Pecuária Sudeste, São Carlos, SP, Brasil. 4 Embrapa Meio Ambiente, Jaguariuna, SP, Brasil. 5 Instituto de Zootecnia, Nova Odessa, SP, Brasil. ABSTRACT - The objective was to assess the effects short-term use of monensin and Acacia mearnsii tannins as feed additives on nutrient intake, digestibility, and CH4 production in cattle. Six rumen-cannulated Holstein cows were distributed in two 3×3 Latin square experimental design, and each experimental period lasted 21 days. The basal diet was composed of corn silage and concentrate in a 50:50 dry matter (DM) basis proportion. Treatments were control, monensin (18 mg kg−1 of DM), and tannin-rich extract from Acacia mearnsii (total tannins equivalent to 6 g kg−1 of DM). Nutrient intake and apparent digestibility coefficients were not affected by the addition of monensin or tannins to diets. However, tannins showed a tendency to reduce crude protein digestibility. Monensin decreased CH4 emission by 25.6% (g kg−1 of body weight) compared with the control treatment. Monensin is more effective than Acacia mearnsii tannins in reducing CH4 emissions in the short term, considering a diet of the same roughage:concentrate proportion for cattle. Keywords: animal nutrition, gas production, methane, ruminants Introduction Methane gas and its environmental effects, particularly on the greenhouse effect, have been increasingly studied, and strategies for emission reduction are increasingly sought (Guan et al., 2006; Wanapat et al., 2015). Methane is a byproduct of the ruminant digestive process and, depending on the components of the diets, its production might represent an energy loss of feed intake up to 2-12% (Johnson and Johnson, 1995). Feed additives such as monensin are widely used to improve feed efficiency of ruminants; however, the use of this ionophore was banned by many countries, and alternatives have been studied (Wanapat et al., 2015), among them the use of Acacia mearnsii tannins (Carulla et al., 2005; Grainger et al., 2009). The extraction of tannins from Acacia mearnsii occurs on an industrial scale in Brazil, because they are widely used in leather tanning, effluent treatment, and in the food sector. Polyphenolic compounds are the main active substances of tannins, which can be classified into hydrolyzable (HT) and condensed (CT), depending on the molecule structural arrangement and the reactivity. Goel and Makkar (2012) highlighted that tannins have great potential to reduce CH4 production; however, more research on Short-term use of monensin and tannins as feed additives on digestibility and methanogenesis in cattle Perna Junior et al. 2 cows is needed to know the best dosage without decreasing organic matter digestibility and animal production. Studies carried out with monensin or tannins on enteric CH4 mitigation demonstrated that additive effectiveness depends on the source and its dietary levels (Oliveira et al., 2005) and species and physiological state of the animals (Makkar, 2003a). According to Johnson and Johnson (1995), after a short-term use (30 days), CH4 production levels return to those observed before monensin administration, probably due to the ability of the microbiota to adapt to the ionophore. Rumen microbes can adapt to tanniniferous diets by increasing the proportion of tannin-resistant bacteria in the rumen, therefore, mitigating the inhibitory effects of these secondary plant compounds (Smith et al., 2005). Staerfl et al. (2012) showed that Acacia mearnsii tannin extract might be useful to mitigate enteric CH4 formation in maize silage-based diets in the long term (nine months). Therefore, it is important to evaluate its short-term effectiveness. The hypothesis of this study is that the inclusion of monensin or low dose tannin extracts from Acacia mearnsii as feed additives in the short term can reduce methanogenesis without altering digestibility. The objective was to compare low-dose tannins to the known monensin effect on intake, digestibility, and methanogenesis in cattle. Material and Methods The trial was conducted in Pirassununga, state of São Paulo, southeastern Brazil (21°59'45"S, 47°25'37" W, and 625 m above sea level). All procedures involving animal care were conducted in accordance with the Institutional Animal Care and Use Committee Guidelines (case no. 8580120514). Six rumen-cannulated dry Holstein cows (average body weight [BW] = 784±87 kg) were randomly allocated in individual stalls with sand bed, fans, and ad libitum access to feed and water. The feed was offered twice daily at 08:00 and 16:00 h as a total mixed ration in a 50:50 (dry matter [DM] basis) roughage to concentrate ratio. The basal diet was formulated to meet NRC (2001) nutrient requirements recommended for dry cows (Table 1). Before the beginning of the experiment, the animals were fed only corn silage. Table 1 - Ingredients and chemical composition (DM basis) of the basal diet Item Ingredient (g kg−1 of DM) Corn silage Dry ground corn grain Soybean meal White salt Dicalcium phosphate Limestone Vitamin and mineral premix1 Chemical composition (g kg−1 of DM) Dry matter (g kg−1) Ash Ether extract Crude protein Neutral detergent fiber Acid detergent fiber 1 Non-fibrous carbohydrates Total digestible nutrients Basal diet 500 347 122 5 1 5 20 531 76 35 120 271 144 498 799 Composition of vitamin and mineral premix per kilogram of product: 200 g of Ca; 60 g of P; 20 g of S; 20 g of Mg; 70 g of Na; 15 mg of Co; 700 mg of Cu; 700 mg of Fe; 40 mg of I; 1,600 mg of M (...truncated)