Elsevier

Small Ruminant Research

Volume 205, December 2021, 106559
Small Ruminant Research

Effects of chestnut bark (Castanea spp.) tannin extracts on selectivity, dry matter intake, weight gain, and enteric methane emission from llamas (Lama glama) under grazing conditions in the high Andean grasslands

https://doi.org/10.1016/j.smallrumres.2021.106559Get rights and content

Highlights

  • Tannins from chestnut bark reduced the emission of enteric methane from llamas by 30 %.

  • Dry matter consumption in llamas under grazing conditions was 1.55 % of live weight.

  • Llamas grazing in the high Andean grasslands selected 91.5 % of grasses/graminoids.

Abstract

The present study's objective was to evaluate the effects of chestnut bark (Castanea spp.) tannin extracts on selectivity, organic matter intake, dry matter intake, weight gain, and enteric methane emissions from llamas as a mitigation strategy. The study was carried out from August to September 2016 at the Experimental Centre IVITA-Marangani-Cusco-Peru (4200 m above sea level). Twenty young female llamas (4.1 ± 0.34 years old) with an average live weight of 99.2 ± 5.21 kg at the beginning of the experiment were used. The llamas were allocated to two treatments (control and tannin). Organic matter intake was calculated from organic matter excretion and organic matter digestibility, the dry matter intake was calculated by using percentage of ash content of the diet, and methane emissions were determined using the SF6 tracer technique over seven days, while the llamas grazed 9 h per day on a native pasture dominated by Festuca rigescens and Calamagrostis amoena. The tannin group was provided with tannin extract derived from chestnut bark at a dose of 12 g/day orally before grazing. The selectivity in both groups was similar (P >  0.05), consuming 91.5 % of grasses and graminoids, 84.5 % of leaves and stems and 61.5 % of green matter. The control group's feed intake was 1614.64 g/day, while that of the Tannin group was 1624.70 g/day (P >  0.05). Weight gain at 31 days was similar for both groups (P >  0.05) (5.7 and 5.2 kg for the control and tannin groups, respectively). Enteric methane emissions were 27.35 ± 1.573 g/day for the control group and 19.32 ± 1.057 g/day for the tannin group (P <  0.001); showing the same tendency when methane emissions were compared according to llama live weight with 0.24 ± 0.012 and 0.17 ± 0.008 g/kg LW/day for the control and tannin group, respectively, (P <  0.001). It was concluded that the use of tannins in the present study reduced methane emissions by approximately 30 % without affecting selectivity, Dry matter intake, and weight gain in llamas.

Introduction

Although Peru is one of the countries with low greenhouse gas production (GHG), it is estimated that livestock contributes 14.5 % of GHG (after land-use and energy changes of 53.1 and 23.3 %, respectively). It is worth mentioning that methane (CH4) from enteric fermentation and manure emissions from ruminants are the main contributors of GHGs in the livestock sector in Peru, representing 64 % of total GHG production in that sector (García et al., 2007)

Peru is the second-largest llama (Lama glama) producer worldwide, with 746,269 animals (representing approximately 27 %, of the World population). Approximately 70 % of the llama population in Peru is in Puno, Cusco, Arequipa, and Huancavelica (INEI, 2012).

Due to its rusticity and adaptability to various ecological zones, the llama provides an essential service as a pack animal within the small breeder's agricultural system, fulfilling an important role in Andean culture's economic and social context. Producers generally maintain these animals until an advanced age of 12–14 years. In addition, interest in llama breeding is increasing due to its peculiarities of adaptation to high altitudes and low-temperature conditions (Franco et al., 2017).

The puna grassland plays a key role economically, providing food security and several other goods and services to society. The structure and function of this ecosystem are threatened by land degradation and climate change. Ecological models predict changes in vegetation cover, productivity, and carrying capacity of pastures, a situation that will most likely affect the local economy and food availability. In this scenario, it is urgent to develop conservation policies and sustainable management of grasslands that contribute to mitigating GHG emissions generated by the livestock activity (Flores, 2016).

Methane is a GHG whose global warming potential has been 28 times greater than that of CO2 over a 100-year horizon (IPCC, 2014). In domestic ruminants, cattle and buffalo are the main emitters of CH4 (Monteiro et al., 2018). The CH4 generated in the rumen as a percentage of the energy of the feed consumed generally varies from 7 to 10% (Knapp et al., 2014), but variations from of 2–12% have also been reported (Johnson et al., 1993).

Camelids have unique digestive characteristics, such as longer feed retention, high rate of passage of the liquid phase, greater digestibility of fibrous feeds, and greater saliva production for buffering activity (San Martín and Bryant, 1989), characteristics that allow them to make more efficient use of high-Andean forage resources. However, the nutritional information available in these species is still scarce, and there are few studies dedicated to nutrient utilization and excretion of digestibility byproducts, such as CH4, under these conditions.

The production of CH4 by ruminants has received considerable attention from the scientific community, and it is expected that its reduction in animals should have positive effects on animal productivity (Moscoso et al., 2017b). For this purpose, several researchers are testing strategies for enteric CH4 emission reduction, by dietary manipulation (Muñoz et al., 2015; Moscoso et al., 2017b), ruminal microbiota manipulation, and animal selection (Pinares-Patiño et al., 2013).

Cattle in developing countries are primarily maintained on high-fibre diets with little or no concentrate, resulting in increased ruminal methanogenesis (Goel and Makkar, 2011). Therefore, the use of forage species rich in secondary plant metabolites (SPM) in many parts of the tropics is increasing to improve animal performance and reduce CH4 emission (Goel and Makkar, 2011).

Condensed tannins (CT), also known as proanthocyanidins, are secondary metabolites of plants (Waghorn, 2008) currently being investigated in several laboratories (Goel and Makkar, 2011). The term "tannin" derives from the tanning of skins to create leather; Tannins also contribute to the astringency of many popular drinks such as tea and wine (Waghorn, 2008).

The role of tannins in plant metabolism is largely unknown, although several hypotheses have been proposed; however, their effects on ruminant digestion are becoming more apparent. Condensed tannins bind to proteins in the rumen, reducing protein degradation, and when dietary crude protein (CP) concentrations exceed animal requirements for CP, these effects can improve performance. However, when dietary CP concentrations are low, and fibre concentrations are high, CTs are nearly always detrimental (Waghorn, 2008).

Forage sources containing CTs have shown significant effects in reducing CH4 emissions (Pinares-Patiño et al., 2003; Moscoso et al., 2017b). It has been postulated that CTs reduce ruminal methanogenesis by decreasing hydrogen formation and also by directly inhibiting the activity of methanogenic microorganisms (Patra and Saxena, 2011); levels of reduction were reported to be up to 23 % kg−1 DM consumed (Moscoso et al., 2017b)

Finally, it is worth noting that there are very few works measuring enteric CH4 emission from llamas under high Andean conditions, and the results are contradictory.

Section snippets

Location of the study

The field study was carried out at the South American Camelids CICAS "La Raya" Research Center located at an altitude of 4200 m above sea level in Maranganí district, Canchis, Cusco, Peru. Gas analysis (CH4 and SF6) was carried out in the Laboratory of Climate Change and Animal Production in the Faculty of Agrarian Sciences at the National University of San Antonio Abad of Cusco, and feed analyses were carried out in the Food Nutritional Assessment Laboratory in the Faculty of Zootechnics at

Estimation of diet quality

The composition of the forage selected for both treatments is presented in Table 1. No significant differences were observed between the treatments (P >  0.05). Although the control treatment had a slightly higher crude fibre content, NDF, and ADF than the tannin treatment, overall nutrient levels were similar in both treatments.

Estimation of selectivity of the diets for functional groups, plant parts and physiological state of the plants

The Steinhaus similarity index for diet selectivity of functional groups was considerably high (Table 2), suggesting that the preference for functional groups in both

Determination of diet selectivity

In the present study, the marked preference (P <  0.05) for grasses and graminoids was similar to that found by San Martín (1991) at 93 % and Achu et al. (2003) at 88.77 %, probably because both investigations were performed in humid puna conditions, where there are more plant species. Furthermore, the results were slightly lower than those found by Choquemamani (2017) at 98.4 %, most likely because these studies were conducted in dry puna conditions.

The marked preference (P <  0.05) for leaves

Conclusions

The use of tannins from chestnut bark did not affect the diet composition in llamas grazing on the high Andean grassland, with an average of 91.5 % of grasses and graminoids, 48 % of leaves, 36.5 % of stems, and 61.5 % of the green phenological stage. In addition, the use of tannins from chestnut bark did not affect the DMI of llamas grazing on high Andean grasslands at 1,614.6 and 1,624.7 g in the control and tannin treatment groups, respectively. Finally, tannins from chestnut bark reduced

Declaration of Competing Interest

All authors have participated in (a) conception and design, or analysis and interpretation of the data; (b) drafting the article or revising it critically for important intellectual content; and (c) approval of the final version.

This manuscript is not under review at, another journal or other publishing venue.

The authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript

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