Effects of quebracho tannin extract and activated charcoal on nutrient digestibility, digesta passage and faeces composition in goats

Abstract

Irrigation agriculture of hot climates suffers from rapid soil organic carbon (C) turnover, high nitrogen (N) leaching and gaseous losses. In this context, we explored the possibility of supplementing ruminants with activated charcoal (AC) and condensed tannins (CT) to increase faecal concentration of long-lived C and slowly decomposable N. For this purpose, we fed AC and quebracho tannin extract (QTE, source of CT) to goats and determined nutrient digestibility, digesta passage and composition of faeces. The feeding trial comprised three periods, with 24 male goats assigned to five treatments and a control. On dry matter (DM) basis, the basal diet (control) consisted of 50% hay, 46.5% crushed maize and 3.5% soya bean meal. Treatment diets contained (on DM basis) 2% and 4% QTE (QTE2, QTE4), 1.5% and 3.0% AC (AC1.5, AC3.0) and a mixture of 2% QTE plus 1.5% AC (QTEAC). Samples of feed, refusals and faeces were analysed for chemical constituents; digesta passage was computed with a one-compartment Gamma-2 model from pulse-dose application of ytterbium-mordanted fibre and quantitative collection of faeces during 7 days. Compared to the control, organic matter and N digestibility were reduced with QTE2 and QTE4 (p ≤ 0.001), that of neutral and acid detergent fibre (NDFom, ADFom) decreased with QTE4, QTEAC and both AC treatments (p ≤ 0.001). Ruminal particle passage ranged from 0.051 h (QTEAC) to 0.056 h (control; p > 0.05). Apart from the correlation between total tract mean retention time and faecal C/N ratio (r = -0.35), passage parameters did not affect faeces quality. While faecal N concentration was not altered by both additives, AC enhanced faecal NDFom, ADFom and C concentrations (p ≤ 0.001). Whereas feeding up to 3% AC might slow down the decomposition of manure in the field without negatively affecting the digestive physiology of goats, including QTE seems not advantageous from a physiological and nutrient recycling perspective.

Supplementation of Pelleted Hazel (Corylus avellana) Leaves Decreases Methane and Urinary Nitrogen Emissions by Sheep at Unchanged Forage Intake

“… 33 ). Still, body N (protein) retention declined with increasing hazel leaf proportions from about 10 to 4 g/day, consistent with the negative effect on the apparent total tract N digestibility found in the present study and elsewhere 17 , 28 . This indicates that the cleavage of the tannin-protein bonds in the lower gut was not efficient enough to maintain or improve the metabolic supply with protein and amino acids.…”

“…Tannins not only bind to protein but also to carbohydrates although to a lesser extent 11 , 27 , thus slowing down their ruminal degradation. Tannins are also known to lower the activity of fibrolytic enzymes, an effect depending on the dose and type of tannins 11 , 28 , 29 . Accordingly, approximately 4% of tannins in the diet are sufficient to lower digestibility of OM, NDF and ADF, as Carulla et al .…”

“… 17 found in growing lambs when using Acacia mearnsii extract and Al-Kindi et al . 28 identified in goats when using quebracho tannin extract. Indeed, the addition of PEG to the diet containing 50% hazel leaves alleviated the adverse effect of the hazel leaves on digestibility, but this only partially and not fully.…”

Effect of tannins and monensin on feeding behaviour, feed intake, digestive parameters and microbial efficiency of nellore cows

“…These differences may be due to the tannin content used by this author, which was probably not enough to alter these parameters. Feeding up to 4% of quebracho extract for goats, Al-Kindi et al (2017) also did not observe changes in the kp, but that difference may be due to the different type of tannins used.…”

Tannins in Goat Diets Modify Manure Turnover in a Subtropical Soil

“…The different mineralization patterns and effects of tannins indicate an effect of the cultivation period. While tannins can inhibit or favour the development and activity of bacteria and fungi (Mutabaruka et al, 2007;Scalbert, 1991), the QT used seems to favour fungal and inhibit bacterial development in the digestive tract as well as in the soil (Al-Kindi, 2015;Mutabaruka et al, 2007;Sradnick et al, 2014).…”