Abstract
This research aims at evaluating the effects of the dietary addition of a supplement containing 75% of chestnut tannins (CT) on growth performance, slaughter traits (Experiment 1) and on nutrient utilisation (Experiment 2) of Italian heavy pigs. Exp. 1 compared a control (C) diet with diets containing 0.15 or 0.30% of CT supplement. Forty-two barrows (91 ± 6 kg of BW) were divided into pairs and kept in 21 partially-slatted pens equipped with individual feeding (7 pens/diet). Animals were slaughtered at a BW of 174 ± 6 kg. The CT inclusion did not modify the performance and the slaughter traits but lowered the intensity of red colour (p < .05) and brightness (p < .05) of the gastric mucosa. Exp. 2 measured digestibility of nutrients, nitrogen (N) balance and energy utilisation of a C diet compared with low protein diets containing 0 or 0.53% of CT supplement (low protein, LP and low protein plus tannins, LPT, respectively). Eighteen barrows (BW 153 ± 4 kg) were housed in 6 metabolic cages in 3 periods of 14 days, with 6 animals per diet. LPT pigs produced less urine than LP (2132 vs. 2561 g/d, p < .05) and both were lower than C (2978 g/d, p < .05). LP and LPT diets had similar digestibility (87.6 vs. 87.8% for DM, and 85.1 vs. 83.9% for CP). N and energy balance were similar among all diets (34.8, 39.0, 39.2% retained N, and 37.6, 35.7, 37.3% retained energy, for C, LP and LPT, respectively). In conclusion, tannins do not exert anti-nutritional effect at the concentrations applied.HighlightsDietary chestnut tannin (CT) addition (at 1.5–5.3 g/kg) does not modify digestibility, metabolic use of nutrients and performance of heavy pigs.Dietary CT addition reduces urine volumes of animals with potential impact on farm slurry management.Changes of colour and hypertrophy of gastric mucosa of pigs fed CT are proxy indicators of metabolic reactions to be further investigated.
Highlights
Tannins are a complex category of secondary plant compounds, classified as hydrolysable or condensed, bioactive in the digestive tract, having antimicrobial effects (Scalbert 1991) and binding properties with protein substances
Acorns are rich in hydrolysable tannins that stimulate the pigs to secrete, trough the saliva and the gastric wall, rich proline proteins (RPP); these proteins have a high affinity for tannins and act as protection against the negative effects of these plant compounds (Cappai et al 2010, 2013; Cappai, Wolf, Pinna, et al 2014; Cappai, Wolf, Dimauro, et al 2014)
The individual daily amount of each experimental compound feed was prepared every day in 2 equal meals and the pigs were fed at restricted level
Summary
Tannins are a complex category of secondary plant compounds, classified as hydrolysable or condensed, bioactive in the digestive tract, having antimicrobial effects (Scalbert 1991) and binding properties with protein substances. Tannins fed to pigs were studied as compounds able to reduce boar taint (Candek-Potokar et al 2015; Bee et al 2017). Acorns are rich in hydrolysable tannins that stimulate the pigs to secrete, trough the saliva and the gastric wall, rich proline proteins (RPP); these proteins have a high affinity for tannins and act as protection against the negative effects of these plant compounds (Cappai et al 2010, 2013; Cappai, Wolf, Pinna, et al 2014; Cappai, Wolf, Dimauro, et al 2014). Chestnut tannins (CT) fed to pigs reduced the apparent digestibility, but did not determine negative effects in terms of N retention (Antongiovanni et al 2007) or growing performance (Prevolnik et al 2012; Bee et al 2017).
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