A Fibre- vs. cereal grain-based diet: Which is better for horse welfare? Effects on intestinal permeability, muscle characteristics and oxidative status in horses reared for meat production.

Federica Raspa,Francesca Rita Dinardo,Daniele Pattono,Pasquale De Palo,Domenico Bergero,Ingrid Vervuert,Maria Teresa Bottero,Elena Bruno,Marica Vinassa,Ermenegildo Valvassori,Alessandra Dalmasso,Emanuela Valle

doi:10.1111/jpn.13643

Abstract

Horses reared for meat production are fed high amounts of cereal grains in comparison with horses raised for other purposes. Such feeding practice may lead to risk of poor welfare consequences. The aim of this study was to investigate the effects of two feeding practices on selected metabolic parameters and production aspects. Nineteen Bardigiano horses, 14.3 ± 0.7 months of age, were randomly assigned to two groups—one fed with high amounts of cereal grains (HCG; n = 9; 43% hay plus 57% cereal grain‐based pelleted feed) vs. one fed with high amounts of fibre (HFG; n = 10; 70% hay plus 30% pelleted fibrous feed)—for 129 days. At slaught on abattoir, biological and tissue samples were collected to evaluate the microbiological contamination of mesenteric lymph nodes and liver; selected meat quality traits (chemical composition and fatty acid profile of the Longissimus thoracis et lumborum muscle); and the oxidative status of the horse. A linear mixed model was used: dietary treatment and sex were fixed effects and their interaction analysed on production and metabolic parameters as dependent variables. Results showed an increased intestinal permeability in the horses fed HCG compared to HFG, according to the significant increased total mesophilic aerobic bacteria counts in mesenteric lymph nodes (p = 0.04) and liver samples (p = 0.05). Horses in HCG showed increased muscle pH (p = 0.02), lighter muscle colour (L) (p = 0.01), increased intramuscular fat concentrations (p = 0.03), increased muscle glutathione peroxidase and superoxide dismutase activities (p = 0.01 and p = 0.03, respectively). Moreover, horses in HCG had lower muscle water holding capacity at interaction with sex (p = 0.03, lower in female), lower muscle protein content (p = 0.01), lower concentration of muscle PUFAs (p = 0.05) and lower plasma catalase activities (p = 0.05). Our results showed that feeding a high cereal grains diet can have global effects on horse physiology, and thus represents a threat for their welfare.

Highlights

Animal welfare is a complex and multidimensional concept
The present study was carried out under field conditions without any possibility of choosing the horses involved in the trial or to change the breeder's management choices for the high amounts of cereal grains (HCG)
The higher TMABc in the lymph nodes and liver samples found in the HCG could be a consequence of higher bacterial translocation

Summary

Introduction

Animal welfare is a complex and multidimensional concept. The feeding practice adopted for horses can affect the welfare of these animals through their direct effects on the animals' health as well as by influencing horse behaviour (Lesimple, 2020). Feeding horses with diets characterised by a high starch content can negatively affect their welfare, increasing the risk for gastrointestinal disorders such as colic and gastric ulcers (Durham, 2009; Hudson et al, 2001). When it reaches the hindgut, the high starch content of a cereal grain-based diet causes microbiome alterations, leading to an increase in lactic acid production and a drop in pH with subsequent acidosis (Geor & Harris, 2007; Merritt & Julliand, 2013). The ingestion of excessive amounts of rapidly fermentable carbohydrates has been associated with the condition of oxidative stress in horses, and biomarkers of oxidative stress have been proposed as indicators of animal welfare (Celi & Gabai, 2015)

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