The effect of supplementing pony diets with yeast on 1. In vivo and in vitro digestibility, faecal pH and particle size

Garber, A. , Hastie, P.M. , Farci, V., Bulmer, L., Alzahal, O. and Murray, J.M.D. (2020) The effect of supplementing pony diets with yeast on 1. In vivo and in vitro digestibility, faecal pH and particle size. Animal, 14(12), pp. 2481-2492. (doi: 10.1017/S1751731120001524) (PMID:32580794)

Abstract

Fibre is essential to maintain healthy gut; however, energy demands of performance horses can be too high to be met by forages alone. Yeast may support the function of cellulolytic bacteria to digest fibre. The aim of this work was to determine the effect of an oral supplement (VistaEQ) containing 4% live yeast on the in vitro and in vivo digestibility of high-starch (HS) and high-fibre diets (HF). Eight ponies were used in a 4 × 4 Latin square design consisting of 4- × 19-day periods and four diets: HF, HF + yeast (HFY), HS and HS + yeast (HSY). In vivo apparent digestibility (AD) was estimated using total collection technique, and faecal particle size was measured using NASCO digestive analyser. Faeces from the ponies were subsequently used as an inoculum in ANKOM RF gas production system to assess fermentation kinetics in vitro. Each module contained 1 g of feed substrate DM in the following combinations: 50% grass hay and 50% alfalfa (HF_50 : 50) or concentrate (HS_50 : 50), and 75% grass hay and 25% alfalfa (HF_75 : 25) or concentrate (HS_75 : 25) with or without yeast. Yeast was able to induce more gas production from HF_75 : 25, HS_75 : 25 and HF_50 : 50 feed substrates incubated with respective faecal inoculum base. Yeast did not affect pH in vitro when the substrates were incubated in 50 : 50 ratio, while the pH was higher for HF_75 : 25 incubated with correspondent faecal inoculum compared to HS_75 : 25 and HSY_75 : 25. Yeast had no effects on ADF and CP AD of either diet. Yeast addition increased DM (HF: 0.2%, HS: 0.4%), organic matter (HF: 0.7%, HS: 1.3%), NDF (HF: 0.5%, HS: 1.5%), total detergent fibre (HF: 0.7%; HS: 0.4%) (P < 0.05) and also tended to increase hemicellulose AD (HF: 0.9%, HS: 1.2%) (P < 0.10). Faecal pH in vivo was higher for both HF diets compared to HS diet without yeast supplementation (P < 0.001, HF and HFY: 6.8; HS: 6.6, HSY: 6.7). However, no difference was observed in faecal pH when HSY was compared to both HF diets. Yeast had no effect on the size of the faecal particles (P > 0.05). Yeast increased in vitro gas production, suggesting more energy could be extracted from the feed, and the in vivo AD of some of the nutrients when HF and HS diets were fed.

• Item Type: Articles
• Additional Information: The authors acknowledge the funding received from AB Vista. The authors gratefully acknowledge the funding received from the Trustees of the Miller Foundation for the postgraduate scholarship awarded in memory of Mr Ronald Miller of Motherwell Bridge Engineering to reflect his special interest in animals.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hastie, Professor Peter and Garber, Dr Anna and Bulmer, Louise and Farci, Miss Viola and Murray, Professor Jo-Anne
• Authors: Garber, A., Hastie, P.M., Farci, V., Bulmer, L., Alzahal, O., and Murray, J.M.D.
• College/School: College of Medical Veterinary and Life Sciences; College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Animal
• Publisher: Cambridge University Press
• ISSN: 1751-7311
• ISSN (Online): 1751-732X
• Published Online: 25 June 2020
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Animal 14(12): 2481-2492
• Publisher Policy: Reproduced under a Creative Commons License