Full Paper

Feeding grape seed extract to horses: effects on health, intake and digestion

J. A. Daviesa1, G. L. Krebsa1 p1 c1, A. Barnesa2, I. Panta3 and P. J. McGratha4

a1 School of Agriculture and Environment, Curtin University of Technology, PMB 1, Northam 6401, Western Australia, Australia

a2 School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch 6150, Western Australia, Australia

a3 Tarac Technologies, PO Box 78, Nuriootpa 5355, South Australia, Australia

a4 Bakers Hill Veterinary Clinic, Great Eastern Hwy, Bakers Hill 6562, Western Australia, Australia


A feeding trial involving four Thoroughbred race horses was undertaken to establish whether inclusion of grape seed extract (GSE) in the diet of horses undergoing mild exercise had any effects on their general health, intake and digestion. Supplementation with GSE had no effect on either feed or water intake of the horses and the supplement was readily palatable to the horses at all levels of inclusion. Feeding GSE caused no adverse effects in terms of animal health (temperature, pulse and respirations rates), and there were some positive effects related to a presumed alteration in fermentation in the hindgut. Feeding GSE increased faecal pH, changing from acid faeces (pH 6.6) when no GSE was fed to neutral faeces (pH 7.0) when 150 mg GSE/kg body weight (BW) was fed. In addition, blood glucose concentrations were significantly (P < 0.05) decreased when GSE was fed at 100 and 150 mg/kg BW (5.50 ± 0.26 and 5.32 ± 0.72 mmol/l, respectively) compared with the control diet (5.77 ± 0.31 mmol/l). The actual mechanisms causing these alterations are yet to be elucidated, but could have important implications for the prevention of acidosis.

(Received September 24 2007)

(Accepted September 30 2008)


c1 E-mail:

p1 Present address: EH Graham Centre for Agricultural Innovation (NSW), Department of Primary Industries, Charles Sturt University, Wagga Wagga 2678, New South Wales, Ausralia