Grape seed extract supplementation in heat-stressed preweaning dairy calves: I. Effects on antioxidant status, inflammatory response, hematological and physiological parameters

Abstract

This study aimed to investigate the effects of grape seed extract (GSE) supplementation on antioxidant activity, inflammatory markers, hematological and physiological responses during the suckling period in heat-stressed calves. Sixty Holstein female calves (3 d of age, 40.6 +/- 2.17 kg of BW) were randomly divided into four dietary groups. Each group consisted of 15 calves; the milk was supplemented with 0 (CON) 25 (GSE1), 50 (GSE2), and 100 (GSE3) mg/kg BW/day of GSE. On d 3, 33, and 63 blood samples were collected, rectal temperatures (RT) and respiratory rates (RR) were measured three days a week. Calves were exposed to chronic heat stress during the study period and were weaned on d 63. Plasma malondialdehyde (MDA) and tumor necrosis factor-alpha (TNF-alpha) concentrations decreased (P < 0.01) in all GSE supplemented groups compared to the CON group. Also, interferon-gamma (IFN-gamma) concentration decreased (P = 0.03) only in calves fed GSE1. Plasma total antioxidant capacity (TAC) concentration increased (P = 0.02) in calves fed GSE3 on d 33 compared to the CON group, while the concentration of superoxide dismutase (SOD) was higher (P < 0.001) in the GSE2 and GSE3 groups compared to CON and GSE1. The hematocrit percentage, hemoglobin value, RBC, and eosinophil counts were higher (P < 0.01) in all GSE supplemented groups compared to CON. Calves fed GSE1, GSE2 and GSE3 had lower (P < 0.001) neutrophil count compared to CON on d 63. All GSE-supplemented groups had a decreased (P < 0.001) RR compared to CON, while calves fed GSE2 had a tendency to decrease (P = 0.10) in RT. It was concluded that supplementation with 50 and 100 mg/kg BW/ d GSE could improve antioxidant, anti-inflammatory activities, and hematological parameters of calves against oxidative stress, and also reduce the effect of heat stress by reducing the respiratory rate.