Effect of seaweed extract supplementation in goats exposed to simulated preslaughter stress

Abstract

A feed supplement containing brown seaweed ( Ascophyllum nodosum) extract may increase anti-oxidant activity in other domestic animals, but its effect on goats has not been studied. Mature female Spanish (S) and Boer × Spanish (BS) crosses (BW = 39 kg, n = 20/breed) were housed in pens (5 does/pen) and fed alfalfa pellets, supplemented either with or without the seaweed extract (treatment) for a period of 3 weeks. The supplement was given at 40% of daily feed intake to allow for a 2% seaweed extract in the diet. Does were then transported 6 h to stimulate stress, and held overnight without feed to simulate preslaughter conditions. Blood samples were collected at 0, 2, and 6 h of transportation, and after overnight holding (24 h) without feed to determine the blood cortisol, differential leukocyte counts, phagocytosis, anti-oxidant and peroxidation status. Plasma cortisol levels were not influenced by treatment and the mean concentrations increased due to transportation and decreased after holding ( P < 0.01). Mean plasma cortisol concentrations were 46.3, 63.5, 56.5, and 38.1 (S.E.M. = 6.1) ng/ml at 0, 2, 6, and 24 h of blood sampling, respectively. Neutrophil (N), lymphocyte (L), and monocyte counts and the N/L ratio was not influenced by treatment, but the seaweed extract supplementation decreased the eosinophil count ( P < 0.05). The mean N/L ratio was 1.2 ± 0.7 at 0 h and increased during transportation and peaked at 6 h (2.3 ± 1.6) before decreasing after holding ( P < 0.01). Lipid peroxidation (LPO) was much lower in treated animals, compared to the controls ( P < 0.01) during transport and holding. Sampling time influenced the LPO in the treated group ( P < 0.01)—resulting in a time × treatment interaction ( P < 0.01). There was also a treatment × breed interaction ( P < 0.05), such that the reduction in superoxide dismutase (SOD) caused by treatment was recorded to be greater in the BS goats, compared to the S goats. Glutathione peroxidase activities were higher in the treated than the control animals ( P < 0.05). The mean RBC GSH-Px activities were 58.2 and 63.4 (S.E.M. = 1.8) mU/mg protein; WBC GSH-Px activities were 98.7 and 115.9 (S.E.M. = 5.5) mU/mg protein in the control and treated groups, respectively. Phagocytosis was also higher at 2 h compared to the other sampling times ( P < 0.01). The results show that transportation is stressful to goats, and that seaweed extract supplementation may help goats by increasing anti-oxidant status, particularly after the onset of stress.