Impacts of feeding several components of the seaweed Ascophyllum nodosum on transported lambs
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Feeding the seaweed Ascophylum nodosum (ANOD) has been previously shown to mediate the body temperature of lambs during transport in hot weather while also negatively impacting antibody production. The aim of this study was to determine if fucoidan, salt (NaCl plus potassium gluconate) or betaine, were the causative agents for the effects seen in previous studies. Each compound was fed at a rate to approximate the intake when consuming 30 g of ANOD per day. Two additional groups were fed either 30 g of ANOD per day or capsules filled with grain (i.e., controls). Fifty-five lambs (19 ewes and 34 wethers) averaging 25 7 kg were used. Each lamb swallowed three gelatin capsules twice daily filled with the appropriate amount of treatment compound for 14 days. Prior to supplementation, all lambs had similar plasma cortisol and aldosterone concentrations. ANOD-supplemented lambs had suppressed (P<0.05) IgG and IgM antibody titers in response to administration of ovalbumin, and tended (P=0.10) to have higher white blood cell counts and more eosinophils (P=0.10) and lymphocytes (P=0.06) than the controls post-supplementation. Salt-fed lambs showed an increase in lymphocyte (P=0.06) counts while betaine-fed lambs had higher (P<0.05) packed cell volume and hemoglobin relative to the controls. Post-supplementation ANOD-fed and salt-fed lambs tended to have lower cortisol concentrations (P=0.08 and 0.12) than controls and all treatments had a trend (P=0.10, 0.07, 0.14, and 0.09) to lower aldosterone concentrations relative to controls. All lambs had similar mean, minimum, maximum, and range of body temperature during transport, although ANOD-fed lambs had less fluctuation in their body temperature than controls. During transport the salt-fed lambs had lower (P<0.05) cortisol concentrations than controls. Control lambs tended to have higher plasma sodium and chloride concentrations (P<0.10) post-transport than ANOD-fed lambs. All lambs lost a similar amount of body weight due to transport. Post-transport, no differences occurred in the latency of lambs to drink, eat or lie down. None of the components studied appeared to be impacting the mediation of body temperature that ANOD exhibits. The salts in ANOD appears to affect both adrenal and immune function, although further studies are needed to determine the mechanism by which it caused such large physiological impacts. 2007 Elsevier B.V. All rights reserved.
