Parker, Anthony Joseph (2004) Water, electrolyte and acid-base balance in transported Bos indicus steers. PhD thesis, James Cook University.

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Abstract

The objective of these studies was to investigate the physiological mechanisms involved in maintaining water, electrolyte and acid-base balance in Bos indicus steers placed under stress. These studies also sought to provide a novel approach to minimize the effects of stress on the physiology of Bos indicus steers during long haul transportation in the seasonally dry tropics.

Merino sheep provided a simulated stress response model, to evaluate the effects of the principle stress hormone cortisol on indices of water and electrolyte balance. This study indicated that stressed sheep suffer from a loss of body water in excess of that associated with a loss of electrolytes to support the hypothesis that elevated physiological levels of cortisol induce a diuresis in ruminants that contributes to dehydration.A second pen study was performed to investigate the effects of excess cortisol on physiological mechanisms that resist dehydration in Bos indicus steers. The presence of excess cortisol suppressed the RAA axis but did not markedly affect plasma AVP concentrations. This reflected the complexity of endocrine interactions associated with water balance in Bos indicus steers that enabled homeostasis to be maintained. A quantitative analysis of acid base balance in Bos indicus steers demonstrated long haul transportation or extended periods of feed and water deprivation to have no effect on blood pH. The primary challenge to a transported or feed and water deprived animal is a mild metabolic acidosis induced by elevated plasma proteins which may be the result of a loss of body water. The loss of electrolytes has little effect on the acid-base balance of the animals.

The treatment of Bos indicus steers prior to long haul transportation with the osmolyte glycerol provided a novel approach to conserving body water, decreasing the energy deficit and preserving muscle quality.

Item ID:	17422
Item Type:	Thesis (PhD)
Keywords:	Bos indicus, steers, stress, effects, physiology, endocrinology, neuroendocrine system, electrolyte balance, acid-base balance, diuresis, dehydration, long-haul transportation, live cattle export, management, animal welfare, production loss, cortisol, metabolic acidosis, Glycerol
Date Deposited:	21 Jun 2011 04:11
FoR Codes:	07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070203 Animal Management @ 50% 07 AGRICULTURAL AND VETERINARY SCIENCES > 0707 Veterinary Sciences > 070702 Veterinary Anatomy and Physiology @ 50%
SEO Codes:	83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830301 Beef Cattle @ 40% 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8305 Primary Animal Products > 830503 Live Animals @ 30% 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8399 Other Animal Production and Animal Primary Products > 839901 Animal Welfare @ 30%
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