Clinicopathology of gout in growing layers induced by high calcium and high protein diets

Abstract

1. An experiment was conducted to test the independent and combined effects of high dietary calcium and protein concentrations on the induction of visceral gout in growing birds of a layer strain. 2. One hundred and sixty healthy birds were randomly divided into 4 groups at 35 d of age. The different groups were given 4 diets containing normal or high concentrations of dietary calcium or crude protein in a 2 x 2 factorial experiment for 30 d. The diets contained normal calcium (Ca) and crude protein (CP) (NCNP, 8.5 g Ca/kg and 175g CP/kg), high calcium and normal protein (HC, 36.3 g Ca/kg and 175 g CP/kg), normal calcium and high protein (HP, 8.8 g Ca/kg and 245 g CP/kg) or high calcium and high protein (HCHP, 36.8 g Ca/kg and 242 g CP/kg), respectively. 3. Typical visceral gout was induced by the HCHP diet. The HCHP and HC diet caused severe kidney damage. The HP diet did not cause kidney damage, but significantly increased plasma uric acid and inorganic phosphorus concentrations. 4. The HC diet significantly increased plasma uric acid, calcium and sodium, but significantly decreased plasma inorganic phosphorus, potassium and magnesium concentrations. The HCHP diet significantly increased plasma uric acid, calcium and sodium. 5. Urine volumes were significantly higher on the HCHP and HC diets than on the control. The growers raised on HC and HCHP diets had significantly higher total quantity of 24 h urinary excretion of uric acid, calcium, magnesium, inorganic phosphorus and potassium and a significantly lower 24 h urinary excretion of sodium. The growers fed on the HP diet had a higher 24 h urinary excretion of uric acid and inorganic phosphorus than the control. 6. It is concluded that growing layer birds should not be fed on layer rations.

High Dietary Calcium Causes Metabolic Alkalosis in Egg-Type Pullets

“…Precipitation and crystallization of urates in the cases were probably favored by the electrolyte changes, disturbed tissue osmotic pressure, and the altered pH of the extracellular fluid (Mubarak and Sharkawy, 1999). Therefore, metabolic alkalosis found in the present study may partly explain why high dietary calcium in domestic birds could induce gout in our previous study (Guo et al, 2005).…”

“…However, the beneficial effects of calcium can only be attained when the recommended doses are administered. Many metabolic problems, such as diuresis, urolithiasis, visceral gout, and poor pullet performance have been reported to be associated with excessive dietary calcium (Siller, 1981;Wideman and Cowen, 1987;Leeson and Summers, 1987;Wideman et al, 1993;Guo et al, 2005;Julian, 2005). Case histories of affected bird flocks often revealed that excessive calcium had been fed.…”

Quantification of Tissue Uric Acid Levels in a Harris's Hawk with Visceral Gout

“…Nutritionally, visceral gout has been caused by water deprivation (9) and excesses of trace elements, e.g., zinc (23), and induced experimentally by highcalcium diets (24), high-calcium and high-protein diets (8), and hypovitaminosis A (7). Sodium bicarbonate, often supplemented to enhance egg-laying performance, caused visceral gout when administered experimentally to pullets in high doses (16).…”

Stress, Metabolism, and Antioxidants in Two Wild Passerine Bird Species

“…Potentially, elevated baseline UA levels indicate poor health and little ability to further increase levels because UA must be kept at concentrations low enough to avoid gout. That is, even if UA has beneficial effects as an antioxidant, high levels may indicate a compensatory response to stress, and there may be a ceiling on these levels imposed by the threat of gout (Guo et al 2005). Furthermore, although UA is a potent antioxidant, its physiological relevance is not well established.…”