Hypercalciuric Response to Dietary Supplementation with DL-Methionine and Ammonium Sulfate

Abstract

Renal Ca and inorganic P (Pi) excretion were evaluated in Single Comb White Leghorn pullets reared on diets containing 1 or 3.5% Ca alone or supplemented with .6% DL-methionine or .53% ammonium sulfate. Plasma and urine samples were collected during a CONTROL period, and while 200 mM Ca was infused intravenously (Ca-LOADING). Excess Ca, whether supplied chronically in the feed or infused acutely into birds fed 1% Ca diets, significantly reduced glomerular filtration rates, effective renal plasma flow rates, and Pi excretion rates and significantly increased Ca excretion rates and urine pH. Birds fed diets supplemented with DL-methionine and ammonium sulfate maintained significantly lower plasma Ca concentrations during the CONTROL and Ca-LOADING periods than birds fed the respective 1 or 3.5% Ca basal diets. When compared with birds fed the respective 1 or 3.5% Ca basal diets, birds fed the 1% Ca diet supplemented with ammonium sulfate or the 3.5% Ca diet supplemented with DL-methionine had significantly higher absolute urinary Ca excretion rates during Ca-LOADING. Fractional Ca excretion during Ca-LOADING was significantly higher in birds fed 3.5% Ca supplemented with DL-methionine or ammonium sulfate than in birds fed the 3.5% Ca basal diet. These results indicate that DL-methionine and ammonium sulfate accelerated urinary Ca excretion and reduced Ca retention in the extracellular fluid. The hypercalciuric efficacies of DL-methionine and ammonium sulfate were revealed only when the filtered load of Ca was increased through intravenous Ca infusions.

Amino acid supplementation alters bone metabolism during simulated weightlessness

“…Because the AA and Con groups consumed identical diets each day (besides the dietary supplement), we must assume that endogenous acid production resulting from diet alone was also similar for the two groups. Several other human and animal studies have shown that methionine supplementation alone elicits similar responses: decreased bone density (51), increased urine calcium excretion (19,48,50), and acidified urine (13,25). In this study, dietary sulfur (calculated from the sulfur content of amino acids in the diet) was correlated with urinary NTX excretion.…”

Responses of Laying Hens to Diets Containing up to 2% DL-Methionine or Equimolar (2.25%) 2-Hydroxy-4-(Methylthio)Butanoic Acid

“…Diets supplemented with ammonium chloride, ammonium sulfate, DL-Met (DLM), or 2-hydroxy-4-(methylthio)butanoic acid (HMB, Alimet®) all successfully acidify the urine and reduce Ca-induced kidney damage in Single Comb White Leghorn (SCWL) pullets and hens (Wideman and Cowen, 1987;Glahn et al, 1988b;Wideman et al, 1989Wideman et al, , 1993Lent and Wideman, 1993). These "acidifiers" consistently function effectively in spite of the fact that urinary Ca apparently is a limiting constituent required for avian Ca-urate urolith formation, and urinary Ca excretion increases significantly (hypercalciuria) when plasma Ca concentrations are elevated in pullets fed urinary acidifiers (Oldroyd and Wideman, 1986;Glahn et al, 1988a;Wideman et al, 1989;Lent and Wideman, 1994). The latter observation raises the possibility that the hypercalciuria triggered by urinary acidification could interfere with Ca utilization, potentially affecting crucial variables such as bone mineralization, egg production, and eggshell quality (Mongin, 1968;Glahn et al, 1988b;Wideman et al, 1993).…”