Dietary Methionine Concentrations Research Articles

1188 COMPLICATIONS OF DIETARY TREATMENT OF TYROSINEMIA

Tyrosinemia was diagnosed in an 8 month old white male infant with liver disease based on: plasma tyrosine(TYR) >6 times normal, high α-fetoprotein(αFP) and liver biopsy findings of post necrotic cirrhosis with fatty change and moderate parenchymal siderosis. Within 3 days of institution of the recommended 3200 AB formula, TYR decreased to normal but plasma methionine(MET) increased 16 times normal. Concornittant with elevation in MET was worsening of liver disease with severe cholestasis as evidenced by marked elevations of serum bile acids(SBA) and gamma glutamyl transpeptidase(GGT) with a mild increase in transaminase(ALT). This resolved when dietary MET content was decreased and MET became normal. αFP however, considered a marker of hepatic regeneration following hepatocellular necrosis, did not increase further during this episode. This suggests 1) High MET may be as important as high TYR in the liver disease associated with Tyrosinemia; 2) Effect of high MET appeared to be cholestatic rather than hepatocellular injury. This suggests caution in using the low TYR, high MET formula designed for dietary management of this disease.

Effectiveness of Rumen-Protected Methionine for Delivering Methionine Postruminally in Dairy Cows

A methionine preparation encapsulated for protection from degradation in the rumen was studied in vitro and in vivo to determine: a) its effectiveness in delivering methionine postruminally; and b) its effect on the concentration of blood-plasma methionine and other amino acids and on production by dairy cows. Rumen-protected methionine was 94% stable in pH 5.4 buffer, which simulated ruminal pH, and it released 94% of methionine in pH 2.9 buffer, which simulated abomasal pH. Twenty-five Holstein cows in early lactation were used to evaluate this preparation in vivo. Cows were assigned randomly to receive one of the following five concentrations of rumen-protected methionine: 0, 157, 315, 472, and 630 mg/kg feed as fed. This trial consisted of a 3-wk base period (no rumen-protected methionine fed) followed by a 3-wk dose period (treatment diets fed). Methionine concentrations in blood plasma for the five dietary rumen-protected methionine concentrations were (µg/ml): 3.4, 4.0, 4.8, 5.1, and 5.3. Corresponding concentrations for the base period were (µg/ml): 3.2, 3.4, 3.5, 3.4, and 3.4. The linear increase of methionine in plasma indicates this preparation delivered methionine postruminally. There was no effect on concentration of other plasma amino acids. The cows receiving rumen-protected methionine consumed more feed and gained more weight than did the control cows. Other production measures were unaffected.

Amino acid requirements of growing pigs 4. Methionine plus cystine

ABSTRACTThe response of the growing female pig (25 to 55 kg live weight) to increasing dietary methionine plus cystine concentrations was assessed by measurement of growth rate, food utilization, ham dissection and changes in blood metabolite concentrations. A range of 13 methionine plus cystine concentrations from 3·5 to 5·79 g/kg resulting from combinations of three basal diets and synthetic methionine, was studied. The diets were formulated using barley, a yeast protein, tapioca and synthetic amino acids to contain similar energy concentrations, 9·5 g lysine per kg diet, and adequate concentrations of other essential amino acids and non-essential nitrogen. They were offered once daily according to a restricted feeding scale.Responses were interpreted by broken line functions which indicated, from the growth performance experiment, a requirement between 4·5 and 4·8 g/kg of the diet, when the complete range of methionine plus cystine concentrations was studied. The influence of a range of dietary methionine plus cystine concentrations from 4·1 to 5·3 g/kg diet on changes in plasma urea, methionine, lysine and threonine concentrations indicated a requirement for methionine plus cystine of 4·5 g/kg of the diet.

Methionine Requirement of the Growing Kitten, in the Absence of Dietary Cystine

This study was conducted to determine the methionine requirement for maximal weight gain and nitrogen retention in growing kittens fed a 24% crystalline amino acid diet containing no cystine. Six male and six female kittens were fed each of six levels of methionine, 0.45, 0.7, 0.8, 0.9, 1.0 and 1.5% of the diet, for 10 days in a 6 × 6 Latin square design. Diets were made isonitrogenous with alanine and were isocaloric with a calculated metabolizable energy of approximately 5.0 kcal/g. Food intake and body weights were recorded daily, and nitrogen balance for each cat in each 10-day period was determined. On the 7th day of each period, blood was drawn for subsequent analysis of plasma methionine concentrations. From growth response results, the methionine requirement in the absence of dietary cystine was estimated to be 0.70% of the diet for male and female kittens. On the basis of nitrogen balance results, the methionine requirement appeared to be slightly higher, at 0.75% of the diet for both sexes. Plasma methionine concentrations appear to increase exponentially with dietary methionine concentrations, and were of limited usefulness in estimating the methionine requirement of the kitten in the context of the experimental protocol used here.methionine sulfur amino acids essential amino acids feline cat nutrition amino acid requirements

Hydrolysed feather protein as a source of amino acids for broilers

1. The inclusion of 25 g hydrolysed feather meal (HFM) in each kilogram of diet (floor experiment) and 60 g/kg (cage experiment) did not depress performance. 2. Chemical tests indicated 72.5% of the total lysine in HFM was available. 3. Total lysine concentration of 11.3 g/kg diet maximised performance during the period 0 to 34 d. 4. Reduction in dietary methionine content during the period 0 to 34 d from 4.2 g/kg to 3.2 g/kg did not depress performance on diets containing 60 g HFM/kg. 5. The results indicate that at least 57% by weight of the total sulphur amino acid requirement of broilers can be provided by cystine.

DIET AND FEEDING INTERVAL EFFECTS ON SERUM AMINO ACID CONCENTRATIONS OF GROWING SWINE

Four experiments were undertaken to establish the effects of diet and feeding regimen on serum amino acid concentrations of growing swine. Single meal feeding resulted in fluctuations in serum amino acid levels that could not be attributed solely to diet. A short-interval feeding regimen was proposed that resulted in relatively stable serum amino acid concentrations during the refeeding program. This procedure was suggested to be useful in attempting to evaluate protein quality by examination of serum amino acid fluctuations. A semipurified diet was observed to result in extremely high serum levels of methionine and several other amino acids, raising the possibility that the dietary amino acid requirements of swine fed semipurified diets were lower than accepted values. When the dietary methionine concentration was altered from 0.41% to 0.70%, an adaptation period of about 3 days was required to stabilize serum methionine at a new level.

Some effects of vitamin B12 in weanling rats consuming hypolipotropic diets.

Kidney lesions may develop and death ensue in very young rats consuming hypolipotropic diets in the presence of vitamin B12 even when subprotective amounts of choline are available unless the diet contains sufficient methionine. The necessity is established for a careful adjustment of the dietary concentrations of both choline and methionine before the protective effect of vitamin B12 on kidney lesions may be elicited.