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R G Derrig

Publications and source records attributed to R G Derrig.

7 recordsLinked to original sources
PubMed1977

Milk production, nitrogen utilization and glucose synthesis in lactating cows infused postruminally with sodium caseinate and glucose.

Four lactating Holstein cows were used in a 4 X 4 Latin Square design to determine the effects of postruminally administering sodium caseinate and/or glucose on milk production, milk composition, nitrogen utilization, amino acid utilization by the lactating mammary gland and glucose turnover rate. An 8.5% increase in milk yield and a 13.3% increase in milk protein production were obtained during infusion of sodium caseinate. No significant production responses were attributed to abomasal infusion of glucose. Arterial concentrations of most essential amino acids were increased during infusion of sodium caseinate. Uptake of phenylalanine, methionine and lysine by the mammary gland most closely paralleled their output in milk. The relative concentrations of methionine, lysine and phenylalanine in arterial plasma were considerably less than their concentrations in milk which resulted in a large percentage extraction of these amino acids by the mammary gland. If the availability of essential amino acids to the mammary gland, per se, was limiting the synthesis of milk protein, methionine, lysine and phenylalanine may have been the three amino acids most limiting. Measurements of glucose entry rate showed a trend toward increased glucose flux when either glucose, sodium caseinate or glucose plus sodium caseinate were infused abomasally. The similarity in glucose entry rates obtained during infusion of glucose and sodium caseinate suggest that the increase in milk production was not due totally to increased glucose flux resulting from sodium caseinate infusion.

Amino Acids↗
PubMed1977

Valine, leucine, and isoleucine metabolism by lactating bovine mammary tissue.

Valine, leucine, and isoleucine were extracted by the lactating bovine mammary gland in excess of outputs in milk protein. Carbon-14 uniformly labeled L-valine, L-leucine or L-isoleucine were catabolized when incubated in vitro with lactating bovine mammary tissue slices. The pathways of degradation of these amino acids by mammary tissue appear to be those common to other tissues. These amino acids represent a potential source of energy to the mammary gland as well as a source of carbon and alpha-amino nitrogen for synthesis of nonessential amino acids.

Acetates↗
PubMed1975

Milk production and nitrogen utilization in response to postruminal infusion of sodium caseinate in lactating cows.

Five lactating, rumen-fistulated Holstein cows were used to obtain additional information concerning the effects of postruminal infusion of sodium caseinate on milk production and amino acid utilization. A 7-day continuous abomasal infusion of approximately 450 g/day of sodium caseinate was preceded and followed by 7-day infusions of an isonitrogenous-isocaloric solution of glucose, monosodium glutamate, and urea. Total collections of milk, urine, and feces were obtained during the last 5 days of each infusion period. On the last day of each period, arterial and mammary venous blood samples were obtained for analysis of plasma free amino acids. During infusion of sodium caseinate, milk production, milk protein (N times 6.38) production, and efficiency of nitrogen utilization for milk crude protein production were increased. Arterial plasma concentrations of free histidine, isoleucine, phenylalanine, valine, and total essential amino acids were elevated above control levels during infusion of sodium caseinate, while ornithine and tryrosine were decreased. Calculation of the relative concentration of essential amino acids in arterial plasma and in milk protein indicated that methionine and lysine were least abundant in plasma relative to their requirement for milk protein synthesis. A high precentage extraction from arterial plasma by the mammary gland also suggested that methionine and lysine may have been the essential amino acids in most critical supply for milk protein synthesis. Calculation of uptake to output ratios of individual plasma amino acids by the mammary gland suggested that significant quantities of extracted arginine, isoleucine, leucine, threonine, and valine were utilized in pathways other than direct incorporation into milk protein.

Amino Acids↗
PubMed1975

Metabolism of arginine and ornithine in the cow and rabbit mammary tissue.

Amino acid uptake by the bovine mammary gland was determined by arteriovenous difference. Extraction of arginine from the plasma by the lactating bovine mammary gland was in excess of requirements for milk protein synthesis. Ornithine and citrulline also were extracted by the gland but are not in milk protein. Incubations of slices of lactating mammary tissue from cows and rabbits indicate that nonessential amino acids, especially proline and glutamate, are the major end products of arginine and ornithine metabolism in the lactating mammary gland.

Abdomen↗