Variation of Inorganic Phosphorus in Blood Plasma and Milk of Lactating Cows

Abstract

Diurnal changes in percents of inorganic phosphorus in plasma were measured in three Holstein cows fitted with indwelling jugular catheters. Blood was sampled 34 times over 48 h. Changes of inorganic phosphorus of blood plasma appeared to be related to patterns of feed consumption. In a second experiment, effects of diet, season of calving, stage of lactation, lactation number, and milk yield on inorganic phosphorus of plasma and milk were measured with 40 Holstein cows. Dietary treatments were 1.0% calcium, .31% phosphorus; 1.0% and .54%; 1.8% and .30%; 1.7% and .54%. Blood and milk samples were taken at wk 6 postpartum and every 5th wk thereafter. Inorganic phosphorus in plasma and milk was higher for cows in first lactation than multiparous cows. Cows which calved in November to December had the highest inorganic phosphorus in plasma but the lowest in milk. Month of year affected inorganic phosphorus in milk but not in plasma. Inorganic phosphorus in plasma increased as milk yields decreased and as inorganic phosphorus in milk decreased. Dietary phosphorus affected inorganic phosphorus in plasma but not in milk. The correlation between inorganic phosphorus in milk and plasma was -.15. These data indicate the limitations of using inorganic phosphorus in plasma or milk as sole or primary means of determining nutritional phosphorus status of lactating cows.

Effects of the hot season on milk protein fractions in Holstein cows

“…Thus, the lower contents of α s -and β-casein of milk yielded during the summer might explain the higher milk pH and the lower milk titratable acidity found in the present study and commonly registered during the hot summer months [6,7,30 U. Bernabucci et al 28]. Furthermore, the lower α s -and β-casein contents might explain the lower milk phosphorous content observed by others [12,22,23] in milk produced by cows exposed to hot environments.…”

Effect of offering dairy cows diets differing in phosphorus concentration over four successive lactations: 1. Food intake, milk production, tissue changes and blood metabolites

“…In addition, there was a trend for plasma P concentrations to decline with increasing lactation number, as observed by Forar et al (1982). Reduced plasma P concentrations have frequently been observed with cows offered 'low' P diets (Brodison et al, 1989;Dhiman et al, 1995;Wu et al, 2000;Lopez et al, 2004), although blood P concentrations do not necessarily provide a good indicator of P deficiency in ruminants (Forar et al, 1982). For example, plasma P concentrations are influenced by a range of factors (exercise, excitement, time of sampling, time of feeding, time of year, age and site of sampling) as reviewed by Beighle et al (1993).…”

“…In agreement with the findings of other studies, blood P concentrations tended to be lowest during the post-calving period, increasing thereafter (Wu et al, 2000). In addition, there was a trend for plasma P concentrations to decline with increasing lactation number, as observed by Forar et al (1982). Reduced plasma P concentrations have frequently been observed with cows offered 'low' P diets (Brodison et al, 1989;Dhiman et al, 1995;Wu et al, 2000;Lopez et al, 2004), although blood P concentrations do not necessarily provide a good indicator of P deficiency in ruminants (Forar et al, 1982).…”

Structural, Biochemical, and Functional Characterization of the Cyclic Nucleotide Binding Homology Domain from the Mouse EAG1 Potassium Channel

“…33 Derivatization of calmodulin with the fluorophore Dansyl-Cl wt human calmodulin was derivatized with 5-(dimethylamino)naphthalene-1-sulfonyl chloride (Dansyl-Cl, Molecular Probes), a reagent that reacts with primary amines, as previously described. 18,34 Fluorescence assay Dansylated calmodulin at 400 nM was incubated with different protein concentrations at room temperature, for at least 20 min, in fluorescence buffer [50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 5 mM MgCl 2 , 0.1 mM ethylene glycol bis(β-aminoethyl ether) N,N′-tetraacetic acid, and 2 mM CaCl 2 (1.9 mM free Ca 2 + )]. Fluorescent measurements were done at 26°C using a Horiba Fluoromax-4 spectrofluorimeter.…”