Factors affecting insulin-like growth factor-I concentration in bovine milk.
To establish the naturally occurring range of insulin-like growth factor-I concentrations in bovine milk, samples from individual cows (n = 409) managed on five Missouri dairy herds were assayed. Parity, stage of lactation, and farm affected milk insulin-like growth factor-I concentration. Milk insulin-like growth factor-I concentration was higher in early lactation than mid and late lactation with concentrations in multiparous cows exceeding those in primiparous cows. Insulin-like growth factor-I concentration was negatively correlated to milk production the day of sample collection (r = -.15) and not correlated to predicted 305-d milk yields. Unprocessed bulk tank milk samples (n = 100) from a commercial processing plant had a mean concentration of insulin-like growth factor-I in milk of 4.32 ng/ml with a range of 1.27 to 8.10 ng/ml. This distribution was similar to the range detected in samples from individual cows, but values were lower than those reported for human milk. Concentration of insulin-like growth factor-I in milk was not altered by pasteurization (at 79 degrees C for 45 s). However, insulin-like growth factor-I was undetectable in milk heated to temperatures (121 degrees C for 5 min) required for infant formula preparation or in commercially available infant formula. These data indicated that insulin-like growth factor-I is a normal but quantitatively variable component of bovine milk that is not destroyed by pasteurization but is undetectable in infant formula. Concentration of insulin-like growth factor-I in bovine milk is lower than concentrations reported for human milk yet similar to those reported for human saliva.(ABSTRACT TRUNCATED AT 250 WORDS)
Collier
R J
RJ
Monsanto Company St. Louis, MO 63198.
Miller
M A
MA
Hildebrandt
J R
JR
Torkelson
A R
AR
White
T C
TC
Madsen
K S
KS
Vicini
J L
JL
Eppard
P J
PJ
Lanza
G M
GM
D000704:Analysis of Variance; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007774:Lactation / Q000502:physiology; D008892:Milk / Q000032:analysis*; D010298:Parity / Q000502:physiology; D011863:Radioimmunoassay
D007334:Insulin-Like Growth Factor I