Environmental and lactational variables affecting prolactin concentrations in bovine milk [Dairy cattle]

Relationships were examined between prolactin concentrations in bovine milk and various environmental and lactational variables. Prolactin was quantified by radioimmunoassay in 1.316 milk samples from two experiments. Environmental temperatures preceding milking, stage of lactation, daily miik yield...

Full description

Saved in:
Bibliographic Details
Published in:Journal of dairy science 1975-02, Vol.58 (2), p.181-189
Main Authors: McMurtry, J. P, Malven, P. V, Arave, C. W, Erb, R. E, Harrington, R. B
Format: Article
Language:English
Subjects:
Animals
Cattle - physiology
Circadian Rhythm
Environmental Exposure
Female
Lactation
Milk - analysis
Milk - cytology
Milk Proteins - analysis
Pregnancy
Prolactin - analysis
Social Dominance
Temperature
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Relationships were examined between prolactin concentrations in bovine milk and various environmental and lactational variables. Prolactin was quantified by radioimmunoassay in 1.316 milk samples from two experiments. Environmental temperatures preceding milking, stage of lactation, daily miik yield, and dominance rank of the cow were correlated significantly with milk prolactin concentration. Stepwise multiple regression analysis was used to determine, in order of importance, the variables having significant independent effects on milk prolactin. Ambient temperature extremes, high and low, exerted the greatest effects and were each associated with elevated concentrations of prolactin. In Experiment I,conducted throughout the year, the variable representing maximum temperature preceding milking accounted for 14.3% of the variation in milk prolactin. In Experiment II, conducted during late fall and early winter, the minimum temperature preceding milking accounted for 21.1% of the variation. Although earlier stages of lactation and larger daily milk yields were associated with higher prolactin concentrations, inclusion of lactation stage in the stepwise regression model tended to eliminate almost all the variance of prolactinpreviously associated with daily yield. Dominance measurements indicated that more submissive cows had higher milk prolactin. Individual cows tended to have characteristic prolactin, but this tendency was eliminated by statistical adjustment of the data for environmental and lactational variables.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(75)84542-5