ANSC 438 Home / Beginning / Milk Composition / Mammary Structure
Mammary Development / Mother & Neonate / Lactation / Mastitis

Milk Composition & Synthesis
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Milk Composition
Stage of Lactation


Stage of Lactation

Composition of milk varies considerably during a lactation, with the major changes usually occurring soon after the start of lactation. The first secretion to be collected from the gland is called colostrum. The composition of the secretion gradually changes to that of mature milk.

Study Question: What do you think causes the primary change in protein concentration in mammary secretions that occurs during the initial couple of days after calving? Also, several milk components decline in concentration during very early lactation. Which milk component increases in concentration during the initial days after calving?


Milk composition varies gradually throughout lactation, as indicated in these curves for fat and protein percentages through a cow's lactation.

Study Question: Would a cow produce more daily milk fat at 4 weeks of lactation or at 40 weeks of lactation?


Stage of Lactation
Milk Composition & Synthesis
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