Introduction

FACTORS AFFECTING COMPOSITION OF MILK
  • Milk differs widely in composition. The constituents of milk are same irrespective of species, breed and age. The vary in quantity of availability. Milk from individual cows shown greater variation than mixed herd milk. In general, milk fat shows the greatest daily variation, then comes protein, followed by ash and sugar.
  • The factors affecting the composition of milk are:
    • Species: Each species yields milk of a characteristic composition eg Cow, buffalo, dog or deer
    • Breed: In general there is difference in composition among different breeds of the same species.
    • Interval of milking: Longer the interval between milking more will be the quaantity of milk with lesser fat and vice versa.
    • Completeness of milking: If the cow is completely milked, the test is normal. Incomplete milk leads to residual milk and thus the fat content gets reduced.
    • Frequency of milking: Whether a cow is milked twice, thrice or four times a day, there is increase in volme during early lactation. ( times/day vs. 2 times/day milking. In dairy cattle, milking 3X/day results in increased milk yield, although the observed increase is variable. Generally 3X/day milking increases milk production by up to 25%. But, ~2/3 of this increase is due to better feeding and management and ~1/3 is due to decreased udder pressure. 3X/day milking must be accompanied by a compensatory feeding program; if not, then yield from the continued 3X/d milking will decline back to that from 2X/d. Three times per day milking is more beneficial in late lactation, for example during the first 4 mos. of lactation 3X/day milking increases yield 7-12% over 2X/d. In contrast, during later lactation 3X/day milking increases yield 16-90% over 2X/d. Both first lactation and older cows show increased yield in 3X/day vs. 2X/day milking. )
    • Irregularity of milking: frequent changes in the time and interval of milking result in lower tests.’
    • Day-to-day milking: May show variations for the individual cows.
    • Disease and abnormal conditions: These end to alter the composition of milk, especially when they result in a fall in yield
    • Portion of milking: fore-milk is low in fat content (less than 1 per cent), while strippings are highest (close to 10 per cent). The other milk constituents are only slightly affected on a fat free basis.
    • Stage of lactation: The first secretion after calving (colostrum) is very different from milk in its composition and general properties. The change from colostrum to milk takes place within a few days.
    • Yield: For a single cow; there is a tendency for increased yields to be accompanied by a lower fat percentage, and vice verse.
    • Feeding: Has temporary effect only.
    • Season: The percentages of both fat and solids not fat show slight but well defined variations during the course of the year
    • Age: The fat percentage in milk declines slightly as the cow grows older.
    • Condition of cow at calving: If the cow s in good physical condition when calving, it will yield milk of a higher fat percentage than it would if its physical condition was poor.
    • Excitement: Both yield and composition of milk are liable to transient fluctuations during periods of excitement, for whatever reason.
    • Administration of drugs and hormones: Certain drug may effect temporary change in the fat percentage, injection of feeding of hormones results in increase of both milk yield and fat percentage.
    • Milk composition is affected by genetic and environmental factors.
Last modified: Thursday, 12 April 2012, 6:45 AM