Factors influencing quantity (Yield) and quality (Composition) of Milk
Factors influencing quantity (Yield) and quality (Composition) of Milk • Species • Breed • Individuality • Interval of milking • Completeness of milking • Frequency of milking • Irregularity of milking • Day to day milking • Disease and abnormal conditions • Portion of milking • Stage of lactation • Yield • Feeding • Season • Age • Condition of cow at calving • Excitement • Administration of drugs and hormones • Genetic • & Environmental
Genetic Factors • Species – Each species yields milk of a characteristic composition. • Breed – breads producing large amount of milk yield milk of a lower fat. Milkfat percentage is partly a hereditary characteristic, and this causes the difference in average fat percentage between different breeds. Dairy cattle: Jersey and Guernsey breeds give milk of higher fat and protein content than Shorthorns and Friesians. Zebu cows can give milk containing up to 7% fat. There is a common tendency, within breeds, for high producing cows to produce milk with a low fat content. • Individuality – each animal yield milk of a composition that is characteristic of that animal. The potential fat content of milk from an individual cow is determined genetically, as are protein and lactose levels.
Environmental Factors • Interval between milkings/Number of milkings per day • Where the milking intervals are uneven, the cows give less milk after the shorter interval, but this milk will have a higher fat content. • The fat content of milk varies considerably between the morning and evening milking because there is usually a much shorter interval between the morning and evening milking than between the evening and morning milking. If cows were milked at 12-hour intervals the variation in fat content between milkings would be negligible, but this is not practicable on most farms. Normally, SNF content varies little even if the intervals between milkings vary. • Stage of lactation • The milk production of cows increases after calving, to reach a maximum (peak) level during the second month of lactation. It then decreases again gradually as lactation progresses. • The fat, lactose and protein contents of milk vary according to stage of lactation. Solids-not-fat content is usually highest during the first 2 to 3 weeks, after which it decreases slightly. Fat content is high immediately after calving but soon begins to fall, and continues to do so for 10 to 12 weeks, after which it tends to rise again until the end of the lactation.
Feeding • Feeding can influence the fat content of milk within the genetic yield potential. Adequate protein and energy in the ration are of primary importance in the effort to increase the fat content of the milk to the inherited maximum. Underfeeding reduces both the fat and the SNF content of milk produced, although SNF content is more sensitive to feeding level than fat content. Fat content and fat composition are influenced more by roughage (fibre) intake. • Disease • Disease normally has a disadvantageous effect on both milk production and milk composition. In cases of mastitis, the fat content decreases, while an increase in the whey protein and chloride content is noticed. • Completeness of milking The first milk drawn from the udder is low in fat while the last milk (or strippings) is always quite high in fat. Thus it is essential to mix thoroughly all the milk removed, before taking a sample for analysis. The fat left in the udder at the end of a milking is usually picked up during subsequent milkings, so there is no net loss of fat.
Age • As cows grow older the fat content of their milk decreases by about 0.02 percentage units per lactation. The fall in SNF content is much greater. • Exercise Over-exercise causes a considerable decrease in milk production. The higher butterfat percentage which is obtained as a result of exercise does not justify the loss in total butterfat. • Climate The fat content may show a slight increase in warm weather (temperatures above 30° C) or when temperatures drop below freezing. • Oestrus and gestation Results show that, once the foetus has reached the age of four to five months, the butterfat percentage in the milk shows an abnormal increase. Gestation suppresses high milk-production after five months, and therefore promotes a higher butterfat percentage.
References: http://www.mkgandhi.org/health/diet_reform/32cowmilk.html http://classes.ansci.illinois.edu/ansc438/milkcompsynth/histology_6.html https://www.uoguelph.ca/foodscience/dairy-science-and-technology/milk-production-and-biosynthesis http://www.diffen.com/difference/Buffalo_Milk_vs_Cow_Milk http://en.wikipedia.org/wiki/Dairy_cattle http://www.slowfood.com/slowcheese/eng/12/many-breeds http://en.wikipedia.org/wiki/Milk http://www.agritech.tnau.ac.in/animal_husbandry/animhus_cattle%20_breed.html http://en.wikipedia.org/wiki/Dairy_cattle http://animals.pawnation.com/cattle-breeds-4731.html http://www.ansi.okstate.edu/breeds/