Introduction - Pedigogy

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Introduction

The various factors affecting the constituents of milk are discussed as follows:

The milk from various species of mammals is of different composition as illustrated in the

following table:

Genetic factor is probably the most important factor to control the composition of milk. E.g

Holstein breed usually gives milk with lowest fat and SNF than Jersey.

It is partly from the heredity differences and partly from environmental and physiological factors. Individuals seem to have characteristic tendency
towards more or less day to day variation in composition of milk.

Shorter the Milking interval higher will be the fat content with decreasing quantity of milk and vice versa.
For each hour the interval exceeds from the normal figure, i.e., twelve hour, the fat is reduced by 0.1 to 0.15 %, and for each hour interval below the normal range, the fat percentage increases by 0.2 to 0.25%.
Milking thrice a day instead of twice a day for an entire lactation period increases the production from 10 – 20 percent.
With milking intervals of 15 and 9 hours the difference in fat content can be 1.0 percent where as with the intervals of 13 and 11 hours the difference is 0.3 percent.

Normally the lactation days are 300 in cattle. It is divided into three parts: Colostrums phase (0-5 days of parturition), normal phase (6-300 days of parturition) and extended phase (300 day onwards)
Following parturition, the milk yield increases in most of the cows for a period of 15 to 30 days.
After a period of 30-50 days the production begins to decline gradually.
Breed , frequency of milking, seasonal changes, nutritional status, pregnancy and general management are factors influencing a decline in production with the advance in lactation.

Fat percent and SNF percent decreases at low age to advanced age.
As cow become older, they produce more milk, but the fat SNF, protein and lactose in the milk decrease slightly.
The average yearly decline in fat and protein content were 0.03 percent and 0.01 percent from first to tenth lactation.

It has been found that feeding of oil, e,g. palm oil, coconut oil, butter fat, increases the fat percent while fish liver oil produces the opposite effect to composition of milk.
The fat content is lowered if diet contents large amount of highly digestible concentrate ration such as oil cakes, corn maize or roughage in finely ground and palette form.
On pasture, the fat content increased only by 0.1 percent as against a rise up to 0.44 percent on stall feeding by supplementation with oil cakes.

When cows are freshen in winter, the total milk yield is 10 -20 higher than that of summer clavers because of favorable conditions and availability of the nutritive forage crop during winter than in summer months.

Temperature from 40 -75 degree Fahrenheit has no effect on milk production of dairy cows.
When temperature drops below 40 degree Fahrenheit there is no adverse effect on milk production if extra feed is supplied.
Conversely with increasing temperature, there is slight decrease in milk yield and slight decrease in milk fat, SNF and TS.

Prolactin, one of the hormones of pituitary gland is responsible for maintenance of lactation.
There is an increase in milk fat, TS and milk yield by 20-3- percent when cows are fed 20-25 grams iodinated casein per head per day.
Milk yield and fat content have been seen to be increased resulting administration of oxytocin over 14 days period during lactation.
Adreno-corticotrophin (ACTH feeding) depresses the milk yield.
Feeding 5gms yeast/cow/day increased fat content of milk of some cows to as much as 0.8 percentages.

11.Effect of excitement:

Sexual excitement, various types of physiological or pathological stress, fire, thunder, storm, biting, dogs barking, attack by external ticks and blood parasites etc. influence both milk yield and composition in the generalized way.