There are a number of factors that affect the quantity of milk produced or milk yield in animals. They include:
- Individuality of Animals
- Stage and Persistency of Lactation
- Frequency of Milking
- Dry period
- Temperature and Humidity
- Changes Occurring during a Normal Lactation
- Milker’s Action
The milk yield varies from species to species. The quantity of milk Holstein Friesian cows produces is greatly more than the quantity of milk White Fulani cows produces.
This is one of the most important factors that affect milk yield. Animals belonging to dairy breeds produce more milk compared to dual purpose breed
3. Individuality of Animals
The strain and the individuality of cows within a breed are different in producing total yield. Larger cows normally secrete more milk. Cows normally will not secrete more milk daily than the equivalent of 8-10 percent of their body weight, whereas goats may secrete enough milk daily to equal 20 or more percent of their body weight.
4. Stage and Persistency of Lactation
There is considerable variation in the persistence of milk secretion following peak production within 2 months after lactation. Some cows are very persistent and their rate of milk secretion declines slowly (6-8 percent of their previous month). The production of other cows may decline very rapidly (8-l2 percent) so that they show poor persistence.
5. Frequency of Milking
As milk accumulates in the lumen of the alveoli and fills the storage areas of the udder, pressure develops inside those areas. This tends gradually to inhibit further milk secretion. The more frequent removal of milk permits maximum intensity of the milk manufacturing process. Therefore, frequent evacuation of the udder is essential for maximum milk production. It has been shown that milking cows three times a day increases milk production 10-25 percent over two-times daily milking. Milking four times a day instead of three results is another 5-15 percent increase in production. Of course, this will involve some more expenditure.
During the first 5 months of pregnancy, the decline in milk yield in pregnant cows is similar to the equivalent lactation period in non-pregnant cows. However, following the fifth month of pregnancy, cows begin to decline more rapidly in milk yield.
The average gestation period of dairy cows is 283 days. The aim is to have each cow mated about 85 days after calving. If mated earlier than 85 days, the total yield for the lactation is reduced as in this case after about 20th week of pregnancy milk yield will start falling more rapidly.
It is believed that there is a slight additional growth of secreting cells of dairy cattle during each pregnancy until cows reach about 7 years of age. This is manifested by- the increase in yearly milk.
The activity of a cow when in heat generally reduces milk secretion, however, this is temporary. To minimize milk loss during estrus, cows should be confined.
9. Dry period
Cows are normally bred 70 to 90 days (average of 85 days) after parturition. It is expected that they will lactate about 305 days and then be given a 60-day dry period before the next calving.
The dry period is important for replenishing body supplies including regeneration of secretory tissue. Allowing dairy cows a dry period has been shown to result in significantly higher production during the succeeding lactation.
A signiﬁcant reduction of milk yield occurs towards the» end of pregnancy. Although the exact reason is not yet known but according to one hypothesis it has been suggested that level of nutrient required for foetal development are highest; however, this appears to be only 1-2 percent of the daily requirement of the cow. Another convincing explanation is that of a change in hormone production, in which large amounts of estrogen and progesterone are released into the bloodstream, which is detrimental to high milk yield. During fourth to ﬁfth months of gestation, there is an increase of SNF (Solid Non-Fat).
11. Temperature and Humidity
Severe weather conditions drastically affect milk production. Temperatures between 40-75°F have no effect on the milk production. In this range (Comfort Zone), no body processes are directly involved in maintaining body temperature. At a very high temperature, feed consumption is greatly reduced, there is an increase in water intake, an increase in body temperature and respiration resulting in a decrease in milk yield with lowered milk fat, SNF and total solids. High relative humidity accentuates the problem of high temperatures.
12. Changes Occurring during a Normal Lactation
The speed of synthesis and diffusion of various milk constituents is dependent on the concentration of milk precursors in blood, which reflects the quality and quantity of the food supply. Nature provides for maintenance, growth, and reproductive needs before energy that is made available for lactation. Inadequate feed nutrients probably limit the secretion of milk more than any other single factor in a dairy cow. Although good nutrition alone cannot guarantee high milk production, poor nutrition can prevent attainment, of a cow’s full potential just as surely as poor management, low genetic potential in an unfavorable environment. The maintenance of lactation (galactopoiesis) is closely related to an adequate feed intake by the lactating animal.
Recently, more attention has been focused on the role of stress in the secretion of milk. As animals are selected to secrete higher levels of milk, any sort of stress will play an increasingly important role in lactation.
15. Milker’s Action
The amount of milk drawn from a cow is definitely inﬂuenced by the change of milker. Due to change of milker, the slight variation in milking process upsets the cow and thereby affects milk yield.
Diseases may significantly reduce the amount of milk secreted. Disease may affect heart rate, and therefore, the rate of blood circulation through the mammary gland, which influences milk secretion is also affected.