Cow's Milk - From Lactation to Managing Cows. Everything a farmer should know.

 

Cow Milk

Cows' milk is a nutrient-dense food consisting of varying amounts of carbohydrate, fat, and protein. The major constituents of cows' milk are water (87.4%) and milk solids (12.6%), which includes vitamins, minerals, carbohydrate, fat, and protein. The principal carbohydrate in milk is lactose. The lactose content of milk varies by species. Cows' milk contains about 4.8% lactose . In addition to lactose, minor quantities of glucose, galactose and oligosaccharides are present.

      Milk fat is a complex lipid existing as an oil-in-water emulsion. Milk lipids are mainly triacylglycerols or fatty acid esters with glycerol, of which more than 400 have been identified. Phospholipids, sterols, waxes, and free fatty acids have also been identified.

       Cows' milk is a heterogeneous mixture of at least 20 proteins. Eighty percent of the total protein is casein proteins and 20% is whey proteins. Caseins are relatively heat-stable, whereas whey proteins are more labile. Casein can be fractionated into four major components: alpha, beta, kappa, and gamma casein. The whey proteins consist of α-lactalbumin, β-lactoglobulin, bovine serum albumin, and several minor proteins, including lactoferrin and lactoperoxidase.

Lactation Cycle

The  Lactation cycle is split into four phases, the early, mid and late lactation   each of about 120 days. The dry period which should last as long as 60 -65 days In an ideal  cow that  calve every 12 months.

Changes during Lactation

A number of changes occur in cows as they progress through different stages of lactation. Although her maintenance requirements will not vary, she will need more dietary energy and protein as milk production increases then less when production declines. However to regain body condition in late lactation, she will require additional energy.

Cows usually use their own body condition for about 12 weeks after calving, to provide energy in addition to that consumed. The energy released is used to produce milk, allowing them to achieve higher peak production than would be possible from their diet alone. To do this, cows must have sufficient body condition available to lose and therefore they must have put it on late in the previous lactation or during the dry period. At calving, appetite is only about 50 to 70 per cent of the maximum at peak intake. This is because during the dry period, the growing calf takes up space, reducing rumen volume and the density and size of rumen papillae is reduced. After calving, it takes time for the rumen to “stretch” and the papillae to regrow. It is not until weeks 10-12 that appetite reaches its full potential.

Peak lactation to peak intake

Following peak lactation ( 6 -8 weeks after calving ), cows' appetites gradually increase until they can consume all the nutrients required for production, provided the diet is of high quality and be fed with High Protein and High Energy  Supplement . Cows tend to maintain weight during this stage of their lactation.

Mid and late lactation

Although energy required for milk production is less demanding during this period because milk production is declining, energy is still important because of pregnancy and the need to build up body condition as an energy reserve for the next lactation. It is generally more efficient to improve the condition of the herd in late lactation rather than in the dry period.

The rate of decline from peak or persistency depends on:
•Peak milk yield
• Nutrient intake following peak yield
• Body condition at calving
•Other factors such as disease status and climatic stress
        
Underfeeding of cows immediately post-calving reduces peak yield but also has adverse effects on persistency and fertility. Poor feeding Management during the Dry period also result in Reproduction problems including the cows not cycle until many months post-calving.

Feeding during first 100 days of calving

Feeding cows in the first 100 days post-calving is very crucial . In the first 3 weeks post calving the cows need to be fed with grain  mixture  and Niacin to cope up with Transition period and later with high protein and high energy ration. In addition :

• The feeding management should aim to increase the intake of ration as much as possible as the appetite will be very low during the initial period. 

• The fodder harvested at correct recommended  interval should be fed

• Always feed the Green forage that contains two or three varieties in each  of Grass, legume and Tree fodders.

• Feed the green forage harvested afresh. Do not feed wilted forages.

• It is better the Green forage to contain 70 % Grass mixture, 20% Legume fodder mixture and  10% Legume mixed  tree fodders. The forages should supply less than 35% Neutral Detergent Fibre component in Fibre.

• Chaff 80 % the Green forages  to  1-1.5 “ and feed. The remaining 20% should be fed as long .This will help the cows to consume  mor forages and better mastication. 

• Include Cotton seed in the Ration to increase the Energy content  of the Feed

• Ensure 16 -18% Protein in the ration for  cows yielding  15 -20 litres milk  and 19% Protein in the ration for  cows yielding  more than  20 litres .For dry cows  10-12% protein is sufficient. 

• Always feed the concentrate mixture free from mould and with Bureau of Indian  Standard.  

• Ensure optimum level of By-pass protein in the ration and the

 “ Acidosis “ should be avoided.

• Ensure the cows receive 30 – 50 gram of Mineral mixture every day

• The total ration should be divided in to 3 -4 meal and fed.

• In high  yielding cows increase the Milking frequency. 

• Supplement the ration with enough Calcium to compensate calcium drain in through milk.

• Usually the appetite increase soon after Milking .First with  feed Forages first  and  one hour later with Concentrate  supplement.

• Milk production increase  Heat production in cows and Vis-à-vis  stress in the Milch cows . Splash cool water daily.

• Try to feed the high protein rations in  cool hours . 

• Do not offer kitchen waste fermented water. Instead offer clean  water 24 x 7. There should be no restriction  for  water .

The Cows during pregnancy be fed in such a way to avoid occurrence of Metabolic  Diseases in post -calving period.

Manage the Cows well during Dry Period

The dry period is a critical phase of the lactation cycle to increase milk yield during the following lactation and minimize metabolic problems at or immediately following calving. 

Maintaining (or increasing) body condition during the dry period is the key to ensuring cows have adequate body reserves for early lactation. If cows calves with adequate body reserves, they can cycle within two or three months after calving. If cows calve in poor condition, milk production suffers in early lactation because body reserves are not available to contribute energy.   High feeding levels in early lactation cannot make up for poor body condition at calving. The cow stops secreting milk and becomes dry due to Involution of the udder: The principal reason for the dry period is to allow the secretary tissue of the udder to involute. During this period, the secretory cells of udder actually break down and are resorbed, and a new set of secretory cells is formed. This cell renewal process takes approximately six weeks and, if a cow is allowed no dry period at all, will result in a loss of milk of at least 30% in the subsequent lactation.

Foetal development:
During the last eight weeks before calving the foetus gains almost 60% of its birth weight, an overall rate of gain for the cow of about 0.75 kg/day. At the very least, the cow must be fed for foetal growth.

Replenishment of body reserves:

Mineral reserves are an entirely different matter to energy reserves.

The high-producing cow will have severely depleted her body reserves of minerals, especially Ca and P, during her lactation. These reserves can only be completely replenished when the cow is dry.

Adequate mineral nutrition during the dry period is very important. If the cow is very weak or underweight, the dry period helps her to replenish body reserves and she may be fed to gain about 20-25 kg body weight during the dry period.   

                        

The length of the dry period:

• It is wise to aim for a dry period of eight weeks (56 days).
• Rations should be formulated to specifically meet the nutrient requirements of dry cows:        body maintenance, foetal growth, and for replacing any additional body weight not replaced during phase.
• Pregnant animals are to be offered extra nutrients during the last 2 -3 months of gestation. 
• The aim is that by the end of gestation period the cows should not only gain their initial body weight but also put on an extra 25 to 30 kg of body weight. 
• This is necessary to enable the animal to withstand the stress of parturition and to maintain the persistency of milk production during the subsequent lactation period. 
• The provision of extra nutrients should be given in the form of concentrate mixture and not as forage because roughages are not as efficient as concentrates in increasing the body weight. 
• The rest of the ration must contain sufficient green feeds so that the colostrum secreted after parturition should be rich in vitamin A.
• DMI will be near 2 % of the cow's body weight. 
• A minimum of 12 % CP in the DM is recommended.
• Meet Ca and P needs, but avoid large excesses. Ca intakes of 60 to 80 g and P intakes of 30 to 40 g are sufficient for most cows.
• Avoid excess calcium and phosphorus intakes
• Dry cow rations above 0.6 percent calcium and 0 .4 percent phosphorus (DM basis) have substantially increased milk fever problems. 
• Provide adequate amounts of vitamin A, D, and E in rations to improve calf survival and lower retained placenta and milk fever problems.
• Trace minerals, including selenium for most producers, should be adequately supplemented in dry cow diets.

The milk secretion  and appetite level change at different stages of lactation. The lactation cycle if divided in to four phases :

Phase I : Calving to 2 ½ months: Immediately after calving the appetite level will be the lowest. At the later part of this phase the appetite will gradually increase. But at the same time there will be greater demand for nutrients as the milk secretion  reaches the peak. 

Phase II : Between  2 ½  and  7 ½ months after calving : Between  4  and 5 months after calving the appetite reaches its peak  and again decreases gradually. The milk secretion continue to decrease gradually.

Phase III : Between 7 ½ and 10  months after calving: The milk secretion continue to decrease and completely stopped at the end of 10th month. The appetite level also decreases.

Phase IV : Between 10 and 12th month of calving: The milk secretion is stopped completely and the appetite level will also be at the lowest.

About the Author

Prof Dr M Murugan- Consultant, Animal Nutrition, Animeta AgriTech YourFarm . Former Dean, Tamil Nadu Veterinary and Animal Sciences University, Chennai. Animal Nutrition Specialist with 35+ years of experience in the field of Teaching, Research and Technology transfer to farming communities. His field of Research is Fodder production with special emphasis to Agroforestry systems and the class of livestock is small ruminant. Dr. M.Murugan has published 43 Research papers in both National and International Journals. He has also published 45 Popular articles ,authored 5 books and 2 manuals. His research articles are cited in several text books. He is the member of several Professional bodies like Indian Poultry Science Association Dairy Technology Society of India , Animal Nutrition Society of India and Tamil Nadu Veterinary Council.