Introduction
Milk is one of the energy-rich foods that contains a significant amount of protein, lactose, fat, and a good source of calcium, phosphorus, magnesium, potassium, and vitamins E, K, D, C, B12, B6, B2, B1, A, and niacin. , and it is folic acid that can provide the amount of minerals needed by the human body. Meanwhile, cow’s milk is one of the most consumed milk in the world, which has reached 85%, and after that, buffalo, goat and sheep’s milk supplies eleven percent of human milk. It is quite evident that the importance of breeding Holstein, Brown Swiss dairy cows is not hidden from anyone and breeding such cows can be of great benefit to the breeder. In addition to the necessary care against disease, a dairy cow must provide the amount of fodder and concentrate to have the highest and highest quality production.
Reduction of cow’s milk fat can occur for various reasons, such as common cow diseases such as milk fever, ketosis, acidosis, transfer of udder, and fatty liver, and in addition, unhealthy nutrition and non-observance of breeding principles may cause reduction of cow’s milk. Therefore, it is better to follow a series of principles to increase milk so that you don’t face problems even in drought years.
Milk produced in America is purchased based on protein, fat and milk solids. This new pricing method is based on the economic value of components and compounds obtained from milk (cheese, butter, skim milk, milk powder or powdered milk), which of course goes up or down with the change of market conditions. As a result, levels of milk compounds have an important relationship with herd management. In addition, the health and nutrition of the cow plays a significant role in the income of the farm. In fact, they are a set of factors that cause changes in the components and compositions of milk. Generally, milk fat and protein have a positive correlation with dairy cow population. With the knowledge that the level of milk compounds differs in different breeds. Holstein has the lowest and Jersey and Guernsey have the highest milk fat and protein. But Holstein compared to Jersey and Guernsey, its milk production can be increased with good management and nutrition.
Milk produced in America is purchased based on protein, fat and milk solids. This new pricing method is based on the economic value of components and compounds obtained from milk (cheese, butter, skim milk, milk powder or powdered milk), which of course goes up or down with the change of market conditions. As a result, levels of milk compounds have an important relationship with herd management. In addition, the health and nutrition of the cow plays a significant role in the income of the farm. In fact, they are a set of factors that cause changes in the components and compositions of milk. Generally, milk fat and protein have a positive correlation with dairy cow population. With the knowledge that the level of milk compounds differs in different breeds. Holstein has the lowest and Jersey and Guernsey have the highest milk fat and protein. But Holstein compared to Jersey and Guernsey, its milk production can be increased with good management and nutrition.
Factors affecting milk protein and fat:
1- Non-nutritional factors 2- Nutritional factors
Non-nutritional factors:
1– Lactation stage:
The highest percentage of milk fat and protein is at the end of lactation and their lowest level is after delivery, especially the production peak.
2– Age:
From the first to the fifth period of lactation due to the increase in milk production level per period, milk fat decreases by 0.2% and milk protein by 0.02 to 0.05%.
3– Season:
In hot and humid seasons, the percentage of milk fat and protein decreases, and in the winter season, we see a gradual increase in the composition (fat and protein) of milk. These changes are moderated or increased under the influence of the type of feed and the way of feeding.
4– Mastitis:
Mastitis reduces fat and casein in milk, but on the other hand, it increases the amount of blood protein (gamma globulin) in milk. Somatic cell volume (SCC) of milk increases during mastitis. Herds in which there is mastitis, SCC causes a 2-3 times decrease in the price of their milk.
5– Technical errors:
Such as milk and tank cooling problems, sampling problems and careless piping in milk transfer can lead to a decrease in milk fat and protein.
6– Genetics and heredity:
Genetics can have up to 55% effect on milk fat and protein in different cows, although the environment and the mutual effects between environment and genetics should not be ignored. Milk fat and protein are more heritable than milk itself and its other components. Milk has a positive correlation with the amount of fat and protein, but it has a negative correlation with the percentage of fat and protein.
Nutritional factors:
Nutritional factors are the most influential factors on milk and its compounds, which have a direct correlation with the way of management. If there is a change in the diet, milk fat is more affected than protein. For example, milk fat will change within 7-21 days when the diet is changed, while protein takes 3-6 weeks to show this change.
One of the factors that increase the fat in cow’s milk is the presence of a large amount of insulin in the blood, which is caused by the decrease in the number of concentrates per day, so research shows that the more the number of times the concentrate is consumed, the more the number of times the concentrate is consumed will prevent the loss of milk fat.
It is not only quantity that is important in consumer concentrate, but its quality should be taken into account and as much nutrients as possible such as fish powder, fat powder, dry residues of distilling industries, molasses, corn gluten and probiotics, yeasts, buffers, mineral and vitamin supplements and Use anti-fungals and molds along with energy and protein rations.
Dynalac and Omega 3 supplement, a product of UFAC, England, with its precise formulation and taking into account the animal’s need for all fatty acids with a standard ratio, increases milk fat and increases economic productivity.
1– The origin of milk compounds
With the microbial digestion of dietary fiber in the stomach, acetic acid and butyric acid are produced, which after being transferred to the breast participate in the production of half of the milk fat, the other half of the milk fat is supplied through the fat in the diet and exchangeable fat in the body. Ruminal microbes convert dietary proteins into microbial proteins that contain essential amino acids. These amino acids are used by mammary glands to produce milk protein; Glucose provides the energy required for this metabolic pathway. Glucose itself is provided either from propionic acid produced in the rumen or from glucose absorbed in the intestinal wall. Therefore, if a little propionate is produced, a little amino acid is also produced, which also enters the process of gluconeogenesis and turns into glucose. Of course, milk casein is produced from available amino acids, which together with albumins and blood immunoglobulins secreted in milk are considered as milk protein, but its quality is low due to the absence of essential amino acids in milk.
2– Rumen effect:
The presence of sufficient amounts of protein, effective fiber, and fast-fermenting hydrocarbons available in the ration are required for the correct functioning of the rumen and maintaining the optimal level of milk compounds.
3– Management in feeding:
The feed is in two forms, TMR and non-TMR. In the non-TMR type, the feed components are provided separately to the animal so that the animal has the ability to choose. In the TMR model, feed components are mixed together in such a way that the animal does not have the power to choose, and thus all the animal’s nutritional needs are met by consuming it. The disadvantage of non-TMR is that the animal may overeat one of the feed components and refuse to eat the other component, which will lead to complications such as acidosis, obesity syndrome, reduction of milk fat, etc. In TMR, there is a possibility that the food is not palatable and the animal does not want to eat it to the full capacity of its digestive system, in such a case, the amount of production will decrease depending on the amount of consumption.
4– Body condition
In the future lactation period, fat and protein of milk will decrease in lean and fat cows in the late pregnancy period. At the beginning of lactation, losing weight for a short period can increase milk fat, which does not exist in thin cows, and fat cows also suffer from ketosis.
5– Ration energy
If dietary energy is high and dietary fiber is low, it will reduce fat and increase milk protein and vice versa. The lack of fodder quality, the lack of balance in the ration in terms of protein and minerals, the low concentration in the ration are some of the factors that reduce the level of milk protein.
6– Dietary protein
In the last three weeks of pregnancy and the beginning of calving, the animal needs protein more than anything else in the diet, otherwise the milk protein will decrease drastically. It should be noted that excessive addition of protein in the ration causes an increase in raw milk protein and the excess of animal needs is excreted. The ration protein should be balanced in terms of degradable and non-degradable protein in the rumen, forage silage level, soluble protein and NPN, even for high-yielding cows, amino acid balance is also needed.
7– Diet concentrate
Using concentrate and high non-fibrous carbohydrates (NFC) and low fodder in the diet increases the production of propionic acid and decreases acetic acid in the rumen, resulting in an increase in milk protein and a decrease in milk fat. Usually, the amount of 38-36% of the dry matter of the ration is NFC, the production of milk compounds will be at a high level.
8– Ration fodder
Forage constitutes 40-45% of the dry matter of the ration of dairy cows, which includes corn silage and forages with a high percentage of fiber. The size of cutting the forage should not be so small that it leads to the production of more propionic acid than acetic acid, and it should not be so long that it physically restricts the animal from eating enough feed to meet the animal’s needs. The size of the fodder should be suitable to provide the ration as TMR to the animals.
9– fat or oil added to the ration
When the fat exceeds 5% of the dry matter of the diet, it will be toxic for the rumen microbes and it will also reduce fiber digestion. If the consumption of fat (especially unsaturated fatty acids) is 6-7%, the rumen stops its normal movement. You should also pay attention to the fact that the fat is not rotten, because if you consume rotten fat, the milk fat will go down to its minimum level. Of course, according to an unproven hypothesis, if the fat used in the low ration is 5%, it will increase milk fat.
Conclusion
Monitoring the milk composition of a herd can help to assess the health and nutritional status of dairy cows. Milk fat is one of the most valuable components of milk. Fat is the most variable composition of milk and many physiological and environmental factors can affect its ratio and amount in milk. If the herd’s milk fat is 0.3% less than the breed average, it can indicate a problem. Diets that provide the possibility of improving the excretion of more fat in milk can be potentially economically beneficial. Therefore, in order to preserve milk fat, it is necessary to identify, monitor and measure the most important factors affecting it.
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