Protein bypass in cow feeding: where to take, and how to use

What is the need for protein in the diet of cows, what is the role of the rumen, and how to control the effectiveness of the diet in terms of protein content and type and its impact on the health of dairy cows? This was reported by the expert Feedlance B.V. Olga Loza

Total protein for ruminants is divided into fractions:

  • RDP fraction (rumen degradable protein) — fermented by microorganisms to nitrogen (N) and used for their vital functions.
  • The bypass protein fraction (RUP — undigestible protein rumen) — is not broken down by microorganisms in the rumen, but is digested and assimilated in the intestine, providing the animal with a reliable source of metabolic protein, which is so necessary for milk production.

Thus, when balancing the diet according to the need for protein, it is necessary to take into account not only the amount of total gray protein, and the levels of its fractions: RDP and RUP.

Otherwise, if you do not pay attention to the level of "scar" (RDP) and bypass (RUP) protein when balancing the diet for crude protein, it can lead to excessive feeding of nitrogen without real stimulation of milk productivity.

The "scar" fraction of RDP protein is fermented by microorganisms to nitrogen, using it for its vital functions. This is the process of formation of microbial protein, which is also necessary for cows.

However, excess nitrogen that has not been used by the microorganisms in the rumen is absorbed through the blood in the form of ammonia to the liver, where it is converted to urea. Some urea circulates in the body, the excess is excreted in urine and milk.

Maximize scarring

The main task of the management of feeding cows at the dietary level is to maximize the work of the rumen. Balancing the protein diet is to maximize the production of microbial protein without overloading the rumen, liver and excessive production of toxic urea in the cow.

Here are some tips to help maximize microbial protein production without adversely affecting rumen and cow health.

  1. Adjust the total crude protein content in the diet with adequate bypass protein content. The content of bypass protein (RUP) in the diet should range from 40-44% of total protein.
  2. Adhere to the balance of "scar" protein (RDP) with the amount of fermented carbohydrates in the rumen (starch, sugar, and effective fiber), which will help maximize the efficiency of microbial protein synthesis. Here the indicator of OEB in a diet (CVB 2007) will orient.

The target content of rumen digestible protein (RDP) is not more than 56-60% of the total protein, or 100-105 g / kg of dry matter of the diet.

If rumen digestible protein (RDP) is not enough, then we "malnourish" rumen microorganisms. This will have a detrimental effect on cicatricial digestion, in particular, reducing the digestion of structural carbohydrates, reducing fat in milk.

When oversaturated with rumen protein (RDP), its fermentation in the rumen will have a toxic effect on the cow's health. This has a particularly negative effect on the liver, and then on the reproduction and productivity of the herd.

There are several ways to control the effectiveness of a diet in terms of protein content and type and the impact on the health of a dairy cow

Method 1. Analysis of milk urea nitrogen (MUN)

Milk urea nitrogen (MUN) is an indicator of the effectiveness of protein feeding and the health of cows. It can be used to evaluate the effectiveness of microbial protein synthesis in the rumen. The norm of milk urea nitrogen (MUN) is considered to be 8-12 mg/dl. However, this figure is quite individual for each farm.

  • ü A low level of MUN (<8 mg / dL) may indicate a deficiency of scar protein (RDP) in the diet or an imbalance in the breakdown of protein and carbohydrates. It is believed that the potential of the scar is not used.
  • üHigh amount of MUN (> 12 mg/dosage) on excess protein scars (RDP), imbalance of protein and carbohydrate imbalance, as well as inefficient scarring, otherwise — lack of energy and fermented carbohydrates.
The amount of nitrogen in the urea of milk is quite an effective indicator for adjusting to working with the herd. Its excess actually indicates an excess of urea in the cow's health, which has a number of negative factors on the economy of milk production and cow health:
  • scar dysfunction;
  • toxic effects on the cow's health;
  • low efficiency of protein feeding;
  • loss of profit;
  • reduction of the reproductive capacity of cows;
  • low viability and development of embryos (effect on progesterone levels);
  • ph uterus, assimilation of Mg and K, which adversely affects the fertility of cows.

Method 2. Analysis of milk fat content

Lack of protein in the rumen leads to a decrease in the synthesis of volatile fatty acids, in particular acetic acid, thereby negatively affecting the fat content in milk.

Method 3. Analysis of the feces of cows

Changes in stool consistency are a direct indicator of scar health. Its visual analysis can help assess the balance of protein and carbohydrate breakdown in the rumen.

Thus, as we can see, balancing the level and types of protein in the diet is a constant battle between reducing costs and increasing profits on a dairy farm. Therefore, our main task is to get maximum, including economic, benefits from protein in the diet

Picture 1. The need for DVE dairy cows depends on the level of productivity.
Table 1. The most common ingredients in the diet of dairy cows.
Table 2. The required amount of protein in the diet of cows on the 60th day of lactation.
Table 3. Comparison of total bypass protein content in soybean meal and Avamix Intense 80

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