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Feed Tech
Tuesday, August 23, 2016 10:48:01 AM
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Improving the dairy cow performance and health by increasing the rumen protected protein in diets with expander treatment

 

Amandus Kahl

 

 

Due to breeding progress and improved keeping and feeding management the milk yield per performance period has been increased considerably in recent decades. However, falling milk prices, rising feed costs and more stringent environmental protection are ongoing challenges. 

 

After calving, most dairy cows are unable to compensate the increased energy and protein delivery resulting from the milk synthesis by a corresponding feed intake, especially since an increase of the concentration of nutrients in the ration is subject to very tight physiological limits. The metabolic situation of the dairy cow in the first third of lactation - the rising milk yield in conjunction with suboptimal environmental conditions - results in high stress for today's dairy cows and can involve an increased risk of disease. With regard to protein metabolism and homeostasis of nutrients, the first third of lactation means a challenge for the organism. With advanced gestation, the fetal demand for energy, protein and minerals also increases significantly.

 

Often greatly increased RNB values ​​(ruminal nitrogen balance) can be found in the feeding ration. In many cases, the nutritional limits are exceeded by more than threefold. The non-usable nitrogen passes through the rumen in the form of ammonia, which must be transformed to urea in the liver and is therefore associated with a high metabolic load. High milk urea contents (> 30 mg/dl milk) prove this nitrogen oversupply which affects the animal health if it lasts longer. A rumen-synchronous feeding and the use of protein components with a high by-pass content in the ration based on usable crude protein (uCP), ruminal nitrogen balance (RNB) as well as starch/sugar and resistant starch, provide a productivity-related feed for ruminants. By means of the hydrothermal crown expander treatment of the protein concentrate, the protein digestibility can be improved.

 

Protein improvement

 

Proteins are high-molecular compounds composed of amino acids. These proteins are necessary for the milk production and muscle and bone growth. They are also constituents of enzymes and hormones, and thus also necessary for the control of the metabolic processes. Even the body's immune system cannot do without proteins. So the health and performance of animals depend on a balanced protein supply. The basic molecules of proteins consist of more than twenty different amino acids, of which ten are vital amino acids. These are essential for the body and must be supplied continuously via the feed intake.

 

Influence of expansion on the proteins

 

High-protein concentrates show a pronounced treatment effect after expansion which is otherwise only achieved by means of chemical processes. The increase in ruminally undegraded protein (UDP) or by-pass protein can be considered in the ration formulation for ruminants and allows a rumen-synchronous feeding. Fig. 1 shows the percentage shift of ruminally undegraded protein by the treatment, the intestinal digestibility of the protein not being limited by the treatment. The percentage of uCP (utilisable crude protein) in a feed mixture is increased by expansion, since the usable protein available in the intestine is composed of the UDP and microbial protein. This enables an optimum protein supply, which is reached by increasing the content of by-pass protein (uCP) by means of increasing the UDP content. Thus, the protein content of the feed can be reduced with the milk production remaining the same, e.g. by a reduction of the percentage of soybean meal.

 
Fig. 1:  Change in the passage rate of the stable protein by hydro-pressure-thermal treatment

 

This also corresponds to the demand made on dairy rations "appropriate for ruminants", since with a milk yield of 30 kg per day and 25 % UDP in the ration the total content of nXP is not sufficient to cover the maintenance requirements. With increasing yields, the importance of the bypass proteins rises, since the microbial protein synthesis in dairy cows suffices only for 12 to 15 kg of milk per day in addition to covering the maintenance requirements. This gap can only be closed by an increase of the UDP content in the total ration to > 35 %. For a high nutrient intake, in addition to the energy and nutrient concentration the feed intake capacity of the animals must be considered, because especially in early lactation in high yielding cows, the nutrient supply according to requirements is difficult due to limited feed intake. Factors affecting feed intake include the body condition of the animals, the stage of lactation and pregnancy, as well as the limited rumen volume. It is important to produce and feed mixed dairy concentrate with a high energy and protein density.

 

Increase of the UDP/bypass protein:

 

Based on the tests currently being carried out, the following UDP values ​​were determined. The crown expander line was set up as shown in Figure 2, and the tests were carried out with the OEK in the Kahl pilot plant. Since the contents of non-degradable proteins depend on the origin of the raw materials, a test was carried out with soybean and rape extraction meal to test different treatment parameters.


 
Fig. 2:  Visualised process line with pre-conditioning, crown expander and post-conditioning

 

Test procedure I:

 
In the test, which was carried out with an expander head temperature of 165°C and a post-conditioning of 10 minutes, the following UDP values were reached (see Table 1). The rape extraction meal was proportioned into the mixing conditioner. In the mixing conditioner the mixture was heated to about 90°C by adding saturated steam as well as water. As a result, the preconditioned raw material had a moisture content of 17 to 19 %. The preconditioned rape extraction meal was proportioned into the expander, conveyed and subjected to high mechanical pressure and intense shear forces. This friction caused that the mechanical drive energy was transformed into heat energy. This process is also called "high-temperature short-time treatment," because the additional heating of the product above the boiling point of 100°C takes place for a few seconds only.
 

Tab. 1:  UDP values ​​for crown expandate of rape extraction meal

 
 

0

     I 

    Increase 

  uCP 

UDP 8 (passage rate of 8%/hour)

42 – 48 %

68 – 73 % 

53%

  32 – 35 % 

 

At the crown outlet, the overheated product was exposed abruptly to the ambient air and pressure influences (expansion), so that a part of the moisture contained in the product evaporated through a flash effect lowering the product temperature. To improve the quality, the product was post-conditioned with a retention time of up to 10 minutes and at temperatures of about 100 °C.

 

The percentage increase described in Tables 1 and 3 refers to the previous test setting (see Table 2).

 


Fig. 3: Percentage increase of the UDP contents   Fig. 4: Granulated crown expandate

 

Test procedure II:

 

In this test, commercial soybean extraction meal was expanded. Here, the crown expandates show a pronounced treatment result. The expander head temperature was in all four parameter settings (see Table 2) at approx. 165 °C. With this treatment at a temperature of about 100 °C and an average moisture content of 16 % during post-conditioning, contents (see Table 3) of bypass protein (UDP) of up to 78 % were reached. This increase of UDP8 results in a shift of the protein availability from the rumen to the intestine, as shown in Fig. 1.

 

Tab. 2:  Test parameters for expansion of soybean extraction meal

 

0

  Raw material 

I 

  Crown-treated, expander head temperature approx. 165 °C

II 

  Crown-treated + 10 min. post-conditioning 

III 

  Crown-treated + 20 min. post-conditioning 

 

Table 3:  Contents of UDP with the parameter settings described in Table 2

 

 

0

I

Increase

II

Increase

III

Increase

UDP 8

8-15 %

46-50 %

approx.

49-65 %

approx.

70-78 %

approx.

300%

30%

20%

 

Conclusion

 

The favourable effect of the feed concentrate by the hydro-pressure thermal treatment of the crown expander leads to a higher bioavailability, a higher digestibility, and thus also to an improved nutrient efficiency at an increased rumen health. By the physical process of expansion, existing natural structures of the vegetable raw materials are "broken". After expansion of the fibre-rich rape hulls, a 30 % higher gas formation was analysed. This increased fibre digestibility thus maximises the energy availability.

 

In the rumen, the feed proteins are largely hydrolysed to amino acids by micro-organisms and almost completely decomposed. Therefore, higher animal performances require an increase of the percentage of undegraded feed proteins (UDP) to allow sufficient proteins and thus the necessary amino acids to reach the abomasum small intestine segment. By means of expansion of the protein components at up to 165 °C in the high-temperature and short-time range, an increase of the by-pass protein concentration in feed mixtures can be reached without the addition of catalyst substances. To obtain particularly high percentages of undegraded proteins (UDP), post-conditioning of the fresh expanded feed with direct steam addition, for example in a 10-min. conditioner or in a steam and retention screw, is recommended. The protein and energy availability improved this way leads to higher milk yields and growth rates of the animals. The feed costs are reduced, the environment is protected, the economic efficiency of animal production and the health status of the herds are improved.

 

The expander technology is one of the most proven and most comprehensive conditioning methods for compound feed and individual components. The benefits of using the expander are in addition to the increase of the protein available in the intestine, the improved pellet quality and higher press capacity, the use of components which are difficult to process, the addition of large quantities of liquid, the inactivation of harmful substances, the elimination of salmonella and the further improvement of the feed value. The reduction of the production costs underlines the economic efficiency. For the development of the Kahl expander technology intensive research is carried out in order to achieve optimum results for each species under animal nutrition and economic aspects. These findings were and are implemented in accordance with the expander types and production capacities.
 
 
Source for calculating the UDP value:
 
 Licitra et al. (1996): Standardization of procedures for nitrogen fractionation of ruminant feeds Animal Feed Science Technology 57, 347-358
 
 S. Shannak et al. (2000): Estimating ruminal crude protein degradation with in situ and chemical fractionation procedures. Animal Feed Science    and Technology 85, 195-214

 

 

For more of the article, please click here.

 

Article made possible through the contribution of Amandus Kahl

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