Protein nutrition strategy for high-yield dairy cows in summer

 It is common phenomenon that southern dairy cows have a large drop in milk production in summer. Because the temperature and humidity index of the summer environment usually exceeds 68, cows are under heat stress, which is the main reason for the sharp decline in milk production.
 
Feed intake of cows under heat stress will usually decrease by 10-40% (West, 2003), resulting in insufficient total metabolic protein reaching the small intestine, and the final impact on the decline in milk production will reach 35-50% (Rhoads, 2009; Baumgard, 2011). In addition, the needs of maintenance metabolic protein in dairy cows under heat stress increase by more than 25% (NRC, 1989), which further reduces milk production.

Increasing the total amount of metabolic protein in the small intestine of cows is an effective measure to increase milk production in summer !

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Problems with common measures

The amount of protein that dairy cows need to maintain metabolism in summer will increase by 25%. Even if the feed intake does not decrease, at least about 225g of metabolic protein needs to be supplemented to maintain a level of milk production comparable to that in the normal temperature season.

Routine Method 1: Increase C:F (the ratio of dietary concentrate to forage)

Very limited improvement: For high-yield dairy cows, the ratio of the concentrate to the TMR is usually 55%, and the highest is not more than 60%. For every 1% increase in the proportion of dietary concentrate, the yield of metabolic protein will increase by about 25g. Even if it is increased by 5%, it will only contribute 125g of metabolic protein, which is far from meeting the demand.

Prone to acidosis: When the proportion of concentrate exceeds 60%, dairy cows are prone to acidosis.

Routine Method 2: Increase the level of dietary protein

Increase rumen heat production and exacerbate heat stress: The crude protein level of TMR diets for high-yield dairy cows is usually 18%. Increasing the level of dietary crude protein in summer will further increase the heat generated by protein degradation in the rumen, thereby enhance heat stress (Huber, 1994) and also reduce feed intake and milk production (Higginbotham, 1989)

In summer, traditional methods to increase the metabolic protein production of lactating dairy cows are relatively limited. Are there other safer and more efficient measures?

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Our recommended solution

The metabolic protein of dairy cows is composed of rumen microbial protein (MCP) and rumen bypass protein (RUP) in the diet. To improve the efficiency of rumen MCP synthesis and to adjust the structure of dietary protein to increase the ratio of RUP, the two paths can be used to increase the production of metabolic protein in dairy cows.

• Improve the production of microbial protein (MCP)

Nitrogen sources that can be directly utilized by rumen microorganisms include ammonia, amino acids, and peptides. Among them, ammonia is also a necessary environmental factor for the normal growth of rumen microbes. The optimal ammonia nitrogen concentration for rumen microbe growth is 6-9mg/dL (Li Shengli, "Ruminant Nutrition"). As the first nitrogen source for rumen microorganisms, peptides have the functions of shortening the cell division cycle and improving the efficiency of microbial proliferation (Hoover, 1991; Griwold, 1996; Fu, 2001).

(1) Provide a stable ammonia environment for rumen microorganisms

(2) Provide functional substances (small peptides) that promote the proliferation of rumen microorganisms

• Increasing the level of dietary RUP

The degradation rate of conventional plant protein in the rumen: >50%

Plant protein with high rumen by-pass rate which treated by special process: >75%

In view of the many benefits of peptides to dairy cow breeding, we will share more information!

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Peptides can enhance rumen fermentation and increase milk production

• Improve the utilization efficiency of ammonia and nitrogen, promote the proliferation of rumen microorganisms, and increase the production of rumen MCP

In vitro experiments have found that adding a certain amount of small peptides to the rumen fluid can promote rumen microorganisms to use ammonia and nitrogen to synthesize MCP, an increase of about 15% (result of the Mytech Interactive R&D project). As the main component of metabolic protein, the increase in MCP production can alleviate the insufficient metabolic protein caused by the decrease in feed intake of heat-stressed cows.

• Improve diet digestibility

Cottonseed, as a natural rumen bypass material, its excretion indirectly reflects the digestion of dairy cows. After feeding small peptides, the number of undigested cottonseeds in cow manure was significantly reduced. (a large farm in Yunnan, 80 vs 80 cows)

Further measurement of the apparent digestibility of nutrients in dairy cows found that the digestibility of NDF and ADF in dairy cows increased by 4.31% and 4.81%, respectively, after feeding small peptides. It shows that feeding small peptides can increase the feed intake of dairy cows to a certain extent (Akbar, 2014), and alleviate the decrease in feed intake caused by heat stress.

• Increase milk production of cows under heat stress in summer

(A ranch in Suqian, Jiangsu, May-June, mid-lactation, milk production increased by 1.85kg/head/day)

(A ranch in Qionglai, Sichuan, August-September, mid-lactation, milk production increased by 1.62kg/head/day)