Choline may reduce ketosis in dairy cows

Choline may reduce ketosis in dairy cows

Supplementing choline can be a practical tool for dairy farmers as part of a total nutritional strategy to lower subclinical ketosis.

By MARC ROVERS*

*Marc Rovers is with Orffa/Excentials.

DURING the start of lactation, dairy cows enter a stage of negative energy balance because energy output for milk production is higher than the energy intake from consumed feed.

Body reserves in the form of fat will be mobilized, and this may lead to fatty liver and (subclinical) ketosis. Choline is known for its positive effects in such a case. This article deals with the question of what, exactly, the role of choline is and in what form choline should be supplied.

 

Ketosis, choline

Ketosis is a metabolic disorder characterized by elevated concentrations of ketone bodies in blood, urine and milk. The disease mainly occurs in early lactation, when body reserves are used to support lactation. The disorder can have both a clinical and a subclinical presentation.

Clinical ketosis occurs less frequently than subclinical ketosis and affects individual animals in a herd. Affected cows show a decrease in feed intake, weight loss, a drop in milk yield, acetone smell of breath, depression and, occasionally, nervous signs.

Subclinical ketosis is often herd related and is associated with lower milk yield, elevated milk fat content (relative to protein content), reduced reproductive performance and an increased risk of removal from the herd. Animals with subclinical ketosis also have higher risks for clinical ketosis and displaced abomasum (van der Drift, 2013).

Ketosis is related to fat mobilization. In early lactation, dairy cows are exposed to an increased mobilization of body fat reserves. Body fat is also called adipose tissue, and the fat in this tissue is present in the form of triglycerides (glycerol with three fatty acids). These triglycerides are released from the adipose tissue into the blood in the form of free fatty acids, also called non-esterified fatty acids (NEFAs).

NEFAs reach the liver, and once there, they can be either oxidized for energy (resulting in higher levels of ketones) or removed again from the liver in the form of very-low-density lipoproteins (VLDL). The rate of fat absorption by the liver can be higher than the rate of oxidation and the transport out of the liver. This may lead to an accumulation of fat in the liver, resulting in fatty liver syndrome.

Choline is a component of phosphatidylcholine, which is necessary for synthesis of VLDL, the lipoprotein that is responsible for the transport of fatty acids out of the liver. Choline is essential for the synthesis of VLDL and, therefore, plays a crucial role in fat metabolism.

Figure 1 shows these pathways of fat metabolism in the dairy cow.

 

Intestinal availability

Choline is considered a non-essential nutrient for ruminants, meaning that the dairy cow can produce it by herself. However, there are indications that the quantity is limited, and consequently, adding extra choline to the ration is a good strategy to optimize health.

Supplemental choline needs to be available on an intestinal level. Unprotected choline will be broken down in the rumen and will lose its effects. To overcome degradation in the rumen, several rumen-protected products are available. Rumen protection or rumen bypass means that the choline is covered by a protective layer.

This is mostly a layer of a fatty acid matrix, which restrains the rumen microbes from utilizing the choline. The protective layer must be broken down later in the small intestine. Here, the digestive enzymes break down the fatty layer, and the choline is free for absorption.

Rumen bypass, as such, does not necessarily mean that the product is effective. Some products overprotect; the protection can be so strong that the choline is not released in the intestine at all. Other products under-protected, which means that the protective layer is not able to provide sufficient rumen survival. This leads to the choline being partially or even completely degraded in the rumen before it even reaches the intestine.

Combined in vitro/in vivo trial work demonstrates this "overprotection" and "under-protection" of some products. In this test, the rumen protection is measured with a so-called "in sacco method" and a Daisy incubator. Samples of the product are introduced into the incubator, and after 12 hours, the choline that remains is measured (rumen stable). Next, the products are placed into the small intestine of a duodenum-canulated dairy cow and collected in the feces. This "mobile nylon bag method" is well accepted for determining the intestinal digestibility of products. The amount of choline that is eventually available for the animal is the result of the rumen stability times the intestinal digestibility.

As shown in Figure 2, there are big differences between products on the market. Product A has very strong rumen protection, so strong that very little is available in the intestines (overprotected). Product B has very low rumen protection (under-protected), so the choline never even reaches the intestines.

The key to developing rumen-protected products is to find the right balance between rumen protection and intestinal digestibility. Orffa and Excentials have developed Excential rumenpass CH that has rumen protection and high intestinal digestibility, which results in high amounts of choline being available for the dairy cow.

 

Practical trial results

Trial results show that the use of protected choline is a preventive measure for avoidance of fatty liver syndrome and ketosis around calving (Lima et al., 2007; Zom et al., 2011) and may improve milk production and reproduction parameters (Piepenbrink and Overton, 2003; Cooke et al., 2007).

To evaluate the effect of supplementing rumen-protected choline under practical conditions, a trial was performed on a Dutch dairy farm with approximately 250 cows.

Lactating cows were housed in four different groups: a heifer group, a fresh cow group and two groups with multiparous cows. Milking was done by an automatic milking system (one robotic milking unit per group).

During a five-month period, all fresh (multiparous) cows were assigned directly after calving to the control or the treatment group, receiving protected choline at a dosage of 60 g per cow per day. After calving, the animals were followed for up to 90 days in milk.

One week after calving, urine samples were taken and analyzed for ketones and given a value from zero (no ketones) to six (extreme level of ketones). The average score for the treatment group was 15% lower than the control group.

Periodic milk sampling showed that cows receiving the choline had numerically higher daily milk production. The fat percentage in the milk was significantly lower, and there was no difference in protein percentage (Table 1).

The lower fat percentage is seen as a positive sign since an elevated fat content with a normal protein level is related to ketosis. A difference between fat percentage and protein percentage of more than 1.25 is considered a high risk for subclinical ketosis.

In this trial, 50% of cows in the control group showed this elevated fat percentage from zero to 30 days. From days 31 to 60, it was 35%. In the treatment group with rumen-protected choline, the percentage of cows with an elevated fat percentage was reduced by 30% and 46% in the 0-30 and 31-60 day periods, respectively (Table 1).

These positive results were confirmed in a follow-up trial on another Dutch dairy farm with 90 cows. All cows were supplemented with rumen-protected choline for four weeks. The results were compared with historical data from that farm. After four weeks of supplementation, the amount of cows "at risk," meaning they had an elevated fat percentage, was reduced almost by half. Also, significantly fewer cows had ketones in their milk (Table 2).

 

Conclusion

Subclinical ketosis is a costly metabolic disorder that has a great effect on dairy production. Studies worldwide show that the incidence is between 20% and 30%. Nutrition is a key in preventing subclinical ketosis, and choline specifically has an important role to play.

Supplementation of choline in a rumen-protected and intestinally available form can be a practical tool for a dairy farmer as part of a total nutritional strategy to lower subclinical ketosis.

 

Choline may reduce ketosis in dairy cows

1. Milk yield (kg/day), fat percentage and percentage of cows with elevated fat percentage

 

Control

Choline

Difference

Milk yield (kg/day)

Days 0-30

37.34

37.43

0.09

Days 31-60

42.2

42.57

0.37

Days 61-90

39.03

39.59

0.56

Fat %

Days 0-30

4.96a

4.58b

-0.38

Days 31-60

4.01

3.92

-0.09

Days 61-90

3.88

3.84

-0.04

Percentage of cows with elevated fat*

Days 0-30

50.0

35.3

-30.0

Days 31-60

35.3

19.4

-46.0

*Fat percent minus protein percent greater than 1.25%.

 

2. Cows with elevated fat percentage and elevated ketones in milk

 

Before
treatment

After four weeks of choline supplementation

% of cows with elevated fat percentage (fat-protein> 1.25)

61

32

Number of cows with elevated ketones in milk

4

1

 

Volume:86 Issue:06

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