Débora_Santschi_1
Quebec Farmers' Advocate Volume Number June 15, 2019
Débora SantschiPh.D., Agr.

An increase in ketone bodies slows down reproductive performance.

 An increase in ketone bodies slows down reproductive performance.
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This article was written in collaboration with YASMIN SCHUERMANN, Research Professional. 

The Lactanet laboratory, tests thousands of milk samples from individual cows daily to detect ketone bodies, which are indicators for ketosis.

It’s common, it’s costly, and it’s a nuisance, but it can be monitored… It’s ketosis! This metabolic disease is characterized by elevated levels of b-hydroxybutyrate (BHB). Typically, elevated BHB levels are present in animals that experience a high degree of fat mobilization, a consequence of calving at a body condition score above recommendation (3.0-3.25), and insulin resistant cows, namely those who consumed too much energy during their early dry period. This form of ketosis (Type II) begins during the dry period and progresses into early lactation. Less widespread is Type I ketosis, a disease observed in high-producing cows that lack nutritional energy in early lactation. It is important to address the fact that both types of ketosis can be subclinical or clinical. Ultimately, all ketotic cows are at an increased risk of suffering from other metabolic diseases including mastitis and displaced abomasum.

1 OUT OF 5 COWS IS AFFECTED!

On our Quebec Holstein herds alone, the prevalence of ketosis stands at a whopping 22.6%. As this disease can cost the average producer $6,000 on a yearly basis, it is a disease that is well-known to the industry. Therefore, a number of tools have been validated in order to measure ketone levels on herds. Conventional on-farm techniques include using the Precision Neo meter to measure ketone bodies in blood (which is the gold standard method) and Ketostix® to evaluate ketones in urine.

DETECTING AND MONITORING KETOSIS IN MILK

BHB levels can also be effectively detected in milk by Fourier-transform infrared analysis. Lactanet offers their clients the opportunity to evaluate BHB levels (KETOLAB) on individual cow samples. This service provides quick, reliable, and cost-effective data to producers in order to help monitor ketosis and accordingly manage the disease on herds. Thresholds for BHB levels in milk have been established as follows: <0.15mM BHB suggests a cow that is negative (NEG) for the disease, while concentrations of 0.15 to 0.19mM BHB is subclinical/suspect (SUS), and ≥ 20mM BHB is clinical/positive (POS) for the disease.

IS THE LEVEL OF BHB IN MILK RELATED TO A NEGATIVE IMPACT ON REPRODUCTION?

Recently, Lactanet has taken on a new quest to evaluate the impact of early lactation ketosis on reproductive performance of Holstein cattle. By comparing the level of milk

BHB from the first test-day (5-35 days in milk (DIM)) from 505,412 Holsteins cows in different lactations from 3,551 herds, a significant decrease in the reproductive performance of cows with elevated ketone levels was observed (Figure 1).

Figure 1

This impact on reproductive parameters was detected across cows from all lactations (1st, 2nd, and 3rd+). Taken together, this would further suggest a longer calving interval, which would further decrease the efficiency of a cow in the herd. Moreover, a higher level of BHB in early lactation was associated with decreased pregnancy rates (Figure 2).

Figure 2

For example, a cow that tested positive for ketosis in early-lactation would have a significantly lower chance (approximately 15% lower) of being pregnant by 150 DIM than a cow that tested negative. In the lactating herd, most of the culling will take place in the first 60 DIM. With that in mind, further analysis from the dataset revealed that regardless of lactation, the culling rate was higher in cows that had elevated levels of BHB compared to cows with low levels of milk BHB (figure 3).

Figure 3

Nonetheless, it should be noted that the highest culling rates in the first 60 DIM was detected in cows in their third or greater lactation with elevated BHB levels.

BUT WHAT ABOUT MILK PRODUCTION?  

How can different levels of milk production and BHB have an impact on reproductive parameters such as the interval from first service to conception? By refining the initial database, cow records were further divided by 305-day lactation milk yields: low; <9,000 kg, medium; 9,000‒11,000kg, and high; >11,000 kg. High producing cows were more likely to have elevated BHB levels. In addition, it was observed that both BHB levels and the level of milk production have an impact on reproductive parameters (Table 1). A combination of elevated milk BHB levels and high milk production led to the most days open, a greatest interval from 1st service to conception, and the most services required for pregnancy.

Table 1: The combined impact of BHB and milk production

Table 1

Overall, elevated BHB levels hindered reproductive performance and increased the likelihood of an individual animal from being culled in the first 60 DIM. Ketosis is one of the most common metabolic diseases and proper management is essential by maintaining cows at proper body condition scores and optimising nutritional management for transition cows and high-producing cows. A good place to start is by monitoring the BHB levels on your farm and seeing where improvements can be made!

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