N-Acetyl-β-D-Glucosaminidase Analysis in Sheep Milk Can Detect Early Intramammary Infection with High Yields If Incorporated into Mathematical Algorithms

Yolanda Miralles ¹, Victoria Fornés ¹, Amparo Roca ²

⁰Responsible Research Office, Miguel Hernández University (UMH), Avda. de la Universidad s/n, 03202 Elche, Spain.

Animals : an Open Access Journal From Mdpi +

|

February 13, 2025

View abstract on PubMed

Summary

This study shows that increased N-acetyl-β-D-glucosaminidase (NAGase) enzyme levels can predict intramammary infection (IMI) in sheep. An algorithm detecting a 30% NAGase increase within four days accurately identified infected mammary glands.

Area Of Science

Veterinary Medicine
Biochemistry
Animal Health

Background

Intramammary infection (IMI) is a significant concern in dairy animals.
Accurate and early detection of IMI is crucial for effective treatment and herd management.
Biochemical markers like N-acetyl-β-D-glucosaminidase (NAGase) offer potential for rapid IMI diagnosis.

Purpose Of The Study

To analyze the impact of IMI on NAGase enzyme activity in sheep.
To evaluate the predictive capability of NAGase levels for IMI detection using various algorithms.
To identify an optimal algorithm for early and accurate IMI diagnosis in sheep.

Main Methods

Selected 26 healthy sheep and monitored somatic cell count (SCC), NAGase levels, and bacteriological cultures for 2 weeks.
Induced unhealthy situations (UHS) for mammary glands and continued monitoring for 4 weeks.
Established IMI in 12 sheep and analyzed NAGase changes in infected vs. uninfected glands.

Main Results

A significant increase in NAGase enzyme values was observed in infected glands within 4 days post-infection.
The best-performing algorithm detected a >30% NAGase increase on at least two of the first four days post-infection.
This algorithm achieved an Area Under the Curve (AUC) of 0.90, with 89.8% accuracy, 95.2% sensitivity, and 85.7% specificity.

Conclusions

NAGase enzyme levels are a reliable indicator of IMI in sheep.
A specific algorithm based on early NAGase elevation demonstrates high accuracy in predicting IMI.
This approach offers a valuable tool for the early diagnosis and management of IMI in sheep herds.

Keywords:

AUC NAGase SCC accuracy algorithm sensitivity specificity