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Updated: Jul 25, 2026
07:32
Isolating and Using Sections of Bovine Mesenteric Artery and Vein as a Bioassay to Test for Vasoactivity in the Small Intestine
Published on: October 7, 2014
Summary
Polioencephalomalacia (PEM) in ruminants is caused by thiamin analogs produced by thiaminase I. Careful use of niacin and antihelmentics is advised, as supplementary niacin benefits postpartum cows by improving metabolic health and milk production.
Area of Science:
- Veterinary Medicine
- Ruminant Nutrition
- Biochemistry
Background:
- Polioencephalomalacia (PEM) is a central nervous system disorder in ruminants linked to thiamin analogs.
- These analogs are produced by thiaminase I enzymes, often from rumen microbes in high-concentrate diets or from plant sources.
- The specific thiaminase I enzymes from Bacillus thiaminolyticus and Clostridium sporogenes differ from rumen-derived enzymes.
Purpose of the Study:
- To investigate the role of thiaminase I and its cosubstrates in PEM.
- To evaluate the effects of supplementary niacin on ruminant health and productivity.
- To understand niacin's impact on microbial protein synthesis, milk production, and metabolic status in cows.
Main Methods:
- Analysis of thiaminase I production and cosubstrate activity in rumen environments.
- In vitro and in vivo studies on microbial protein synthesis with supplementary niacin.
- Field trials assessing the impact of niacin supplementation on milk production, blood parameters, and ketosis incidence in postpartum and mid-lactation cows.
Main Results:
- Niacin and certain antihelmentics are identified as thiaminase I cosubstrates, necessitating cautious use.
- Supplementary niacin enhanced microbial protein synthesis, particularly with urea over soybean meal.
- Niacin supplementation improved milk production in postpartum cows, increased blood glucose, reduced ketones, and prevented ketosis.
- Heating of soybean meal may reduce niacin availability for rumen protozoa.
Conclusions:
- Thiamin analog production by thiaminase I is a key factor in PEM development.
- Strategic niacin supplementation can improve metabolic health and productivity in postpartum dairy cows.
- Understanding cosubstrate interactions is crucial for preventing thiamin-related disorders and optimizing ruminant nutrition.
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