Veterinary Public Health: Heat Stress Effects on Gastrointestinal Tract

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Questions and Answers

What is the main effect of heat stress on the gastrointestinal tract in ruminants?

Increased short-chain fatty acid metabolism

Improved nutrient absorption

Increased feed intake

Reduced barrier function (correct)

What is the primary function of the rumen epithelium?

Hormone regulation

Nutrient absorption and transport (correct)

Lipid metabolism

Protein synthesis

What are the sources of endotoxins?

Fungi

Gram-negative bacteria (correct)

Viruses

Gram-positive bacteria

What is the toxic part of lipopolysaccharides (LPS)?

Lipid A Signup and view all the answers

What happens to the rumen and intestine barrier during heat stress?

It is disrupted Signup and view all the answers

What is the result of the translocation of toxins and unwanted metabolites into the blood circulation?

Endotoxemia Signup and view all the answers

How many cell layers does the intestinal epithelium have?

One Signup and view all the answers

What is released during lysis of Gram-negative bacteria?

Endotoxins Signup and view all the answers

What is the primary purpose of installing fans and sprinklers above the feed tools?

To increase the consumption of feed by the animals Signup and view all the answers

Why is it necessary to provide sufficient areas for feeding and drinking?

To prevent overcrowding around the barns Signup and view all the answers

What type of feedstuff is recommended to provide to animals during heat stress?

Non-concentrated feed like hay or barley Signup and view all the answers

Why is it recommended to avoid high feed temperature during heat stress?

To reduce the heat stress caused by high feed temperature Signup and view all the answers

What is the recommended feeding strategy during heat stress?

Increasing the frequency of feeding with small quantities Signup and view all the answers

Why is it necessary to separate small animals from large and pregnant females?

To provide feed specific to each breed Signup and view all the answers

What is the main consequence of heat stress on the rumen in cattle?

Sub-acute rumen acidosis (SARA) Signup and view all the answers

What is the primary function of the barrier in healthy animals?

To prevent endotoxins from entering the blood circulation Signup and view all the answers

What is the recommended temperature of water for cattle in hot weather?

Cold water Signup and view all the answers

What is the consequence of heat stress on the animal's energy resources?

Energy is redirected from growth and milk production to the inflammatory response Signup and view all the answers

What is the consequence of heat stress on the concentration of endotoxins in the blood circulation?

Massive increase in concentration Signup and view all the answers

What is the recommended placement of water troughs in hot weather?

At a suitable level with shaded places Signup and view all the answers

What is the role of LPS-binding protein in the inflammatory response to heat stress?

To bind to endotoxins and trigger an inflammatory response Signup and view all the answers

What is the ultimate consequence of heat stress on the animal's performance?

Reduced reproductive performance and energy availability Signup and view all the answers

What is the primary purpose of putting water tanks under umbrellas?

To avoid exposure to direct sunlight Signup and view all the answers

What determines the amount of feed consumed by animals in hot weather?

Amount of energy in the diet Signup and view all the answers

What is the recommended percentage of protein content in animal diets during hot weather?

17% Signup and view all the answers

What is the purpose of adding fiber to animal diets?

To support normal digestive functioning of the rumen Signup and view all the answers

What is the recommended maximum percentage of fat that can be added to animal diets?

5-6% Signup and view all the answers

Why is it important to provide adequate shade for animals?

To lower the body temperature and respiratory rate Signup and view all the answers

What is the purpose of designing animal houses with high roofs and gradual slopes?

To stimulate air flow and reduce thermal transfer Signup and view all the answers

What is the benefit of adding oily seeds such as whole soya cotton seeds to animal diets?

To provide a good source of oil and protein Signup and view all the answers

Study Notes

The Effects of Heat Stress on the Gastrointestinal Tract

Heat stress affects the gastrointestinal tract, particularly in ruminants, by:
- Reducing feed intake
- Releasing heat shock proteins and cytokines
- Disrupting the rumen and intestinal epithelium barrier
This disruption can lead to the translocation of toxins (endotoxins, mycotoxins) and unwanted metabolites (biogenic amines like histamine) into the blood circulation

Endotoxins

Endotoxins are lipopolysaccharides (LPS) found on the outer membrane of Gram-negative bacteria
The lipid A part of LPS is the toxic component
Endotoxins are released during bacterial lysis and are always present in the rumen due to the presence of Gram-negative bacteria

Temperature Ranges and Cow Health

Different temperature ranges can affect cow health, including:
- Mild heat stress: 23°C - 26°C
- Moderate heat stress: 26°C - 31°C
- Severe heat stress: 31°C - 37°C
- Emergency heat stress: ≥ 37°C

Heat Stress and Sub-Acute Rumen Acidosis (SARA)

Heat stress can lead to SARA, which can cause a massive increase in endotoxin concentration
In healthy animals, the barrier prevents endotoxins from entering the circulation, but heat stress can impair this barrier, leading to an inflammatory response

The Inflammatory Response

Heat stress can trigger an inflammatory response, characterized by the release of:
- Cytokines (histamines)
- Acute phase proteins (haptoglobin)
- Heat shock proteins
- LPS-binding protein
This response consumes a lot of energy, which the animal cannot use for growth, milk production, or reproductive performance

Practical Management to Reduce Heat Stress Effects

Nutritional System in Hot Weather

Water consumption:
- Provide clean, fresh water in suitable quantities
- Offer cold water to soothe and stimulate the cows
- Ensure easy access to water with shaded areas and umbrellas to protect from direct sunlight
Feedstuffs:
- Provide high-energy, protein-rich feed
- Increase energy, protein, and fiber in the diet
- Add fat to the diet (up to 5-6% of dry matter) from sources like oily seeds
- Limit protein content to 17% or less in hot weather
- Provide fiber for normal rumen functioning
- Add mineral elements and vitamins, especially sodium, potassium, magnesium, and vitamins C and A

Other Practical Management Strategies

Ensure appropriate shade to lower body temperature and respiratory rate
Design animal houses with high, sloping roofs to stimulate air flow and reduce heat transfer
Avoid direct sunlight entry into animal houses
Use fans with sprinklers to moisturize and evaporate the animal's surface, reducing body heat
Provide sufficient feeding and drinking areas, and avoid crowding
Offer non-concentrated feedstuffs like hay and sweet clover hay
Increase food intake with small quantities, multiple times a day
Avoid high feed temperature and spoilage, and prevent external parasites
Separate small animals, large animals, and pregnant females, and provide breed-specific feed
Process grains before serving, such as crushing or grinding, and ensure complete mixing of foodstuffs

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Description

This quiz covers the effects of heat stress on the gastrointestinal tract in ruminants, including reduced feed intake and protein release. Designed for undergraduate students in the second stage of veterinary public health studies.