Nutrition Exam 1: Comparative Anatomy

What is the definition of feed?

Any material that can be digested, absorbed, and utilized by the animal

What is the definition of nutrient?

A component of feed that supports life (i.e. water, minerals, carbohydrates, lipids, vitamins)

What is the definition of dry matter intake (DMI)?

The amount of feed consumed minus its water content

What are real life examples of feed?

- Watermelon and chocolate used as cattle feed (waste products from industry)
- Pasta waste trial for cattle diets
- Importance of clean water: Increases feed intake and reduces stress

What is a monogastric?

One stomach chamber, digestion starts in the mouth, absorption in small intestine

What is a ruminant?

Four stomach chambers, fermentation in rumen, absorption in rumen

What is a hindgut fermenter?

Monogastric with fermentation in cecum and colon (i.e. horses)

Digestive process steps 

Ingestion, Mastication, Digestion, Absorption, Excretion

What are the two ways to classify animals?

- By Diet: Herbivores (plants), Omnivores (plants + meat), Carnivores (meat)
- By Physiology: Monogastric, Ruminant, Hindgut Fermenter

What does a wide muzzle signify?

Grazers (i.e. cows and horses)

What does a narrow muzzle signify?

Selective feeders (i.e. goats and sheep)

Cows use ___ and horses and goats use ___ to graze

tongue, lips and teeth

What is saliva and its role in the digestive process?

Contains enzymes and buffers

Helps with digestion, lubrication, and pH regulation

Cows produce up to 48 gallons/day

What is the function of the stomach?

Mixes food and regulates pH

Acidic environment activates enzymes like pepsin

Bariatric surgery example: reduced digestion and absorption 

What is the function of the small intestine?

Has 3 sections: duodenum, jejunum, and ileum

Main site of nutrient absorption in monogastrics

pH neutralized by bile salts 

How does the rumen function in cattle?

Fermentation by microbes that produces VFAs (propionate, acetate, and butyrate)

VFAs absorbed in rumen and processed by the liver 

What is the function of the large intestine?

Has 3 sections: cecum. colon, and rectum

Does microbial digestion, water absorption, and waste elimination 

Species differences of the GI tract

Pig: 29% stomach, 35% small intestine, 7% cecum
Cow: 68% rumen, 20% small intestine, 9% cecum

What are some practical farm insights?

Hay quality affects digestion, especially in horses
Timing of hay harvest impacts nutrient content
Poor-quality hay can lead to digestive issues

What do VFAs produced in the rumen get converted into?

Glucose and fat

What kind of direction does the esophagus in monogastrics perform?

One-way transport

What kind of direction does the esophagus in ruminants perform?

Bidirectional

Fermentation in the rumen breakdown

Microorganisms: Bacteria, Protozoa, Fungi
Break down carbohydrates into VFAs
VFAs Produced:
- Propionate= glucose
- Acetate= fat synthesis
- Butyrate= energy for rumen tissue
Key Point: Microbes convert food into usable energy

Rumen development in calves

Calves start with milk-only diets
Rumen develops with forage and grain
Microbes transferred from mother

What are the 4 compartments of the rumen?

1. Reticulum- honeycomb structure; fermentation & VFA absorption
2. Rumen- largest; microbial fermentation; papillae absorb VFAs
3. Omasum- water & mineral absorption
4. Abomasum- true stomach; enzymatic digestion; HCl production
Key Point: Only abomasum has glands and enzymes

Papillae and diet impact

Papillae: absorb VFAs
- Corn-based diets= more papillae growth
- Forage-based diets= less stimulation

What are the risks of sudden diet changes?

Acidosis, bloat, and papillae damage

Safe transition strategy- gradually increase grain in diet

What is the microbial population in the rumen?

Protozoa: ~1 million/cc
- Bacteria: billions/cc
- Produce vitamins (K, B-complex) and microbial protein

What is the function of the omasum and abomasum?

Omasum- absorbs water, VFAs, minerals
Abomasum- produces enzymes and HCl; similar to monogastric stomach

Comparison of horse vs chicken digestive system

Horse- enzymatic digestion in small intestine, fermentation in cecum (less efficient)
Chicken- beak, gizzard for mechanical digestion, enzymatic digestion in proventriculus