ruminant nutrition 2

What does a body condition score (BCS) measure in livestock?

The amount of fat and muscle on an animal's body.

How do BCS scales differ between beef cattle, dairy cattle, and sheep/goats?

Beef: 1-9

Dairy: 1-5 with decimals

Sheep/Goats: 1-5 whole numbers.

Why is monitoring BCS important for herd health and productivity?

Helps evaluate nutrition, reproduction, health status, and adjust management before problems occur.

What management actions might you take for an animal with a low BCS?

-Increase energy/protein intake

-reduce competition

-treat disease/parasites

-separate into a higher-nutrition group.

Explain the relationship between ruminant digestion and microbial digestion.

-Ruminant digestion = microbial digestion

-microbes ferment feed and synthesize nutrients.

What is the primary function of rumen microbes in nutrient metabolism?

Ferment feedstuffs and synthesize amino acids and VFAs.

How do microbes convert nitrogenous compounds into usable amino acids for the host?

They use ammonia and other N sources to synthesize microbial protein.

What happens to microbial protein after it leaves the rumen?

It is digested and absorbed in the small intestine.

Define crude protein (CP) and explain why it is not a true measure of actual protein.

CP measures nitrogen content; it does not represent true protein structure.

What proportion of CP intake should come from natural protein vs. NPN?

• ≥2/3 from natural protein

• ≤1/3 from NPN.

What are common NPN sources, and why must they be limited?

-Urea; limited because excess can cause ammonia toxicity

-NPN ≤2% of diet.

Compare structural and non-structural carbohydrates.

Structural: fiber (cellulose, hemicellulose, lignin), fermented by microbes.

Non-structural: sugars and starches, digested enzymatically.

How do volatile fatty acids (VFAs) contribute to energy production?

VFAs are absorbed and used for ATP and fat synthesis.

Why is fat supplementation limited in ruminant diets?

Fats inhibit intake and rumen microbes;

exception: essential FA supplements for high-producing dairy cattle.

List three physiological functions of water.

Waste elimination; thermoregulation; production of saliva, milk, and blood.

How does water intake affect dry matter intake?

Increased water intake increases dry matter intake.

Which vitamins are synthesized by rumen microbes, and which require supplementation?

-Microbes synthesize B vitamins

-vitamins A, D, E, K may need supplementation depending on forage/sunlight.

Describe two mineral deficiency disorders and clinical signs.

-Grass tetany: low Mg; signs — twitching, staggering, collapse.

-White muscle disease: selenium/Vit E deficiency; signs — muscle weakness, stiffness.

What are the main components of a Total Mixed Ration (TMR)?

Forage, cereal grains, protein sources, vitamin/mineral premix.

How does particle size influence digestibility and feed efficiency?

Proper particle size improves mixing, rumen function, and digestibility.

Define NDF and ADF and how they affect feed intake and energy.

-NDF: total plant fiber; ↑NDF = ↓intake.

-ADF: indigestible fiber; ↑ADF = ↓energy and digestibility.

What does TDN (total digestible nutrients) indicate about a feedstuff?

Percentage of digestible nutrients; higher TDN = higher digestibility.

Explain the Law of Mass Action and its importance in Ca:P ratios.

Too much of one mineral causes a functional deficiency of the other; balance Ca:P in diet.

What information do you need for a Pearson Square calculation?

Desired nutrient %, nutrient % of each of the two feeds.

What is the purpose of a Pearson Square calculation?

Determine proportions of two feeds to reach a target nutrient level.

Describe the step-by-step process of determining % and weight of each feed in a ration.

Insert nutrient values → subtract diagonally → determine parts → convert to % → multiply by total weight.

How to check math on the final ration CP level?

Multiply % of each feed by its CP, then add to confirm target CP.

What causes grass tetany and how can it be prevented?

Low Mg in lush spring forage; prevent with Mg supplementation.

Which species is more susceptible to copper toxicity and why?

Sheep; they store copper in the liver and release it suddenly, causing toxicity.

Describe the metabolic process leading to ketosis.

Energy demands exceed intake → fat mobilized → ketone buildup → low blood glucose → fatty liver.

What is rumen acidosis and what feeding practices contribute to it?

-Low rumen pH from excessive rapidly fermentable carbohydrates;

-caused by high-grain, low-fiber diets.