14: Ruminant Nutrition 2

Systems for evaluating energy in a diet

Net energy and TDN

When is the NE system used

Dairy and young animal

When is the TDN system used

Beef

Types of NE measurements

• NE_m

• NE_g

• NE_l

Energy losses between gross energy in diet and net energy

• Feces

• Urine

• Gas

• Heat

Systems for evaluating protein in a diet

CP and metabolizable protein

When is the CP system used

Beef

When is the MPS used

Dairy and young

What makes up metabolizable protein

RUP and MCP

What happens to RDP

Turns into MCP or is deaminated into C skeleton and ammonia

What types of feed are high in RDP

Forages

What types of feed are high in RUP

Byproducts

3 questions to ask when evaluating a diet

• What is provided in the diet

• What does the animal need

• What does the animal actually eat

Ways to determine what nutrients a feedstuff provides

• Look at tables

• Sample the feedstuff

Factors that influence nutrient requirements

• Age

• Sex

• Production type

• Stage of production

When do you use dry matter basis numbers

When doing feed calcs

When do you use as fed basis numbers

When mixing the ration

Which is crucial for linking what we provide and what they need

DMI

Factors that influence DMI

• Age

• Production type

• Production stage

• Size

• Lactation

• BCS

• Environment

What limits forage intake

GIT capacity

Average DMI based on body weight

2%

Relationship between forage quality and DMI

Lower quality forage takes longer to digest, which means less DMI

Relationship between protein content and DMI

Lower protein means less microbes, which means slower digestion and less DMI

What limits concentrate intake when the feed has >70% digestibility

Physiological mechanisms

Beef BCS scale

1-9

Target BCS for beef cows

5-6

Dairy BCS scale

1-5

What bodily function is the first to go when BCS is not ideal

Reproductive efficiency

Areas to analyze when determining BCS

• Tail head

• Ribs

• Spine

• Brisket

How does forage quality relate to plant maturity

The older the plant, the lower the quality

Factors when considering what feedstuff to use to supplement protein

• Cost

• Availability

• Delivery

• Economic value ($/lb)