ASB 221 - Lesson 11

Flashcards on Feed Intake in Ruminants

Dry matter (DM) intake of grazing animals

The amount of feed without water consumed by an animal.

Dry Matter

Ruminants generally consume 2 – 3.0% of their body weights as this.

Depress DM intake

Acetic and Propionic acid infused into the rumen does this.

Receptors

These exist on the luminal side of the reticulo-rumen to detect Acetic and Propionic acid.

Feed Intake

This appears to depend on the digestive system and feed characteristics for control of roughage intake.

Digestibility of the feed

This is +vely related to the DM intake.

Rate of digestion

The primary nutrient which affects this is the NDF.

NDF

A measure of the cell wall content of the plant.

NDF

Feeds rich in this have low rate of digestion.

Addition of concentrates to roughage of low digestibility

Improves the intake of the roughage but where the roughage has high digestibility its replaced by the concentrate.

lignification

In legumes this occurs in the vascular bundle whereas in grasses its more widespread on the entire plant → inhibitory effect on intake.

Leaves

Cell walls in this are more easily broken down than those in the stems.

rumen microbial activity

Nutrient deficiencies that retard this may reduce feed intake e.g. protein or N.

off-smell

Badly fermented silages and feeds with this are poorly consumed

Fat deposits on the animals body

Excessively fat animals have a stable DM intake compared to their metabolic body weight due to this effect.

DM intake to increase

During pregnancy, the increased need for nutrients for foetal dev causes this to happen.

Lactation

The onset of this is accompanied by an increase in DM intake

Feed Intake

Ill health can affect this.

Grazing

Normal duration of this in cattle is 8-10hrs.

Swards

Short and dense examples of this allow maximum bite size and rate for cattle

thermoneutral zone

Feed intake decreases at temperatures above this zone and it increases when temperatures fall below that zone.

Day

This length affects DM intake in some species and not others e.g. Deer>Sheep>Cattle.