Digestibility | Animal Nutrition Exam 3

Produce

Nutrient Management Goals

• “Eat More ___ More”

• Why we want to increase consumption, typically we want animals that will eat more and be effecient

Dry Matter Intake (DMI)

Nutritional Management Goals (1/7)

1. Maximize (optimize) nutrient consumption: ________

• We don’t actually know the max it can change over time

Digestibility

Nutritional Management Goals (2/7)

2. Maximize (Optimize) nutrient digestion: ___________

• If the animal is consuming more digestibility is likely to decrease

• Digestibility is a function of feed → want to feed digestible feed

Highly Digestible

Currently, the size of dog poop is smaller meaning dog food is more digestible than it was some time ago

• Dog foods are now formulated to be ______

• Firm poop → little food left

Nutrient Utilization Within the Body

Nutritional Management Goals (3/7)

3. Maximize (optimize) metabolism: _____________

• Want nutrients to play a role in the body

• Promote sweat

Nutrient Management Goals (4/7)

4. Maximize (optimize) animal welfare: ____

• Producers want to keep animals healthy so they can continue producing

Global Changes

Nutrient Management Goals (5/7)

5. Minimize (optimize) enviornmental impact: _____

Livestock Operations Profits

Nutrient Management Goals (6/7)

6. Maximize (optimize) economical issues: _________

• Can be very slim if you are a producer

• Feeding organic might be a good way for producers to make more money → can charge more

Global Food Supply

Nutrient Management Goals (7/7)

7. Maximize (optimize) social issues: _______

• Food is a National Security Issue

Animal

Dry Matter Intake (DMI)

• Factors that affect DMI

1. _____: stomach capacity, food preferences, physiological state (gestation, lactation → increased food requirement), sickness (don’t like eating when sick)

Food/Dietary

Dry Matter Intake (DMI)

• Factors that affect DMI

2. _____

Management

Dry Matter Intake (DMI)

• Factors that affect DMI

3. _______: competition from other animals

Animal Factors

Factors that affect DMI: ______

1. Animal Health

2. Animal Physiology

3. Animal Production Levels

2. (Food) Passage Rate

3. (Food) Particle Size

Dietary Factors that affect DMI

1. Diet Digestibility: not linear → low quality feed can be made more digestible and eat more

2. ___________: not linear → more you consume the faster it goes through

3. ___________: not linear → smaller particles go through faster

Eat Less

Dietary Factors that affect DMI

4. Energy Density

5. Fiber Content (opposite of energy) → eat a lot of fiber to feel full and ____

Essential Nutrients

Dietary Factors that affect DMI

6. ____________: If you have an essential nutrient that is missing the animal will eat MORE becuase they are trying to compensate for the nutrient, eventually through the lacking nutrient will cause the animal to eat LESS because it will limit the animals growth and production

Palatability

Dietary Factors that affect DMI

7. ______: adding bacon will increase intake: increased palatability increased eating but it is difficult to measure/quantify

8. Aroma: animals may like different smells

Diet Avaliabiity

Management Factors that affect DMI

1. _______: animals eat more when it is availiable (common in production systems) → but there are differences between animals and species.

Feeding Frequency

Management Factors that affect DMI

2. _________ (how many times food is offered): usually increases intake

• if you like snacking you always keep your blood glucose levels high → not great for your pancrease continously secreting insulin → prediabetic

• Not a problem for producing animals because they do not live long enough for it to become problematic

Enviornmental Conditions

Management Factors that affect DMI

3. __________ (temperature, wind, light)

• HOT: animals eat less when they are hot/heat stress

  • fans

  • feed less energy in the winter, feed more energy (oils/fats) because they are eating less.

  • **Lipids are considered “cool calories” because they generate less heat and pack calories (training horse in the sun → eats less → feed lipids)

• In the wind animals don’t want to eat: need a barn/place to eat

Digestibility

______

• Affects how much of any nutrient consumed actually reaches the animals tissues

Digestion

By definition, ____ refers to the changes which food undergoes within the digestive tract to prepare it for absorption

Digestion Protein Overview

Digestibility Coeffecient

Digestibility

• A certain fraction of each nutrient is consumed is digested (ie is absorbed by the GI tract)

• This fraction is referred to as the ________

Digestibility coeffecient

_________ is the fraction of the consumed feed that is not excreted in the feces

Undigested nutrients

The feces are mainly composed of _____ of the diet

Endorgenous Nutrients

But feces also contain _________ (nutrients that don’t come from the feed/ come from body or within) such as materials secreted by the host animals into the intestine

• Ex

  • Microbial protein

  • Pancreatic enzymes (other enzymes produced by the body)

  • Fiber CANNOT be endrogenous becuase we cannot produce it

Review

Review

Apparent Digestibility

__________: Easier to measure, however it does not account for endogenous secretions. It assumes that all nutrients in feces are from food!

True Digestibility

_________: Accounts for endrogenous secretions (sloughed cells from intestine, digestive enzymes, and pancreatic secretions)

Underestimate

Apparent digestibility is an _____ of true digestibility because endogenous nutrients are presumed to be undigested feed nutrients

Negative

Think of an animal that is fed no protein. There would still be CP flowing into feces. So, the apparent digestibility would be _____, which is impossible!

Constant

Endrogenous CP stays relatively _____ as dietary CP increases. Therefore, as the amount of dietary CP increases, the error associated with neglecting the endogenous CP contribution when calculating apparent CP becomes smaller.

Low-Protein Intake

Apparent vs. True Digestibility

• _______________: greatest difference between apparent and true digestibility

High Protein Intake

Apparent vs. True Digestibility

• __________: endrogenous makes less of a total contribution

Nutrient Composition

Factors that Affect Digestibility

1. ________: (Protein, Fiber, degree of lignification in fiber, lipids)

Diet Composition

Factors that Affect Digestibility

2. _________: (ingredient composition, “associative effects” → A little bit of starch can increase fiber digestion)

• Pasta has different digestibility than pasta with bacon → different ingredients (fats)

Food Processing

Factors that Affect Digestibility

3. ________: (Grinding, heat, moisture, chemical)

• Burn steak: get less protein

• Grind Cellulose: decreases digestibility because it passes faster

• Grind Starch: increases digestion

Dry Matter i

Factors that Affect Digestibility

4. _______: (DMI)

• More consumed less total digestibility, but still increased energy

• Chocolate bar example

Passage Rate

Factors that Affect Digestibility

5. __________: particle size and particle density

• faster = less digestion

Animal Factors

Factors that Affect Digestibility

6. _________: (Influences on DMI and therefore passage rate)

• Consumed

• Excreted

Calculation of (Apparent) Digestibility

• To calculate apparent digestibility, you need:

  • Amount of nutrient ______

  • Amount of nutrient ______

0.2 pounds

Calculation of (Apparent) Digestibility***

• Calulcation #1

0.125 pounds

Calculation #2

Underestimation

Apparent digestibility is always an ______

Coefficient of Digestibility

This is the equation for the ___________

62.5%

Coeffecient of Digestiblity (Apparent)

• Calculation #3

Coeffecient of Digestbility (True) Equation

65%

Energy

Digetsible Organic Matter (DOM) contains the _______

Digestible Organic Matter

Energy

Total Digestible Nutrients (TDN)

• The EE Is multiplied by 2.25 to account for that it packs a lot of ____

DOM

Digestibility Terminology/Estimations of Energy Content

________ = digestible CP + digestible CF + digestible NFE + digestible EE

TDN

Digestibility Terminology/Estimations of Energy Content

**More Accurate _______ = digestible CP + digestible CF + digestible NFE + (digestible EE * 2.25)

• Takes into account that fats contain more energy than starches & proteins

• TEST Q: usage depends on the amount of lipids in the diet, if you have few lipids in the diet use DOM, high lipids use TDN

Energy Content

DOM and TDN are terms that provide an estimate of the _________ of the feed.

14.4%

Digestible Nutrient Calculation

1. Total Collection

2. Marker Methodology

Methods for Determining Digestibility

• There are basically two methods for determining the digestibility of a diet

  • _______

  • _________

Total Collection

Methods for Determining Digestibility

• The __________ method requires one to measure total feed intake, total fecal output, and the nutrient composition of the diet and feces.

  • Becomes more difficult with larger animals

Marker Method

Methods for Determining Digestibility

• In the ______, the diet must contain something (a marker) that allows us to quantify specific nutrients.

Assayed

Marker Methodology

• Marker Characteristics → must go through animal and be excreted

  • Indigestible

  • Non-absorbable

  • Inert (doesn’t affect digestibility) → cannot affect other nutrients

  • Easily _____

    • Color maker can be used to see how long something remains in the tract but it is difficult to measure and is expensive

Total Collection

The best methodology for determining digestibility is ________

• Best approach because you have everything the animal consumed and excreted

• difficult to measure fecal in wild animals → must use markers

  • Marker is an alternative to total collection but no marker is perfect

External

Some markers are _______ (ex, chromium or ytterbium → rare elements that are not part of the diet/being consumed, food coloring) in that they are applied to the feed.

Interal

Some markers are _______ in that they are a constituent of the feed (ex, lignin, iNDF, or insoluble ash)

• ex) lignin in elephants is a good marker for carbohydrates but not proteins

Ratio

With the marker method small samples of feed and feces are acquired and assayed for the marker and the nutrients of interest.

• The ____ of nutrient to marker is determined in the feed and feces

Concentration

With the marker we are looking to see if its ______increases in the feed.

• Marker concentration should increase → how much of the feed disappeared?

Marker Digestibility Calculation

54.4%

If the marker concentration in feed is 0.52% and Marker concentration in feces is 1.14% then DM Digestiblility Coefficient is ______ (percent of diet being digested)

Formula for Nutrient Digestibility

50%

Example 1: If the ratio of marker to nutrient is 1:4000  in feed and 1:2000 in feces, then based on the  assumption that some of the nutrient is absorbed but  none of the marker is absorbed, we can calculate its  digestibility

Answer = ______