Digestibility & Energy Flashcards
What are the Nutritional Management Goals?
- Maximize (Optimize) nutrient composition: Dry Matter Intake (DMI)
- Maximize (optimize) nutrient digestion: Digestibility
- Maximize (optimize) metabolism: Nutrient Utilization Within the Body
- Maximize (optimize) animal welfare: Health
- Minimize (optimize) environmental object: Global Changes
- Maximize (optimize) economical issues: Livestock Operations Profits
- Maximize (optimize) social issues: Global Food Supply
What does Dry Matter Intake (DMI) depend on?
- Animal ( Varies by PH, Rumen size, Behavior, Selection of food)
- Food (Gut fill, physical filling, food affecting PH)
- Management (how much is ate, sufficient amounts)
When it comes to DMI what are specific animal factors that affect it?
- Animal Health (Abnormality in consumption of food)
- Animal Physiology (Pregnant cow less consumption change in rumen space)
- Animal Production Levels (What is lacking in production, could be milk, egg etc)
What are some factors that affect DMI in the terms of Dietary factors?
- Diet digestibility (how easily it can be consumed and processed)
- (food) Passage rate ( how fast food is consumed and secreted)
- (food) Particle size (Big size particles stick for a longer time in rumen = lower intake)
- Energy density (food is rich or energy dense, signals to body will lower appetite)
- Fiber content ( how much time it takes because of physical filling)
- Essential nutrients (how much it needs based off food)
- Palatability (taste of diet, affecting consumption)
- Aroma ( smell of food affecting consumption)
What are some factors affecting DMI management factors wise?
- Diet availability ( What can be given to them for food)
- Feeding frequency ( amount fed at a time)
- Environmental conditions ( temperature, wind, light)
What can digestibility be referred to as? describe how? What does it affect?
- Changes which food undergoes within the digestive tract to prepare it for absorption
- It affects how much of the nutrient consumed actually reaches animal tissues.
When it comes to digestibility how is it digested and what is it referred to as?
A certain fraction of each nutrient consumed is digested and it is referred to as digestibility coefficient.
What is the Digestibility coefficient?
The fraction of the consumed feed that is not excreted in the feces.
What is feces comprised of?
Undigested nutrients of the diet and contain endogenous nutrients.
What is Apparent Digestibility ?
It is a measurement that is easily obtained but does not account for endogenous secretions, it assumes all nutrients in feces are from food.
What is True Digestibility?
A digestibility that accounts for endogenous secretions, digestive enzymes, and pancreatic secretions.
What is the difference between apparent digestibility and true digestibility?
True digestibility accounts for endogenous secretions and is more accurate than Apparent, and it normally higher than Apparent. Apparent digestibility is an underestimate of true digestibility.
- As dietary CP increases…….
2. As Amino acids increase…..
- Endogenous CP stays relatively constant
2. endogenous digestion decreases
What factors affect digestibility ?
- Nutrient composition: (Protein, fiber, degree of lignification in fiber, lipids)
- Diet composition (ingredient composition, “associative effects”)
- Food processing: (grinding, heat, moisture, chemical)
- Dry matter intake (DMI)
- Passage rate ( particle size and particle density)
- Animal Factors (influences on DMI and therefore passage rate)
What exactly is “associative effects”?
How one feed can affect the digestibility of the other
What do you need to calculate apparent digestibility ?
- Amount of nutrient consumed
2. Amount of nutrient excreted
What do you need to calculate apparent digestibility ?
- Amount of nutrient consumed
2. Amount of nutrient excreted
What is the formula for Apparent Digestibility?
CD= (intake-excreted)/intake X100
What is the formula for true digestibility?
CD= (intake-excreted + endogenous)/ intake X 100
What is the formula for DOM (Digestible Organic Matter) = _______________________
DOM = digestible CP + digestible CF + digestible NFE + digestible EE
What is the formula for TDN (Total digestible nutrients)= ______________________
TDN= digestible CP + digestible CF + digestible NFE + (digestible EE * 2.25)
What are DOM and TDN used for in terms of?
Used in energy content of the feed
What are two methods for determining digestibility ?
- Total collection (collect everything that comes out)
2. Marker methodology (measuring quality in feed, like fiber seeing what goes in and out)
What does the total collection method require?
Total feed intake, total fecal output, and nutrient composition of the diet and feces.
What does the marker method require?
Contain a marker that allows us to quantify specific nutrients.
What are Marker Characteristics?
- Indigestible
- Not-absorbable
- Inert (doesn’t affect digestibility)
- Easily assayed (measured)
What types of markers are there?
- External marker (Chromium or ytterbium)
2. Internal marker (lignin, iNDF, or insoluble ash)
How is a marker in nutrient measured?
Determined in ratio through feed and feces.
What is the Dm Digestibility Coefficient % formula?
1 - (% marker in feed/ % marker in feces)
What is the Nutrient Digestibility formula?
100- (100 X %marker in feed/%marker in feces X %nutrient feces/ %nutrient feed)
What is the Nutrient Digestibility formula?
100- (100 X %marker in feed/%marker in feces X %nutrient feces/ %nutrient feed)
What is the Marker Recovery % formula?
Marker in total collection (g per d) / Marker intake (g per d)
What is the formula for Fecal Excretion (g per d) ?
Marker intake (g per d) / Marker fecal concentration (%)
What is Energy ?
The capacity to do work.
What does 1 Calorie equal to?
1000 calories since Calorie spelled with a large C is 1.
What are Carbohydrates used for in terms of energy?
They are the cheapest and most abundant source of energy thus comprising the majority of the diet
What can be used as energy?
Carbohydrates, Lipids and Proteins while Mineral (ash) cannot serve as an energy source
What are two major systems used to describe energy content of feed?
- Net Energy (NE) System (used for dairy)
2. Total Digestible Nutrients (TDN) System
How does the Process of Net Energy System go?
Gross Energy (GE)-> Fecal Energy-> Digestibility Energy (DE)-> Urine Energy-> Gas Energy-> Metabolizable Energy (ME)-> Heat Increment (HI): Ferment. + Nut. Metab. -> Net Energy (NEm NEg NEl)
How do you find GE what do you use?
You use a Bomb Calorimeter to find the GE
What is unique about the Gross energy value
The Gross energy value does not change and is not affected by anything
GE is a value that is considered what?
A not very meaningful measurement, and it determines POTENTIAL amount!
What does the net energy system systematically do?
It takes those losses into account.
How do you determine Digestibility Energy (DE)?
GE - fecal energy
The amount of energy available after subtracting energy lost in feces
How is Mcal represented as?
10^6
How is Kcal represented
10^3
What is the con of using DE? What is the pro
It does not tell how well the energy is absorbed from the GI tract; Utilized for productive functions. The pro is that it is easy to measure
What is DE most like?
It is most like TDN
How do you calculate Metabolizable Energy (ME)?
DE-energy loss in urine and gas
When it comes to Poultry how easy is it to measure ? What is also not considered in Poultry?
It is very easy to measure (experimentally) because it excretes urine and feces together. What is not considered in Poultry is gas because it is so minor it is ignored.
In Carbohydrates, Protein and Fat what is their physiological fuel value.
- 4Kcal/gram for Carbohydrate
- 4Kcal/gram for Protein
- 9Kcal/gram for Fat
Fat is has how much more than carbohydrate and protein?
2.25X
Protein in the body does not yield what? Instead in yields?
It does not yield N2 instead it yields urea and other nitrogen compounds.
What do Urea and other organic nitrogenous compounds share in common?
They are combustible, however they represent a less complete oxidation of protein in the body than in the bomb calorimeter.
Why is Protein 4.35?
It is because of the energy lost due to incomplete oxidation that turns protein from 5.65 to 4.35
What is Heat of Fermentation (HF)
Heat generated by microbes in the GI tract during the fermentation of feed.
What is Heat of Fermentation
Heat generated by microbes in the GI tract during the fermentation of feed.
What is the Heat of Nutrient Metabolism (HNM)?
Heat production associated with nutrient digestion and metabolism above that produced prior to ingestion of food
Where is the Heat of Nutrient Metabolism coming from?
It comes from the energy required for events such as
- Muscular contractions of the GI tract
- Nutrient transport across the gut
- Waste production associated with meal consumption (e.g. kidney function)
What does NEm stand for?
Energy to support maintenance (most important)
What does NEg stand for?
Energy to support growth (getting bigger)
What does NEl?
Energy to support lactation. (milk, mammary gland, weaned)
How do you find Net energy?
ME- Heat increment
What is Net Energy Maintenance
It is the energy used to keep a nonproductive animal in a state in which is neither gains nor loses weight. it shows up as heat loss, requirement of animal equal to the basal metabolic rate plus energy required for normal daily activity.
What is the basal metabolic rate?
heat production of the animal in a post absorptive state, in a thermo neutral environment, in a state of muscular rest.
Why do grains and fats have less energy loss to feces than forages?
Due to digestibility
Why do grains have less energy loss to urine and gas than forages.
it is because of gas stand point both fermented but grains turn into propionate.
When it comes to fat from DE to ME what loss is there?
There is no loss because no gas or urine energy was lost “for fats”
In a High Forage Diet what occurs?
There is more Acetates meaning there is more methane
In a High concentrate Diet what occurs
More propionate= less gas
The efficiency of conversion ME to NE is?
- Greatest for fats
- Intermediate for grains
- Least for forages
How do you determine the efficiency of utilization of ME?
You must measure heat production through
- Direct Calorimetry
- Indirect Calorimetry
How does one perform a Direct Calorimetry?
- Thermocouples
2. Transfer to circulating water (in heat chamber)
How does one perform indirect Calorimetry?
- O2 consumption and CO2 production are measured.
Which is the more accurate TDN and less accurate TDN?
- TDN = Dig. CP + Dig. NDF+ Dig. NFC+ (Dig. FA x 2.25)
2. TDN = Dig. CP + Dig. CF+ Dig. NFE+ (Dig. EE x 2.25)
What are the advantages of the TDN system?
- It is relatively easy to do
- Easy to understand
- There is more date in the literature of the TDN value of feeds than the NE value of feed.
What is disadvantage of using the TDN system?
TDN values are table values; therefore, are only accurate when nutrition composition of feed is the same as table value
TDN vs NE system what is the difference?
Normally NE systems are the preferred system however, there are very few values available for feeds. NE values are predicted from TDN (NE system is expensive and difficult to measure.
How is TDN used?
It is rarely ever measured it is typically predicted from measurements and practical to make (chemical composition of the feed)
When there is a higher feed intake?
There is a lower TDN value
How is heat production determined in an animal?
It is determined by its size live stock are homeotherms they attempt to maintain a constant body temperature.
How does one Predict Heat Loss?
- Body size is not a perfect predictor of heat loss
2. Surface area of an animal is more closely related to energy loss
What is the equation of Basal Metabolic Rate (BMR)?
What is the equation for Metabolic Body Weight (MBW)?
- Mass^3/4
2. BW^3/4
Heat production by an animal varies but heat loss occurs by?
- Conduction (Direct transfer by contact)
- Convection ( Moving air removes radiated heat)
- Radiation ( Emission of electromagnetic heat)
- Evaporation ( Loss of heat by evaporation of water ‘ via respiration’)
How does an animal control body temperature?
Changing the blood flow to the skin, perspiration, respiration
Zone of Thermoneutrality is what?
A temperature range that an animal does not need to expend energy to warm or cool the body
Cattle: 45-55 F
Calves: 55-68 F
Humans 68-77 F
What is a Lower Critical temperature?
Temperature in which an animal must increase heat production to prevent body temp. from falling
What is Upper Critical Temperature?
Temperature in which animal must expend energy to cool itself
What can help an animal when it gets cold or hot in temperature?
The brainstem region called thermoregulatory center in which hair coat is told to grow thicker in fall and shed out in spring.
It also makes animal shiver when it is cold or sweat when it is hot.
What can fat help with and why?
It can be an excellent feed source to help animals deal with heat stress it also has a low HI.
In order for an animal to try and stay near the thermoneutral zone it needs?
It needs more energy, which means more feed must be provided or the animal just has less energy available for growth.
If an animal is not able to thermoneutral zone what occurs?
It gets sick and the body’s immune system requires a lot of energy as well
How does one help the livestock stay near its thermoneutral zone?
- Providing plenty of clean and dry bedding
- Provides shelter from the wind
- Increase amount fed
- Minimize amount of manure accumulating on their legs and bellies (keep the pen clean)
What are some method of cooling?
Methods animals use to cool themselves
- Perspiring
- Enhancing Evaporation of Water from the Body Surface
- Increasing Respiration and Panting
- Emersion into water
Bottoming Line what does Heat or cold stress represent?
Significant caloric cost
By increasing productivity of an animal is an important way to ?
Increase energetic efficiency
Having the maintenance cost of one animal producing two gallons of milk is better than?
Having two animals together producing two gallons of milk.
