ANSC 433 Lecture Notes - Lecture 14: Atwater System, Basal Metabolic Rate, Energy Principles In Structural Mechanics
23 May 2018
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14. ANSC 433: Animal Nutrition & Metabolism
1
Feeding Standards and Requirements
Terminology Used In Feeding Standards
- Definition: the amounts of nutrients required by animals
- Distinction of feeding standards = second assumes how much animal eats in a day i.e. need to make sure nutrients are
concentrated enough to get all the required ones each day
o Quantities of nutrients required per day (e.g., g/day)
o Dietary proportions or concentration (e.g. % of
- Units: weight, percentage, parts per million (ppm), and international units
- It is desirable that the units used in the standards should be the same as those used in feed evaluation
- For proteins and amino acids, requirements are expressed as:
o Metabolizable protein in dairy cows
o Crude protein in horses
o Standardized ileal digestible amino acids in swine and poultry
- For energy, requirements are expressed in various systems:
o Effetie ME for sie NE used i Freh sste
o ME for poultry
o NE for dairy cattle
o DE for horses
***ME = metabolizable energy
***NE = net energy (intake - (excretion + heat)), used for pregnancy, lactation, etc. – energy left after used for maintenance
(maintenance energy is lost as heat)
***DE = digestible energy
Methods for Estimating Nutrient Requirements In Livestock
- Factorial approach – tells total requirements are sum of maintenance plus whatever productive functions applied to
case
o Additive approach hat sums the known source of nutrient or energy expenditure and retention and adjust
for efficiency in utilization
- In cases where nutrient or energy retained is in lactation or pregnancy, energy retained and deposited are added in
the equation
Example: what are the energy expenditure and retention that we need to sum to calculate the energy requirement of pregnant
third lactation dry cow?
- Key concept: in many species, nutrient requirements are with the factorial approach
o Add together to get total requirements
Feeding Standards
- In North America, the NRC nutrient requirements are widely used for most livestock species
- The current version of NRC requirements for livestock species are:
o Nutrient Requirements of Dairy Cattle: seventh Revised Edition (2001)
o Nutrient Requirements of Beef Cattle: Eight Revised Edition (2016)
o Nutrient Requirements of Swine: Eleventh Revised Edition (2012)
o Nutrient Requirements of Poultry: Ninth Revised Edition (1994)
o Nutrient Requirements of Horses: Sixth Revised Edition (2007)
- Formulated by room full of academics
Nutrient Requirements for Maintenance
- Maintenance: oditio i hih a aial’s od opositio reais ostat, he it does ot gie rise to any
product and does not perform any work on its environment
- Important because of factorial approach to estimate nutrient
requirements
- Maintenance can contribute substantially to total nutrient and energy
requirements
Relative Contribution of Maintenance and Production to Total Energy
Requirements
find more resources at oneclass.com
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14. ANSC 433: Animal Nutrition & Metabolism
2
- Do’t keep as pets; use for ilk
Body Size and Basal Metabolic Rate
- Smaller body = smaller metabolic rate
Fasting Metabolism in Adult Animals
Feeding Standards for Maintenance – Energy
Energy Requirements for Dairy Cows
Maintenance Requirements
- In lactating cows, metabolizable energy is utilized for maintenance, lactation and pregnancy with similar efficiency
(60-70%)
- Therefore, energy requirements for these functions are expressed as a one term: net energy of lactation (NEL)
o Can use to calculate for fat percentage (uses another multiplying factor)
- Energy values of feed for dairy cows are expressed as NEL
- Base energy requirements relate to body surface area or metabolic size
- On average, fasting heat production in non-lactating, non-pregnant cows was measured as 0.073 Mcal NEL/kg
BW0.75/d
- A 10% activity allowance was added to account for normal voluntary activity in dry lot and free stall systems
- Maintenance requirement for mature dairy cows: 0.08 Mcal NEL/kg BW0.75/d
Activity Requirements
- Because no work is actually done, increased energy required for physical activity is reflected in increased heat
production and by definition is equivalent to NEL required for maintenance
- For grazing animals
o Walking on flat terrain: 0.00045 Mcal NEL/kg of BW/km walked
o Walking on hilly terrain: 0.006 Mcal of NEL/kg BW
o Eating = 0.0012 Mcal NEL/kg of BW
- Grazing animals tend to use more energy than stall animals since they have to walk or get ot nvedcile
Exercise - Solution
- Base maintenance requirement = NEl = 0.08*600^0.75 = 9.7 Mcal NEL
- Walking = 2 km * 0.00045 Mcal NEL/kg BW/km *600kg BW = 0.54 Mcal NEL
- Eating = 0.0012 Mcal NEL/kg of BW * 600kg BW = 0.7 Mcal NEL
- Total maintenance energy requirement = 10.94 Mcal NEL
***Do’t aout for reed sie ou use od eight i the forula i.e. alread take ito aout
Pregnancy Requirements
- Energy required for gestation assumed to be 0 until d 190, then increases to 279 d
- Efficiency of ME use by the gravid uterus was assumed to be 0.14
- The NEL requirement for gestation is described as (NRC, 2001):
-
NEL (Mcal/d) = [(0.00318 x D – 0.0352) x (CBW/45)] / (0.14 x 0.64)
Where:
➔ D = day of gestation between 190 and 279
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Definition: the amounts of nutrients required by animals. Units: weight, percentage, parts per million (ppm), and international units. It is desirable that the units used in the standards should be the same as those used in feed evaluation. For proteins and amino acids, requirements are expressed as: metabolizable protein in dairy cows. Standardized ileal digestible amino acids in swine and poultry. For energy, requirements are expressed in various systems: (cid:862)effe(cid:272)ti(cid:448)e(cid:863) me for s(cid:449)i(cid:374)e (cid:894)ne used i(cid:374) fre(cid:374)(cid:272)h s(cid:455)ste(cid:373)(cid:895: me for poultry, ne for dairy cattle, de for horses. ***ne = net energy (intake - (excretion + heat)), used for pregnancy, lactation, etc. Energy left after used for maintenance (maintenance energy is lost as heat) Factorial approach tells total requirements are sum of maintenance plus whatever productive functions applied to case: additive approach hat sums the known source of nutrient or energy expenditure and retention and adjust for efficiency in utilization.
