70 Questions
What is the main factor affecting the availability of phosphorus in food?
Presence of phytases
What happens to the availability of mineral elements as an animal's diet changes from milk-based to solid foods?
It declines
What is the primary purpose of metabolizing proteins, carbohydrates, and lipids in animal feed?
To synthesize animal products like eggs and milk
What type of energy conversion occurs during the metabolism of proteins, carbohydrates, and lipids?
Chemical energy to chemical energy
What is the primary source of phosphorus in many foods?
Phytic acid
What is the significance of phytases in phosphorus availability?
They break down phytic acid, increasing phosphorus availability
What is the formula to calculate the efficiency of ME utilization (k)?
k = Net Energy output/ME intake
What is a factor that affects the variation of 'k' values?
The process for which ME is being used
What is the reason for ruminants having lower 'k' values than non-ruminants?
Heat of fermentation
Which type of foods tend to have higher 'k' values?
Foods with high ME values
What is the purpose of the subscript letter in 'k' values?
To indicate the function for which ME is being used
What is the source of the information about 'k' values?
McDonald et al. (2022). Animal Nutrition, 8th ed.
What is the primary consideration when formulating diets for animals?
Satisfying the animals' energy requirements
What is the system used for ruminants in the British system?
Metabolisable energy system
What is the unit of measurement for net energy requirement for growth?
MJ/kg
What is the formula to calculate the efficiency of ME utilization?
k = NE output / ME intake
If an animal growing at 1.0 kg/day stores 15.0 MJ of energy, what is its net energy requirement for growth?
15.0 MJ/kg
What is the purpose of the additional factor in the Blaxter system?
To account for the variation in energy utilization
If food has an ME content of 10.0 MJ/kg and the efficiency of ME utilization for growth is 0.5, what is the NE content of the food?
5.0 MJ/kg
If the food to be fed contains 5.0 MJ/kg (NE), how much quantity is required to meet the animal's energy requirement?
3.0 kg
What is the basis for the efficiency of Metabolisable Energy (ME) utilization?
The metabolisability (qm) of the diet
What is the value of kg in relation to km for high-quality foods?
74% of km
What is the unit of measurement for Metabolisable Energy (ME)?
No specific unit mentioned
What is the purpose of using efficiency factors (k) in animal nutrition?
To calculate the nutritional requirements of animals
What is the relationship between ME and BE in the equation 𝑞𝑚 = 𝑀𝐸 / 𝐵𝐸?
ME is directly proportional to BE
What is the reference for the equation to predict the efficiencies of ME utilization?
McDonald et al. (2022)
What is the value of kg in relation to km for low-quality foods?
34% of km
What is the purpose of calculating the ME requirements of animals?
To ensure the optimal energy supply for different productive processes
What is the formula for RDP (Rapidly Degraded Protein) in terms of CP (Crude Protein)?
RDP = a x CP
What is the purpose of the nylon bag technique in determining the degradability of a food?
To determine the rapidly degradable fraction of a food
What is the meaning of the parameter 'a' in the formula for RDP and SDP?
Rapidly degradable fraction
What is the formula for ERDP (Effective Rumen Degradable Protein)?
ERDP = CP x [0.8 a + (c / (c + r))]
What is the meaning of the parameter 'c' in the formula for RDP and SDP?
Utilization yield by microorganisms
What is the purpose of determining the degradability of a food?
To determine the nutritional value of a food for ruminants
What is the volume of one gram-molecule of oxygen?
22.4 litres
If an animal obtains all its energy from the oxidation of glucose, what is the thermal equivalent of oxygen?
20.98 kJ/litre
What is the average thermal equivalent of oxygen for a mixture of carbohydrates?
21.12 kJ/litre
Why is it necessary to have different approaches to evaluate protein sources in animals?
Because the nitrogen requirements of animals and the nitrogen status of foods are stated in terms of protein
What is the thermal equivalent of oxygen for lipids?
19.61 kJ/litre
What is the primary purpose of measuring the protein content of a food?
To ensure the food provides sufficient essential and nonessential amino acids
What is the thermal equivalent of oxygen for proteins?
18.8 kJ/litre
What is the energy production from 1 litre of oxygen when an animal obtains all its energy from the oxidation of glucose?
20.98 kJ
What is the basis for calculating the protein content of a food?
The nitrogen content of the food determined by the Kjeldahl technique or Dumas method
How do animals normally obtain energy?
From a mixture of carbohydrates, lipids, and proteins
What is the significance of essential and nonessential amino acids in animal nutrition?
They are necessary for the synthesis of protein
What is the significance of thermal equivalents of oxygen in animal nutrition?
To determine the energy production from oxygen
Why is protein synthesis important in animal nutrition?
Because most of the nitrogen required by the animal is used for protein synthesis
What is the relationship between the nitrogen content of a food and its protein content?
The protein content is calculated from the nitrogen content
What is the purpose of evaluating protein sources in animal nutrition?
To ensure the food provides sufficient essential and nonessential amino acids
Why is it necessary to consider the type of animal being fed when evaluating protein sources?
Because the nitrogen requirements of animals and the nitrogen status of foods are stated in terms of protein
What is the current limitation of mechanistic models in predicting animal requirements and responses to changes in nutrient supply?
Inability to accurately predict energy values of foods
What happens to protein in the rumen of ruminant animals?
It undergoes considerable degradation and synthesis
Why do mechanistic models include equations for predicting energy values of foods?
Because energy values are variable and depend on chemical composition
How do simple-stomached animals obtain amino acids from food?
Through breakdown of food proteins during digestion and absorption
What is the purpose of determining the degradability of a food in sacco studies?
To determine the rapidly degradable, slowly degradable, and undegradable fractions of a food
Why is it important to consider the chemical composition of foods in animal nutrition?
All of the above
What is the unit of measurement for RDP (Rapidly Degraded Protein)?
g/kg DM
What is the formula for SDP (Slowly Degraded Protein) in terms of CP (Crude Protein)?
SDP = b x CP / (c + r)
What is the expected outcome of using computers in animal nutrition in the future?
More accurate prediction of animal requirements
What is the meaning of the parameter 'b' in the formulas for RDP and SDP?
Slowly degradable fraction
What is the formula for ERDP (Effective Rumen Degradable Protein)?
ERDP = CP x [0.8a + (c+r) / (c+r)]
What is the purpose of the nylon bag technique in determining the degradability of a food?
To determine the rapidly degradable, slowly degradable, and undegradable fractions of a food
What is the basis for the Essential Amino Acid Index (EAAI)?
The geometric mean of the ratios of the essential amino acids
What are the two sources of protein for ruminant animals?
Microbial and food
What is the advantage of using the Essential Amino Acid Index (EAAI)?
It predicts the effect of supplementation in combinations of proteins
What is the relationship between the Chemical/Amino Acid Score and the Essential Amino Acid Index (EAAI)?
They are both measures of protein quality based on amino acid composition
What is the reference pattern used for the Essential Amino Acid Index (EAAI)?
The pattern of essential amino acids in egg protein
What is the unit of measurement for protein quality?
There is no unit of measurement for protein quality
What is the purpose of measuring protein quality?
To evaluate the nutritional value of protein sources
What is the difference between the Chemical/Amino Acid Score and the Essential Amino Acid Index (EAAI)?
The Chemical/Amino Acid Score is based on the ratios of all amino acids, while the EAAI is based on the ratios of the essential amino acids
Study Notes
Mineral Availability
- Phosphorus (P) is present in many foods as a constituent of phytic acid, and its availability depends on the presence of phytases of animal, microbial, or exogenous origin.
- Mineral availability is generally high in young animals fed on milk-based diets, but generally declines as the diet changes to solid foods (trapped in food matrix).
Energy Content and Partition
- Energy from feed is used to synthesize animal products like eggs and milk through metabolism of proteins, carbohydrates, and lipids.
- Efficiency of ME (Metabolizable Energy) utilization (k) varies depending on animal species, process for which ME is being used, and nature of ME supply (= feed type).
- Foods with high ME values tend to have higher k values because they are digested and metabolized with less energy expenditure.
- Ruminants have lower k values than non-ruminants, mainly because of the heat arising from microbial metabolism (heat of fermentation).
Diets Formulation
- First, ensure that the animals' energy requirements are satisfied.
- Second, maintain the correct balance between energy and other nutrients.
Systems to Express Feed Energy Supply
- The British system used for ruminants is based on Metabolizable Energy (ME) and considers an additional factor, the efficiency of ME utilization (k).
- Animal requirements are expressed in terms of Net Energy (NE).
- Food energy values are expressed as Metabolizable Energy (ME).
- Efficiency factors (k) are used for different productive processes (e.g., maintenance, lactation, and growth), which depend on the ME concentration of the diet (ME/DE).
Blaxter System
- Animal ME requirements are calculated using efficiency factors (k) for different productive processes.
- For low-quality foods (qm = 0.4), kg is only 34% of km.
- For high-quality foods (qm = 0.7), kg is 74% of km.
Efficiency of Metabolizable Energy (ME) Utilization
- The efficiency of ME utilization (k) is based on the metabolisability (qm).
- ME utilization (k) is predicted using a series of equations.
RDP (Rumen Degradable Protein)
- RDP (g/kg DM) = a x CP, where a is the rapidly degradable fraction (water-soluble N).
- SDP (g/kg DM) = bc x CP, where b is the slowly degradable fraction (N potentially degraded).
- ERDP = CP x [0.8 a + (c+r) / (c+r)], where c is the utilization yield by m.o.
Oxidation of Glucose
- One gram-molecule of oxygen has a volume of 22.4 liters (normal temperature and pressure)
- The overall reaction for oxidation of glucose is: C6H12O6 + 6O2 -> 6CO2 + 6H2O + 2820 kJ
- The utilization of 1 liter of oxygen leads to the production of 2820/ (6 x 22.4) = 20.98 kJ heat
Thermal Equivalents of Oxygen
- Carbohydrates: 21.12 kJ/ liter
- Lipids: 19.61 kJ/ liter
- Proteins: 18.8 kJ/ liter
Energy Content and Partition
- Animals do not normally obtain energy exclusively from carbohydrate or fat, but tend to oxidize a mixture of these (and protein)
- Mechanistic models may be able to predict animal requirements and responses to changes in nutrient supply in the future
- The energy value of some foods is variable and can be predicted from their chemical composition
Measurements of Food Protein
- Simple-stomached animals obtain amino acids from the breakdown of food proteins during digestion and absorption
- Ruminant animals have a more complex situation, with considerable degradation and synthesis of protein occurring in the rumen
- Different approaches are necessary for evaluating protein sources for ruminant and non-ruminant animals
Protein Evaluation
- The nitrogen requirements of animals and the nitrogen status of foods are stated in terms of protein
- The protein content of a food is calculated from its nitrogen content determined by a modification of the classical Kjeldahl technique or the Dumas method
Amino Acid Profile
- The amino acid profile of a food is important for its efficient use by the animal
- Essential amino acid index (EAAI) is the geometric mean of the egg, or standard pattern, ratios of the essential amino acids
Protein Quality for Ruminant Animals
- Protein comes from two sources: microbial (obtained by microbial metabolism in the rumen) and food (not degradable in the rumen but is digestible in the abomasum)
- RDP (rapidly degradable protein), SDP (slowly degradable protein), and ERDP (effective rumen degradable protein) are measures of protein quality for ruminant animals
This quiz covers the role of phosphorus in animal nutrition, its availability, and the importance of phytases in absorption. Relevant for Master Degree in Veterinary Medicine students.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
