Nutrient Requirements & Rumen Assessment Flashcards
T/F: Cows are rarely at maintenance
True - usually asking them to grow, lactate, gestate, etc so often times they are above maintenance
What is maintenance?
Calories required to live life, but not do anything crazy
Should be able to maintain body weight
Total energy requirement can be determined by the _______ method
Factorial method
Maintenance + Factors (ex. Gestation, lactation, growth, cold)
Based on the average population, how much protein should be in the diet?
10% or 2lbs/day
What determines an animal’s maintenance?
Weight
Sex
Type (Beef vs Dairy)
T/F: A 1000lb angus bull, lactating jersey cow, and yearling brahma heifer all have the same maintenance requirement
False
How much higher is the maintenance of a dairy cow compared to a beef breed (the standard)?
20%
Within a breed, what sex will have higher maintenance requirements?
Bulls have 15% higher maintenance requirements than heifers and steers
More lean and less fat
Testosterone
Lactation is _______ to ______% higher than maintenance
200 to 400
Gestation is _____ to _____% higher than maintenance
30 to 50
T/F: Restricting feed may decrease energy requirements.
True - the gut and liver (high energy using organs) adjust to intake
What is the thermo-neutral comfort zone for cows?
41-77F
Need more energy if they are above or below that zone to stay warm or cool
What happens if an animal is fed below maintenance?
Breakdown own body tissues
How does a cow convert grass and hay into nutrients for metabolism?
Rumen microbes and enzymes break down feed into VFAs and microbial protein
Where does glucose come from in the cow?
Glucose precursors go to liver for gluconeogenesis
Unlike monogastrics, if a cow is fed a candy bar, the glucose doesn’t go straight into their blood. Rumen microbes eat it all up before it has the chance. Instead the bugs break down glucose into VFAs where propionate is used as a primary glucose precursor.
What VFA is a key glucose precursor?
Propionate
Aside from propionate, what are some other substrates for gluconeogenesis?
Lactate, Glycerol, Amino Acids
Acetate is used primarily as a _________ precursor
Fat
What is butyrate used for?
Fuel for rumen and LI epithelia
Name the three primary ketone bodies
B-OH Butyrate
Acetone
Acetoacetate
T/F: A ruminant is ketotic relative to a monogastric
True
What are insulin independent tissues?
Tissues that will snatch up glucose regardless of blood glucose levels
Ex. Fetus, mammary gland
What is a challenge of using BCS?
BCS is looking at fat or lack thereof
It gets tricky when you have an extremely muscular athletic animal that has little fat. We don’t tend to give them a lower BCS score, but in reality we should
As you go from moderate to fat, what are you adding to or losing from the body?
Adding subcutaneous and omental fat
As you go from moderate to thin, what are you adding to or losing from from the body?
Loss of muscle mass as most subcutaneous fat is gone
Explain how when a cow at a high BCS starts dropping BCS scores, it is initially slow but then rapidly accelerates
In order to meet her maintenance needs, she initially will be utilizing fat, which provides more calories per gram of body weight.
However, she will eventually run out of fat to burn and will start relying on muscle tissue.
Muscle tissue provides fewer calories per gram, so she will need to lose more muscle to reach maintenance.
