ANSC 301 Exam 3 Growth

What is a key tissue that helps keep young animals warm? How is the mitochondria and the electron transport chain involved? Is this mechanism present in adults?

Brown adipose tissue is the key tissue.

There is abundant mitochondria that oxidizes fatty acids. This oxidation uncouples from ATP synthesis. ATP synthesis comes from the electron transport chain producing ATP from NADH. NADH passes electrons through a series of proteins to oxygen, which pumps H+ into the intermembrane space. H+ flows back to the matrix through ATP synthase, which turns ATP into ATP.

Yes; Brown adipose tissue was recently identified in deep muscle tissue in adults when previously thought to only be present in kidneys and necks in newborns.

Where will a newborn get its blood glucose?

Their dietary source is from lactose. They also use gluconeogenesis and liver glycogen mobilization immediately after birth.

Is protein deposition high or low in a young animal? How does milk support this?

It is high in young animals (around 2-7 days old) and there is rapid rates of lean growth and tissue protein synthesis.

Milk protein is rich in EAA (essential amino acids), which are high in biological value

What does a normal growth curve look like? What does the curve look like for bone, muscle and fat?

Rapid growth in early life that slows over time

Bones grow first and level off fairly quickly. Muscle rapidly increases and then eventually levels off. Fat slowly increases but continues to increase over time.

What do proteins contain that makes them unique? What is true protein vs. non-protein N?

They contain nitrogen

True protein N is amino acids and chains of AA (proteins). Non-protein N is ammonia and urea.

Does the concentration of proteins change much over development?

No, they tend to be a rather constant percent in the body.

What is the largest protein depot in the body?

Body fluids

What does protein turn-over mean? Why is body protein turned-over? Do all proteins have the same turn-over? What happens to AA during protein turnover?

It is the replacement of proteins

It enables a change in the protein composition and ensures that they’re functional

75-80% are reutilized for protein synthesis

20-25% have the amino group removed

How do we make proteins?

Through protein synthesis; which requires the expression of mRNA for the protein and then synthesis of the protein on a ribosome

Protein synthesis is driven by hormones that change cellular signals that turn on gene expression and translation, genetic differences in hormone secretion and responsiveness, physiological state or stage of life, and environmental effects. There is also a major cellular signal called mTOR that regulates protein synthesis and is responsive to some amino acids.

What tissue has the highest rate of protein synthesis, gut or muscle?

The gut because there is rapid cell loss. The liver is second highest because of the number of enzymes made, while muscle is last.

How would you increase protein deposition even if protein degradation was increased?

The formula to follow is synthesis - degradation = deposition

Mainly increasing synthesis is the key

What optical form of amino acids are found in normal feeds?

There are two optical forms: L (levo-rotational) and D (dextro-rotational); the L form is found in normal feeds

Why do synthetic amino acids differ in their ability to meet an amino acid requirement?

The D-form must be able to be transaminated. The animal will take 80% of D-form and convert it to the L-form for amino acids. For some amino acids, like lysine, the D-form has little nutritional value because the animal does not have the enzymes required to convert it to the L-form.

What is transamination? What is formed?

Transfer of the amino group of one AA to the C-skeleton of a keto-acid. This is amino acid synthesis.

What is a glucogenic amino acid? Ketogenic AA? Essential and non-essential AA?

Glucogenic amino acids form glucose through gluconeogenesis

Ketogenic amino acids can be converted into ketones

Essential amino acids can’t be made in the body but are required in the diet

Non-essential amino acids aren’t required in the diet because the body can synthesize them on its own

What is used and what is produced during deamination?

Deamination is the removal of an amino group from the C-skeleton of an AA

AA, water and coenzymes are used

Keto acid, ammonia and coenzyme-2H are produced

What needs to be detoxified after deamination? What cycles do this?

Ammonia is detoxified. The Urea cycle does this.

What are the benefits of the Uric Acid cycle?

It produces urea from ammonia and detoxifies ammonia

When is amino acid catabolism increased?

Dietary protein intake exceeds requirements, composition of absorbed amino acids is imbalanced, and gluconeogenesis from amino acids is increased

What does muscle do with AA after a meal? During a fast?

After a meal: peripheral muscles extract AA

During a fast: muscle is the main storage site of AA

A protein requirement is actually a requirement for?

Amino Acids

Would two proteins that differ in their amino acid profiles have the same effect on growth?

No; If a protein has a poor AA balance, it has to be fed more and will take longer to reach the appropriate growth rate compared to a protein that has the proper AA balance.

What is biological value? If a protein has a less ideal amino acid profile, will it have a high or low biological value? Is biological value of a protein the same for an animal growing vs. lactating?

The ability of a specific dietary protein to supply amino acids in the relative amounts required for protein synthesis by body tissues.

If the amino acid profile is less ideal, it will have a low biological value.

Biological value varies with the varying needs of different species and physiological and nutritional states, so it will be different for an animal that is lactating vs. growing.

What do we mean by an ideal protein?

In an ideal protein, all the essential amino acids are included at least 100% of their requirement in the diet.

If one amino acid is provided at 50% of requirement, but all others are adequate, what would you expect for performance/growth?

Performance and growth would decrease because you are only getting 50% of that amino acid when you should be getting 100%.

Does one feed have an ideal amino acid profile? Rank plant proteins, microbial proteins, and animal proteins.

Not all feeds have an ideal amino acid profile

Microbial proteins → animal proteins → plant proteins

What are two feeds called that when mixed together have an amino acid profile better than either alone?

Complementary feeds

How are proteins broken down? What do we absorb?

Proteins must be broken down to small peptides and amino acids. We absorb di- and tri- peptides.

What is an AA antagonism?

Growth depression from an excess of one AA that can be reversed by adding a second AA

What is an AA toxicity?

Growth depression from an excess of one AA that cannot be reversed by adding a second AA

What is an AA imbalance?

Deficit of one or several AA that can cause depression in growth or production and can be reversed by addition of small amounts of the AA

What happens if we have a slight or severe protein deficiency? What happens if we have too much dietary protein?

Low dietary protein: reduced growth rate, increased fat, low milk or egg production, poor feed efficiency

Severe protein deficiency: reduced growth rate, weight loss, scruffy hair and other standard deficiency signs

Excess protein: high feed costs, normal growth, enlarged kidneys, excess water intake

Why does feeding too much energy have an energetic cost to the animal?

There’s an increased synthesis of urea

What are the environmental emissions from feeding excess protein?

Nitrogen is leaching into the ground and runoff into surface water.

What is the main contributor to ammonia emissions in the US?

Urease in feces creates ammonia when mixed

What is the environmental risk of underfeeding dietary protein?

Animals are deficient and it takes more animals to meet demand for the product they are producing, which is still producing more ammonia emissions.