ANSC 301 exam 3 review

Will animals that are not fed well reproduce optimally or at all?

No they will not optimally reproduce, some animals require a stockpile in order to reproduce/ need a basic level of leptin which regulate sex hormones

What is required before an animal will become fertile? What predicts age at puberty?

An animal needs to meet certain levels f growth before it can become fertile (faster growth = faster purity) body weight and adipose amount can determines leptin quantity which determines puberty

What hormone signals energy status that allows reproductive cycles to start? What
hormones does it change in the brain? How does this control population size in wild
rodents?

Leptin, GnRH which releases FSH and LH

food supply limits reproductive rate thus population size

Why would there generally be a negative relationship between fertility and milk
production in dairy cows?

negative energy balance and weight loss in early lactation

Body fat loss decreases leptin signaling, leading to delayed estrous cycles and lower fertility

Increasing fatness before calving can worsen these effects by causing more body fat loss earlier in lactation 

What maternal tissues contribute to the requirement for pregnancy?

Nutrients are required by uterus, placentaGes and fetus

What two factors are important to know to determine the impact of a pregnancy on the
mother/dam?

Gestational length and fetal % of dam BW

What period of gestation are nutrient requirements the highest? Why?

last trimester because most growth occurs here

Is under or over-feeding an issue in early pregnancy?

yes this results in (barker hypothesis) and thrifty phenotype

Why do we not want to over feed during late gestation?

Over-feeding during late gestation can cause complications for both mother and fetus.

If an animal is underfed during late gestation who gets higher priority for the nutrients- mom or fetus

Fetus

What is fetal programming and the “Barker Hypothesis”? What is the biological
explanation?

inadequate nutrition is a significant contributor to adult disease later in life. explained by epigenetics

What is unique about the kangaroo?

it has 2 teats which can produce different milk fat levels for different joeys

What is unique about the Northern Elephant Seal? How does their milk composition
differ from a cow?

Northern elephant seal does not eat during lactation. Their milk fat composition is significantly higher

To determine amount of a nutrient required for milk synthesis (say Ca) we need to know
milk yield and ?

Milk nutrient conc.

Does milk composition match growth rate and requirement of the offspring? What are
some examples?

—-

How do we classify sugars?

Mono- 

Diacc-

Tris- (need microbes to break down)

Polysaccharides

What happens to glucose requirement during lactation? Where does the cow get this glucose?

Cows glucose requirement is much higher during lactation. gluconeogenesis

What is the link between milk protein and milk lactose? Do all animals have the same
amount of casein (the protein that makes cheese)?

Both lactose (sugar) and casein (protein) are standard components of all mammalian milks, but they are chemically, nutritionally, and physiologically different.​

The amount and kind of casein varies significantly between cows, humans, goats, sheep, and other animals, affecting cheese-making properties and nutritional aspects

What happens to energy requirements during lactation? Where does the energy come from?

There is a dramatic increase in nutrient requirements. The energy comes from mobilization of endogenous reserves, especially fat

When we release fatty acids from adipose tissue how are they transported in blood?
Are they quickly or slowly used?

NEFA is transported into the blood via Lipolysis of adipose tissue triglyceride TG to Glycerol and NEFA

Transport of NEFA to other tissues

Fatty acid uptake an oxidation by these tissues 

NEFA is rapidly used 

Where and how do we complete oxidize fatty acids? What cells are not able to do this?

mitochondria oxidizes a long chain fatty acid by a 2 stage process called beta-oxidation  

What are the key steps of beta-oxidation?

Fatty acids are transported into the mitochondria for oxidation 

Fatty acid are activated to fatty acyl-CoA

The two carbon- Acetyl CoA is formed in each round of the cycle

When are we not able to completely oxidize acetyl-coA coming from beta-oxidation?
What do we do with the acetyl-CoA? What tissue does this occur in?

When the TCA cycle does not run due to low OAA the liver uses the Actyl-CoA to do ketone synthesis

When an animal has high ketones, what can we smell on their breath?

fruity smell

If the liver is taking up more fatty acids than it can export as vLDL, oxidize completely, or
make ketones our of, what does it do with them?

Stored them as triglycerides within the liver leading to hepatic lipidosis

What can ketones be used for by other tissues in the body?

The heart brain and muscle can use them to make acetyl CoA but too many can become a problem

Where can we look for ketones to determine if an animal is ketotic.

Blood then urine then milk

What are four things that can contribute to metabolic diseases?

1. Failure to adapt to new physiological state

2. Very low intake

3. Hormone deficiency/imbalance

4. Obesity

What is a primary metabolic disease? A secondary metabolic disease? Do we have to treat the secondary? What happens if we only treat the secondary?

Primary disease is something like diabetes

Secondary is symptoms directly related to dysfunction like ketosis which reduced intake due to milk fever

To treat the secondary we must address the primary 

 

What causes lactation ketosis, pregnancy toxemia?

Cant eat enough to keep up to demand for lactation

Cant keep up with the demand for fetal growth in ewes carrying twins or triplets

What happens in Feline Hepatic Lipidosis? What increases the risk? What is the short
and long-term treatment?

NEFA is mobilized from adipose tissue and uptake excessively in liver limiting livers ability to export TAG or VLDL

Older obese cats are at risk 

Short term is tube feeding 

long term is weight loss

What is a common description of lipids

Lipids function in a cell as structure, signaling, and storage

Which lipids have the highest energy density? Which have very little nutritional value?

Triglycerides are most energy dense

Cholesterol / steroids provide very little nutritional value

Which lipid do we make to store energy?

Triglycerides

Which lipid do mostly find in forages? Are they as energy dense as triglycerides?

Glycolipids, and they are less energy dense than triglycerides (2 fatty acid chains rather than 3)

What do we use phospholipids for in cells? Are they as energy dense as triglycerides?

Typically used as a structural aspect in membranes

They are less energy dense than Triglycerides

What are some examples of steroid derived compounds?

Cholesterol, Vitamin D, Steroid hormones

How can fatty acids be different from each other? Are these important to their
metabolism?

Structure is very important to their metabolism

differences include # of carbons, # of double bonds, Location of bonds and cis vs trans bonds

Where do we find trans fatty acids? Are they all bad?

Trans fatty acids re commonly found in industrial processed oils and ruminant fat and are considered very bad if produced industrially 

What is palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid? Are arachidonic
acid, EPA, and DHA omega-3 or omega-6 FA?

16:0

18:0

18:1 cis-9 

18:2 n-6

What oil is high in palmitic acid? High in oleic acid? High in omega-6 FA? Highest in omega- 3 FA? What common oil is considered more “balanced” because of more omega 3 and less
omega-6?

Palm oil 

olive oil 

Corn and soybean oil

Flax oil 

Canola oil 

Forages and corn and soybean are generally high in omega-3 or omega-6? Tallow (and also lard) are higher or lower in saturated, mon-unsaturated, and polyunsaturated fatty acids
compared to normal plant oils?

Corn soybean  omega 6

Forges omega 3

tallow saturated 

Has genetic selection been successful in changing fatty acid profile of oilseeds?

Yes a good example is canola oil

What does saponification number, iodine number, and fatty acid profile tell of about an oil?

Saponification number- average chain length of FA

Iodine number- measure of unsaturated fat (double bonds)

Fatty acid profile- actual conc of fatty acid in the oil

What is produced after hydrolytic rancidity? What problems does it cause?

triglycerides are broken down into free fatty acids and may lead to odors

What is produced during oxidative rancidity? What problems does it cause?

free radicals are formed

free radicals can be potentially dangerous

How do we prevent oxidative rancidity?

Antioxidants like BTH

Where are VFA absorbed? Where are long-chain fatty acids absorbed?

short chain are absorbed in rumen, omasum and hindgut

long chain are absorbed in jejunum

How does lipase assist in triglyceride digestion?

lipase breaks down triglycerides into monoglycerides 

What do bile salts do to assist in lipid digestion and absorption?

they emulsify fats into micelles

What molecules are absorbed from triglycerides?

free fatty acids 

monoglycerides

Cows don’t have monoglycerides, how do they form micelles?

they use lysolecithin

What do we need to synthesize bile? What happens to bile salts? What do we do to bile
salts to decrease plasma cholesterol?

cholesterol

most bile salts are reabsorbed so we prevent the reuptake of them to reduce cholesterol

Fatty acids are packaged into ________ in the intestine? How do they enter the circulation?

chylomicrons they enter circulation through lymph vessels

What are some key components and aspects of a lipoprotein that allows it carry fatty acids in the blood?

phospholipids, apolipoproteins

VLDL come from _________ and carries __________ to the peripheral tissues.

Liver, triglycerides

HDL comes from _________ and carries _________ back to the liver. 

Liver and Intestines, cholesterol

VLDL break down to ________. This is considered good or bad cholesterol?

LDL (bad)

Triglycerides in lipoproteins are broken down to what by what enzyme?

LPL (lipoprotein lipase)

How are triglycerides transported into an egg yolk? Is LPL involved?

VLDLy, LPL is sorta involved

What is the energy density of lipids compared to carbohydrates and proteins?

2.25

What are some uses of fatty acids in the body?

energy

Triglycerides

Phospholipids

Essential fatty acids 

Carrier of fat-soluble vitamins

What are the two “essential” fatty acids? What do we mean by a conditionally essential FA and which ones are they?

Linoleic (C18:2) and Linolenic (C18:3)

Arachidoic acid can be synthesized from C18:2

EPA and DHA can be synthesized from C18:3

What are made from the essential fatty acids?

Eicosanoids

What is a symptom of essential fatty acid deficiency? Is it commonly observed?

skin lesions, reproductive failure, edema, subcutaneous hemorrhage

Is synthesis of the “very long-chain” omega-3 fatty acids from C18:3 efficient? Do we find
EPA in plants?

No very inefficient not in plants 

What do we make the eicosanoids from? What is the different between eicosanoids made from omega-3 and omega-6 fatty acids? How does this explain omega-6 to omega-3 ratio?

They are made from Arachidonic acid or EPA

Omega 3 are more anti-inflammatory

Omega 6 are more pro-inflammatory

Which FA are essential to brain development? Reduce inflammation?

EPA (omega-3)

Are industrially produced trans fatty acids good or bad for humans? Ruminant trans FA?

Yes ruminant trans FA are considered good

How do absorbed fatty acids differ from the diet in the ruminant?

Fatty acids absorbed do not absorb directly

What happens to triglycerides in the rumen?

Fatty acids are hydrolyzed to release free fatty acids by bacteria in rumen

What happens to double bonds in fatty acids in the rumen?

Biohydrogenation convers cis to trans before removing the double bond

What happens when the microbial population changes and the “alternate” pathways of biohydrogenation is used? What is the mechanism (how does this occur)?

• Microbial community changes alter which bacteria dominate biohydrogenation.

• Different bacteria have different pathways, leading to “alternate” trans-10 intermediates instead of typical trans-11.

• This shift occurs due to dietary/environmental pressures favoring bacteria with alternate enzymatic activity.

• Mechanism is driven by changes in enzymatic isomerization and hydrogenation steps encoded by microbial populations.

What three things do we use glucose for when we synthesize fatty acids from scratch?

Glucose carbon→ fatty acid carbon

(de novo fatty acid synthesis)

Glucose metabolism → reducing equivalents for de novo fatty acid synthesis 

Glucose→ glycerol 3-P for fatty acid esterification→ triglyceride 

What does insulin do to lipogenesis?

it increases it

During de novo fatty acid synthesis we make fatty acids up to __ carbons long. What can
then happen to these fatty acids?

16 After synthesis, these 16-carbon fatty acids can undergo several modifications:

• They may be elongated to longer chains (more than 16 carbons) by elongase enzymes, often in the endoplasmic reticulum.

• They can be desaturated by desaturase enzymes to introduce double bonds, creating unsaturated fatty acids.

• These modified fatty acids can then be incorporated into complex lipids such as triglycerides, phospholipids, or cholesterol esters for storage or membrane synthesis.

• They also serve as precursors for bioactive lipid molecules and signaling compounds.

Can we synthesize omega-3 fatty acids?

No

What is the carbon source for fatty acids in ruminants? Non-ruminants?

Ruminant- acetate and ketones

Nonruminant- glucose

Both ruminants and non-ruminants get around half of their NADPH from? What is the implication for glucose requirement for the cow?

Pentose Phosphate Cycle 

In cows, the glucose requirement is high because glucose supplies substrates for NADPH generation needed for biosynthesis.

Ruminants get the rest of the NADPH from? Normal non-ruminants get them from?

isocitrate and malate pathway

When non-ruminants bring NADPH out of the mitochondria they also bring out ___ that is used in fatty acid synthesis?

citrate

Are horses and other non-ruminant herbivores (for example the horse) are more like ruminants or traditional ruminants

What is the glucose source for ruminant and non ruminant

Non-ruminant- Glucose, MTC+PP

Ruminant- Acetate, PP+ IC

After a high fat meal we would expect what to be high in the plasma?

chylomicrons

Would lipid synthesis be high or low after a high carbohydrate meal?

high

What form of lipids are high in blood during fasting?

Chylomicrons

What are some advantages of storing lipids as fat?

high energy value 2.25 

not associated with water

Efficient synthesis

If a cow made fat from acetate while she was not lactating, stored the fat, and then
mobilized that fat for use during lactation would the energy loss be high or low?

Low

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

Uncoupling protein 1 allows H to flow back into the matrix without making ATP and heat instead

Where will a newborn animal get its blood glucose?

Lactose

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

very high milk protein is rich in EAA( high biological value)

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

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

Nitrogen

True protein has amino acids and chains of AA

Non protein is ammonia or urea

Does the concentration of proteins change much over development?

no they are rather consistent

What is the largest protein depot in the body?

Body fluids 37%

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

Proteins need continuous replacement

Turn over rates vary with biological role

Turned over AA are recycles up to 75-80%

How do we make proteins?

Expression of mRNA for the protein and then synthesis of the protein on a ribosome

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

gut

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

increase synthesis

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

L and D isomers (L is natural)