Carbohydrate and Protein Requirements for Lactation and Metabolic Diseases Flashcards
What has the most influence on milk composition?
Nutrient requirement of the offspring
Discuss kanagroo lactation
They are unique in nursing two joeys at once and will make different milk compositions for newborn vs. older joeys
i.e. milk is matched to individual requirements
Discuss lactation in the Northern Elephant Seal
These seals do not eat during lactation
The dam loses 42% of their body weight during lactation, roughly equivalent to 58% body fat and 14% lean tissue
The mother tries to rapidly transfer body fat to her young
The mother does not make much lactose because it requires different body reserves
Describe net nutrient requirements for lactation
Net nutrient requirements for lactation = milk yield x milk nutrient concentration
How does milk composition vary?
It varies greatly by species
How are carbs classified?
Carbs are classified by the number of sugars in them
monosaccharides are simple sugars like glucose and fructose
disaccharides are two simple sugars bound together such as sucrose or lactose
trisaccharides are three simple sugars; cannot be broke down by most animals due to lack of proper enzymes
Polysaccharides have more than three simple sugars; ex. starch, cellulose, chitin
What is needed for lactose synthesis in the cow?
A large amount of glucose because lactose, a disaccharide, is composed of glucose and galactose
Ruminants don’t absorb much glucose because of their rumen microbe populations, but they still need it to make lactose
Cows also need a considerable amount of essential amino acids
How does metabolism in different tissue adapt to support lactation?
There is a dramatic increase in nutrient requirements during early lactation that is met by …
- rapid mobilization of endogenous reserves, especially fat (also calcium, some protein)
- slower increase in maximum voluntary feed intake in many animals
Discuss lipid catabolism
Lipid stores make up for deficits in dietary energy supply
Caused by low feed intake or too high demand
Net release of nonesterified fatty acids (NEFA; not bound to glycerol) from adipose tissue represents balance between rates of lipid synthesis and breakdown (lipolysis)
Discuss the three major processes of lipolysis
- Lipolysis of adipose tissue triglycerides to glycerol and NEFA
- transport of NEFA to other tissues
- fatty acid uptake and oxidation by these tissues
Discuss the movement of NEFA
NEFA released from adipose tissue are transported in blood bound with plasma albumin
Plasma NEFA is directly related to rate of fatty acid mobilization and can vary from <100 to >1500 mol/L
Turnover is very rapid and concentrations reflect the extent to which body fat is being mobilized
Discuss tissue utilization of NEFA
Most tissues can take up and oxidize NEFA for energy (exceptions: brain, red blood cells, testes)
Uptake increases as plasma concentration increases
Complete oxidation of long-chain fatty acids to CO2 and H2O occurs in the mitochondria by a two stage process called beta-oxidation
Discuss beta-oxidation
fatty acids are transported into the mitochondria for oxidation
fatty acids are activated to fatty acycl-CoA
The two carbon acetyl-CoA is formed in each round of the cycle
Complete oxidation occurs after acetyl-CoA enters the TCA cycle
Describe ketone synthesis
Ketone synthesis occurs in the liver when TCA does not run
Ketone synthesis uses acetyl-CoA that is exported from the liver; it is originally converted to acetoacetate
The acetoacetate is then broken down to 2CoA, acetone, and 3-hydroxybutyrate (aka a ketone body)
How does acetone cause sweet smelling breath?
After the breakdown of the intermediate acetoacetate, acetone is one of the products formed
It enters the bloodstream and travels to the lungs, where it evaporates and makes the breath smell sweet
How is excess NEFA stored?
As triglycerides (TAG) in the liver
How does fatty liver occur?
accumulation of triglycerides in the liver, which can lead to liver failure
Discuss ketone levels and their detection
ketones rise first in blood, then in urine and milk
How can ketone and glucose levels be quickly measured?
Milk or urine samples can be ran with strips that provide qualitative levels
Describe the causes and contributing factors of metabolic diseases.
A. Failure to adapt to a new physiological state
ex. start of lactation
B. Very low intake
ex. hungerstrike
C. Hormone deficiency/imbalance
ex. Diabetes mellitus (type 2)
D. Obesity
ex. feline hepatic lipidosis
Describe the primary problem of a metabolic disease
Symptoms are directly related to primary disfunction.
ex. type 1 diabetes causes inadequate pancreatic secretion of insulin
Describe the secondary problem of a metabolic disease
Symptoms are indirectly related to the primary dysfunction.
ex. secondary ketosis in dairy cows caused by decreased intake due to milk fever, mastitis, etc.
Secondary issues are harder to diagnose of provide a treatment for because you must treat both the primary AND the secondary issue
Describe lactation ketosis
Animal cannot keep up to demand for lactation
Normally occurs in early lactation before intake increases
(failure to keep up with a metabolic demand)
Describe pregnancy toxemia (sheep)
The sheep cannot keep up with demands for fetal growth in ewes carrying twins or triplets; lower incidence in beef cows
Low blood glucose, high ketones, and metabolic acidosis
Decrease in intake and milk yield
Increased weight loss
Increased excitability (sometimes) or apathy (more often)
Recumbency, death if not treated
Describe feline hepatic lipidosis
More common in older, obese cats
Incidence in greater in females than in males
Usually caused by prolonged anorexia, initiated by acute stress
Symptoms:
- anorexia (> or equal to 7 days)
- depression
- juandice
- weight loss
- muscle wasting
- fatty liver (requires a biopsy)
Describe the series of events that leads to feline hepatic lipidosis
NEFA is mobilized from the adipose tissue, and there is an excess uptake of NEFA by the liver.
There is a limited ability of the liver to oxidize or export fatty acids as TAG in VLDL, which leads to fat accumulation.
How can feline hepatic lipidosis be treated?
- restore energy intake
- tube feeding
- slowly reduce weight of obese cats
- minimize stress
