Final - Nutrition Flashcards
(179 cards)
1
Q
What monosaccharide do all three disaccharides have in common?
A
glucose
2
Q
_____ is the storage form of carbohydrates in animals, while _______ is the storage form in plants
A
glycogen; starch
3
Q
_______ link sugars together
A
glycosidic bonds
4
Q
In a “D” carbohydrate isomer, the functional group is oriented to the ______, while it is oriented to the ______ in the “L” isomer
A
right; left
5
Q
List the enzymes involved with carbohydrate digestion in autoenzymatic digesters vs. alloenzymatic digesters
A
Autoenzymatic: salivary and pancreatic amylase
alloenzymatic: ingested carbohydrates metabolized by microbes as energy sources; due to anaerobic conditions, sugars cannot be completely oxidized; lack carbohydrate digestive enzymes; amylolytic bacteria degrade starch, cellulolytic bacteria degrade cellulose (with assistance of fungi)
6
Q
What are the end products of carbohydrate digestion in autoenzymatic digesters vs. alloenzymatic digesters?
A
Autoenzymatic: monosaccharides
Alloenzymatic: microbial cell mass, gasses (methane and CO2), heat, VFAs (main)
7
Q
Name the three VFAs
A
propionic acid, acetic acid, butyric acid
8
Q
Where does glycolysis occur?
A
In the cytoplasm of pretty much every cell
9
Q
What are the products of glycolysis?
A
2 pyruvate, 2 ATP, 2 NADH
10
Q
How many ATPs are formed in glycolysis?
A
4 formed, net gain of 2
11
Q
What are the functions of glycolysis?
A
energy production
12
Q
Where does the krebs cycle take place?
A
mitochondrial matrix in eukaryotes, cytoplasm in prokaryotes
12
Q
What is the purpose of the krebs cycle?
A
producing energy for our cells
13
Q
How many ATP does the krebs cycle produce?
A
the krebs (or tca cycle) produces 1 GTP/ATP
also produces 3 NADH, 1 FADH2, 2 CO2
14
Q
Does Krebs cycle require oxygen?
A
yes, the krebs cycle is aerobic, as energy-rich molecules like NAD+ and FAD can only be retrieved from their reduced form once they transfer electrons to molecular oxygen
15
Q
What is the difference between endopeptidases and exopeptidases?
A
endopeptidases: hydrolyze peptide bonds within primary structure (break protein into smaller fragments → polypeptides)
exopeptidases: cleave AA off terminal end of molecule
16
Q
What is the difference between aminopeptidases and carboxypeptidases?
A
carboxypeptidases: remove AA from carboxyl group end
aminopeptidases: act on terminal AA with free amino group
17
Q
In what part of the gastrointestinal tract do pepsin and rennin function?
A
stomach
18
Q
What common crop plant contains trypsin inhibitors?
A
raw soybeans (and other legume seeds and nuts)
19
Q
Two amino acids are strictly ketogenic. Which two?
A
leucine and lysine
20
Q
____ is the mechanism of direct removal of an amino group
A
deamination
21
Q
How many reactions occur in the urea cycle?
A
pathway involves 5 reactions; 2 in the mitochondria, 3 in the cytoplasm
22
Q
List the possible fates of the carbon skeletons remaining after protein degradation
A
don’t just “hang around,” are utilized by the body:
1. gluconeogenesis
2. ketogenesis
3. oxidation
23
Q
What happens to urea in the ruminant?
A
ammonia is converted to urea in ruminants, and the urea is then excreted in urine
24
Name the linkage between two amino acids in a protein.
peptide bond - amide linkages between the ɑ-carboxyl group of one amino acid and the ɑ-amino group of another
25
Differentiate between essential and nonessential amino acids. What are the essential amino acids? Why are they essential?
essential - must be obtained from diet because they cannot be synthesized by the body (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, theonine, tryptophan, valine)
nonessential - can be synthesized by body
26
Compared to carbohydrates, why are proteins unique?
proteins contain nitrogen, carbohydrates do not
carbohydrates have identical repeating units, while proteins are made up of amino acids that are different from one another
27
Which amino acid is essential to chickens but not humans? How about to cats?
chickens: glycine
cats: taurine
28
Name one amino acid from the following groups: acidic, basic, aromatic, and sulfur-containing.
acidic (negative R): aspartic acid and glutamic acid
basic (positive R): lysine, arginine, histidine
aromatic (aromatic ring in R): phenylalanine, tyrosine, tryptophan
sulfur-containing: methionine and cysteine
29
Give an example of a globular, fibrous, and conjugated protein.
globular: albumin and globulin
fibrous: collagen, keratin, elastin, and fibrin
conjugated: lipoproteins, hemoproteins, glycoproteins, nucleoproteins
30
List the enzymes involved in protein digestion in the stomach and in the small intestine.
stomach: pepsinogen, activated to pepsin by HCL
small intestine: trypsinogen, chymotrypsinogen, proelastase
31
What animals can utilize nonprotein nitrogen (NPN) and why?
ruminants can utilize nonprotein nitrogen because the microbes in the rumen are able to convert nonprotein nitrogen to ammonia, which can be used to synthesize microbial proteins
digestion of microbes make synthesized protein available to the host
32
In monogastric animals, where does protein digestion begin?
begins in the stomach with pepsinogen secretion, HCL activates pepsinogen to pepsin
33
What is the major digestive enzyme secreted by the stomach?
pepsinogen/pepsin
34
Proteins that are not extensively degraded in the rumen are also called what?
rumen undegradable protein (RUP)
(may be referred to as “escaped” or “bypass” protein)
35
What happens to amino acids in the rumen?
proteins and other nitrogenous compounds are degraded (fermented) in the rumen by miroorganisms
rumen bacteria produce proteases and peptidases that digest proteins, these enzymes are normally elaborated on to feed particles after the bacteria have attached to them, rather than being secreted into the rumen fluid
36
What are the functions of ornithine and citrulline?
ornithine is a crucial intermediate in the urea cycle, where it acts as a carrier of nitrogen, facilitating the conversion of toxic ammonia into urea, a less toxic waste product that can be excreted by the kidneys
citrulline is a key intermediate formed from ornithine and carbamoyl phosphate, playing a crucial role in the body's detoxification process by facilitating the removal of ammonia in the form of urea
37
In what form is nitrogen excreted in (a) swine and (b) chickens?
swine: urea
chickens: uric acid
38
In the urea cycle, what does carbamoyl phosphate condense with? What does it to form?
carbamoyl phosphate condenses with ornithine to form citrulline, a process catalyzed by the enzyme ornithine transcarbamoylase
39
Proteins can be used for what other metabolic processes?
Proteins are crucial for numerous metabolic processes, including acting as structural components, enzymes, hormones, and building blocks, as well as playing a role in energy production, nutrient transport, and immune function
40
Differentiate between deamination and transamination.
deamination - direct removal of amino group from amino acids; two methods: oxidative (removal of amino and addition of oxygen) and non-oxidative (removal of amino through hydrolysis or reduction)
transamination - amino group from AA is transferred to a keto acid; provides a link between protein and carbohydrate metabolism → certain amino acids can use their C skeleton for glucose or ketose synthesis
41
What is protein quality? List the factors that affect protein quality.
how well a protein matches animal requirements (how well amino acid composition matches amino acid requirements)
factors affecting quality:
1. amino acid profile
2. content and balance of essential and nonessential amino acids
3. content of limiting amino acids
4. protein digestibility and bioavailability
42
What is a limiting amino acid? What are the two most common limiting amino acids in animal diets? Why?
essential amino acids that interrupt protein synthesis due to the limited amount of them and great demand for them
two most common are lysine (#1) and methionine (#2) in US corn/soy-based diets because these diets are relatively low in those amino acids
43
Differentiate between digestibility and bioavailability.
digestibility - efficiency w/ which body can break down feed and absorb nutrients
bioavailability - extent and rate at which a nutrient is absorbed and utilized by the body after it has been digested
44
List two in vivo tests for protein quality.
protein efficiency ratio (PER) and net protein utilization (NPU)
45
Which bioassay method would you use to assess protein quality? Why?
net protein utilization, as it takes digestibility into account
46
What is an amino acid score?
amino acid score = (mg of amino acid per g of test protein)/(mg of amino acid per g of reference protein)
laboratory analysis of AA profiles using high-pressure liquid chromatography
results compared to a reference, usually egg protein (albumen)
quick and easy method to conduct; does not consider digestibility or palatability
47
In what important ways do starch and cellulose differ?
starch is much easier to digest than structural carbohydrates (cellulose)
specific population of microbes that work on carbohydrates (amylolytic as opposed to cellulolytic)
cellulose fermentation produces more methane than starch fermentation
48
What are the disaccharides of nutritional significance?
maltose, sucrose, and lactose
49
Nutritionally important sugars are of the D-form or the L-form?
nutritionally important sugars, or monosaccharides, are predominantly of the D-form
most naturally occurring monosaccharides are D-stereoisomers, and metabolic and digestive enzymes are specifically designed to work with them
50
What is considered the most important sugar in nutrition?
glucose
51
Identify the two forms in which starch exist. Which form of starch is found in the animal body and which is found in plants?
starch exists as amylose (straight chain) and amylopectin (branched chain)
carbohydrates are stored as starch in plants, and as glycogen in animals
52
What are the three principal fates of glucose after absorption?
1. storage as glycogen
2. oxidation for energy
3. fatty synthesis and storage
53
How much ATP is generated during the complete oxidation of glucose under aerobic conditions?
38 ATP molecules
54
What is the readily available form of energy for cells?
ATP
55
The site of glycolysis and the tricarboxylic acid (TCA) cycle in the cell is ______ and ______.
glycolysis occurs in the cytoplasm
TCA cycle occurs in the mitochondria
56
_____________________ links glycolysis with the TCA cycle.
oxidation, pyruvate produced by glycolysis is oxidized to acetyl coA in the mitochondria, and the acetyl coA then enters the TCA cycle
57
The end-product of glycolysis under aerobic conditions is _____.
pyruvate
58
Acetyl CoA enters the TCA cycle and condenses with this 4-Carbon compound to form citrate _____.
acetyl coA and oxaloacetate combine to form citric acid via citrate synthase
59
Define bioenergetics. Why is it important to animal nutrition?
energy metabolism, it is important because it provides animals the energy vital to all function
60
What is a calorie?
measure of the chemical energy (potential energy) of food
amount of heat required to increase the temperature of one gram of water by one degree Celsius
61
How are the total calories of a feed determined?
bomb calorimeter
one calorie = 4.183 Joules
62
Explain energy balance. What is positive energy balance vs negative energy balance?
energy maintenance - energy required to maintain constant body weight
goal: metabolize energy intake = energy expenditure
positive energy balance = weight gain
negative energy balance = weight loss
63
Draw the energy diagram from gross energy to net energy
Gross energy (total amount of energy consumed) - fecal energy = digestible energy
digestible energy - urinary energy - gaseous energy = metabolizable energy
metabolizable energy - heat increment = net energy
64
What is digestible energy?
amount of energy that is digested and potentially available for utilization
digestible energy = gross energy (GE) - fecal energy (FE)
65
What is metabolizable energy (ME)?
energy used for metabolism
metabolizable energy = digestible energy (DE) - urinary energy (UE) - gaseous energy
66
What is heat increment (HI)?
heat increment = heat loss of eating animal - heat loss of fasting animal
67
How do you define net energy (NE)?
represents the fraction of the total energy consumed that is utilized for production purposes
NE = metabolizable energy (ME) - heat increment (HI)
68
Obesity
associated with excess energy intake
commonly seen in companion animals and horses
69
Fatty liver disease
energy demands exceed intake
fat stores are mobilized
excessive NEFA accumulation in liver
most often seen in high producing dairy cows
70
Ketosis
body mobilizes large amounts of fat for energy
due to a lack of available glucose
results in buildup of ketone bodies in the blood
most often seen in high producing dairy cows
71
Pregnancy toxemia (aka pregnancy disease, lambing sickness, and twin-lamb/kid disease)
caused by low blood sugar (glucose)
onset often triggered by stress - nutritional, inclement weather
most prevalent in ewes/does carrying multiples and over- or under-weight ewes/does
72
Equine metabolic syndrome
disorder associated with insulin dysregulation
characterized by regional fat deposition and reduced ability to lose weight
commonly seen in ponies, donkeys, Arabians, and mustangs
increases the risk for laminitis
treated through diet and exercise management
73
What are vitamins? How would you describe them?
“vital amines”
organic molecules; DO NOT provide energy
needed in minute amounts
classified based on solubility in water
74
List the general functions of vitamins.
1. metabolism
2. growth and development
3. immune function
4. nerve function
5. blood clotting
6. bone health
7. vision
8. skin health
9. antioxidants
75
Identify the two classes of vitamins and which vitamins are in each class.
fat soluble - A, D, E, K
water Soluble - B complex and C
76
What are the general functions, bioactive form and toxicity symptoms of vitamin A?
includes several related compounds:
1. retinol (alcohol) - biologically active form
2. retinal (aldehyde)
3. retinoic acid
required in animal diets
functions: vision, bone growth, reproduction, epithelial cell maintenance
toxicity:
1. long-term overconsumption may lead to toxicity
2. common symptoms include skeletal abnormalities and thickening of skin
3. other symptoms may vary by species, age, physiological condition
77
What do carotenoids do?
provide pigmentation to plants
two forms:
1. carotenes (Vitamin A precursor)
2. xanthophylls
78
What are the general functions, bioactive form and deficiency symptoms of vitamin D?
group of sterol compounds that regulate calcium and phosphorus metabolism
formed by the irradiation of sterols in plants or in the skin
two major forms of vitamin D are:
1. ergocalciferol (D2; activated plant form)
2. cholecalciferol (D3; activated animal form)
functions:
1. steroid hormone
2. blood Ca regulation
deficiency - impaired bone mineralization, abnormal skeletal development, rickets (young animals), osteomalacia (growing animals)
79
What are the general functions, bioactive form and deficiency symptoms of vitamin E?
group of chemically related compounds called tocopherols and tocotrienols
α-tocopherol is the most active biological form
functions:
1. free radical scavenger
2. antioxidant function
3. affects immune response
deficiency - white muscle disease, crazy chick disease
80
What are the general functions and bioactive form of vitamin K?
group of compounds called the quinones:
1. K1 (phylloquinones): found in plants
2. K2 (menaquinones): metabolically active form; synthesized by hindgut bacteria or converted from K1 or K3 in liver
3. K3 (menadione): synthetic form
required for the synthesis of prothrombin, a blood-clotting protein
81
What are the general functions, bioactive form and deficiency symptoms of thiamine (B1)?
one molecule of pyrimidine and one of thiazole
functions as a component of thiamine pyrophosphate (TPP):
1. pyruvate dehydrogenase
2. a-ketoglutarate dehydrogenase
deficiency can lead to stargazing
82
What are the general functions and deficiency symptoms of riboflavin (B2)?
functions as a component of two coenzymes:
1. flavin mononucleotide (FMN)
2. flavin adenine dinucleotide (FAD)
deficiency can lead to curled toe paralysis
83
What are the general functions and deficiency symptoms of niacin (B3)?
functions as a constituent of NAD and NADPH
can be synthesized from tryptophan in most animals (except cats)
deficiency can lead to black tongue disease (dogs) and spectacled eyes (chickens)
84
What are the general functions of pantothenic acid (B5)?
functions: energy production, metabolism, growth and development, immune function, wound healing
85
What are the general functions and bioactive form of pyroxidine (B6)?
three forms:
1. pyridoxine (plant)
2. pyridoxal (animal) - biologically active form
3. pyridoxamine (animal)
functions:
1. amino acid metabolism reactions
2. synthesis hemoglobin
3. conversion of tryptophan to niacin
86
What are the general functions and deficiency symptoms of biotin (B7)?
functions:
1. crucial for various metabolic processes
2. aids in maintaining healthy skin, hair, and nails
deficiency unlikely in normal dietary conditions
87
What are the general functions and deficiency symptoms of folic acid (B9)?
essential for DNA synthesis, repair, and methylation in animals
deficiency may cause neural tube defects
88
What are the general functions of vitamin C?
essential for tissue growth and repair, immune system support, antioxidant protection
89
Water is one of the most important essential nutrients. Why?
cheapest and most abundant nutrient
essential for life
makes up:
½ to ⅔ of adult body
Up to 90% of newborn body
90
Describe the functions of water.
thermoregulation (high specific heat capacity and high heat of vaporization):
1. evaporative cooling (metabolic reactions give off lot of heat)
2. blood flow regulation
3. internal fluid balance (don’t have storage mechanism for water, so proper level needs to be maintained)
body metabolism: solvent (maintain cellular functions, enzyme activity, pH regulation, chemical reactions), transport medium, dilutant, hydrolysis and oxidation
91
What is metabolic water? How much is produced each day?
water created through metabolism
amount depends on feed nutrient being broken down
1. protein = 0.4 g water/g protein
2. carbohydrates = 0.6 g water/g carbohydrate
3. fat = 1.0 g water/g fat
may account for 5-10% of daily water needs
92
How is water lost from the body?
urine, feces, lungs (breathing), skin (sweating), milk (85-87% water)
93
Describe the factors that regulate water intake.
physiological - thirst, hormonal control, kidney function, osmoregulation
environmental (external cues) - temperature, humidity, water quality, water availability, feed DM
94
Water quality can affect cattle health. Identify & describe common contaminants that influence water quality.
sulfates - compounds containing SO4-; Limit = 500-1,000 ppm; Diarrhea, Polioencephalomalacia (PEM) - excessive sulfates can lead to thiamine deficiency, causes stargazing
nitrates - compounds containing NO3-; Limit = less than 100 ppm; Death without warning → binds to hemoglobin, so blood can’t be transported (animal suffocates from inside)
cyanobacteria - blue-green algae, gram-negative bacteria; blooms produce harmful toxins
95
List the average water requirements of livestock and pets.
varies based on species, size, age, activity level, diet, environmental conditions
livestock = 1 gallon/100 lbs body weight
dogs = 1 oz/lb body weight
cats = 5-10 oz/day
96
Describe ways that might cause water intake to be restricted and list some of the consequences associated with water restriction.
intentional:
1. limited availability (i.e. drought)
2. cleanliness (i.e. algal bloom)
3. surgery
4. competitions (weight classes)
unintentional:
1. failure of water supply
2. inappropriate design for species
3. competition (not enough headspace)
4. poor quality
5. extreme ambient temperature
6. inappropriately balanced diet
7. stray voltage - wiring problem causes water to be electrified, so the animals avoid the water because it is painful (could be deadly)
consequences of water restriction:
1. electrolyte imbalances
2. dehydration
3. frustration
4. stereotypies
97
What are minerals? How are they like vitamins and how are they different?
naturally occurring inorganic elements
essential for proper function
cannot be synthesized by body - must be obtained from diet
98
How are minerals classified?
major minerals vs. trace minerals
essential vs. nonessential
99
Compare the terms “essential” and “nonessential” regarding minerals vs. amino acids.
in amino acids, essential means they must be provided in the diet because the body cannot synthesize them. Non-essential amino acids are able to be synthesized, and therefore don't need to be provided in the diet.
in minerals, no minerals can be synthesized, so essential refers to minerals the body requires to be provided for life, while non-essential refers to minerals the body can live without for some time
100
List the major minerals. How can they be subcategorized?
structural components: calcium (Ca), phosphorus (P), magnesium (Mg), sulfur (S)
cell function and acid/base balance: sodium (Na), potassium (K), chlorine (Cl)
101
Describe the major functions and common toxicity or deficiency symptoms of calcium.
most abundant mineral in the body
functions: skeletal formation, blood clotting, rhythmic heart action, neuromuscular excitability, membrane permeability, enzyme activation
too much calcium can override phosphorus
calcium deficiency:
rickets, osteomalacia, osteoporosis, milk fever, hypocalcemia, egg shell deformities
102
describe the major functions and common toxicity or deficiency symptoms of phosphorus.
often considered with calcium
ideal Ca:P ratio = 1:1 or 2:1
functions: skeletal formation, regulation of blood Ca, formation of phospholipids, nucleic acids, coenzymes, and energy metabolism (ADP and ATP)
103
Describe the major functions and common toxicity or deficiency symptoms of magnesium.
required for normal bone mineralization
functions: skeletal formation, nerve and muscle function, enzyme cofactor, metabolism of ATP and ADP
magnesium deficiency:
hypomagnesemia (grass tetany) - causes muscle tetany (rigidity), fast growing grass is low in Mg, high in K (an Mg antagonist)
104
Describe the major functions and common toxicity or deficiency symptoms of sulfur.
functions: AA synthesis, vitamin synthesis, coenzyme formation, structural support, antioxidant activity and immune system support
105
Describe the major functions and common toxicity or deficiency symptoms of sodium.
functions: nerve impulse transmission, muscle function, nutrient absorption, pH regulation, blood volume and pressure
106
Describe the major functions and common toxicity or deficiency symptoms of potassium.
functions: electrolyte balance, nerve impulses and muscle contraction, cellular function, metabolism, heart function
107
Describe the major functions and common toxicity or deficiency symptoms of chlorine.
distributed throughout the body as chloride ions (Cl)
functions: fluid and electrolyte balance, nutrient absorption, muscle function
108
What are the differences between osteomalacia and rickets?
rickets - occurs in young animals, causes misshapen bones, enlargement of joints, lameness, stiffness
osteomalacia - occurs in adult animals, causes misshapen bones, enlargement of joints, lameness, stiffness
109
What minerals are associated with bone and teeth formation?
calcium, phosphorus, and magnesium
110
Calcium levels in the blood are tightly regulated by a complex series of events. Describe this process.
when we need more calcium, PTH release increases from the thyroid and parathyroid, telling the bones to release some calcium and the kidneys to increase calcium reabsorption and vitamin D (also increases calcium absorption in the small intestine)
if we have too much calcium, feedback mechanisms help shut it down, because too much calcium in the kidneys forms kidney stones
111
What minerals are considered electrolytes?
cations: sodium, potassium, calcium, magnesium
anions: chlorine, sulfur, phosphorus
112
Outline what happens in a dairy cow with low blood calcium during early lactation (hypocalcemia). How can the DCAD help prevent this?
milk fever - occurs shortly after calving, increased calcium demand for milk production, mobilization of calcium from body stores, lack of calcium reduces muscle contraction
DCAD = Dietary cation/anion difference (measure of difference between cations, Na and K, and anions, Cl and S, in diet)
dry period = negative DCAD (more anions than cations), helps speed up calcium mobilization to prevent milk fever
lactation = positive DCAD (more cations than anions), supports milk production and overall health
113
List the trace minerals.
zinc, copper, selenium, manganese, iodine, cobalt, iron, molybdenum
114
Describe the functions of copper and why copper intake is highly regulated in sheep.
red blood cell production, immune function, bone development, wool, skin, and hair pigmentation (melanin production)
sheep are vulnerable to toxicity: inefficient excretion, high affinity in hepatocytes (causes build-up)
tight regulation can lead to deficiencies: changes wool quality and pigmentation, swayback in lambs
115
Describe the functions of selenium. Why is white muscle disease a potential issue in livestock? How is it treated?
thyroid metabolism, immune function, and muscle function
deficiency may cause myodegeneration (white muscle disease): may also be caused by vitamin E deficiency, blood work needed to determine exact cause, usually treated with both
116
How would you define “nutrition”?
the integrated processes through which food is utilized to provide nutrients necessary for life
117
Why is nutrition important in today’s livestock production?
good animal nutrition promotes health and wellbeing, improves productivity and performance, saves money and resources, and supports sustainability
nutrients provide energy, give the body structure, regulate chemical processes
118
What are the six major classes of nutrients?
proteins, carbohydrates, lipids, vitamins, minerals, water
119
Who are some of the influential scientists in the field of Nutrition?
Antoine Lavoisier: metabolism & respiration; "father of nutrition"
François Magendie: importance of nitrogen in the diet
Jean-Baptiste Boussingault: animals cannot obtain nitrogen from atmosphere
Justus von Liebig: animals can convert starches to fat
Nathan Zuntz: formulated the “Fermentation Hypothesis” to explain forage utilization by ruminants
120
Describe the purpose of proximate analysis.
chemical analysis, determines composition of animal feed in terms of its nutrients
developed in the mid-19th century at the Weende Experiment Station in Germany by Henneberg & Stohmann
121
Dry matter proximate analysis
most common procedure:
1. dry feed material at 105oC overnight
2. calculate: (dry weight/fresh weight) x 100 = % DM
122
Compare and contrast the gastrointestinal tract of a pig to that of a cow and a chicken.
cow: alloenzymatic ruminant, four-chambered stomach
chicken: autoenzymatic, two compartment stomach (mechanical and chemical), crop, paired ceca, performs reverse peristalsis, less distinct and proportionally smaller small intestine
123
List the three sections of the small intestine.
duodenum, jejunum, ileum
124
The small intestine is the primary site of digestion of several nutrients. What are the special anatomical features of the small intestine helping in this process?
regulates gastic motility: presence of unabsorbed lipid in the small intestine influences gastric emptying; mediated through cholecystokinin (CCK)
absorptive surface area = 250 meters2
produces many digestive enzymes (amylase, protease, lipase)
124
List the sites of fermentation in foregut fermenting and hindgut fermenting animals.
foregut: rumen
hindgut: cecum
125
Identify and describe the sections of the ruminant digestive tract along with their functions.
1. mouth (mastication, enzymatic breakdown)
2. esophagus (peristalsis)
3. rumen (microbial anaerobic fermentation)
4. reticulum (particle separation and digestion)
5. omasum (omasal leaves function as a sieve, retaining material in the rumen until it has been degraded into small particle sizes)
6. abomasum (true gastric stomach; secretes pepsinogen and HCl)
7. small intestine (nutrient digestion and absorption)
8. large intestine (water absorption)
9. rectum
10. anus
126
What are the functions of lipids in animal diets?
source of energy
membrane structure
signaling molecules
insulation and organ protection
127
What is the difference between saturated, unsaturated, and polyunsaturated fatty acids?
saturated: single; unbranched linear CH2 groups linked together by carbon-carbon single bonds; 'saturated' indicates that the maximum number of hydrogen atoms are bonded to each carbon atom
unsaturated: one or more carbon-carbon double bonds are present; bent chain groups linked together by one or more carbon-carbon double bonds; may have 'cis' or 'trans' formation
monounsaturated = one double bond
polyunsaturated = multiple double bonds
128
What is the difference between omega-3 and omega-6 fatty acids? Give an example of each.
omega-3 fatty acids such as linolenic acid have their first double bond at carbon 3
omega-6 fatty acids such as linoleic acid have their first double bond at carbon 6
129
What is a conjugated fatty acid? Give an example.
polyunsaturated fatty acids that have double bonds positioned directly next to each other (C=C-C=C)
linolenic and linoleic acids
130
What is the difference between cis and trans fatty acids? Give an example of each.
cis = hydrogen atoms on the same side of the double bond (linoleic and linolenic acid))
trans = hydrogen atoms on opposite sides of the double bond
131
What are the essential fatty acids, and why are they essential?
not synthesized in vivo due to lack of delta-12 & delta-15 desaturase enzymes
MUST be obtained from diet
linolenic and linoleic acid
132
What is meant by biohydrogenation?
bacteria convert unsaturated fatty acids to saturated fatty acids
linoleic & linolenic acids are the primary substrates for biohydrogenation
two groups of bacteria: Group A & Group B
overall goal: alter double bond positions to make more stable compounds
stearic Acid (saturated)
133
How do micelles differ from chylomicron?
micelles:
1. disk-shaped cluster of amphipathic lipids
2. hydrophobic tails on the inside and hydrophilic heads on the outside
3. brush border membrane separated from intestinal lumen by unstirred water layer
4. hydrophilic surface of micelle facilitates transport of lipids through water layer to membrane for absorption
5. short- & medium-chain do not require micelle transport
chylomicrons:
1. transport lipids from enterocytes, travel through lymphatic system to circulation
2. largest size plasma lipoprotein
3. lowest density, as they are more full of fat and have less protein molecules in their shell
4. resynthesized TAG & CE packaged into chylomicron
5. released by exocytosis from enterocytes into lymphatic system
6. follow lymphatic system to thoracic duct; enter circulation (majority go to the liver)
134
High density lipoprotein (HDL)
smallest size plasma lipoprotein
greatest density, as it has a high amount of protein in its shell and less fat
heterogeneous family of lipoproteins
135
Why do most plant and animal fats have even-numbered fatty acids?
because fatty acids are made up primarily of two-carbon acetyl-coA molecules
136
What are the sites of fatty acid synthesis and oxidation in the cell?
fatty acid synthesis takes place in the cytosol of primarily mammary, liver and fat cells
oxidation takes place in the mitochondria of liver cells
137
What is the starting material for fat synthesis?
1. Citrate transported to cytoplasm via Citrate Shuttle
2. Citrate acted on by ATP citrate Lyase; Acetyl CoA produced
3. Acetyl CoA carboxylated to Malonyl-CoA by Acetyl CoA Carboxylase
4. Fatty Acid Synthase adds 2-C units until Palmitate is produced
138
In ruminants fed concentrate-rich diets, the major VFA produced in the rumen is? What about when forage-rich diets are fed?
concentrate-rich: propionate
forage-rich: acetic acid
139
What are the site(s) of glycolysis and the tricarboxylic acid (TCA) cycle in the cell?
glycolysis: occurs in the cytoplasm under both aerobic & anaerobic conditions
TCA: eukaryotes = mitochondria and prokaryotes = cytoplasm
140
Outline the major steps in glycolysis.
1. hexokinase turns glucose into glucose-6-phosphate (costs 1 ATP)
2. phosphoglucoisomerase turns glucose-6-phosphate into fructose-6-phosphate
3. phosphofructokinase 1 turns fructose-6-phosphate into fructose-1,6-bisphosphate (costs 1 ATP)
4. fructose bisphosphate aldolase turns fructose-1,6-bisphosphate into GADP and DHAP
5. triosephosphate isomerase turns DHAP into GADP
6. glyceradlehyde phosphate dehydrogenase turns GADP into 1,3-bisphosphoglycerate (costs 1 NAD+)
7. phosphoglycerate kinase turns 1,3-bisphosphoglycerate into 3-phosphoglycerate (produces 1 ATP)
8. phosphoglycerate mutase turns 3-phosphoglycerate into 2-phosphoglycerate
9. enolase turns 2-phosphoglycerate into phosphoenolpyruvate
10. pyruvate kinase turns phosphoenolpyruvate into pyruvate (produces 1 ATP)
140
Outline the major steps in the TCA cycle.
1. condensation of acetyl CoA with oxaloacetate
2. isomerization of citrate into isocitrate
3. oxidative decarboxylation of isocitrate
4. oxidative decarboxylation of α-ketoglutarate
5. conversion of succinyl-CoA into succinate
6. dehydration of succinate to fumarate
7. hydration of fumarate to malate
8. dehydrogenation of L-malate to oxaloacetate
141
Describe how glycolysis and the TCA cycle are linked.
the pyruvate produced in glycolysis can be oxidized into acetyl co-A, which is the first reactant in the TCA cycle
142
Explain how carbohydrate and lipid metabolism are linked.
interconversion of metabolites (lipid and carbohydrate metabolism):
1. acetyl coA
2. DHAP
3. glycerol 3-phosphate
143
Identify and describe the benefits of including feed additives in animal diets.
improve feed quality (better binding of pellets, longer shelf life), promote animal health (antibiotics, antimicrobials), enhance animal performance (hormones)
144
Explain what agency regulates the use of feed additives, the approval process and categories of drugs.
FDA approval, to gain approval:
1. establish drug is safe and effective for specific species
2. establish safe for humans and environment
3. establish chemical and manufacturing specifications
requires extensive research
subsequent approval:
1. monitors labeling and feeding
2. monitors safety of animal products
145
From a practical standpoint, additives are categorized into three groups, based on their general function or goal. Identify those groups and which additives would be included in each.
categorized based on what they are intended to improve
1. manufacture and/or properties of feed - antifungal agents (propionic acid), antioxidants (ethoxyquin, BHT, BHA, vitamin E/C, selenium), pellet binders (bentonites, molasses, lipids, wheat)
2. efficiency of animal production - flavoring agents, enzymes (phytases, carbohydrases), direct-fed microbials (probiotics, prebiotics, symbiotes), hormones (MGA), antibiotics (ionophores, coccidiostats, anthelmintics)
3. consumer acceptance - xanthophylls
146
Kjeldahl procedure
estimates crude protein (CP) content of a feed sample
determines nitrogen content of the sample
to convert the measured N content of the test material to crude protein, a calculation factor of 6.25 (N x 6.25) is applied
potenital problems:
1. assumes all nitrogen is from protein (also comes from free amino acids, nitrates, nitrites, and others not freely available to be broken down)
2. assumes all proteins are 16% nitrogen when they are not
147
Ether extract (EE) proximate analysis
represents the fat content of a feed sample
1. boil dried sample in diethyl ether for 4 hours
2. ether separated and evaporated
3. residue is weighed, residue = EE (crude fat)
potential problems:
1. assumes all substances soluble in ether are fats
2. error is generally small
148
Ash proximate analysis
burning sample, all organic matter is burned leaving only inorganic residue
measures inorganic compounds in feed
provides an estimate of total inorganic component
high values indicate feed contamination
method:
1. weigh portion of dried feed sample
2. heat sample in oven at 500-700oC for 2-4 hours
3. reweigh sample
potential problems:
1. some trace mineral may be lost to volatilization
2. does not provide content of specific minerals
149
Crude fiber (CF) proximate analysis
measures indigestible components of feed
has little energy value but is important for gut health
procedure:
1. dried sample boiled in 1.25% H2SO4 and filtered
2. residue boiled in 1.25% NaOH & filtered
3. remaining residue dried and ashed
4. crude fiber = filtered dried sample – ash
potential problems:
1. underestimates true fiber in feed
2. does not differentiate between fiber sources
150
Nitrogen-free extract (NFE) proximate analysis
NFE is a calculated value, not an analyzed value
% NFE = (% DM - (% ether extract + % crude protein + % ash + % crude fiber)
potential problems:
1. accumulates error from all other analyses
2. does not differentiate between carbohydrate sources
151
Van Soest fiber analysis
Improved methods of crude fiber analyses
Includes neutral detergent fiber (NDF) and acid detergent fiber (ADF)
Divides plant cells:
Contents (starch and sugars)
Walls
Method:
1. Boil feed sample for 1 hour in neutral detergent (SLS and EDTA) ; pH 7 (neutral)
2. Boil residual sample for 1 hour in acid detergent (H2SO4 and CTAB); pH ~4.9 (acidic)
152
What does the neutral detergent separate in Van Soest fiber analysis?
Separates fiber from other carbohydrates and nutrients
Neutral detergent solubles (NDS) are dissolved (cell contents - soluble carbs, proteins, lipids, minerals, and vitamins)
Neutral detergent fiber (NDF) are left over (cell wall - insoluble fiber and fiber-bound compounds)
153
What does the acid detergent separate in Van Soest fiber analysis?
Separates neutral detergent fibers (hemicellulose) from acid detergent fibers (cellulose and lignin)
154
Very low density lipoproteins (VLDL)
2nd largest plasma lipoprotein
more dense than chylomicrons
produced in the liver
composed of chylomicron
carry lipid to peripheral tissues
155
Low density lipoproteins (LDL)
2nd smallest plasma lipoprotein
moderately dense
156
Is LDL or HDL considered "good cholesterol"?
LDL has more cholesterol contained in it than HDL, and is therefore considered "bad cholesterol"
The cholesterol in LDL can build up in the arteries as plaque, constricting blood flow and lead to heart issues
157
How do antifungal agents work and why are they included as feed additives?
prevent growth of fungi and mold in feeds
fungal actions - produce toxins, alter chemical composition, alter animal metabolism
effects on the animal - reduce palatability, detrimental to health and productivity, varies with species and physiological state
examples of antifungal agents - propionic acid (most economical = most commonly used), sodium propionate, calcium propionate, sodium diacetate, sorbic acid, ammonia, phosphoric acid
158
How do antioxidants work and why are they included as feed additives?
various feedstuffs susceptible to oxidation and rancidity - reduces palatability and reduces nutritional value
antioxidants minimize oxidation - interfere with lipid peroxidation process by donating hydrogen atoms or electrons to free radicals
synthetic - ethoxyquin, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA)
natural - vitamin E, vitamin C, selenium
159
How do pellet binders work and why are they included as feed additives?
enhance firmness and strength of pellets
prevent crumbling
reduce sorting and waste
examples - bentonites, molasses and lipids, wheat
160
How do flavoring agents work and why are they included as feed additives?
improve palatability and acceptance of feed
especially beneficial for rations with low palatability, animals in distress, and high-producing animals
classification:
1. natural - derived from plant or animal sources
2. nature-identical - chemical synthesis; chemically identical to natural products
3. artificial - chemical synthesis; higher consistency and quality compared with natural
161
How do enzymes work and why are they included as feed additives?
commonly added to monogastric diets
reduce antinutritional effects - phytate, non-starch polysaccharides (NSP)
examples:
1. phytases - release P from phytic acid; increase P retention
2. carbohydrases - aid in degradation of complex carbs (rye/wheat = arabinoxylans, barley/oats = 𝛽-glucan)
benefits - improved growth rate, improved feed efficiency, reduced inflammation
162
How do direct fed microbials work and why are they included as feed additives?
substances containing live microorganisms (bacteria, fungi, yeast)
added to animal feed to enhance health and performance- improve digestion, boost nutrient utilization, strengthen immune system
1. probiotics - live cultures of microorganisms; provide a balance of bacteria in the gut (lactobacillus, bifidobacterium)
2. prebiotics - non digestible ingredients that serve as “food for the good microbes” (lactulose, Mannan-oligosaccharide aka MOS, inulin, fructooligosaccharides aka FOS)
3. symbiotes - mixture of probiotics and prebiotics
163
How do hormones work and why are they included as feed additives?
chemical compounds produced in specific region; transported to other region to perform compound’s specific physiological function(s)
utilized to improve animal production
melengestrol acetate (MGA)- only hormone product approved as feed additive
- synthetic progesterone
- suppresses estrus and ovulation
- improves gain and feed efficiency in feedlot heifers
- maintains intake and performance of steers in feedlot
164
How do antibiotics work and why are they included as feed additives?
produced by living microorganisms (i.e. bacteria and fungi)
bacteriostatic or bactericidal properties on 1+ microorganism(s)
in US, majority of production animals receive at least 1 antibiotic
165
How do ionophores work and why are they included as feed additives?
rumensin
alter population of rumen microorganisms, resulting in alteration of rumen metabolism
named based on mode of action - carriers for metal ions across cell membranes
approved for beef cattle and dairy heifers:
1. responses in growing and mature animals
2. responses in high-forage and high-concentrate rations (reduces risk of bloat)
not approved for lactating dairy cattle, poisonous to horses
mode of action - produce responses via alteration of population of microorganisms in rumen:
1. inhibit growth of gram positive bacteria; facilitate growth of gram negative
2. produces shift in metabolism of CHO from acetic to propionic acid
166
How do coccidiostats work and why are they included as feed additives?
prevent and control coccidiosis
inhibit reproduction and development of coccidia protozoa
often classified as an antibiotic
may have a secondary function
167
How do anthelmintics work and why are they included as feed additives?
additives to prevent and control parasitic organisms in the animal
control losses in productivity and profitability from parasitic organisms
also referred to as dewormers
may be added to ration or water
168
What does "subtherapeutic levels" of antibiotics mean and what are some concerns about it?
as feed additives, administered at low levels
increased intake, growth rate, and/or feed efficiency
aid in control of infectious diseases
maintain optimal health and production, especially during distress
response varies with species, physiological state, and environmental conditions - greatest for young, unhealthy, and/or stressed animals
concerns:
1. subtherapeutic levels controversial - improve efficiency of animal production (benefit producer and consumer), extensive utilization promotes resistance
2. no evidence to support risk to human health and safet
169
What does "therapeutic levels" of antibiotics mean?
control or treat various diseases
control GI parasites in animals:
1. prevent or control disease associated with transportation or adjustment to new facility
2. anaplasmosis in cattle
3. bacterial enteritis in swine
4. respiratory diseases, diarrhea, fowl cholera, and fowl typhoid in poultry
administered for short period of time
170
What process shortens fatty acid chains?
Beta-oxidation
171
What is the difference between type I and type II diabetes?
Type 1 - immune system attacks and destroys pancreatic beta cells (dogs)
Type 2 - insulin production is reduced and/or cells become resistant (cats)
172
What enzyme is responsible for the production of carbamoyl phosphate in the urea cycle?
Carbamoyl phosphate synthetase
173
Which enzyme is responsible for the cleavage of fructose 1,6-bisphosphate in glycolysis?
Phosphofructokinase
174
How many Watts is the energy expenditure of an Australian shepherd compared to a lactating dairy cow?
55 lb Australian shepherd = 75-Watt light bulb
lactating dairy cow = 20 100-Watt light bulbs
175
A fruit bat is an example of a _______ feeder
specialized
176
Where is the primary site of action for the following molecules (circulation, small intestine, or lymphatic system): chylomicron, serum albumin, LDL, mixed micelle, VLDLS
chylomicron - circulation
serum albumin - circulation
LDL - circulation
mixed micelle - small intestine
VLDLS - circulation
