lecture quiz 3: fats Flashcards
lipids
organic compounds insoluble in water but soluble in organic solvents (e.g. ether)
lipid subclasses
- glycerides
- phospholipids
- glycolipids
- lipoproteins
glycerides aka
fats
main type of fat important in animal nutrition
triglycerides
elemental components of fats
C, H, & single O (in carboxylic acid end)
all glycerides are made up of…
a glycerol backbone attached to either 1, 2, or 3 fatty acids (mono-, di-, or triglycerides)
fat (glycerides) energy-density compared to carbs or proteins
yield ~2.25x more energy than carbs & proteins
digestibility of fats (glycerides)
highly digestible
main purpose of fats (glycerides) in animal nutrition
energy
carbohydrate classification for animal nutrition
1) structural carbohydrates: fiber (cell wall fraction; cellulose, hemicellulose, lignin)
- important for the structure of the plant
- only digestible to ruminants & hind-gut fermenters b/c of microbial enzymes in rumen/cecum, but less digestible than starches & sugars
2) non-structural carbohydrates (NSC): starch & sugars
- highly digestible
- too much NSC in ruminant diet can lead to severe health issues
- recommended not to exceed 10-12% of diet in horses
carbohydrate classification for human nutrition
1) simple carbs
- mono & di
- digested quickly & send immediate bursts of glucose ➞ spike in BG
- found in table surgar, juices, & foods w/ “added sugar”
- can cause insulin resistance & T2D
2) complex carbs
- mostly polyasaccharides including starch & fiber
- digested more slowly & supply a lower more steady release of glucose (no spike)
- some complex carb-rich foods are healthier (e.g. whole grains over refined grains)
why is fiber recommended even though it cannot be digested?
- reduces calorie-density of diet ➞ important for weight control
- important to maintain the GI health for ruminants & hind-gut fermenters (microbes ferment fiber producing VFAs)
concerns RE non-structural carbohydrates
too much NSC in diet of ruminant & hind-gut fermenters can cause:
- acidosis in ruminants
- bloat in ruminants & horses
- colic in horses
- insulin resistance in horses
- laminitis in horses (long-term)
differences in carbohydrate classification for human vs animal nutrition
human: classified by simple or complex regarding glucose release mechanisms ➞ concerned with health & longevity
animals: classified by structural or non-structural regarding digestibility ➞ concerned w/ growth & production
monomers of lipids
fatty acids
fatty acid classes important in nutrition
- volatile fatty acids (VFAs) (aka short-chain fatty acids - SCFA)
- long-chain saturated fatty acids
- non-essential long-chain unsaturated fatty acids
- essential long-chain unsaturated fatty acids (EFAs)
volatile fatty acids (VFAs)
produced from microbial fermentation of carbs in the rumen or cecum & colon (aka short-chain fatty acids)
- acetic acid (2C) - CH₃COOH
- propionic acid (3C) - CH₃CH₂COOH
- butyric acid (4C) - CH₃CH₂CH₂COOH
long-chain saturated fatty acids
- palmitic acid (16C) - CH₃(CH₂)₁₄COOH (16:0)
- stearic acid (18C) - CH₃(CH₂)₁₆COOH (18:0)
non-essential long-chain unsaturated fatty acids
oleic acid (18:1)
essential vs non-essential fatty acids
essential = body cannot make ∴ must obtain from diet
- linoleic acid (18:2)
- linolenic acid (18:3)
- arachidonic acid (20:4) → only for cats
non-essential = body can make
- oleic acid (18:1)
long-chain unsaturated essential fatty acids (EFAs)
- linoleic acid (18:2)
- linolenic acid (18:3)
- arachidonic acid (20:4) ➞ essential only for cats
fatty acid structure
- fatty acids contain an carboxyl group attached to a hydrocarbon chain
- C has 4 bonds:
- 2 bonds used to create C chain
- other 2 bonds either bond H or to C for a second time to form a double bond
saturated vs unsaturated fatty acids
saturated fatty acids (SFAs) have single bonds only ➞ straight structure
- all bonds are occupied or “saturated” with H
- packed orientation ∴ stay solid at room temp
unsaturated fatty acids have 1+ double bond ➞ causes kinks in structure (bent)
- cannot be as packed ∴ liquid at room temp (oils)
- monounsaturated (MUFA) have 1 double bond
- polyunsaturated (PUFA) have 2+ double bonds
examples of polyunsaturated fatty acids (PUFAs)
- omega-6 (n-6)
- omega-3 (n-3)