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LIPID DIGESTION

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Galactosyl diglyceride. O C-O-gal O gal. R-C-O-C O. C-O ... CH2-O-C-R2 CH2-O-C-R2 CH2-O-C-R2. Galactosyl diglyceride. Lipases. Galactose. Propionate -Glycerol ... – PowerPoint PPT presentation

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Title: LIPID DIGESTION


1
LIPID DIGESTION
  • References
  • Church 298-312

2
  • Lipids in ruminant diets
  • Usually a low percentage of the diet, 1-4 of the
    DM
  • Amounts have been increasing
  • Lipids in feeds
  • Feed EE Form
  • Corn and 4-20 Triglycerides
  • other seeds
  • Forages 4-6 Galactosyl

  • glyceryl esters
  • pigments
  • waxes, essential

  • oils

3
  • Structure
  • Triglyceride O

  • O C-O- C-R
  • R-C-O-C O

  • C-O-C-R
  • 46 oleic acid (181) and 42 linoleic acid
    (182)
  • Galactosyl diglyceride



  • O C-O-gal O
    gal

  • R-C-O-C O

  • C-O-C-R
  • 31-61 linolenic acid (183)

4
  • Common fatty acids in ruminant diets
  • Fatty acid CarbonDouble Bonds
    Double bond position
  • Myristic 140
  • Palmitic 160
  • Palmitoleic 161 Cis-9
  • Stearic 180
  • Oleic 181 Cis-9
  • Linoleic 182 Cis-9, 12
  • Linolenic 183 Cis-9,
    12, 15
  • Arachidonic 204 Cis-5, 8, 11, 14
  • Eicosapentaenoic 205 Cis-5, 8, 11,
    14, 17
  • Docosahexaenoic 226 Cis-5, 7, 10,
    13, 16, 19

5
  • Unsaturated fatty acid isomers
  • Cis isomers (Naturally found in feeds)
  • H H
  • \ /
  • CC
  • / \
  • C C
  • / \
  • R R
  • Trans (Found in ruminant meat and milk as well as
    hydrogenated oils)
  • R
  • \
  • C H
  • \ /
  • CC
  • / \
  • H C
  • \
  • R

6
  • Lipid digestion in the rumen

  • alpha-galactosidase
    beta-galactosidase
  • O CH2-O-Gal-Gal
    O CH2-O-Gal
    O CH2OH



  • R1-C-O-CH2 O --------------------?
    R1-C-O-CH2 O ---------------------?
    R1-C-O-CH2 O



  • CH2-O-C-R2
    CH2-O-C-R2
    CH2-O-C-R2
  • Galactosyl diglyceride






  • Lipases

  • Galactose





  • Propionate
    ?------------Glycerol?--------





  • Unesterified


  • FA


  • (Rn)

7
  • Fatty acid metabolism
  • Minimal absorption or degradation of long chain
    fatty acids in the rumen
  • Lipids leaving the rumen
  • 80-90 are free fatty acids bound to feed
    particles or microbes
  • 10 leaves as microbial phospholipids
  • If not protected, small quantities of undigested
    fats may pass
  • More fat leaves the rumen than enters
  • Major alterations of long chain fatty acids in
    the rumen
  • Biohydrogenation
  • Microbial synthesis of long-chain fatty acids

8
  • Biohydrogenation
  • Microorganisms
  • Primarily bacteria, particularly cellulolytic
    bacteria
  • Protozoa
  • Contain 75 of the microbial fatty acid in rumen
  • Not actively involved in biohydrogenation
  • Contains high concentrations of 182 CLA
  • Obtained by ingesting bacteria
  • Fungi have capability for biohydrogenation, but
    make up a small proportion of the microbial
    biomass

9
  • Processes
  • From Linoleic acid
  • High roughage diet
  • Linoleic acid (cis-9, cis-12 182)
  • cis-9, trans-12
    isomerase
  • from Butyrvibrio
    fibrisolvens
  • (Rapid)
  • Conjugated linoleic acid (CLA, cis-9,
    trans-11 182)
  • Also called Rumenic
    acid
  • cis-9 reductase
  • from Butyrvibrio
    fibrisolvens
  • (Rapid)
  • Vaccenic acid (trans-11 181)
  • trans-11 reductase
  • from Clostridium
    proteoclasticum
  • (Slow)
  • Stearic acid (180)

10
  • High grain diet (Low pH)
  • Linoleic acid (cis-9, cis-12 182)
  • trans-9, cis-12
    isomerase from
  • Megasphaera elsdenii,
    Streptococcus bovis
  • (Rapid)
  • Conjugated Linoleic Acid isomer (trans-10,
    cis-12 182)
  • cis-12 reductase from
  • Megasphaera elsdenii,
    Streptococcus bovis
  • (Rapid)
  • Trans-10 181
  • trans-10 reductase
  • (Slow)
  • Stearic acid (180)

11
  • From Linolenic acid
  • High roughage diet
  • Linolenic acid (cis-9, cis-12, cis-15 183)
  • Cis-9, trans-11, cis-15 183
  • Trans-11, cis-15 182
  • Vaccenic acid (trans-11 181)
  • Stearic acid (180)

12
  • Why do bacteria reduce unsaturated fatty acids
  • Mechanism to use excess hydrogen
  • Detoxify unsaturated fatty acids

13
Results of biohydrogenation in the rumen
  • On all diets
  • Higher concentration of saturated fatty acids
    leave than the rumen than enter in the diet
  • Higher concentration of stearic acid (180) leave
    the rumen than enter in the diet
  • High roughage diets
  • High concentrations of CLA (cis-9, trans-11 182)
    and vaccenic acid (trans-11) 181 in the rumen
  • High concentrate diets
  • High concentrations of trans-10, cis-12 182 and
    trans-10 181 fatty acids in the rumen
  • These fatty acids will be absorbed in the small
    intestine and represent a high proportion of the
    fatty acids presented to tissues

14
  • Results of long-chain fatty acid metabolism

  • Feed
  • Fatty acid Corn SBM Barley-SBM-Tallow Grass
  • Saturated
  • 140 - - 2.5 4.6
  • 160 7.0 11.0 32.7 20.8
  • 180 2.4 4.1 20.6
    3.3
  • Unsaturated
  • 161 - - .8
    2.4
  • 181 45.6 22.0
    25.1 5.7
  • 182 45.0 54.0 16.5 14.0
  • 183 - 7.5 1.9 49.2

  • Intramuscular fat
  • Swine
    Beef
  • Saturated Barley-SBM-Tallow Grass
  • 140 2.0 2.3
    2.7
  • 160 23.8 27.4 22.8
  • 18.0 10.6 16.0 14.7
  • Unsaturated

15
  • Tissue metabolism of trans isomers of fatty acids
  • Conversion of trans-11 181 to CLA (cis-9,
    trans-11 182)
  • Occurs in mammary gland and adipose
  • Major source of CLA (cis-9, trans-11 182) in
    meat and milk
  • Mechanism
  • 9 - desaturase
  • Trans-11 181
    CLA (cis-9, trans-11 182)

  • 2H

16
  • Effects of biohydrogenation of unsaturated fatty
    acids in ruminants
  • Increased concentrations of saturated fatty acids
    in meat and milk
  • Increased concentrations of CLA (cis-9, trans-11
    182) in ruminant meat and milk
  • Anticarcinogenic
  • Reduces atherosclerosis
  • Alter body composition
  • Diabetes control
  • Improved immune response
  • Improved bone mineralization
  • Milk fat depression in lactating dairy cows
  • trans-10 , cis-12 CLA produced from linoleic acid
    in cows fed high grain diets will directly
    inhibit long chain fatty acid synthesis in the
    mammary gland
  • Reduces the vitamin E requirement of ruminants
  • Indicates a low essential fatty acid requirement
    in mature ruminants

17
  • Microbial synthesis of fatty acids
  • Distribution of lipid in the rumen

  • of total lipid (Wet digesta)
  • Bacteria 4.1
  • Protozoa 15.6
  • Feed particles in rumen fluid 80.3
  • Bacterial synthesis
  • C180 and C160
  • From acetate and butyrate
  • Long straight-chain, odd-numbered fatty acids
  • From propionic acid or valeric acid at the
    initial step
  • Increase in cobalt-deficient animals because
    vitamin B12 is needed for animals to use
    propionate for glucose
  • Long branched-chain fatty acids
  • From branched chain VFAs (Isobutyrate,
    Isovalerate) at initial step
  • Flavor components in meat and milk
  • 15-20 of the bacterial fatty acids are
    monounsaturated
  • Can not synthesis polyunsaturated fatty acids
  • Bacterial synthesis increases on low fat, high
    concentrate diets

18
  • Lipid digestion in the small intestine
  • Mechanism similar to nonruminants
  • Ether extract digestibility in small intestine is
    lower than in nonruminants
  • Saturated fatty acids are better absorbed in
    ruminants than nonruminants
  • Unsaturated fatty acids are less absorbed in
    ruminants than nonruminants

19
  • Mechanism of lipid digestion in small intestine
  • Unesterfied Triglyceride
    Phospholipid
  • fatty acids
  • Pancreatic
    Phospholipase A1
    lipase
    Phospholipase A2
  • Unesterfied Monoglyceride
    Lysolecithin
  • fatty acid
  • Bile salt

  • Phosphatidylcholine

  • Phosphatidylethanolamine
  • Micelles
  • Absorbed into
    mucosa
  • Micelles break
    up
  • Fatty acids lt 14 C are transported directly
    in the blood
  • 10 of the 180 is
    desaturated to 181
  • Long chain fatty acids combine with
    lipoproteins to produce VLDL and
    chylomicrons

20
  • Lipid transport in the blood
  • Transport from the intestine
  • Very low density lipoproteins
  • Major transport structure from the small
    intestine
  • Favored by saturated fatty acids
  • Chylomicrons
  • Less prevalent than in nonruminants
  • Smaller than nonruminants
  • Contain 2x more phospholipid than nonruminants
  • Freeesterified cholestrol ratio is 41 compared
    to 11 for nonruminants
  • VLDLs and chylomicrons contain apoprotein-C
  • Inhibits liver removal of VLDLs and chylomicrons
  • Activates lipoprotein lipase at muscle, adipose,
    and mammary tissue
  • VLDLs and chylomicrons are very short-lived in
    ruminants
  • 70 of lipids are on HDL
  • 20 of lipids are on LDL

21
  • Liver synthesis of lipoproteins
  • Little synthesis of fatty acids in liver and
    lipoproteins from intestinal mucosa are not
    utilized by liver
  • Liver synthesis of triglycerides are dependent on
    the concentrations of circulating non-esterified
    fatty acids (NEFAS) and glycerol from glucose
  • If glucose is limiting glycerol synthesis and
    fatty acid oxidation, the NEFAS are oxidized to
    ketones
  • Synthesized triglycerides are incorporated into
    VLDL to be transported throughout the body

22
  • Fat depots
  • Location
  • Subcutaneous
  • Inter and intramuscular sites
  • Visceral sites
  • Fatty acid composition
  • General
  • 80 of FA are 140, 160, 180, and 181
  • Small amounts of 182 and very little 183
  • Unsaturated fatty acids will have both cis and
    trans isomers
  • Odd-numbered chain length fatty acids
  • Branched chain fatty acids
  • Effects of body location of fatty acid
    composition
  • Subcutaneous fat has more unsaturated fatty acids
    the inter and intramuscular fat which has more
    than internal fat
  • Most external subcutaneous fat and fat in limbs
    is more unsaturated than more internal
    subcutaneous fat

23
Roles of lipid stores in the body of ruminant
animals
  • Provides an energy reserve when needed
  • Provides internal insulation against cold stress
  • Maintenance of reproduction
  • Long-term feed intake control

24
Proportion of empty body lipid at each condition
score and the amount of energy provided by losing
1 body condition score unit (9-point scale)
25
Effects of excessive mobilization of fat stores
  • Metabolic diseases
  • Ketosis in dairy cattle
  • Pregnancy disease in sheep
  • Causes
  • Animal factors
  • Dairy cows
  • High production
  • Reduced feed intake immediately before and after
    calving
  • Ewes
  • Multiple fetuses
  • Metabolic factors
  • Excessive mobilization of fat reserves
  • Inadequate blood glucose

26
  • Ketosis-fatty liver syndrome (Dairy cattle)
  • In early lactation, energy must be
    mobilized from tissue reserves

  • Inadequate
    glucose
  • Excessive mobilization of adipose tissue


  • Lack of OAA


  • Lack of carnitine


  • Lack of niacin
  • Overcomes limit of fatty acids to be
  • transported from liver as VLDL
  • oxidized in TCA cycle in liver
  • Fat accumulates Acetyl-CoA
  • in hepatocytes
  • (Fatty liver)
    Acetoacetate

  • B-OH-Butyrate Impairs gluconeogenisis
  • Impairs feed intake
    Appear in milk Reduces


  • glucose

27
From Van Soest, 1994
28
  • Symptoms
  • Metabolic profile
  • Normal
    Ketosis (2-4 weeks PP)
  • Blood
    mg
  • Glucose 52
    28
  • Ketones 3
    41
  • Plasma
  • Free fatty acids 3
    33
  • Poor appetite
  • Loss of body weight
  • Gaunt and dull appearance
  • Irregular rumen contractions
  • May stagger or appear uncoordinated
  • Milk production will decrease
  • Complications
  • Displaced abomasum, milk fever, retained
    placenta, and mastitis
  • In ewes,
  • Death

29
  • Ketosis or pregnancy disease prevention
  • Avoid excessive fatness (or thinness) in cows or
    ewes
  • Maximize intake immediately before calving (or
    during pregnancy in ewes)
  • Avoid abrupt change to high grain lactation diet
    at calving
  • Feed balance ration
  • Use high quality forages
  • Drench cows with propylene glycol (1L/day) for 1
    week daily before calving
  • Propylene glycol is metabolized to lactate that
    can be used for gluconeogenisis
  • Supplement with nicotinic acid (6 12 g/d) ?????
  • Increases DMI
  • Reduces lipolysis
  • Recommendations
  • Use in ketosis prone cows
  • Use from 14 days prepartum to 120 days postpartum
  • Use palatable carrier

30
ROLE OF LIPID STORES ON FEED INTAKE
  • Leptin
  • Produced primarily by white adipose tissue
  • Also duodenum and mammary gland
  • Concentration increases with increasing fatness
    or plane of nutrition
  • Binds to Neuropeptide Y in the dorsomedial,
    ventromedial and arcuate nuclei of the
    hypothalamus
  • Reduces long-term food intake and maintains
    energy balance

31
RELATIONSHIP OF LEPTIN WITH ENERGY BALANCE, BODY
CONDITION, FEED INTAKE IN LACTATING DAIRY COWS
(Reist et al., 2003)
32
EFFECTS OF LEPTIN ON REPRODUCTION
  • Cows with higher leptin concentrations has
  • Earlier first estrus after parturition
  • Stronger estruses
  • Accelerated puberty
  • Mechanism
  • Stimulation of GnRH in the hypothalamus
  • Greater Follicle Stimulating Hormone
  • Greater Luteinizing Hormone
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