Fats in ruminant diets

1
Fats in ruminant diets

• Diets are low
• Ruminants evolved as herbivores
• Forages are typically 1-4 lipid (stems leaves)
• Corn 4
• Added fat should limited to 3 4 (DM basis)
• Do not exceed 6 7 of total diet (DM basis)

2
Feeds

• Types of fat supplements
• Unprotected oils
• Vegetable oils
• Highly unsaturated
• Expensive
• Most adverse affects
• Animal fats (tallow, grease etc.)
• Most commonly added to beef and dairy diets
• More saturated
• Less adverse affects
• Difficult to mix in cold weather

3
Feeds

• Whole oil seeds
• Higher proportion escapes ruminal metabolism
• Less adverse effects than free oils
• Easy to use
• Cost effectiveness
• Solvent extracted, expeller pressed

4
Feeds

• Examples
• Soybeans 17-19 (meal 1-3)
• Flax/Linseed 40-45 (meal 2-4)
• Canola/rapeseed 40-45 (meal 3-5)
• Sunflower 30-45 (meal 0.5-1.5)
• Cottonseed 17-18 (meal 2-3)

5
Feeds

• High oil feeds
• Distillers grains 8-11
• Brewers grains 10-11
• High oil corn (7 8)
• Fish meal (10 11)

6
Feeds

• Ruminally inert fats
• Escapes ruminal digestion
• Less adverse than free oils
• Will reduce feed intake
• Types
• Ca salts of long chain fatty acids - Megalac
• Prilled (saturated fat processed in small
  spheres)
• Expensive

7
Feeding fat to ruminants

• Why feed fats to ruminants?
• Increase energy density (growth, reproduction)
• Carbohydrate 4.0 kcal/g
• Protein 3.2 kcal/g
• Fat 9.0 kcal/g little fermentative loss
• Can increase dietary energy without decreasing
  forage level
• Can reduce acidosis effects
• Forage needed to minimize fat effects on milk fat
  percentage
• Also need to mainain NFC level (30 40)

8

• Fats increase energy without increasing heat
  increment
• Change nutrient profile of products
• Increased milk fat
• Fatty acid content
• Health benefits (CLA, unsaturated fats)
• Decrease dustiness

9

• Improved reproduction
• Improved conception rate
• Increased energy balance
• Increase follicle size and number
• Decreased insulin and increased progesterone
• Increase persistence of corpus luteum
• Decresased prostaglandin F 2 alpha
• Depends
• Inadequate energy to begin with
• Decrease methane production?
• Growth modification?

10

• Why dont we supplement?
• Interferes with rumen fermentation
• Physically coats fiber
• Toxic effect on microbes
• Decreased cation availability

11
Inhibitory effects on rumen fermentation

• Inhibit gram- bacteria and protozoa
• methanogenic and cellulolytic bacteria
• Decreases fiber digestion
• Addition of 10 lipid decreased by up to 50
  (Jenkins and palmquist (1984)
• Decreases VFA production (energy source for
  animal)
• More of a concern in high forage diets (dairy)
• FFA TAG
• SCFA LCFA (SCFA are more soluble)
• Unsaturated saturated (UFA more soluble)

12
Feeding fat to ruminants

• Decreased feed intake
• Decreased fiber digestion
• Decreased gut motility
• Decreased palatability
• Oxidation of fat in liver exceeds capacity
• Milk fat depression
• Decreased fiber digestion
• Production of trans fatty acids

13

• Decreased mineral digestion
• Formation of soaps with Ca and Mg
• Decrease in milk protein in dairy cows
• Milk protein, 101.1 0.6381x 0.0141x2
• Where x total dietary fat
• Caused more by increase milk production rather
  than a decrease in protein synthesis
• Effects arent consistent

14

• Fats are
• Nutritive (energy source)
• Fatty acids, triglycerides, galactolipids,
  phospholipds
• Nonnutritive (less nutritive)
• Waxes, pigments (chlorophyll, carotenoids,
  xanthophylls, saponins), sterols
• Forages as high as 50 is nonnutritive
• Cereal grains

15
Forms of dietary lipid

• Cereal grain Triacylglycerol (TAG)

16

• Forages - galactolipid

17

• Phospholipid
• Structural, found in forages and grains
• Ethanolamine, choline, serine, inositol

18

• How do we measure dietary fat
• Ether extract historically
• Fatty acid content of ether extract
• Forages
• Grains 65 80
• Oilseeds 90
• Remaining
• Nutritive glycerol, galactose (fermented)
• Low utilization some waxes (25 30 carbon)
• Very low utilization carotenoids
• Indigestible waxes ( 30 carbon), chlorphyll
  (some bacterial degradation)
• Gas chromatography to measure feed lipids

19
Fatty acid classification

• Chain length (C1 C30)
• Volatile fatty acids (VFA C1 C6)
• Found free in fermented feeds
• Short chain fatty acids (SCFA C1 C8)
• Medium chain (MCFA C10 C14)
• Long chain (LCFA C16 and )
• Linkages
• Free fatty acid (FFA), non-esterified fatty acids
  (NEFA)
• Esterified attached to glycerol backbone

20

• Hydrogenation
• Saturated (C180)
• Mono-unsaturated (C181)
• Poly-unsaturated (C182, C183)

21

• Optical isomers (1 or more double bonds)

trans-10, cis-12 182
cis-9, trans-11 182
Most ruminant dietary fats are in the cis form
22
Essential fatty acids

• Omega-3 (?-3, n-3)
• Eicosapentaenoic (EPA, 205)
• Docosahexaenoic (DHA, 226)
• Omega-6 (?-6, n-6)
• Arachidonic acid (AA, 204)
• Required for
• Prostaglandin synthesis
• Phospholipid synthesis, cell membranes
• Animals are unable to synthesize

23
Essential fatty acids

• Acquired through chain elongation and
  desaturation
• Linoleic (C182)
• Linolenic acid (C183)
• Ruminants vs non-ruminants
• Born with very low PUFA reserve
• Requirement is much lower

24
Church, Table 15-2 Palmquist and Jenkins, 1980
25
Ruminant lipid metabolism

• Hydrolysis
• Galactolipid ? galactose DAG
• DAG, TAG ? FFA glycerol
• Esterified FA ? NEFA
• Galactose, glycerol ? VFA
• VFA ? Absorbed
• Saturated FA
• Form carboxylate salts
• pass to small intestine
• Unsaturated FA
• Biohydrogenation
• Form carboxylate salts pass to small intestine

26

• Hydrolysis
• Most bacteria
• Some protozoa
• Rapid, but rate limiting
• Prevent build-up of unsaturated fats
• Plant oils (90 ) fish oil (50 )

27

• Biohydrogenation
• Occurs on feed particles
• Add H to double bonds
• Hydrogen sink
• detoxification
• C183 ? C182 ? C181 ? C180
• Trans configurations result

28
(No Transcript)
29

• Distribution of lipid in the rumen
• of total lipid (wet digesta)
• Bacteria 4.1
• Protozoa 15.6
• Feed particles in rumen fluid 80.3

30
linoleic cis-9, cis-12 C182
Isomerase
CLA trans-10, cis-12 C182
CLA cis-9, trans-11 C182
Hydrogenase
Vaccenic Acid trans-11 C181
Vaccenic Acid trans-10 C181
Hydrogenase
Stearic acid C180
31
a-linolenic cis-9, cis-12, cis-15 C183
Isomerase
trans-10, cis-12, cis-15 C183
cis-9, trans-11, cis-15 C183
Hydrogenase
trans-10, cis-15 C182
trans-11, cis-15 C182
Hydrogenase
Vaccenic Acid trans-10 C181
Vaccenic Acid trans-11 C181
Hydrogenase
Stearic acid C180
32
From Wallace, 2008
33

• Non-ruminants
• Depot fat reflects dietary fat
• Ruminants
• Depot fat is more saturated
• Contains more trans configurations
• Tallow vs. lard
• Distillers grains

34
Fatty acid composition of beef and milk
Van Soest, 1994
35
Protected fat

• Carboxylate salts (soap)
• Ca, Mg
• Insoluble
• Escape biohydrogenation
• More favorable for saturated fatty acids
• Dissociate at low pH
• Saturated pKa 4.5
• Unsaturated pKa 5.5

36

• Carboxylate salts
• Would they work in high grain diets?

37
Protected fats

• Pre-formed carboxylate salts (soaps)
• Used in dairy rations, not beef
• Increases energy density of the diet without
  affecting fiber digestion

38
CLA

• Only produced by ruminants rumenic acid
• Conjugated 2 double bonds separated by 1 single
  bond
• trans-11 C181
• Can be converted back to cis-9, trans-11 CLA
• ?9-desaturase mammary gland
• trans-10 C181
• Cannot be converted back to trans-10, cis-12 CLA
  in mammary gland
• cis-9, trans-11 CLA 10 20-fold higher vs
  trans-10, cis-12 CLA

39
CLA

• Anticarcinogenic
• Antiatherogenic
• Antiobesity
• Grass fed
• Can double or triple cis-9, trans-11 CLA
• Fat content
• Grain-fed 3-5
• Grasss-fed 1-3

40
CLA
41
Milk fat depression

• Inhibitory
• Trans-10, cis-12
• Cis-10, trans-12
• Trans-9, cis-11

• Non-inhibitory
• Cis-9, trans-11

• Mechanism?
• Inhibits Sterol Regulatory Element Binding
  Protein (SREBP)
• Lipogenic transcription factor

42
Effect of 182 isomers on SC adipocyte growth in
vitro
Differentiation medium
Zhou et al., 2007
Decreased cell size
43
Dietary CLA and marbling

• Swine 2 CLA-mix fed for 45 days (Meadus et al.,
  2002)

• Sheep (70 d) no change NS dose effect (Wynn et
  al., 2006)
• Beef (final 30 60 d) no change (Gillis et al.,
  2004) corn oil

44
Rumen synthesis of lipids

• Non-ruminant fat even chain
• Acetyl-CoA attached
• Ruminants
• Even chain ? 160, 180
• odd chain and methyl branched chain fatty acids
• Cattle 1-2
• Up to 15 in sheep and goats
• VFA produced
• Propionic (30) and valeric (50) ? odd chain
• Iso-acids (iso-butyric, iso-valeric) ? BCFA
• Trans configuration
• High dietary fat will inhibit microbial synthesis
  of lipid

45
Intestinal digestion of lipids

• No significant absorption of lipid in omassum or
  abomassum
• Lipid arriving in duodenum is often higher than
  dietary lipid
• Approximately 20 lipid disappearance in rumen
• Contribution of microbial synthesis
• Greater in high forage diets

46
Intestinal digestion of lipids

• Fatty acids are in free form (80 90)
• Fatty acid soaps from rumen are now free (pH)
• Attached to feed particles
• Remaining are microbial PL, small amounts of TAG,
  glycolipid
• Non-ruminants TAG, DAG, MAG

47
Intestinal digestion of lipids

• Fat absorption occurs in jejunum
• Non-ruminants
• MAG are required for micelle formation
• pH 6-7
• Bile salts can form an emulsion

48
Intestinal digestion of lipids

• Ruminants
• Fatty acids are in free form (microbial
  hydrolysis)
• Attached to feed particles decreased solubility
• pH is 2-3
• Pancreatic secretions low in bicarbonate
• Fatty acids are protonated at this pH
• pKa of fatty acids 4.5 (saturated), 5.5
  (unsaturated)
• Low for most of the proximal half of small
  intestine
• Limited pancreatic lipase activity because of low
  pH
• Pancreatic lipase converts TAG to MAG
• Non-ruminants
• Phospholipase A2 active at low pH
• Converts phospholipid and lecithin to
  lysolecithin
• Lecithin secreted in bile

49

• Ruminants
• Must be transferred to micelle
• Desorb from feed particle
• Bile salt
• Non-ruminant glycocholic (pK 3.7)
• Ruminant taurocholic (pK 1.5)
• Increase solubility (form micelle)
• Lysolecithin (lysophosphatidylcholine)
• Secreted as lecithin (bile)
• Converted to lysolecithin by phospholipase A2

50

• Lysolecithin
• High in 181
• Way for ruminant to preserve 181 essential
  fatty acid
• 181 is preferentially absorbed and esterfied as
  phospholipid
• Phospholipid
• Only 20 of total esterified fatty acid
• Carries over 50 of 181

Lysolecithin
51
Intestinal digestion of lipids

• Lysolecithin bile salts
• Desorb fatty acids from feed
• Allows formation of micelles
• Micelles taken up by epithelial cells
• Re-esterified and packaged into chylomicrons

52
Intestinal digestion of lipids
53

• 20 absorbed in upper jejunum
• 60 in the remainder of jejunum
• Nearly complete by ileum
• Acidic environment
• Non-ruminants neutral environment

54
(No Transcript)
55

• Unsaturated fatty acids
• Lower digestion vs non-ruminants
• Saturated fatty acids
• More complete digestion vs non-ruminants
• Non-ruminants digestibility decreases as chain
  length increases
• Ruminants digestibility not decreased as much

56
Resynthesis and transport of lipids

• Enterocyte
• Fatty acids absorbed
• C14 - lymph
• Chylomicrons, VLDL synthesized

57

• Chylomicrons, VLDL synthesis
• Fatty acids re-esterified to TAG, DAG, MAG
• Non-ruminants 2-monoglyceride pathway
• Ruminants alpha glycerophosphate pathway
• little or no monoglyceride present
• 2-monoglyceride pathway present, but used little
• Inert fat
• Glucose used as glycerol source
• Essential FA are conserved through preferential
  esterification as phospholipid
• TAG are packaged with phospohlipid, cholesterol,
  apoproteins

58

• Ruminants VLDL predominates
• Non-ruminants chylomicrons predominate
• Why?
• Phospholipids, cholesterol, apoprotein synthesis
  is slow
• Ruminants lipid digestion
• continuous, slow
• Phospholipids, cholesterol, apoproteins readily
  available
• Fatty acids are more saturated favors VLDL
• Non-ruminants lipid digestion
• meal oriented, rapid
• Phospholipids, cholesterol, apoproteins not
  readily available
• Fatty acids are more unsaturated favors
  chylomicrons

59

• Ruminant chylomicrons
• Favored if high unsaturated FA reach small
  intestine
• Smaller than non-ruminants
• Nonruminants 1000 5000 nm
• Ruminants 75 1000 nm
• VLDL 25 75 nm
• Contains 2x more phospholipid than nonruminants
• Freeesterified cholesterol ratio is 41 compared
  to 11 for nonruminants

60
Lipid transport in blood

• Ruminant VLDL and chylomicrons
• Contain apoprotein-C
• Inhibits liver removal
• Activates lipoprotein lipase at muscle, adipose,
  and mammary tissue
• Very short-lived
• 70 of lipids are HDL
• 20 of lipids are LDL

61
Liver synthesis of lipoproteins

• Little fatty acid synthesis
• Lipoproteins from intestinal mucosa are not
  utilized by liver
• Dependent on NEFA and glycerol (from glucose)
  concentration in circulation
• If glucose is limiting glycerol synthesis and
  fatty acid oxidation, the NEFAs are oxidized to
  ketones
• Synthesized TAG are incorporated into VLDL

62
Ketosis

• High producing dairy cows
• Lactose in milk derived from glucose
• Lactose concentration needs to be maintained
• Glucose production cant keep up
• Increased fat mobilization (low blood glucose)
• Decreased milk production
• Ketone bodies
• Beta hydroxybutyrate
• Acetoacetate (blood, urine analysis good
  marker)
• Acetone (minor)
• Acetate is not ketogenic, butyrate is

63
Ketone Bodies
AcAc
BHBA
Acetone
VFAs
Butyrate
Acetate
64

• Sequence
• Reduced glucose (and insulin)
• Increased lipid mobilization
• Elevated blood NEFA
• Elevated ketones
• Fatty liver

65
(No Transcript)
66
Fatty Liver

• Capacity for liver to produce ketones is exceeded
• Early ketosis - 7.4
• Late stage of ketosis 20

67
Fat cow syndrome

• Cows overfed during dry period and carry too much
  condition into calving
• Feed intake is low at calving
• Excessive fat mobilization
• Similar to ketosis
• Ketones and NEFA are high
• Glucose may or may not be high