Forage Lipids –
More Than You
Think?
Tom Jenkins
Emeritus Professor
Dairy Nutrition
John Andrae
Associate Professor
Forage Extension Specialist
Forage Lipids – More Than You Think?
Nutrients
Proteins
Vitamins
Minerals
Sugars
Lipids?
Fiber
Forage Lipids – More Than You Think?
Forage Lipids
CPM Dairy v 3.0.8
NRC (2001)
% of DM
Ether Extract
Fatty Acid
Ether Extract
Alfalfa Hay
2.1–3.5
1.4–1.9
2.5
Mixed
Grass Hay
3.00
1.82
2.5–3.3
Orchard
Grass Hay
3.60
2.24
2.4
Fatty acids in hay range from 1.5 to 2.5% DM
Forage Lipids – More Than You Think?
Total Fatty Acids in Forages at Vegetative State
7
6
5
4
3
2
1
0
%
Red Clover
Andrae and Jenkins, unpublished
Alfalfa
Crimson Clover
Wheat
Ryegrass
Forage Lipids – More Than You Think?
Forage Lipids
Pasture
Planted
Grazed
Rye
October
Nov 18–Mar 17
Annual
Ryegrass
October
Mar 17–June 3
Freeman-Pounders et al. 2009. Forage and Grazinglands. doi: 10.1094/FG-2009-0130-01-BR.
Initial FA, % DM
Final FA, % DM
Forage Lipids – More Than You Think?
Effects of 5% Added Soy Oil
% Total Diet FA
CON
SBO
DMI, lb/d
47.4
43.5
Milk, lb/d
66.6
63.3
Milk Fat, lb/d
2.5
1.9*
Milk Fat, %
3.53
2.73
*CON and FAT diets differed (P < 0.05).
From Huang et al., 2008. J. Dairy Sci. 91:260–270.
Forage Lipids – More Than You Think?
UFA in Silages from Netherlands
% DM
Grass
Silage
Corn
Silage
Mean
1.49
1.61
Minimum
0.56
0.96
Maximum
2.78
3.38
Anim. Feed Sci. and Technol. 2012. 174:36.
Forage Lipids – More Than You Think?
Lipid Availability
Bound
• Mainly bound to glycerol
• Little effect on rumen fermentation
Free (FFA)
• Released by plant or rumen lipases
• Disrupt rumen fermentation
Forage Lipids – More Than You Think?
Availability?
Availability
Microbial Exposure
Corn Oil
High
Immediate
Corn Silage
Medium
Slower release from plant structure
Cottonseed
Low
Slow release from outer seed coat
Forage Lipids – More Than You Think?
Release from Ensiling
FFA, % of Total Lipid
Fresh
Ensiled
Reference
Ryegrass
Elsgersma et al. 2003
Timothy
Vanhatalo et. Al. 2007
Red Clover
Vanhatalo et. Al. 2007
Plant lipases release FFA after cutting (Thomas, 1986) or during ensiling (Chow et al. 2004).
Forage Lipids – More Than You Think?
Percentage of C18:3 in FFA as DM Varies
WCS Source
Normal
No Heating
Overheated
Moisture, %
9.4
10.6
11.9
Oil, %
18.4
17.1
15.9
FFA, % of oil
6.8
24.1
22.3
DMI, kg/d
Milk, kg/d
Fat, %
a,b P
< 0.05
Cooke et. al., 2007. J. Dairy Sci. 90:2329.
Forage Lipids – More Than You Think?
Percentage of C18:3 in FFA as DM Varies
WCS Source
Normal
No Heating
Overheated
Moisture, %
9.4
10.6
11.9
Oil, %
18.4
17.1
15.9
FFA, % of oil
6.8
24.1
22.3
DMI, lb/d
47.5
48.4
51.7
Milk, kg/d
77.0
74.8
77.2
Fat, %
a,b P
< 0.05
Cooke et. al., 2007. J. Dairy Sci. 90:2329.
Forage Lipids – More Than You Think?
Main Points
§  Fatty acids in some early vegetative grasses and legumes
are comparable to many high-fat TMR fed to dairy cows.
§  Ensiled forages, including corn silage, have wide
variability in fatty acid content and accumulation of free
fatty acids that can define the amount and type of lipid
consumed by cows.
§  Changes in amount and characteristics of forage lipids
over time can play a role in determining overall diet
effects on rumen function and lactation performance.
Forage Lipids – More Than You Think?
Questions & Answers
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