Lecture 11 - Ruminant Protein and Lipids Flashcards
What breaks down protein in ruminants? Into what? Which is utilized for…
Microbial fermentation
Ammonia
Uses for microbial protein synthesis
The primary source of amino acids absorbed in the small intestine of ruminants is…
Microbial protein (60-70%)
Slide 4
Urea recycling
What are two pros of ruminant protein digestion
- Urea recycling provides rumen bacteria with N even during starvation
- Ruminant animals can convert low quality protein (N) to high quality protein (microbial)
Characteristics of high quality protein
Essential a.a. present
Highly digestible
Slide 9
Know flow of protein
Cons of ruminant protein digestion
- When not enough CHO available, microbes rely on aa for energy, leads to lots of protein degradation to ammonia
- Efficiency of N utilization is lower compared to non-ruminant animals (not very efficient protein digestion)
What factors affect microbial protein synthesis
- Ruminally degradable N (how much protein is in diet)
- Energy from CHO fermentation
- Quality of ruminally degradable N
- Passage rate of digesta
How does passage rate affect microbial protein synthesis
Microbial turnover in the rumen and predation by protozoa can result in excessive loss of microbial protein before it reaches the small intestine
What factors affect rate of passage
- Feed intake
- Particle size (smaller retained in rumen for less time = less protein breakdown)
- Digestibility of fiber
Ammonia toxicity is induced by
Excess urea or protein in the diet (from particularly high protein forage)
What deaminates urea to ammonia
Ruminal urease
How does microbial VFA production affect ammonia use
Insufficient microbial VFA production = ammonia not used up for microbial protein production
Slide 15
Idk
Why are fatty acids the most important lipid fraction
High energy
Some are essential
Impact rumen
Majority of f.a. are bound to… e.g.
Glycerol
e.g. triglyceride
What happens to triglycerides in the rumen
Degraded to free f.a. and glycerol (microbial lipase)
Glycerol ferments in rumen to VFA
What happens to f.a. in the rumen
Not degraded by ruminal microbial organisms
Extensively biohydrogenated in the rumen (saturated)
Phospholipids utilized as bacterial cell membrane
E.g. of biohydrogenation of f.a. in the rumen
Linoleic acid (18:2) -> Stearic acid (18:0)
What happens once f.a. are saturated
Absorbed in the duodenum
Why is biohydrogenation important
Unsaturated f.a. are toxic to bacteria
Slide 19**
Slide 19, 20
Transformation of lipids/f.a. in the rumen
Goal of biohydrogenation? Why?
Remove double bonds
- they have antimicrobial properties
- if too high = reduced microbial activity
Is biohydrogenation a direct process
No, intermediates are formed during the process and some of these are absorbed
What kind of fat do plants make
Unsaturated
Cis isomer
Double bonds separated by two single bonds
Describe structure of conjugated linoleic acid (CLA)
Unsaturated
Trans isomer
Double bonds are separated by one single bond
Main CLA intermediates formed… What determines which CLA type if produced?
Cis-9, trans-11, then trans-10 cis-12
Diet
Low ruminal pH leads to formation of what CLA isomer
trans-10, cis-12
What impact does the trans-10, cis-12 have on the ruminant
Results in suppressed milk fat production (inhibits lipogenesis in the mammary)
How does rumen lipid metabolism impact human health
- meat and milk higher in saturated fat
- bioactive metabolites (anti-carcinogenic, anti-atherogenic, enhance immune system)
How does rumen lipid metabolism impact animal performance
- biohydrogenation reduces supply of essential f.a. (impacts reproduction and immune system)
- too much f.a. can have antimicrobial effects
- produces bioactive metabolites (e.g. suppressed milk production by trans-10, cis-12)
Best substrate for the synthesis of CLA in the rumen
Essential f.a. e.g. C18:2
