Lecture 11 - Ruminant Nutrition 1 Flashcards
The fermentation vat; anaerobic environment with a constant temperature and pH, responsible for mixing ingesta
Rumen
Feed, water, and saliva are delivered to the __________ through the esophageal orifice, while heavy objects (such as grain or foreign objects like rocks/nails) go to the __________.
Reticulorumen; reticulum
What is the main gas produced in the rumen during the anaerobic fermentation process?
Methane
What are the benefits of saliva for the ruminant?
Provides lubrication and hydration to the rumen, and acts as an alkaline buffer
Where do ruminal contractions push lighter/larger and denser/smaller particles of food, respectively?
Lighter/larger = back into rumen
Denser/smaller = into reticulum, and through reticulo-omasal orifice into omasum
True or False: In young ruminants, suckling causes reflexive closure of the esophageal groove so that the milk by-passes the rumen and goes directly to the omasum
True
In the young ruminant stomach, milk is curdled by _______ and eventually digested enzymatically.
Renin
Regurgitation of ingesta from reticulum, followed by remastication and re-swallowing; allows for effective mechanical breakdown of roughage, which increases substrate surface area for fermentation microbes
Rumination
True or False: Rumination typically occurs when the ruminant is at rest
True
What happens to carbohydrates during carbohydrate metabolism?
They are fermented to VFAs in the forestomachs (namely propionate, butyrate, and acetate)
True or False: Acetate is metabolized to glucose via hepatic gluconeogenesis, but other VFAs (such as propionate and butyrate) cannot be converted to glucose
False; PROPIONATE can be metabolized to glucose, but ACETATE and BUTYRATE cannot
Why is it important for VFAs to be adequately removed from the rumen and sent towards the liver?
Excess build-up of VFAs in the rumen can cause rumen acidosis
How is acetic acid utilized in the ruminant body?
It is oxidized to generate ATP, and it is used as a source of acetyl CoA for lipid synthesis
True or False: Glucose production is directly correlated to milk production (volume), as it is needed to form lactose.
True
The liver is in a constant state of gluconeogenesis during __________, and requires a constant supply of propionate.
Lactation
What are some metabolites utilized by the hepatocytes to provide glucose for the body?
(5 possible answers)
- Propionate
- Glycerol (from dietary fats)
- Lactate (from anaerobic glycolysis / fermentation)
- AA’s (from dietary protein / muscle catabolism)
- Glycogen (storage pool of glucose for emergencies)
Negative energy balance occurs when…
Energy requirement > energy intake
Why does gluconeogenesis increase when there is a negative energy balance?
Insulin decreases, so glucagon increases, causing increased gluconeogenesis
What does the body use as an energy substitute when glucose is in short supply?
Triglycerides (because lipids are energy dense)
The process of breaking lipids down to glycerol and FFAs; facilitated by hormone sensitive lipase (HSL); promoted by negative energy balance, high glucagon/low insulin, & cortisol/epinephrine release due to stress
Lipolysis
The metabolization of FFA to 2-carbon units (acetyl CoA), which will combine with oxaloacetate to enter the TCA cycle for ATP production
Beta-oxidation
What are some consequences of long-term negative energy balance (in terms of energy metabolism)?
- Glycogen reserves quickly deplete
- Limited breakdown of muscles to provide AA’s for oxidation
- Oxaloacetate for FA oxidation is limited and depleted long before acetyl CoA is used up
Why does the body make ketones, and can they be beneficial?
Utilizes and removes unstable acetyl-CoA; can be effectively used as an energy source in moderate amounts when energy requirements are high
Why is it bad for ketones to exist in excess?
Ketosis will occur, which can lead to neurological signs, decreased appetite, pica, and many other things
What is the difference between primary and secondary ketosis?
Primary = caused by diet too low in carbohydrate
Secondary = caused by the animal being unable to feed due to a disease
High concentrations of FFAs in the blood, hypoglycemia, and increased blood ketones are all clinical pathology changes associated with…
Ketosis
Ketosis can be treated with high quality carbohydrate supply - what are some ways to provide this to a ruminant experiencing ketosis, and also guarantee they are consuming these carbs?
- Fresh forage
- Molasses in water
- Transfaunation (to stabilize microbiota and increase appetite)
- Orogastric feeding of alfalfa gruel
- Feeding via rumen fistula (severe cases)
The process of transferring ruminal fluid via orogastric tube from a healthy cow to a sick cow (with a fistula) to help to stabilize microbiota and increase appetite
Transfaunation
Why are animals in ketosis often given propylene glycol?
It can be metabolized by the liver to propionate to be used as a source of glucose
It is important to __________ energy density in a cow’s ration in the last 3 weeks of their dry period, since appetite gradually decreases after calving, in order to prevent ketosis.
Increase
What can NEFA measurements be used to monitor/measure?
Effects of ration changes, intake, and risk of ketosis
If more than 40% of cows in a group are exhibiting elevated NEFAs, what are some steps that can be taken to rectify this problem?
(Multiple answers)
- Increase energy density
- Review BCS in mid-lactation and dry cows
- Ensure sufficient space per cow
- Ensure feed is always available
In obese, lactating ruminants, there is higher availability of FFAs in the body that can cause saturation of the ketone synthesis pathways. This can cause a condition called…
Fatty liver disease
In fatty liver disease, hepatocytes esterify FFAs to ____________, which are then stored in the cell until the cytosol is full of fat and cell function is impaired.
Triglycerides
True or False: Ketosis is a more severe condition than fatty liver disease
False; fatty liver disease is more severe than ketosis
Pregnancy toxemia is most common in small ruminants when they are pregnant with __________ offspring
Multiple
(Pregnancy toxemia also called “twin lamb disease”)
True or False: Ketosis is very commonly seen in conjunction with pregnancy toxemia, and this can be fatal to the dam and fetus(es)
True
Which three diseases associated with negative energy balance share an overall similar pathogenesis?
- Ketosis
- Fatty liver disease
- Pregnancy toxemia
