Lecture 11 - Ruminant Nutrition 1

Question 1

The fermentation vat; anaerobic environment with a constant temperature and pH, responsible for mixing ingesta

Answer 1

Rumen

Question 2

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 __________.

Answer 2

Reticulorumen; reticulum

Question 3

What is the main gas produced in the rumen during the anaerobic fermentation process?

Answer 3

Methane

Question 4

What are the benefits of saliva for the ruminant?

Answer 4

Provides lubrication and hydration to the rumen, and acts as an alkaline buffer

Question 5

Where do ruminal contractions push lighter/larger and denser/smaller particles of food, respectively?

Answer 5

Lighter/larger = back into rumen

Denser/smaller = into reticulum, and through reticulo-omasal orifice into omasum

Question 6

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

Answer 6

True

Question 7

In the young ruminant stomach, milk is curdled by _______ and eventually digested enzymatically.

Answer 7

Renin

Question 8

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

Answer 8

Rumination

Question 9

True or False: Rumination typically occurs when the ruminant is at rest

Answer 9

True

Question 10

What happens to carbohydrates during carbohydrate metabolism?

Answer 10

They are fermented to VFAs in the forestomachs (namely propionate, butyrate, and acetate)

Question 11

True or False: Acetate is metabolized to glucose via hepatic gluconeogenesis, but other VFAs (such as propionate and butyrate) cannot be converted to glucose

Answer 11

False; PROPIONATE can be metabolized to glucose, but ACETATE and BUTYRATE cannot

Question 12

Why is it important for VFAs to be adequately removed from the rumen and sent towards the liver?

Answer 12

Excess build-up of VFAs in the rumen can cause rumen acidosis

Question 13

How is acetic acid utilized in the ruminant body?

Answer 13

It is oxidized to generate ATP, and it is used as a source of acetyl CoA for lipid synthesis

Question 14

True or False: Glucose production is directly correlated to milk production (volume), as it is needed to form lactose.

Answer 14

True

Question 15

The liver is in a constant state of gluconeogenesis during __________, and requires a constant supply of propionate.

Answer 15

Lactation

Question 16

What are some metabolites utilized by the hepatocytes to provide glucose for the body?

(5 possible answers)

Answer 16

• Propionate
• Glycerol (from dietary fats)
• Lactate (from anaerobic glycolysis / fermentation)
• AA’s (from dietary protein / muscle catabolism)
• Glycogen (storage pool of glucose for emergencies)

Question 17

Negative energy balance occurs when…

Answer 17

Energy requirement > energy intake

Question 18

Why does gluconeogenesis increase when there is a negative energy balance?

Answer 18

Insulin decreases, so glucagon increases, causing increased gluconeogenesis

Question 19

What does the body use as an energy substitute when glucose is in short supply?

Answer 19

Triglycerides (because lipids are energy dense)

Question 20

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

Answer 20

Lipolysis

Question 21

The metabolization of FFA to 2-carbon units (acetyl CoA), which will combine with oxaloacetate to enter the TCA cycle for ATP production

Answer 21

Beta-oxidation

Question 22

What are some consequences of long-term negative energy balance (in terms of energy metabolism)?

Answer 22

• 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

Question 23

Why does the body make ketones, and can they be beneficial?

Answer 23

Utilizes and removes unstable acetyl-CoA; can be effectively used as an energy source in moderate amounts when energy requirements are high

Question 24

Why is it bad for ketones to exist in excess?

Answer 24

Ketosis will occur, which can lead to neurological signs, decreased appetite, pica, and many other things

Question 25

What is the difference between primary and secondary ketosis?

Answer 25

Primary = caused by diet too low in carbohydrate Secondary = caused by the animal being unable to feed due to a disease

Question 26

High concentrations of FFAs in the blood, hypoglycemia, and increased blood ketones are all clinical pathology changes associated with…

Answer 26

Ketosis

Question 27

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?

Answer 27

- Fresh forage - Molasses in water - Transfaunation (to stabilize microbiota and increase appetite) - Orogastric feeding of alfalfa gruel - Feeding via rumen fistula (severe cases)

Question 28

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

Answer 28

Transfaunation

Question 29

Why are animals in ketosis often given propylene glycol?

Answer 29

It can be metabolized by the liver to propionate to be used as a source of glucose

Question 30

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.

Answer 30

Increase

Question 31

What can NEFA measurements be used to monitor/measure?

Answer 31

Effects of ration changes, intake, and risk of ketosis

Question 32

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)

Answer 32

- Increase energy density - Review BCS in mid-lactation and dry cows - Ensure sufficient space per cow - Ensure feed is always available

Question 33

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…

Answer 33

Fatty liver disease

Question 34

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.

Answer 34

Triglycerides

Question 35

True or False: Ketosis is a more severe condition than fatty liver disease

Answer 35

False; fatty liver disease is more severe than ketosis

Question 36

Pregnancy toxemia is most common in small ruminants when they are pregnant with __________ offspring

Answer 36

Multiple (Pregnancy toxemia also called “twin lamb disease”)

Question 37

True or False: Ketosis is very commonly seen in conjunction with pregnancy toxemia, and this can be fatal to the dam and fetus(es)

Answer 37

True

Question 38

Which three diseases associated with negative energy balance share an overall similar pathogenesis?

Answer 38

- Ketosis - Fatty liver disease - Pregnancy toxemia