Voluntary Feed Intake Flashcards
How to Measure Feed Intake?
- Difficuty of metabolic weight is that cows will all be a different weight

Mixer Wagon

- To properly cut the straw and other rations until they are of appropriate size
- they won’t eat it if it is too long!!
Need to increase the roation and leave in for longer for shorter straw
Why is Feed Intake Imp?
- having a lower maxiumum feed intake and having a better utilization?
- we don’t want our dry cows to gain much weight
- we need to look after their weight and feed intake for the animals to thrive to best potential

Distension Feedback

- the idea that when you are full you stop eating, but is not always true
Other Factors affecting VFI
- effects of Feed Intake

Distension or Fill Feedback
- Try to fill the rumen to reach that stretch factor..
- Distension will stop the feed intake at some point even though there may be weight loss

Water in Rumen
- 2 types of water
- water with dry food will not have much affect on VFI
- but the water within plants will- the bulk is still there

Water Holding Capacity
- essentially osmosis
- slower transit through the guts, which is good for absorption of nutrients, but also means lower food intake
- chopping of the feed will have the opposite effect: make the transit time faster and increase VFI (fiber is shorter, will pass through rumen faster)

DMI and retention time
- Low DMI in the trial will have a lower passage through the gut, will affect how this matter is digested
- proteins will go quicker and be absorbed less efficently
- farmers try and balance this

Maintenance Level
- Intake of food will heavily affect the production level

Inert Fill
- happens to cows and sheep in late pregnancy
- nutrients will be in the gut for shorter
- means we need to feed more nutritious or digestible feed, need to optimize increased flow rate
- ex: twin lamb or triplets

Rumen Outfow Rate
- a bout of rumen acidosis will lead to more pressure in the rumen due to the stasis

VFA’s
- another chemical reason that we have an effect on the feed intake
- the more fermentation there is, the lower feed intake?
- Poorly fermentated silages produce a lot of butyrate and lead to poor intake

Thermostatic theory
- ruminal process is actually exothermic, they get warm by eating
- they will start eating more at -15C to keep themselves warm
- so more of an issue for chickens in cold than cows

Cows and Heat Stress
- Cows have more of an issue with overheating as the rumination is exothermic
Post Digestive Feedback

- If you have a low glucose level in your blood, you want to go feeding

Glucose: how about Farm Animals?
- have less glucose dependance than other species
- hgiher proprionic acid will reduce feed intakes
- all the glucose preferentially goes into our production cows for milk and that is the way we have bred them

Lipostatic Theory
- Higher the fat store, the lower the appetite
- theory is not very effective in cows

Hepatic Oxidation Theory (HOT)
- Idea that there is plenty of E in the liver which should decrease need to feed?
- resources for ATP are plentiful in liver and that is why they don’t eat more since liver is saying that is enough

Leptin
- We have been breeding cows for high growth route
- It is developed in the fat tissue

Dairy Cows and Negative E Balance
- Negative E balance is what we refer to as the lag phase

So How much Do animals eat?

Factors for feed intakes
(Dairy, Beef, Dog)
- demand for production in cows will mainly outweigh all the others

Nutrient Needs
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Maintenance

Feed Intake and Maintenance

- the more milk she makes the more she will need for production
- pregnancy equates to about an 8L milk yield

High E diets

- apples can be too digestible and lead to acidosis
Body Weight Loss

Two Sources for E in Forages
- cell wall is good for bulk but not necessarily the E req.

Plant Composition

- higher the lignin factor the lower the digestibility
- The more bulky the plant is the “ “
- The older the plant the higher the lignin

NEutral Detergent Fiber
(NDF)

Forage NDF vs. Intake
(NDF intake graph)
- curved linear relationship

Acid Detergent Fiber
- ADF is a good indicator of the digestibility

Silage Quality
- silage pH is highly dependent on the dry matter quality of that silage
- Amount of protein that has been degraded (ammonia N) will have a massive impact on the intake of that ration by the cow

Anti-Nutritional Factors
- tannins will have a large impact on the ……..
- Tannins are quite casutic to the gut lining and this can be a major consequence: oak poisoning –> especially after a stormy day
- GI ulcerations will allow tannins and toxins to be absorbed

Anti Nutritional Factors
(Lectins, Glucosinolates, Saponin)
- Farmers can only include a certain amount of oilseed rape as they are restricted by anti-nutritional factors
- Saponins can negatively affect the ruminal flora

Other Factors on Feed Intake
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