ruminant nutrition

what does nutrition affect

concentrate examples

40 percent

• cereals

• cake

• soya

• rapeseed

• molasses

forgage 60

• grass

• brassicas

• roots

• straw

• maize

relative neonate stomach volumes

• rumen 25

• reticulum 8

• omasum 8

• abomasum 60

adult

• rumen 62

• reticulum 11

• omasum 5

• abomasum 22

normal condition

• temperature

• aerobic or anaerobic

• pH range

• how much saliva per day

• how much bacteria per ml

• how much protozoa per ml

• 38-40 degrees

• anaerobic

• ph 6.0-6.5

• buffering capacity- salivation (150l/day cows)

• prouces gas co2 and ch4

• 10^9-10^10 per ml of bacteria

• 10^6 per ml of protozoa

normal rumen including

• what do large particles form

• what is this important for

• innervation

• size of particle required to leave the rumen

• aim

• as food enters same vol leaves

• soluble components ie sugars soon fermented

• insoluble gradually broken down by microbes

• large particles form a fibrous mat until broken down

• the fibre mat is important for rumen movements and saliva flow

• via cnx

• particles need to be about 3-4mm to leave rumen

• high oughage diets increase transit time due to salivation but this decreases digestion

• aim to have quickly digestible small sized conc that tprovide max energy quickly w/o rumen acidosis

reticulum

• no absorptove capactuy

• cnx

• mechanical

• rumen contraction start

• microbial

• larger proportionally in small ruminatns

omasum

• biphasic

• first contraction removes fluid

• fluid with vfa and nacho3

• ths is then absorbed

• second cotnraction expel solids into abomasum

• cnx

abomasum

• proteins broken down to absorb in si

• intrinsic motility

• weak contracton strenghten as they reach the pylorus to aid expulsion of contents

• larger proportionally in small ruminant

small intestine

• where does neutralisation of stomach acid take place

• where is the site for absorption

• what does the ileum absorb and what else does it contain

• what prevents backflow

• duodenum neutralise stomach acid

• pancreas and bile duct secrete here

• jejunum site for absorption

• ileum absorb remaining nutrient and b12, contain lymphoid tissue

• ileocaecal valve prevent backflow

large intestine

• where is the caecum blind ended sac

• what is absorbed in the colon

• what do bacteria produce

• smaller than si

• caecum blind ended sac in right sub lumbar fossa

• storage and breakdown

• colon primary site for water and na absorption

• bacteria in colon produce necessary vit k and thiamine

• used as channel for removal of waste

microbes

• bacteria protozoa and fungi

• feed on forages

• via anaerobic fermentation they produce end products that can be utlised by the cow as well as the microbes themselves

• digest up to 70 percent dry matter but microbes have differing fnction

• essentail diet contains sufficient energy and protein for the growht and mutiplication of microbes so that rate of digestion is maximised

end product of microbes

• VFAs- main energy source

• ammnia- used to form micorbial protein, microbial bacteria are digested and are cows main source of protein

• gases co2 and methane

fibre analysis

Crude Fibre (CF):  Crude fibre is a traditional measure of fibre content in feeds.

Neutral detergent fibre (NDF) and acid detergent fibre (ADF) are more useful measures of feeding value, and should be used to evaluate forages and formulate rations.

Neutral Detergent Fibre (NDF):  Structural components of the plant, specifically cell wall. These are slowly digested. An increased NDF → decreased intake

Acid Detergent Fibre (ADF):  The least digestible plant components, including cellulose and lignin. This often has a poor energy content and is excreted in the faeces

fermentation of carb such as straw and fibrous hay

• which fatty acid

• what are bacteria sensitive to and why is this an issue

• straw, fibrous hay:

• large proportion of acetate

• bacteria that do this are sensitive to fat and high acifity

• so cows with high fat diets or have acidosis are unable to break down celluloses

carbs consist of…

• cellulose

• hemicelluloses

• starch

• water soluble sugars- fructans mainly

lush pasture

fermentation of potatoes/beet

• which volatile fatty acid

• what does this bacteria supress

• rapidly digeted

• starch

• incresae level of propionate rapidly

• bacteiria not affected by acidity but supress acetate forming cellulose diesting bactera

• 
  

fermentation of molasses, glucose, dissolved sugar

• similar bacteria to thse that break down potatoes and beet

• do not have a profound effect on reducing rumen pH

vfa

• what are they used for

• percent of energy that they provide

• what do they help promote the growth of

• are major end products of fermentation because c skeletons cannot be completely oxidised to co2 in the absence of o2

• readily absorbed into the blood stream and transported to the liver where they are covnerted to other energy sources

• used for hepatic gluconeogenesis, lipogenesis in peripheral tissues and milk synthesis

• 
  

  

  Rapidly absorbed to minimise acidosis

  

  This is why try to dissuade farmers from feeding in parlour

  

  Determine milk fat and protein content

  

  Provide 70% cows energy

  

  Help promote growth of rumen papillae

  

  Absorbed through rumen wall and go to liver

  

  Used as an energy source by the liver

acetate

• what percent of vfas produced does it make up

• what kind of diet does it predominate in

• function

• what is it a precursor for

• how many moles atp per mole cetate via acetyl coa?

55-65% of VFAs produced is acetic acid

It predominates on a high roughage diet

Synthesis of fatty acids in adipose

•Is a precursor for mammalian milk fat

•Found in peripheral circulation

•Some is also used for muscle metabolism and body fat

•

Net gain of 10 (moles) ATP per mole acetate via acetyl CoA entering Krebs (TCA) cycle

butyrate

• percentage

• function

• what kind of food is it found in

• what does the liver turn it into

• net gain of how much ATP per mole butyrate

10-15% of VFAs produced is butyric acid

Provides energy to the rumen wall

It doesn't vary in proportion to other volatile fatty acids

Found in poorly fermented silage

Liver turns into betahydroxy-butyrate (BHBs), used by muscle, milk gland

Net gain of 25 ATP per mole butyrate (via acetyl CoA entering Krebs)

propionate

• percentage

• what kind of diet

• what is it a precursor for

• how does it provide energy

• what is it used for

• net gain how much atp per mole

18-21% of VFAs produced is propionic acid

Predominates in a high concentrate diet

Precursor of glucose

Provides energy via the conversion of blood glucose in the liver

Used in lactose (milk sugar) synthesis

Net gain of 18 ATP per mole propionic acid via Krebs cycle

proteins which do not get broken down in the rumen

undegraded dietary protein- UDP

rumen degradable protein

• rumen microbe

• nitrogen and amino acid used by the rumen microbes to grow

• as microbes can use any source of nitrogen little is needed

• must be sufficient as if insufficientthen not enough microbes and carb breakdown slow

microbial crude protein

• what is it

• composition

• or BCP- bacterial crude protein

• flow of protein contained in rumen bacteria which is produced in the rumen and is passed into the intestine for digestion

• 80 true and 80 digestible

• protein that reaches abomasum and si is euther mcp or udp

non protien nitrogen- how can more protein reach the small intetine than actually consumed

If excessive RDP then the excessive ammonia is absorbed into the blood and carried to the liver

Liver turns NH4 into urea, then excreted in urine

If insufficient protein in diet then more ammonia returned to rumen

This ammonia is then turned into MCP

In this way, more protein may reach the SI then is actually consumed

non protein nitrogen compoud

This is why urea added to the diet

Rumen acts as a leveller so constant stream of protein passing to SI

Must ensure enough energy in the diet for protein synthesis

If ammonia too high can overload liver capacity and cause toxic levels of NH4 in the blood.

lipid

• ideal amounts

• what amount inhibits microbe action

• what type is not absorbed by the rumen

Minimal digestion in rumen (ideally <50g/kg)

>100g/kg inhibits microbe action

LCFAs not absorbed by rumen

Most fats consumed are triacylglycerides (TAGs) which are hydrolysed by lipases

Fats are then saturated in the rumen

Pass to SI for digestion

If treated, dietary fats can remain unsaturated when get to SI and these alter milk fat content

what happens to unsaturated fat

become saturaed in the rumen

why is lignin not digested

low o2 content and condensed structure which prevents hydrolysis

it hinders the breakdown of associated cellulose so lower the liginin more is digested