ruminant nutrition 2

voluntary feed intake

• aims

• what percent of bodyweight

• high NDF does what to the DMI

aim for at least 3 percent bodyweight per day- expressed as dmi

defined as the amount of feed which will be consumed when the animal has access to feed throughout the day

higher the ndf the lower the dmi

but if too rapidly digested then can cause rumen upset and reduce dmi

factors affecting feed intake

total mixed ration

• what is it

• what does it minimise

• by how much percent does it improve vfi

• why is fibre breakdown quicker

• mixture of both forage and concentrates

• minimises fluctuation in rumen pH

• improves vfi of a cow, up to 30 percent

• fibre breakdown quicker due to maintained pH and sufficient ERDP

• can add tasy supplements to feed

• make sure sorting is prevented

energy

• second to dmi when formulating a diet

• use megajoule

• must be fed with care to avoid excessive acid build up in rumen

• sufficient protein needed for breakdown

• sufficient long fibre to stimulate the buffering effect of saliva and the slow release of VFA

types of energy

• gross energy- total amount of energy the feed contains

• digestible energy- GE minus food that is not digestible and is therefore passed in the faeces

• metabolisable energy- DE minus losses in methane and urine

• ME is the energy available to the cow to use, roughly 80 percent of dietary energy

net energy

• ME-heat loss, as ME is turned into a useable form

• used for maintenance of body functions, milk productions, body tissue growth, foetal growth

• use ME when stating energy of a feed as have no idea how the erngy will be utlised by the animal

protein

• 2 types

• which protein is good at forming essential amino acids

• why cows with high vfi struggle to properly degrade protein

• what can excessive amino acids be used for

• third most important limiting factor

• udp and rdp

• non protein nitrogen must also be considered

• not only does the animal need protein but so do the microbes to form VFAs

• MCP very good at forming essential amino acids so ensure diet sufficient in them

• udp important to make sure some protein does reach small intestine (deliver essential amino acid to intestine)

• cows with high vfi will not always degrade protein sufficiently due to increased gas ransit

• excess9ve amino acids that are not needed for making prtein can beused b liver to form eneryg

protein aim for early, middle and late lactation

what is fermentable metabolisable energy

proportion of organic matter of a feed that is fermented in the rumen

effective rumen degradable protein

the microbial requirement for nitrogen ie the more the microbes have to work the more nitrogen they need

important not to have wasted fme in rumen with insufficient erdp and not have excessive erdp for fme available

what must foods be

• low energy low nitrogen eg straw

• low energy high nitrogen eg urea, pulps

• so that these can be used to supplement

• high energy low nitrogen eg molasses beet grain potatoes

• high energy high nitrogen eg oil seeds

metabolisable protein

• converted to net protein after loses taken into account

• maintenance has a 100 percent conversion rate to NP

• but loses due to weight gain, pregnancy, milk production, wool and hair growth

fats

• what does this allow farmers to do

• cost

• disadvantages and how is this overcome

• very high energy

• allow farmers to feed less conc to cows so they in turn eat mroe roughage

• cheaper than grain

• but impair microbe digestion so cause fall in food intake and rediced use of nitrogen which is then removed as ammonia

• protected fats given to prevent harming microbes eg whole oil seed

aims of diet

• when ammonia released from the breakdown of protein it must soon be assimilated into microbial protein so an energy soure must be on hand to do this

• energy and protein need to be released at the same rates throughout the day to ensure no wastage

• benefits of tmr

• urea added as a source of nitrogen when erdp is low

• argument for givving rup as that protein will be brken down by si and used for tissue protein or energy

how to know if cows are being fed correctly

• BCS

• bloat

• milk yield

• milk fat

• protein

• faecal consistency

• fertility record

• look at feed and left over

what is energy needed measured in

MJ/kg DM

energy consumed formula

energy consumed= DM x MJ/kg DM

problems with:

• how much percent NDF

• consequence of high conc

• with high energy concnetrate diets

• high protein diets

• high fat

-

BUT

•Need at least 30% NDF to promote rumination and help rumen health – but slower energy!

•

•SARA a possible consequence of high concentrates

§Crushing grain helps to make the starch slower release

§

•High energy concentrate diets increase proprionate production, and decrease the production of acetate which is needed to maintain milk fat levels

•

•High protein diets lead to excessive deamination, reduces liver function and fertility

•

•Excessive fat, which are high in energy, in the diet depresses appetite and alters milk fat %

formation of clot and what enzymes break it down

• milk ingested into abomasum

• milk (casein) clots due to pH, rennin and pepsin

• whey/lactose moves on to small intestine for digestion

  • clot is broken down by pepsin and lipase and the products absorbed in the small intestine

  • replacement feeds have less protein but higher energy, so often no clot

calf milk replacer

• how much crude protein is needed

• how much crude fat is needed

• what vitamin must be in adequate amount

crude protein

• protein provides essential amino acids for tissue synthesis in ruminants

• require more than 22 percent crude protein

crude fat

• provides a conc energy source and essential fatty acids

• calves raised in a cold env have higher requirement for energy

• require more than 20 percent

all contain adeuqat vitamin e

how much calf milk replacer

• how many times a day

• how much percent of bodyweight

• weight gain aim per day range

• little and often

• at least twice a day

• aim to feed 15 percent bwt daily up to 20 percent

• aim 500-1000g/day calf weight gain

dietary diarrhoea

• milk enter rumen due to failure of oesophageal groove/drink for thirst

• lack of clotting and digestion

• whole milk passes into SI where good source for bacteria replication

• putrefication causes malabsorption in SI and thus diarrhoea

how do bacteria develop in the rumen?

• which vfa is important for papillae

• what will happen to restricted calves

• initially none

• ad lib water needed to allow bacteria growth

• can offer conc as soon as possible

• no anaerobic bacteria until calf starts to eat conc

• anaerobic bacteria ferment carbs and protein in pellets to form VFAs partcularly propionate which is essential for papillae formation

• conc fed ad lib, as if restricted calves will gorge and cause rumen pH to drop

forage

• what does is promote growth of

• what does it prevent formation of

• promote growth of muscular part of rumen

• prevent formation of keratin on papillae which would prevent vfa absorption