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practical dairy cow nutrition
Veterinary Medicine

Additional Veterinary Medicine Flashcards




feed for ruminants derived from plants
Buffer feeding

ensuring maximum DMI of good quality forage is by the use of buffer systems: 

need to be 

1. nutritious

2. palatable

3. confine the cows with access to buffer only so they eat it 

concentrate: forage DM ratio cannot exceed 60:40 because ruminal acidosis may become a problem. may be purchased as compound feeds, blends, or as raw materals ( straigts) which are fed as part of a TMR
Feeding strategies

traditional method was to feed forage in a trough ad lib with concentrates in the milking parlour but there is a risk of ruminal PH fluctuations.

- various methods were devised to try and reduce levels of concetrate slug feeding:

1. split concentrate feed into 3 meals a day, by feeding a third midday meal

2. TMR/complete diet feeding. receive this mixture 24 hrs a day, minimal rumen fluctuations a day

4. out of parlour feeders to spread the concetrate load out throughout the day- expensive 

one problem with practical feeding on farms?

group feeding

most farms will have a max of three feeding groups ( high, mid and low yielding group). but there is a recent trend of feeding single TMR to the whole herd in that the cows will regulate their own DMI in relation to requirements thus high yielding cows will eat more. HOwever late lactation cows become fat, leading to overfat dry cows at calving with further reduced DMI. 

Dry/ transitional cow nutrition

the dry period can be split into two periods: 

1. the first month of the dry period ( far off dry period), 2-1 month prior to calving, should be viewed as a period to allow the cow to recuperate after calving and get her into the correct BCS at calving2.5-3. Overfat cows should be slimmed on low quality rations ( straw based diets), whereas thin cows should be fed to gain BC. 

2. The transitional period: 3wk pre to 3wk post calving. feeding during this period is crucial to the success of the subsequent lactation, succesful transition will lead to increased DM intakes. 

The dry cow during this period in the run up to calvin as to cope with increasing nutrient demands from the foetus and increasing requirements for the initiation of milk production- all combined with a reduction in DMI. 

Therefore: cows should be in BCS of 2.5-3 at calving. fat cows at calving have depressed DMI, thus rapidly lose BC during early lactation leading to subsequent health and fertility problems. only alter BC during the far off period ( 1-2 months prior to calving). 

- provide 24 hour access to food. 

- should be fed 2-3kg of concentrates per day during this period which will : 

- increase the energy density of the ration as DMI falls ( maintaining energy intake)

- allows acclimatisation of the rumen microves to the post calving diet. 

- maximise DMI to reduce the extent and duration of the drop in DMI at calvin, cows that eat more prior to calving, eat more after calving. 


milk quality influences

1. stage of lactation: butterfat and protein tend to decrease as milk yield increases. dilution effect

2. age:quality tend to decrease as animal gets older 

3. genetics

4. disease

5. nutrition

Milk butterfat

50% of milkfat is synthesised from the VFAs butyrate, acetate from the rumen, produced by the optimum digestion of fibre in the rumen. 

may be altered by:

1. increasing the amount of effective long fibre in the ration, wil increase levels

2. high levels of concentrate feeding: leads to an increase in propionate and reduced acetate ( reduced milkfat)

3. rumen PH altered by adding bicarb, get more acetate production

4. adding saturated fats will increase levels since 40% of butterfat comes from fat in the diet. 

Milk butterfat is very responsive to dietary changes 

Milk protein

mostly obtained from microbial protein which is dependent on the energy content of the diet. nearly reflects long term energy status. May be increased by:

1. forage changes- maximising DMI during early lactation to minimise NEB

2. concentrate changes: increased levels 

3. dry cow management: control BCS to ensure minmise NEB


Subacute ruminal acidosis 



with the increase in conctrates in feeding, results in increased quantities of rapidly fermentable carbohydrates that result in acid production in the rumen and a consequent fall in rumen ph below optimal range of 6-7. 

You can see loose faeces, with excessive soiling of hindquarters, cows swishing their tails due to gut upset, reduction in milk butterfat, reduction in milk yield, spilling their cud, going off their food

Risk factors for the development of SARA

1. inadequate effective long fibre in the ration

2. excessive levels of concentrate feeding, starch and sugars

3. poor nutritional management: poor dry cow transitional diet, variable DMI

4. poor cow comfort

Diagnosis of SARA

assess ration

assess cows- rumen fill, faceal consistency

herd assessment: presence of NEB/ketosis in early lactation, milk production, quality ( butterfat levels), rumination, incidence of disease, cow comfort

Rumen ph measurements, ph sample from 12 cows is measured using a ph meter or indicator papers. DEFINED BY THE RUMEN PH LESS THAN OR EQUAL TO 5.5 in ATLEAST 30% of the animals sampled. 

Prevention and treatment of SARA

1. feed a suitable transitional diet for 3-4 weeks prior to calving

2. increase amount of effective long fibre in the ration

3. increase DMI to ensure ingestion of sufficient forage. 

4. avoid sudden increases in concentrate feeding                       

5. improve cow comfort. 

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