Dairy Rations Flashcards
What best determines productivity of lactating dairy cows?
Feeding
Feed represents how much of total feed cost?
~50%
Nutrient requirements for ____ are often several times the requirements for ____
lactation
maintenance
More variation exists in ____ content than ____ among various forages and concentrates
protein
energy
What to use when balancing dairy cow rations
NEL, CP, and fiber content
Can a producing dairy cow eat enough forage to meet her nutrient needs during lactation?
No
Feed intake may be stimulated by:
feeding several times per day
providing a variety of forages
Concentrate mixture includes:
grains
milk feeds
protein supplements
minerals
The mixture fed will depend on:
forage being fed (low protein forage = high protein concentrate)
availability
cost
Amount of concentrate fed will depend on:
amount of forage consumed
amount of milk produced
composition (% fat) of milk produced
Limit concentrate to a maximum of ____ regardless of comparative costs
65%
What happens when more than 65% of concentrate is consumed?
change in VFA production causing a decrease in milk fat
Concentrate intake can be affected by
palatability
time available to consume
Describe early lactation
- milk production rapidly increases, peaking at 6-8 weeks after calving
- increase grain intake to meet energy requirements, but avoid excessive levels (<65% of total DM)
- extra dietary protein allows more efficient use of body fat for milk production since cows are usually losing BW
- limit urea to 0.4-0.5 lb/d
Describe peak lactation
- max intake is reached at ~12-14 weeks and cows should be kept at peak lactation as long as possible
- grain intake may reach 2.5% BW, forage intake should be at least 1-1.25% BW to maintain rumen function
- feed several times daily
Describe mid- to late lactation
- milk production is declining, cow is pregnant
- match grain intake to milk production ; avoid wasteful grain feeding to low producers
- avoid overconditioning
Describe dry period
- forage quality not as critical
- DM intake ~2% of BW
- ~2 weeks before calving increase grain feeding (~1% BW) ; helps decrease ketosis
- feed low Ca ration to help prevent milk fever at calving
- 4-8 week dry period, depending on age and physical condition
Describe ketosis
- high blood and urine ketone levels
- low blood sugar
- depleted glycogen reserve
- LACK OF APPETITE
- just giving glucose will not work in ruminants
- propylene glycol is best - use steroids
- high producing cow -> needs glucose for milk -> begins using body fat -> acetoacetic acid, b-hydroxybutyrate, and acetone -> KETOSIS!
- cattle prone can be fed high quality before calving and increase substantially after parturition
Describe milk fever
- correlated with number of lactations
- 75% of cases occur at or within 24 hours of parturition
- decrease in blood Ca (hypocalcemia)
Milk fever symptoms
drowsy
head turns to flank
Milk fever treatment
IV calcium
Milk fever prevention
- low Ca diet 2-3 weeks before calving
- Vit. D before calving -> BUT toxic so must know exact calving date
- decrease DCAD (ratio of cations to anions in the diet)
Feed young growing cows enough for …
growth as well as for maintenance and milk production
It is best to group cows by ____
production level
More cows are underfed on ___ than ____
energy
protein
Concentrate mix should contain:
- energy
- protein
- 0.5-1% trace mineralized salt
- 1-2% Ca-P supplement
- No more than 6% molasses
- No more than 1% urea
It is best to feed some ____ with silage
hay
Fiber requirement
CF = ~17%
ADF/NDF = ~21%/35%
Cow will consume ____ of water per lb of milk produced
3-5 lbs
Relationship of feeds and milk flavor
remove from wheat pasture several hours before milking to prevent off-flavor
2 protein sources ingested
CP and NPN
2 protein sources available in the small intestine
bypass (from CP)
microbial (from NPN)
DIP
Rumen Degraded Intake Protein
- degraded by microbes in the rumen
- microbial protein
- end up in SI
UIP
Rumen Un-digestible Intake Protein
- by-pass/escape protein
- end up in SI
Advantage for using DIP/UIP
- decrease overall CP in diet
- resulting in reduced cost of ration
Describe Urea Fermentation Potential
- evaluation of the useful urea in the ration
- estimation of the g urea/kg DM that can be converted to microbial protein
- value is dependent upon the energy in the diet
- negative value indicates no protein would be synthesized with the energy available
BST
bovine somatotropin = natural product produced in the pituitary (growth hormone)
BST injected SQ every ____
14 days
BST is FDA approved for healthy cows beginning
9th week of lactation
BST injection results in
- immediate (2-3 d) increased milk production (8-12% or 5-15 lbs milk/d)
- Nutrients directed from body tissues to mammary gland
- increased intake (nutrients) needed because of improved performance
- DM intake not increased (as result of BST) until 3-6 wks post injection (3-5 lb/d) - usually results in decreased body condition
BST effect on reproduction
- increase days open (decrease pregnancy rate)
- increase twinning
- increase lameness (decrease bone and muscle mass)
- increase mastitis
