Lecture 17: Dairy Nutrition 1

What is the DMI and as-fed intake for a dairy cow?

DMI: 50 lb/day (3.7% BW)

as-fed: 100 lb/day

Early lactation = ______ deficit.

energy

When is peak milk yield?

30-150 DIM

What peaks first after calving?

milk production

What is the typical dairy cow lactation cycle?

• Calving (Day 0)0–120 days: Open + lactating (non pregnant)

• 120–340 days: Pregnant + lactating

• Last 60 days: Dry period

• Calving interval: ~400 days

In peak lactation, how much DM does a Holstein consume?

3.7% of BW

What are the reproductive benchmarks of dairy cows?

Reproductive benchmarks

• Calving interval: ~400 days

• Days open: ~166 (goal lower - as close to 120 days as possible)

• First service: 45–60 days (ideal)

• Services per conception: ~2

What milking parlor has the milking machine in the middle and 2 rows of cows on each side?

Herringbone

What type of milking parlor has one set of milkers, so swings from one side to other?

swing over

What type of milking parlor allows more cows through and all cows exit on both sides at once?

rapid exit parallel

What type of milking parlor turns and has cows stepping on and off?

rotary

What confinement system provides shad and shelter, has non-slip floors, and stalls?

free stall + parlor

What confinement system has a base of sawdust and fresh bedding to provide improved cow comfort?

compost-bedded pack barn + parlor

Why is milking highly variable with intensive grazing pasture-based systems?

due to changing forage quality

What is the advantage and disadvantage to confinement production systems?

A: controlled nutrition

D: higher cost

What is the advantage and disadvantage to pasture production systems?

A: lower feeding cost

D: variable intake and milk production

What is the typical calving interval for a dairy cow?

13.2 months

Forage alone is insufficient for _______.

lactation

Why should grain be < 60% of ration?

> 60% grain → drastically alter rumen VFA production → decrease milkfat

Why should forage be fed before grain?

for rumination (saliva production) → buffer VFAs

What are the advantages to total mixed ration (TMR) where all ingredients are blended together so each bite is nutritionally balanced?

• Reduced sorting

• Consistent intake

• Easier monitoring

• Supports higher milk production

True or false: DMI is limiting in early lactation.

true

What are the diet composition guidelines for early lactation?

• NDF > 30% (mostly forage)

• balanced protein (RDP + RUP)

• fat: 1-1.5 lb/day

What is the optimal mBCS range to avoid metabolic diseases or low milk production/infertility?

3-3.5

What is the optimal BCS range for first-calf heifers to support growth and lactation?

3.25-3.5

Cows should not lose more than ______ BCS point(s) in first 60 days of lactation.

0.5-1