Merck Manual

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Parameters Useful to Monitor Health and Production of Dairy Herds

Parameters Useful to Monitor Health and Production of Dairy Herds

Parameter

Goal

Adult Cow Disease

Average percent of herd lame

<25%

Metritis/endometritis incidence

<5%–25%

Subclinical ketosis (>1.2 mmol/L)

<10%

Clinical ketosis

<2%

Left displaced abomasum

<3%–5%

Milk fever

<3% of adult cows calving per month

Retained fetal membranes

<3% of cows calving per month

Cut point for ruminal acidosis

pH <5.5

Clinical mastitis monthly incidence

<3% of lactating herd

Culling and Death Loss

Annual average overall cull rate

35%

Annual average selective cull rate

>15%

Annual death loss

<10%

Annual disease and injury culling

<5%

Annual reproductive cull rate

5%–10%

% Removed <60 days in milk (lactation = 1)

<4%

% Removed <60 days in milk (lactation >1)

<6%

Udder Health and Milk Quality

SCC legal limit

750,000 cells/mL

SCC farm goal

<150,000 cells/mL (or adjust for a dairy)

Standard plate count legal limit

100,000 CFU/mL

Standard plate count farm goal

2,000–4,000 CFU/mL

Preliminary incubation count

2,000–6,000 CFU/mL

Bulk Tank Cultures - Bacterium

Streptococcus agalactiae

0 CFU/mL

Staphylococcus aureus

<50 CFU/mL

Staphylococcus spp

<1,000 CFU/mL

Mycoplasma spp

0 CFU/mL

Environmental streptococci

<1,000 CFU/mL

Coliforms

<500 CFU/mL

General Reproductive

Standard

Average days open

100–110 (ideally low 100's to achieve 12-mo calving)

Average gestation

283 days

Calving interval

13.5 mo

Average days in milk

200

Percentage of cows <90 days in milk

25%

Percentage of cows 90–180 days in milk

25%

Voluntary waiting period (VWP)

50–60 days for cows; 80–90 days for heifers

Days in milk at first breeding

Goal: VWP + 11 days

First service conception rate

40%

Heat detection

Goal overall >50% (national average <40%)

Intervals between breedings

18–24 days for 65% of cows

Length of estrous cycle

18–24 days

Overall conception rate

>35%

Services per conception

2

Definition of pregnancy rate

Heat detection rate × conception rate (21-day interval)

First cycle pregnancy rate

>30%

Percent pregnant by three cycles

>50%

Overall pregnancy rate

>20%

Percent of herd pregnant

50%

Pregnancy Diagnosis

When to do pregnancy checks

>40 days after being bred

Ability to locate amnion

42–65 days

“Membrane slip”

Day 30 to term

Ability to locate fetus

65–95 days

Placentomes present

After 3 mo of gestation

Ability to sex fetus

After 60–70 days of gestation

“Placentomes"

Day 70 to term

By amnion size (days)

35

7 mm (½ finger)

42

15 mm (1 finger)

48

35 mm (2 fingers)

53

55 mm (3 fingers)

58

75 mm (4 fingers)

62

90 mm (palm)

65

105 mm (hand)

By fetal crown-nose length (days)

70

1.5 cm (1 finger)

80

3.5 cm (2 fingers)

90

5.5 cm (3 fingers)

100

7.5 cm (4 fingers)

110

9 cm (palm)

120

10.5 cm (hand)

Postpartum Involution

Lochia (normal)

Day 1–2

Bright red blood, thick mucus, little smell

Day 3–7

Dark red, thin, odor not foul but objectionable

Day 7–14

Progressively less red to white to translucent, thicker, smell improves

Entire uterus palpable

2 wk

Full reduction in size

40–45 days

Epithelialization complete

40–45 days

Occurrence of endometritis

>26 days after calving

Full uterine involution

40–45 days postpartum

Abortion

Normal embryonic loss (<50 days)

<10%

Average rate of early embryonic loss

15%

Normal rate of abortion

3%

Major infectious abortion agents

Bovine viral diarrhea, mycotic, leptospirosis, Neospora

Noninfectious causes

Heat stress

>90°C, 80% relative humidity

Toxins

Nitrates: methemoglobinemia

Plants

Locoweed, snakeweed, pine needles, lupine

Urea

Excess rumen degradable protein or nonprotein nitrogen; milk urea nitrogen 10–14 mg/dL