1. Estrus Detection
Dr. Ray Nebel
Dept. of Dairy Science
Virginia Tech

2. Estrus Detection Estrus Behavior Evaluation of Estrus Detection
Factors Affecting Estrous Behavior
Methods to Enhance Efficiency of Estrus Detection

3. Estrous Behavior Primary sign of estrus Secondary signs of estrus
“Standing to be mounted”
Secondary signs of estrus
Attempting to mount other cows
Mucous discharge
Swelling & reddening of the vulva
Restlessness, bellowing, chin resting, trailing other cows

4. What Causes Cows to Express Estrus?
High blood level of estrogen in presence of a low level of progesterone
pre-ovulatory follicle in absence of a functional corpus luteum
Involuntary expression
edema & hyperemia of vulva, mucus secretions
Voluntary expression
Influenced by environment

5. Days of the Estrous Cycle
walking
Time eating
milk yield
Mounting activity
Standing to be mounted
Estrus
onset
ovulation
Days of the Estrous Cycle

6. Variation in Estrus Activity
(Duration) ( Intensity)
Beef heifers:  8 h  19 std
Dairy cows:
Holstein:  7 h  7 std
(17 Herds)  5 h  7 std
Jersey:  5 h  7 std
Dairy heifers:
Holstein: 11  7 h  7 std
Jersey:  6 h  17 std

7. Factors Affecting Estrus Behavior
Influence of Herdmates
Environmental Temperature
Footing Surface
Foot and Leg Problems
Nutrition and Level of Milk Production

8. Calving Interval Days to First Service Estrus Detection
Breeding Season
Max. Number of Services
Estrus Detection
Conception Rate

9. Evaluation of Estrus Detection
Pre-Service
Post-1st Service

10. Pre-service Estrus Detection Efficiency
Days in estrous cycle
X 100
((Days 1st Service - VWP) + 11) 21
X 100 = 41.2%
( ) + 11

11. Post-1st Service Estrus Detection Efficiency
(S/P-1)  (ADO - DFS) 21
( )  ( )
X 100
X 100 = 61.7%

12. Characteristics of Herds with Inefficient Estrus Detection
Very few estrus periods observed or recorded before first service
Average days to first service greater than 20 days beyond the VWP
Excessive interval between services. Average interestrual interval greater than 30 days.

13. Characteristics of Herds with Inefficient Estrus Detection
More than 15% of the cows open at pregnancy examination 35 to 45 days
Palpation confirms cows are cycling normally but estrus periods are not detected
Less than 50% heats observed on DHI 202 Herd Summary

15. 14 12 10 8 6 4 2 Seasonal effects on standing activity for cows
Holsteins 14
Jerseys 12 10 8 6
Mean No. of Standing Events 4 2
Dec.-Feb.
March-May
June-Aug.
Sept.-Nov.
Seasonal effects on standing activity for cows
by breed.

16. Seasonal effects on standing activity for heifers40
Holsteins
Jerseys 35 30 25 20 15
Mean No. of Standing Events 10 5
Dec.-Feb.
March-May
June-Aug.
Sept.-Nov.
Seasonal effects on standing activity for heifers
by breed.

17. Estrus Detection Aids Record systems and estrus expectancy chart
Pressure-sensitive mount detectors
Kamar and Beacon
Tailhead chalk, paint, or crayon
Estrus-detector animals
vasectomized or surgically altered bulls, androgenized females

19. Automated Estrus Detection Systems
24-h continuous surveillance
Accurate and automatic identification of cows in estrus
Operational for productive life of the cow
Reduce or eliminate labor requirements
Highly accurate ID of estrus
Senger, 1994

20. Available Estrus Detection Systems
Pedometry
Integrated with milking system
Walking activity increases 2 to 5 times
Compared to within cow baseline within defined period of time
HeatWatch
electronic pressure sensing system
Radio Frequency Data Transmission
Transmitter/sensor glued to tailhead
Software - “standing list”, “suspect list”, individual cow files

21. HeatWatch Configuration HW HW HW HW Transmitter Receiver Repeater
Buffer
HeatWatch
Configuration

22. When is the beginning of Standing Heat!?
Why is it important to know the beginning of standing heat?
How many times per day are cows visually observed?

23. 24 - 32 h Onset of Estrus Ovulation Sperm Viability 12 to 30 h
Ova viability
sperm transport
6 h
8 to 12 h h
Onset of Estrus
Ovulation

24. Timing of AI for Dairy Cows ID in Estrus by HeatWatch System%
Pregnant
Interval from first standing event to AI
2661 inseminations, 17 herds

25. 18:00-
18:00-
24:00
24:00
21%
21%
24%
24%
12:00-
12:00-
18:00
18:00
00:00-
30%
21%
21%
30%
22%
06:00
27%
27%
00:00-
22%
06:00
31%
31%
24%
24%
06:00
06:00-
12:00
12:00
Time of first standing event (estrus onset) for Holstein and Jersey cattle as determined by the HeatWatch® estrus detection system

26. Timing of Insemination
HeatWatch
5 to 16 hrs after 1st stand
Frequency of visual observation
Every 4 to 6 hours “AM-PM” guideline
Twice or less daily - within 6 hrs

27. Management Requirements for Enhanced Estrus Detection
Improved Cow ID
Cow Interaction
Nutrition & Health
Provide Good Footing Surface
Utilize Records
Employee Responsibility
Establish an Aggressive Program

28. If a Cow is Mounted and No One
Sees It, Did It Happen?