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

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

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

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

Days of the Estrous Cycle walking Time eating milk yield Mounting activity Standing to be mounted -4 -3 -2 -1 Estrus 1 2 3 4 onset ovulation Days of the Estrous Cycle

Variation in Estrus Activity (Duration) ( Intensity) Beef heifers: 16  8 h 60  19 std Dairy cows: Holstein: 7  7 h 7  7 std (17 Herds) 7  5 h 9  7 std Jersey: 8  5 h 10  7 std Dairy heifers: Holstein: 11  7 h 17  7 std Jersey: 14  6 h 30  17 std

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

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

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

Pre-service Estrus Detection Efficiency Days in estrous cycle X 100 ((Days 1st Service - VWP) + 11) 21 X 100 = 41.2% (95 - 55) + 11

Post-1st Service Estrus Detection Efficiency (S/P-1)  (ADO - DFS) 21 (2.5 - 1)  (146 - 95) X 100 X 100 = 61.7%

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.

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

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.

Seasonal effects on standing activity for heifers 40 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.

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

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

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

HeatWatch Configuration HW HW HW HW Transmitter Receiver Repeater Buffer ® HeatWatch Configuration

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?

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

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

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

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

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

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