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|0408 EL: The art and science of heat detection|
|El Lechero Dairy Basics - Herd Health|
|Written by Tom Fuhrmann DVM|
|Monday, 30 June 2008 17:00|
Heat detection always requires some degree of human intervention.This is because our only indication of estrus is the cow’s abnormal behavior. Consider these facts: 1) the average cow is in heat 10/504 hours (10 hours out of every 21 days); 2) abnormal activity occurs in spurts (riding, being mounted) that last approximately 8 seconds each; 3) cows demonstrate significant variation in strength and length of this abnormal estrus activity due to footing, environment and number of herd mates in estrus at the same time.
Observation for estrus activity is no longer used on most dairies as a primary method to detect heat; it requires intense human interaction. Acceptable heat detection rates are attainable only when persons are available both day and night to observe cows continuously. Observation as the main type of detecting heats is generally thought to be not cost-effective for the man-hour investment required.
Crayon tail stripe is a widely used technique that depends heavily on the ability of the breeder. The principle: inspect every cow every day for evidence of crayon rub-off suggesting mounting activity since the last crayon application. Examining animals for secondary heat signs, e.g. swollen vulva, mucus, ruffled hair on the back, or palpating for uterine tone and mucus are additional steps a herdsman can use to determine estrus with this method. I find there is great variation in heat detection success with crayon tail stripping due to “people error”. Cows exhibit large variation in demonstrating signs of estrus (see Figure 1). Herdsmen or breeders may not be able to evaluate every cow daily, making reading the “partial rub off” (the cow in heat but with weak signs of standing) extremely difficult. Many breeders are not organized or focused in their routine to first, READ the crayon tail stripe, then to REAPPLY the crayon stripe once again. When expected to evaluate several hundred cows every morning, herdsmen and breeders may hurry, cut corners and fail to take sufficient time to thoroughly evaluate the “questionable” cow. Especially when breeders are unsupervised or results are not monitored, poor heat detection can result from worker error.
Technology such as pedometers and heat mount patch systems seemingly take human error out of the heat detection program. But these systems have not gained widespread acceptance, possibly due to cost. But worker intervention is still essential: someone still needs to attach the pad or strap, account for those rubbed off or lost, read and analyze daily activity reports and make the ultimate cowside decision “to breed or not to breed”.
To circumvent all human intervention and error, hormone injection programs to control ovarian activity are popular. While these seemingly eliminate “the human element”, this is simply not the case. Most Ovsynch-type programs require a minimum of four critically timed hormone injections in sequence over 10 – 14 days on all cows enrolled in these programs. Several field studies have identified that, due to human error, compliance rates to inject all cows occurs only 85% of the time. So fifteen percent of all cows are guaranteed not to become pregnant because injections are missed, poorly administered or not given at the correct hour. Here is another consideration: even if all hormone injections and breeding are done correctly, only 4 out of every 10 cows will become pregnant (assumes a 40% conception rate). That means 6 of every 10 cows will come back in heat in 21 days…..who is going to find them?
If you are a herdsman or breeder, your role to find cows in heat and administer hormone injections correctly is crucial. As I work on dairies across the U.S. and Mexico, I see the best heat detectors have these things in common:
1. They are organized……..cows are locked or available; their heat detection work system is planned and these workers proceed through corrals or pens according to a consistent plan.
2. They are focused………all attention is on cows, and cow activity; no distractions allowed.
3. They like cows, their jobs and the challenge…….they are “the right person for the job”.
4. They know their results and try always to improve…..they are professionals at what they do and take pride in their accomplishments.
Let me describe one of the best heat detectors I’ve ever seen. He works in a 1,500-cow freestall herd that utilizes both Ovsynch and crayon tail striping. Records identified his heat detection results to be above industry standards. He wears a miner’s light headband (daytime and in the dark) which he focuses on the crayon-marked back of every single cow. He READS, then REAPPLIES crayon to every cow. He concentrates on both the crayon stripe on the cow’s back as well as the vulva for all signs of heat. He identifies the special marks used in this herd to identify cows in various stages of the Ovsynch program. He carries a herd report of all previous heats for each cow in the herd. He strides through the pen at a rapid pace, restriping every cow. This technician is so focused on tailheads, cows’ backs and vulvas and making decisions, that he is seemingly unaware of anything or anyone else around him. He is a successful breeding specialist.
Heat detection is both an art and a science. You must know the facts (see side bar) and you must practice the art of focusing on cows for their signs of abnormal behavior. You can be the breeding specialist that is the key to outstanding results. EL
Dr. Tom Fuhrmann DVM
This article topic also appears in Progressive Dairyman. This article has been written specifically for dairy employees. The article in Progressive Dairyman is written for dairy owners and herdsmen.