Purdue University
Agricultural Extension Service
Mimeo DH-21
June 1952 (2c)
RECOMMENDATIONS FOR OBTAINING A GOOD BREEDING RECORD To have a workable program for successful Artificial Insemination of Dairy Cattle
1.	Carefully observe cows for heat in the morning and late afternoon. Also at noon if time permits.
2.	Females in heat should be reported to the technician promptly in the morning and cows to be bred that day must be reported by the hour designated by the local association which usually is not later than 10:00 A.M.
3.	For good results females must be bred not later than six hours after the end of heat. The length of heat period ranges from 3 to 28 hours and averages 17 hours. However, 90 per cent of the females are in heat from 10 to 24 hours.
4.	Females first observed	in heat in	the morning must be bred the same day for
good results.	If bred the second	day results may drop as low as 30 percent for conception from the first service.
5.	Females not in	heat in	the morning, but in later during the day, will have
somewhat lower 	rate of	conception	 (usually a decrease of about 20 percent) if bred during the first six hours of heat. Such females may be bred successfully up to noon or the middle of the afternoon the next day. Report these cows early in the morning and explain when calling that the cow was in heat the previous afternoon so the technician can arrange his route to breed the “afternoon” cows as early as possible.
6.	Recorded heat periods on barn breeding charts give you a good opportunity to tell you when cows are due in heat.
7.	Cows should be given one "free" heat period without service if they have been fresh less than 60 days.

Note:	A normal rate of conception based on 22,684 natural services to the bull
is 60 per cent from the first service. Artificial insemination matches this and 6 cows out of 10 served should take from the first service.
         THE TABLE FOR BEST RESULTS IN BREEDING DAIRY COWS ARTIFICIALLY		
Heat First Observed	When to Breed	Too Late
In the Morning Afternoon or evening*	The same day Forenoon next day	The next day After middle of afternoon next day
    *Cows definitely not	in heat in the morning	
The above recommendations are made by New York and are based on several year's of breeding records in the Pioneer Artificial Breeding Association and several other associations in New York. Professor George W. Trimberger developed the same recommendations from carefully controlled research data over a period of six years in the University of Nebraska dairy herd.
Dairymen can assist in improving artificial breeding results by watching their cows closely for the first signs of heat. Technicians should arrange their daily routes to take advantage of the facts given in the table above and improve the service they are giving their members.
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