Benchmarks for Evaluating Reproductive Performance

Transcript of Select Sires' Reproductive Moment Program
on DairyLine Radio, Which Aired Oct. 26, 2006
with Ray Nebel
Senior Reproduction and Herd Management Specialist, Select Sires Inc.

This week’s Reproductive Moment: Benchmarks for Evaluating Reproductive Performance. Ray, what benchmarks should producers be using on a herd level to monitor reproductive performance?
When we evaluate reproductive performance, there are different areas we normally look at. Days-open is from the time that the cow calves to the time she conceives. Our goal, in general, is 140 days, that’s a thirteen-and-a-half month calving interval. There is also a level where we need to so something, or an intervention level, and my number has been set at 175. That directly relates to calving interval. Calving interval takes that 140 days and adds the gestation length, or how long she is going to be pregnant. In cattle, that’s 280 days. So, 140 plus 280 gives us our total days from when she calves to when she calves again. Now, most of us think of months, so we divide the total number of days by 30.4, which is the average days in a month, and that comes out to 13.5 [months]. So, 140 days open equals a 13.50-month calving interval:
140 days-open + 280 days gestation = 420 days gestational interval / 30.4 avg. days in a month = ~13.5 months
What are the other parameters that constitute days-open?

1. When do we start, days to first-service?
2. How well do we get the cow pregnant: conception rates?
3. Heat detection.

These three combined go in to factor in days-open. Days-open is a general goal and the three that determine that are when do we start—the goal there would be 75 days. We don’t want any cow to be bred past 100 days. We want them all bred prior to 100.
The goal for conception rate would be about 45 percent, so if we breed 100 cows we want 45 of them pregnant. We definitely want to be above 30.
Heat-detection is probably one of our most critical areas today, and the goal I have is to catch six out of ten. If you are catching less that four out of ten, then you need to beef up the program.

Ray, if you could pick one category, and only one, which one would it be?

Historically, it has been days-open. But, days-open doesn’t really tell you what you need to prove. So, in the last five years the category that has really gained a lot of popularity, which we really didn’t touch on, is called pregnancy rate, because it combines the two most important factors, conception-rate and heat-detection. Pregnancy rate is the conception rate times the heat-detection. It really tells you how fast cows are getting pregnant.
So, if we had a 45 percent conception rate and 60 percent heat-detection, it says every 21 days, we are getting roughly 24 percent of the cows pregnant. It says, every 21 days—because that’s the average estrus interval—how many cows are eligible to catch in heat? And, of the cows we catch, how many get pregnant? So, it says the speed of getting cows pregnant.
That is really the most important figure because it changes every 21 days. When we change something on the farm, we can monitor it almost immediately. Days-open and calving intervals take so long to see a change because they are yearly averages that, when we make a change, we almost forget what we did by the time we can find if it changed or not. There is a decline in reproductive performance in today’s dairy herds because of the demands we are putting on them as far as milk production. But, the biggest factor is good management: knowing our cows, doing a good job and looking at the details. It is interesting that the highest-producing herds also do the best jobs as far as reproduction. So, that negative effect of production and reproduction is kind of contradictory. But, what it says is that good managers that get more milk are also good managers who do a better job at reproduction.

Thanks to Ray Nebel, senior reproduction and herd management specialist at Select Sires.