Although most cows are with calf, reviewing cow herd reproduction dates is important. Typically, 85 percent or more of all cows should be calved within 42 days of the calving season. Calving is a memory for now, but during the many upcoming winter meetings, the number of cows calving within the first 21 days of the calving season or first cycle conception rate will be mentioned often.
Do you know yours? The number means a lot because early born calves grow well. These calves are indicative of good reproductive success and ultimately add pounds to the truck. However, care needs to be taken to make sure one always is comparing the numbers presented at meetings with one’s own production numbers.
Generally, the standard numbers referred to are easy to calculate and include more than the number of cows calving within the first 21 days of the calving season. As with most numbers, saying they are easy to calculate is not always true.
For example, often the overall reproductive success of a herd is calculated as a percentage of cows pregnant and percentage of cows calving. These numbers are common numbers printed by cattle performance programs or simply calculated by hand.
The North Dakota State University Extension Service publishes annual numbers that serve as benchmarks for those who utilize the CHAPS (Cow Herd Appraisal Performance Software) program. These numbers are collected with the help of the North Dakota Beef Cattle Improvement Association.
Typical values for the percentage of cows pregnant are 93.5 percent. Of those cows, 92.9 percent calve. This means of all the cows exposed to the bull, a little more than 7 percent of the cows never calve. In terms of overall evaluation of the cow herd, these numbers are good comparative numbers to see how one herd ranks against another.
Most herds cull the open cows, make managerial adjustments and anticipate a better calf crop the next year. These good managerial efforts help keep some positive reproductive pressure on the herd. Reproduction, considered by many to be a lowly heritable (in other words, genetic selection has less impact than environmental effects or general management) trait, is fairly stable in most herds pending any detrimental health effects.
Returning to the ease of calculation, both of these numbers need accurate breeding cow inventories to be accurate. Often, the number of cows exposed to the bull is not available. Given the traditional way to look at reproduction, another method is available, which is to develop a calving distribution table.
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