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Pregnancy And Calving Percentages Are Stable

published: November 23rd 2011
by: Kris Ringwald
source: NDSU Extension

It often is said that growth is a very bigi trait in the beef busines, but reproduction is an even bigger one.

The main point is that the components of reproduction are very hard to pull out and fix. However, the sum of the pieces produces a calf at least 93.6 percent of the time for CHAPS (Cow Herd Appraisal Performance Software) producers.

It often is said that growth is a very big trait in the beef business, but reproduction is even bigger. The ability to reproduce is critical for the cow and essential for the cow-calf producer. Various statements often are made about good or poor reproductive rates. Perhaps a better question to ask is: Just what are typical reproductive rates for cows? Of course, such data needs to be collected and summarized to help producers evaluate and re-evaluate their herd’s reproductive rate through time.

The data from individual years provides insight and integrates well into the decision-making process for individual producers. During the last 20 years, reviewing the herd reproductive data certainly is fodder for the coffee shop. The reproductive data collected or, more appropriately, calculated includes total cows exposed to the bull, the percentage of cows considered pregnant in the fall and the percentage of cows that actually calve. Calving percentage is a key reproductive trait for cattle producers.

Obviously, the pathway to a successful calving season is not simple. The process starts with a fertile bull and fertile cow. Throughout the evolution of the cow, the process has not changed a great deal. Since the advent of new technology, the process still has not changed a great deal. In other words, cattle producers literally need to make sure management accommodates a successful breeding season.

Reproduction in cattle is never one point in time. The processes that influence reproduction are often subtle, overlapping and are more like passing a torch from one event to the next, just like a good daily relay.

The bottom line is that successful reproduction often is difficult to measure, except for evaluating composite traits that combine many of the pieces that lead to a live calf.

Producers who utilize the CHAPS program through the North Dakota Beef Cattle Improvement Association have several composite traits to evaluate the genetic and managerial processes at the ranch. Simple traits include pregnancy and calving percentage.

Calving percentage is the pregnancy percentage minus any embryonic or fetal death loss. The current benchmark for these herds is 93.6 percent for pregnancy percentage and 92.9 percent for calving percentage. The benchmark is the average for all the herds through the last five years.

The trend for pregnancy percentage during the last 20 years is interesting. Starting in 1990 and ending in 2010, the pregnancy percentages were 94, 94, 95, 94, 94, 93, 93, 92, 93, 93, 93, 93, 93, 93, 93, 93, 94, 93, 94, 94 and 94, respectively. Although the numbers all have been rounded to the nearest whole number to make the point, the trend is quite stable, with no real gains or losses.

Regarding calving percentage (also rounded to the nearest whole number), the same is true if one looks at the data from 1990 through 2010. Starting with 1990, calving percentages were 94, 94, 95, 94, 94, 92, 92, 91, 92, 92, 92, 92, 93, 93, 93, 93, 93, 93, 93, 93 and 93, respectively. Obviously, the same stable pattern exists. The average pregnancy loss percentage for those same 20 years is 0.7 percent.

Another number that often is quoted about the reproduction rate is the percent of open cows. Obviously, this number is the reverse of the pregnancy percentage, so it is 6.4 percent.

Again, the main point is that the components of reproduction are very hard to pull out and fix, but the sum of the pieces produces a calf for our CHAPS producers 93.6 percent of the time. These data may seem to be monotonous and a little on the boring side, but that is good. Cattle producers, for all practical applications, seem to have found a plateau for acceptable reproductive rates. Perhaps some producers can do better, but every producer will have some year-to-year variation. However, if one is to be in the cow business, meeting the current benchmarks for cow reproductive performance is a realistic demand.

Years of good management and the culling of open cows has paid off. To push to higher levels probably is impractical because, even with these data, early embryonic loss is not accounted for. Of the 6.4 percent of open cows, even some of those would have cycled, bred and conceived.

Hats off again to some very productive cattle producers.