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The Long-Term Impact of a Few Days

By John F. Grimes
 
For spring-calving beef herds, the breeding season is currently or soon will be underway. Many decisions have been made in terms of the genetic makeup of the 2020 calf crop. Natural herd sires or sires to be used through artificial insemination have been selected. Mature cows have been retained and replacement heifers have been introduced to the breeding herd. Hopefully the genetic decisions that have been made will prove profitable when next year’s calf crop is sold.
 
Reproduction is the most economically important trait in beef cattle for the cow-calf producer. Numerous studies have shown that reproduction is several times more important than growth or carcass traits. Simply put, genetic superiority in any trait does not matter if the beef female is not bred and deliver a live calf for the producer.
 
Regardless of the size and scope of your operation or your preferred time of year to calve, there is little economic justification for a lengthy calving season. The arrival of breeding season for many herds seems like an appropriate time to revisit this issue. A 60-day breeding season is an ideal goal to shoot for and I would recommend nothing longer than 90 days. If you are currently involved in a longer breeding season, there are valid economic and management reasons to make a change. It requires a little discipline, some rigid culling, and a willingness to use technology and other resources available.
 
A joint study between Oklahoma State and Texas A&M Universities found a positive relationship between number of days of the breeding season and the production cost per hundredweight of calf weaned. In addition, they reported a negative relationship between number of days of the breeding season and pounds of calf weaned per cow per year. The data suggested that for each day the breeding season was lengthened, the annual cost of producing a hundred pounds of weaned calf increased by 4.7 cents and pounds of calf weaned per cow per year decreased by 0.158 pounds.
 
The range of breeding seasons in the data set was from extremely short (less than one month) to 365 days or continuous presence of the bull. The trend lines that resulted from the analysis of the data give us an opportunity to evaluate the economic importance of a defined breeding season. The producer that leaves the bull out year-round (365 days) would sell 45.82 fewer pounds of calf per cow per year on the average than producers with a 75-day breeding season. That same producer would have $13.63 greater costs per hundredweight of weaned calf than the producer that used a 75-day breeding season. In this era of cost/price squeezes, a well-defined breeding and calving season provides a better opportunity to survive the volatility of cattle prices and input costs.
 
Fescue is a common component of many Ohio pastures and those in surrounding states. While this cool-season grass has several beneficial production traits, endophyte is present in much of the fescue that can result in reduced animal performance. The timing of the breeding season combined with endophyte-infected fescue pastures can have a huge impact on conception rates.
 
Research at the University of Kentucky demonstrated the impact of breeding dates on conception rates. Similar cows were separated into three breeding periods of 45-days each on high-endophyte fescue. Cows were exposed to bulls from April 21 to June 5, May 21 to July 6, and June 19 to August 4. Conception rates were the highest in the early breeding group at 89%, the middle group achieved 78%, and the latest group had a pregnancy rate of only 59%. Rising temperatures as summer progresses coupled with the endophyte that is present in most fescue pastures, likely contributed to that decreased performance.
 
The results of these two studies challenge traditional management decisions that I believe have been counter-productive for cow-calf production. Extending the breeding season in an attempt to get more females bred is simply not practical or reasonable. The reality is that not all females are fertile as some females may eventually be bred outside a targeted window or never become pregnant. Each scenario is very costly.
 
I have seen several beef and farm management specialists encourage cow-calf producers to match their calving season with the onset of pasture forage growth. On the surface, this concept may seem appealing. In Ohio, this would target a calving season in April and May when temperatures are warming, moisture is typically plentiful, and cool season grass growth is at its highest level. If your pastures are comprised primarily of fescue, I would caution you to not adopt this strategy. The negative effects of endophyte-infected fescue are a large obstacle to achieving satisfactory reproduction rates when targeting later spring calving dates.
 
A shorter calving season will eventually lead to greater efficiencies in reproduction rates. Palpate shortly after the conclusion of the breeding season, cull heifers and cows that do not conceive within your given calving season and do not look back. Keep daughters of the cows that are bred early each calving season. If necessary, buy bred females that calve within your desired window to replace the open females. Implementation of these practices will certainly improve your herd’s reproductive performance over time.