Improving Reproduction Management, Part 2

John Grimes, OSU Extension Educator, Highland County

Last week in the Ohio BEEF Cattle newsletter, we addressed improving reproductive management by discussing the impact of the timing of calving seasons on Ohio’s cow-calf producers. Once a producer has determined what time of year is the best calving season for them, it is imperative that they get as many cows bred as possible in the shortest amount of time.

The United States Department of Agriculture’s Animal and Plant Health Inspection Service recently released the results of a very important study of the nation’s cow-calf producers. This study, the National Animal Health Monitoring System (NAHMS), is designed to collect data on cattle health and management practices on cow-calf operations from across the country. The 2007-08 NAHMS Beef study was conducted in 24 states gathering information from operations representing 79.6% of the U.S. cow-calf operations and 87.8 % of the beef cows. Results from the 2007-08 NAHMS Beef study give us insight about producer’s attitudes and management practices relating to reproduction.

A defined breeding season is a sound management practice that allows producers to devote more attention to animals during the calving season. In this study, a defined calving season was determined by removal of the bull from the female herd for at least 30 days. The survey indicated that over one-half of the operations (54.5%) – accounting for about one-third of beef cows (34.1%) – had no defined breeding season.

A short calving season allows for more intense monitoring of animals during calving and can result in a more uniform calf crop. For operations with one breeding season, a significant portion of the operations (26.2%) had their most recent breeding season last 64 days or less. Extending the breeding season an additional 21 days added another 12.7% of the operations. However, 61.1% of the operations indicated that they had a breeding season 85 days or more.

There are several reproductive technologies available to beef producers including practices such as semen evaluation, palpation, body condition scoring, artificial insemination, estrus synchronization, and others. The 2007-08 NAHMS beef study indicated that these practices are underutilized by all operations. Semen evaluation was the practice most frequently used by operations at 19.5% followed by palpation for pregnancy (18.0%), body condition scoring (14.3%), estrus synchronization (7.9%), and artificial insemination (7.6%). Utilization of these practices varied greatly by the size of the operation. In operations with 200 or more cows, 78.5% used at least one of the reproductive technologies listed, compared to 25.3% of the operations with less than 50 cows. For each of the reproductive technologies listed, the top- ranked reason given each time for not using a technology was labor/time.

I believe that the results of this study mirror the practices carried out by Ohio’s cow-calf producers. What can we do to improve the reproductive efficiency of our beef herds? One thing is for sure, nothing will improve unless we are willing to make some basic changes in our management practices.

Regardless of the size and scope of your operation, I doubt you prefer that your breeding season and the resulting calving season should extend longer. The easiest practice that any producer can implement to improve reproductive performance is to shorten the calving season. All it takes is some discipline and perseverance to see the benefits of a shorter schedule. A shorter breeding season will probably result in more open cows in the short-term. However, this can be a long-term reproductive benefit for your herd. Females that are slower to breed or unable to conceive will be more quickly identified through a shorter breeding season and can be culled from the herd. Culling hard for poor reproductive performance will eventually result in a very fertile herd over time. You can love your wife, love your children, but don’t love your cows! WARNING: The implementation of a shorter breeding season is significantly complicated by the presence of former show heifers in the herd owned by children! This author has vast experience with this situation.

Estrus synchronization has historically been used to enhance the use of artificial insemination. However, producers unwilling or unable to utilize artificial insemination can use estrus synchronization to improve reproductive performance in natural mating systems. Data from the University of Kentucky illustrates that estrus can be synchronized before a natural breeding season. In this trial, mature cows and 2-year-old cows approximately 65 days after calving were assigned to one of three treatments. The cows in the first group were not treated (CONT) and were exposed to natural service for 60 days. The cows in the second group (MGA) were fed the orally active progestin melengestrol acetate (MGA, .5 mg/hd/d) for 7 days and were exposed to natural service for 60 days beginning the day after MGA feeding ended. Cows in the third group (CIDR) had an EAZI-BREED CIDR device inserted for 7 days before being exposed to a 60-day natural service season. All bulls used in this experiment were mature and were subjected to breeding soundness exams approximately 30 days before the breeding season. Bull-to-cow ratios (BCR) ranged from 1:23 up to 1:42. Date of conception was determined using rectal palpation approximately 30 days after the end of the breeding season. The results of this experiment are illustrated in Table 1. More cows conceived and conceived earlier in the treated than in control groups. Treatments did not differ because of BCR.

Table 1. Effects of estrus synchronization prior to natural service on reproductive response in postpartum beef cows.

Treatment Number of Cows Pregnancy Rate (%) Pregnant in the First 30
Days (%)
CONT 1,040 83 46
MGA 614 93 78
CIDR 421 91 80

Those individuals willing to use estrus synchronization and artificial insemination have many options available to impact reproductive rates and potentially shorten the breeding season. Producer testimonials and surveys speak loud and clear that time and labor are the main reasons that artificial insemination is not a more widely used practice. Several universities have worked together to help perfect many different synchronization protocols to enable producers to more easily implement an artificial insemination program. Outlines of these protocols can be obtained through your local Extension office or in bull catalogs from major A.I. studs.

If a producer is willing to devote 10 days or less to an artificial insemination program, there are certainly viable options available. One of the more popular heat synchronization programs has been the “7 day CO-Synch + CIDR” program for observed heat and timed A.I. systems. Here is a basic outline of this program: Today you insert a CIDR and administer a shot of gonadotropin-releasing hormone (GnRH). Seven days later you remove the CIDR and administer a shot of prostaglandin (PGF). You can breed A.I. based on observed heat or utilize timed breeding at 60-72 hours following the administration of PGF. If you utilize timed breeding, administer another shot of GnRH at the time of breeding. Research involving over 3,000 cows in this program with a 60-72 hour timed breeding system resulted in average conception rates of 51-54%.

Modifications to the “7 day CO-Synch + CIDR” program have been recently investigated to determine if timed-AI pregnancy rates could be improved. Although similar in design to the 7 day program, the “5 day CO-Synch + CIDR” program pioneered at The Ohio State University by Dr. Mike Day and collaborators was demonstrated to be a more effective program for timed-AI in postpartum beef cows than the “7 day CO-Synch + CIDR” program. The primary differences between the two programs is that the “5 day program” features two days shorter use of the CIDR, a second shot of PGF 8-12 hours after the CIDR removal, and timed breeding at 72 hours after the first PGF shot.

The “5 day program” requires one additional trip through the chute. This extra trip through the chute can pay big rewards. Successful results have been observed by several institutions with the “5 day CO-Synch + CIDR” program in cows with pregnancy rates averaging 68.2% in 1,162 cows. Remember, this program requires an eight day commitment to artificial insemination. This would seem to be a natural fit for a producer wanting to add high quality, proven genetics and eventually shorten the length of the calving season.

Hopefully this discussion has given you some ideas that can be practically implemented in your operation to improving your reproduction management. This is a good time to remind you of one of my favorite definitions of insanity. It goes something like this: Insanity is defined as doing the same thing over and over and expecting different results. You can’t expect better success with reproduction in your herd without trying something different!