Profitability in dairy operations is directly related to reproductive performance. The results of the preferred reproductive program in the dairy farm will be used to measure essential parameters of success, for instance, decreasing replacements due to reproductive failure and increasing the number of heifers for replacement due to reproductive success.
These examples are directly connected to dairy revenue and must be considered before making any reproductive management decision. Many different reproductive strategies are available for dairy managers. However, the complexity of these choices interacting with biological and economical factors can make the best management decision a difficult challenge.
Synch protocols
In spite of the undeniable success of the use of hormonal protocols to synchronize ovulation in the dairy industry since the early 1990s, the first timed artificial insemination (TAI) protocol, termed Ovsynch, increased the insemination risk but not the fertility of dairy cows. However, in recent years, new protocols such as Presynch-Ovsynch or Double Ovsynch were developed to increase both the insemination risk and the fertility of TAI programs. Lately, these protocols have been improved, with modifications such as giving an extra PGF2-alpha injection on day eight of the protocol in order to improve luteolysis and the subsequent ovulation.
Accordingly, many dairy farmers in the Midwest have decided to perform 100% TAI without estrus detection (ED), thus not taking any advantage of the traditional heat detection. On the other hand, many producers in the West and Southwest with relatively efficient estrus detection programs still resist the idea of implementing any TAI protocols in their herds, deciding to ignore any benefit the synchronization protocols could bring to their dairies. They still breed 100% of the cows after estrus detection, probably due to labor constraints and hormone costs. There will be pros and cons in either case, but we should be able to take advantage of both programs and consider that combining TAI and estrus detection could benefit the modern dairy operation.
A combined approach
The combination of TAI and estrus detection has been used by the majority of the dairy farms in the U.S. Basically, the dairy producer uses the TAI program, starting with the pre-synchronization injections. However, only those cows not detected in heat during the protocol are bred by TAI. This allows some flexibility in the timing and type of injections. For example, the commonly used Presynch-Ovsynch protocol, which consists of a pre-synchronization with two PGF2-alpha injections 14 days apart, and 10 to 14 days later followed by the Ovsynch as a TAI program (D0 GnRH, D7 PGF2-alpha [a second PGF2-alpha could be given here on D8 to improve luteolysis], D9 GnRH in the afternoon and D10 TAI in the morning). The two main advantages of this program are: The cows showing heat after the second PGF2-alpha injection of the pre-synchronization can be bred, reducing the number of cows that will complete the program, decreasing hormone costs; and the cows that did not show heat will probably be in a better stage of the estrous cycle (between days five and nine) to reach higher fertility in the TAI program.
Other implicit advantages of using the combination of TAI and estrus detection can be verified in both larger and smaller herds. In larger herds, if we rely only on estrus detection by using tail chalking with an additional secondary sign of estrus, such as a red swollen vulva, ride marks, vaginal mucus or a normal 18 to 24 days estrous interval, we know that periodic evaluations and retraining of technicians will be required. Absent these steps, poor results may occur. On the other hand, in smaller herds only visual methods are used to detect heat, but in the U.S., the sizes of the herds are trending upward. In the last 20 years, U.S. average herd size has increased 142%, from 74 to 179 cows. Traditional methods of visual estrus detection do not work well when cows are managed in larger groups, simply because there are more cows, meaning less accuracy, more time for estrus detection, identification, sorting, breeding and record-keeping.
The bottom line
These factors aside, we still must determine the importance of the use of estrus detection combined with TAI to the dairy farm’s bottom line. To answer this question in a more precise way, many simulation models have been used to predict the impact of a wide range of reproductive management scenarios and performance levels.
One model was developed by the University of Wisconsin – Madison. The UW-DairyRepro$ model uses Markov chains to predict the future profitability of a dairy, comparing different reproductive management programs.
This specific model was used in 2012 to compare the profitability (net value, NV) of 19 different programs including one that used 100% TAI (42% conception rate for first TAI), while the others combined estrus detection with TAI programs in the proportion ranging from 30% to 80%, with conception rates (CR) of 25%, 30% and 35%. As the proportion of cows receiving A.I. after estrus detection increased, the conception rates of cows receiving TAI decreased. When compared with the program relying 100% on TAI, programs reaching 25% conception rates to the estrus detection had a lower net value at all levels of estrus detection. On the other hand, combined programs reaching 30% conception rates with the proportion up to 60% of cows receiving A.I. after estrus detection had greater net value than the program that used only TAI. Also, the combined program with conception rates of 35% for cows receiving A.I. after estrus detection had the greatest net value and reproductive performance at all levels of estrus detection. In summary, the economic value of reproductive management programs combining TAI and estrus detection depended on the proportion of cows receiving A.I. after estrus detection and the resulting conception rate.
Following the same trend, another group of researchers did an economic comparison among TAI, estrus detection or a combination of both, and found that the combination of TAI with estrus detection resulted in increased reproductive and economic performance compared with either TAI or estrus detection alone only in certain level of estrus detection accuracy or compliance with injections. In other words, the greatest improvement from combining TAI and estrus detection was detected when compliance with injections was relatively poor (85%), combined with poor estrus detection accuracy (85%). On the other hand, when assessed separately, TAI with an efficiency as high as 95% compliance or estrus detection with 95% accuracy were as profitable as or more profitable than the combination TAI and estrus detection with low accuracy or compliance.
In summary, producers can improve their profits by combining TAI and estrus detection depending on their level of compliance, accuracy and conception rates. If a herd can achieve high estrus detection with high accuracy or have high compliance with injections for TAI, using only estrus detection or TAI might be as profitable as or even more profitable than attempting to do both.
