Ultrasound is being used on an increasing number of dairy cattle around the U.S. It is most often thought of as a means of early pregnancy diagnosis or, more importantly, early “open cow” diagnosis. It is a superior tool at doing so.
However, just thinking about ultrasound as a way to find open cows misses most of the benefit it can offer to a dairy’s reproductive management. Ultrasound can result in further financial gains by providing additional information that can be used both immediately and also for tracking long-term trends that can help identify problems sooner.
With ultrasound in the properly trained hands, there is an enormous amount of information that can be gathered and used immediately. For most dairies, especially larger ones that we have in the West, gone are the days of sitting on the fencepost watching cows for standing estrus.
We have relied more and more on secondary signs of heat such as chalking, which can result in mistakes. Studies measuring progesterone of cows bred to estrus diagnosed by chalk find mistakes anywhere from 5 to 30 percent. How often do you find cows at pregnancy check that are pregnant to a previous breeding?
These are just the “tip of the iceberg,” since most cows, if pregnant to the previous breeding and bred, will lose the fetus, delaying the cow for another chance at a fertile breeding. Incorporating ultrasound into the daily heat-detecting routine will dramatically reduce these and other mistakes by being able to visualize the ovaries and determine if there is a functioning corpus luteum (CL) or not.
The corpus luteum is a structure on the ovary that produces the progesterone to maintain pregnancy. Ultrasound essentially provides an instant and much cheaper progesterone test. If a cow is in heat, she will have neither high blood progesterone levels nor a good CL.
Another example of the immediate use and benefit of ultrasound is incorporating it into your timed-A.I. breeding program. Have you ever wondered why our synchronization programs keep adding more shots into their protocols, like G6G and double-Ovsynch? The reason is that cows respond much differently to Ovsynch depending on where they are in their estrus cycle.
These new synchronization protocols try to get more cows “synchronized” so that they will respond better, which leads to higher conception rates. However, these programs require considerably more injections (increasing costs on drugs and labor) and time before placing semen in the cow.
Time is not as much of a problem when we are talking about first-service breedings because these cows can be set up during their voluntary waiting period, but the cows not pregnant to the first breeding and needing to be resynchronized are a different story.
Using ultrasound to “check in” on cows during an Ovsynch program will allow the dairy to identify cows that are not responding properly and alter the protocol slightly, which can vastly improve synchrony and conception rates.
The most important time to identify if a cow is synchronized or not is on the day of prostaglandin within the Ovsynch synchronization program. Cows that respond the best to timed A.I. have an active CL at the day of prostaglandin.
Studies consistently show that cows that do not have an active CL on the day of prostaglandin result in conception rates lower than 15 percent and can make up as much as 35 percent of total cows in a standard Ovsynch.
Restarting these cows in the Ovsynch program or a CIDR-synch program (which basically is the Ovsynch program with the progesterone-releasing device inserted at the first GnRH and then pulled on the day of prostaglandin) or waiting a week and restarting cows that have a CL and enrolling those that do not into a CIDR-synch program will usually result in conception rates 35 to 50 percent and higher (depending on the management of the dairy).
By doing this, the dairy improves conception rates without adding excessive injections and, more importantly, not losing too much time on all resynchronized cows.
My veterinary practice has made this a central part of what we do and, by incorporating these protocols into our practice, we are able to provide conception rates so high that most of our clients are able to rely on near 100 percent timed A.I. and achieve pregnancy rates of 20 to 30 percent. This allows them to structure their reproductive management to a very limited amount of time, reducing labor and locked cows.
In more than eight years of our practice applying these protocols, the clients that still incorporate some heat detection into their reproductive management never have conception rates higher than we can obtain with timed A.I., which is remarkable considering they are selecting the more fertile group of cows (because they are actually cycling), and we are left with a higher percentage of less fertile problem cows to time A.I.
Another immediate benefit of ultrasound is determining the sex of the fetus, which can be done after two months of gestation and has been used in the management and marketing of some beef cattle – but has never really caught on in the dairy industry. Even with the use of sexed semen, there are still many cattle carrying bull calves.
Being able to identify which animals are carrying females will allow producers to make better decisions on pregnant cull cows and when selling any heifers (by keeping only those carrying females or marketing them for a premium).
Ultrasound can also provide information used to track the overall trends in reproduction, and changes in these trends can alert management to problems such as an increase in acyclicity and follicular cysts, which could be a result of some stressor. As mentioned, ultrasound can be a great tool for checking in on cows during timed-A.I. synchronization programs to determine which cows are “synchronized” and which ones are not.
Most of the cows that are not “synchronized” have nothing wrong with them but are just around an estrus and at a wrong point in their estrus cycle to respond.
When checked again a week later, the vast majority of these cows will be fine; however, there are some that still do not respond (two weeks in a row without an active CL). These cows are your acyclic or persistently cystic cattle – every dairy has some of these – and their percentage within the herd stays pretty consistent most of the time.
When reviewing our practice data of the cows that do not have a CL on the day of prostaglandin, less than 25 percent of these cows will not have a CL the next week. If herds exceed this (you can see the percentage rise as high as 50+ percent), it is a clue that there may be a feed issue, transition cow problem or heat stress. These are also the cows that respond better to a CIDR-synch.
Reproduction is such an important economic driver on a dairy, and if we can apply simple management changes to improve performance it can result in substantial returns. Ultrasound is a great tool to incorporate into your reproductive management. Make sure to take advantage of all the benefits it can provide. PD