PD Poll Question
|Dairy basics - A.I. and Breeding|
|Written by Kevin McSweeney|
|Friday, 27 July 2012 07:27|
When people think of the benefits ultrasound provides in a dairy’s reproductive management, they think of early pregnancy diagnosis. Ultrasound is in fact a great diagnostic tool for finding pregnancies early, but the true benefit to reproduction comes from identifying the open cows sooner.
Skilled ultrasonographers are able to identify the fetus and heartbeat reliably as early as day 26 of gestation. At this early stage of the pregnancy, the fetus and pocket of fluid are very small and requires a more methodical scan to find the fetus or to be secure in calling the cow “open.”
Because of this, and the way the schedule works for timed A.I. programs, most people who incorporate ultrasound into their pregnancy diagnosis wait until after 32 days bred to check for pregnancy. At this point the fetus is much bigger and there is more fluid to help identify a pregnancy.
The majority of embryonic loss has occurred by this later point, which leads to finding more open and actionable cows to resynchronize thus increasing your heat detection rate.
Shortly after fertilization occurs there is some embryonic loss starting to happen. This loss continues after fertilization in a diminishing rate, with most of loss occurring prior to day 45 of the pregnancy. There can be many fetuses dead or dying at the time of pregnancy diagnosis depending on when the pregnancy diagnosis occurs.
Below, view a video featuring images and clips of ultrasounds during different stages of pregnancy. Video also features examples of dead fetuses and cases of pyometras. Story continues below video.
Identifying these dead fetuses and applying strategies to resynchronize them as quickly as possible will improve heat detection rate and ultimately increase pregnancy rates. Ultrasound is clearly superior to rectal palpation for identifying these dead and dying fetuses. Experienced palpators diagnose pregnancies early to mid 30 days post-breeding.
At this stage, they are only palpating for fluid within the uterus to diagnose pregnancy. However, fluid may be present but the fetus can be dead, or the fluid may be in fact a small pyometra (pus filled uterus). Since the ultrasound allows the scanner to visualize the fetus and its beating heart, identifying a dead fetus is quite simple at this stage.
For bull-bred herds, identifying pregnancies and staging them accurately so that the dairy knows when to dry the cow is essential to maximizing profits. Ultrasound is superior at doing this because it can more accurately find pregnancies earlier in gestation and by applying measuring techniques to the fetus, the stage of the pregnancy can be predicted with strong accuracy.
Small pyometras in a bull-bred herd can be difficult for a palpator to diagnose and for fear of it being an early pregnancy, therapy is withheld. Using ultrasound, a small pyometra can clearly be distinguished from an early pregnancy and strategies can be applied to return the cow to a fertile state (giving an injection of prostaglandin).
In nearly all situations, pregnancy diagnosis is best performed by using ultrasound. Not only is it the earliest most reliable tool to pregnancy diagnose, but it provides more and better information than other means of pregnancy diagnosis, such as being able to identify dead fetuses and pyometras. Even in bull-bred herds ultrasound provides better returns by finding more pregnancies early and staging them more accurately. PD