There are many things that managers can do to maximize conception rates. Initially, determine what the ideal lactation length is for your farm, based on cow performance and management needs. Monitor the cows to understand the strong and weak areas.
History and Vision
I have 34 years of veterinary practice experience, predominantly dairy related. I was board certified in Theriogenology (Animal Reproduction) in 1980. Currently, I have been with Alta Genetics for 18 months as a Field Fertility Specialist. My work area covers all of the United States East of the Rocky Mountains. Since August of 2002, I have made over 1000 herd visits to over 600,000 cows.
My mission is to support improved reproduction on every dairy that I visit. To do this, I work with herd owners, herd managers, Alta field staff and other associated professionals such as nutritionists, veterinarians and other advisors.
Dairy Farming as a Business
Dairy farming is a business. In a business, the goal is to have a functional economic engine, fed by inputs of resources and assets and resulting in outputs of profit and equity. Quite simply, the engine of a dairy farm is production and reproduction. This is supported by the interactions of people, nutrition, care, housing, knowledge and health. There are many important components that function together to make a successful dairy.
The following are some of the more important attributes that I have noticed on successful dairies. A dedicated staff is very important to a successful dairy. A good staff helps to keep operations running smoothly and is more likely to notice details and to correct issues before they become problems. Cattle health is another factor that is extremely important and ties right in with good staff. Without prime health, milk production and reproduction both suffer- which ultimately affects the health of the business. Good execution of all tasks is also important. This includes all details, no matter how minor. The use of written standard operating procedures and protocols in addition to proper training and follow up will help to ensure proper execution of tasks. Setting reasonable goals helps to ensure that the staff and managers do not become over whelmed and frustrated. Understanding the most limiting factors in an operation is key to working to overcome or minimize these limitations. Successful dairies are also good at prioritizing their resources. Deciding where to spend time and money is a key to efficiency. Another key is to have a focused and consistent plan for the operation. Everyone involved in the farm should be involved in this, and buy into the overall goals of the dairy.
The Perfect Visit
Ideally, a farm visit should yield a wealth of communication and understanding. Good communication with both decision makers and cowside staff enables an advisor to understand both how the animal management system functions and its current and past performance. This understanding allows the advisor to make informed decisions to maximize benefits to that particular farm. With the help of everyone involved, it is possible to develop, implement, modify and monitor an effective reproductive strategy.
A good reproductive goal is to create pregnancies at the rate of 10% of the milking herd per month. If the herd is milking 1000 cows, this would mean an average of 100 pregnancies a month or 23 pregnancies per week. The farm should also strive to create pregnancies in a time frame that allows for the maximum number of most profitable lactations. To do this, determine what percent of the herd has a lactation length between 300 and 400 days.
Service rates and heat detection rates are both areas that can be addressed to improve pregnancy rates. Service rate (SR) is the percentage of eligible animals serviced in a 21 day period. Heat detection rate (HDR) is the percentage of eligible animals observed in estrus in a 21 day period. The conception rate (CR) is the percent of animals that become pregnant as a result of some number of services.
For example, if there are 100 open cows past the voluntary waiting period (VWP) and open and 50 of the 100 are serviced in a 21 day period, the service rate is 50%. If 15 of the 50 that are serviced become pregnant, the conception rate is 30%. To determine pregnancy rate, multiply the service rate by the conception rate (PR=SR x CR). In this case, the pregnancy rate would be 50% x 30% (.5 x .3) or 15% (.15).
Pregnancy rate is a tool to help understand how service rates and conception rates are performing as we work to increase the “hard count” of pregnancies. Pregnancy rates above 22% will move actual Pregnancy Creation close to the goal of 10% of the milking herd per month. Both service rate and conception rate must be good to achieve a pregnancy rate of over 22%. The following examples illustrate this:
SR x CR = PR
60% x 23% =14%
35% x 40% =14%
45% x 31% =14%
63% x 36% =>22%
Conception rate is also affected by the quality of the semen that is used for insemination. Semen quality is depends on a number of factors, from bull health and fertility to semen processing and transport. On the farm, there are semen storage, handling and placement issues and estrus detection issues that affect conception rates. Factors that should be considered in semen handling are straw identification and removal, proper thawing, gun management and straw handling and time from thawing to semen placement in the cow. Proper semen placement in a cow that has been correctly identified as being in estrus is key to improving conception.
Infectious Diseases Affecting Conception Rate
There are a number of infectious diseases that affect conception rates. Bovine Viral Diarrhea (BVD), Leptospirosis, Trichomoniasis and Campylobacteriosis (Vibriosis) are some of the more common ones.
In terms of reproduction, BVD causes a depressed conception rate, increased fetal loss and abortion and also produces persistently infected (PI) calves. A PI calf is one that is infected in utero and is born a carrier of the disease. To control BVD, a program should be implemented to identify and eliminate PI animals, regularly vaccinate remaining animals and to monitor new additions to the herd and their offspring for PI status.
The organism Leptospira borgpetersenii serovar hardjo (type hardjo-bovis) commonly called Lepto hardjo-bovis, will also cause a depressed conception rate as well as increased incidence of early embryonic death (EED). The main impact of leptospirosis on dairies is a function of the herd level of infection. This disease spreads easily throughout the herd and is difficult to detect without specifically testing for it. Cows act as the maintenance host for the bacteria, but the prevalence of the disease in the herd is variable and may be stress related. The disease may be transmitted venereally but again, the reproductive impact is variable. The typical L5 vaccination will protect against other types of bovine Leptospira, but not hardjo bovis. Correctly timed vaccination with the appropriate vaccine can prevent new infections, but will not eliminate the bacteria from the herd. There are a few types of antibiotics that can be used to treat and clear maintenance animals, but these must be used according to guidelines and at the advice of a veterinarian.
Trichomoniasis is a venereal disease of cattle that is caused by motile protozoa. Both bulls and cows can be affected, and the organism can also survive in frozen semen. Cows carry the organism in the vagina and uterus, where it can cause irregular estrus, pregnancy failure and pyometra. There is no approved treatment available for trichomoniasis, but there is a commercial vaccine available.
Another economically important bovine venereal disease is Bovine Venereal Campylobacteriosis or Bovine vibriosis. This disease is caused by the bacterium Campylobacter fetus, and is venereally transmitted. Infection with this organism can cause both impaired conception and post breeding endometriosis. There is a commercial vaccine available.
Other Factors Affecting Conception Rate
Other factors that affect conception rates are general cow comfort, health and well being. If cows are not healthy and comfortable, it could lead to irregular cycling and reduced conception rates. Body Condition Scoring is a good indicator of cow health, and should not change drastically from the time of dry off to first service. Cow moves and grouping strategies should be taken into consideration and done at the appropriate time and in the appropriate fashion. Stall design and management are critical cow comfort issues that should be addressed. Stalls should be adequately sized and situated and bedded appropriately. Transition cow management is another critical factor that affects conception. Managing to prevent metabolic disorders and periparturient disease will result in better conception rates. Nutrition and foot health are other areas that should be managed correctly to ensure that the cows are in good overall health.
Tools to Assess Reproductive Efficiency
To find the palpated pregnancy rate (PPR), divide the number of pregnant animals by the number examined (PPR= #PG/#Examined). For example, if 30 cows are examined, and 15 are found to be pregnant, the PPR would be 50%. This is an indicator of your estrus detection efficiency—the higher the rate the better. Both estrus detection and subsequent conception rates ultimately depend on both the people and the systems in place to monitor the cows—for signs of estrus as well as for general cow health and comfort.
There are many things that managers can do to maximize conception rates. Initially, determine what the ideal lactation length is for your farm, based on cow performance and management needs. Monitor the cows to understand the strong and weak areas. On average, 10 % of the milking herd should be made pregnant each month. Tracking pregnancy rates helps to pinpoint what works and what doesn’t as far as cow management. To truly monitor the cows, managers need to have knowledge of all aspects of the dairy—from the parlor to the feedbunk. When addressing management concerns, solve the most critical issues first to make progress towards maximum reproductive efficiency. There is no magic wand! Remember, depositing viable, fertile semen in the correct location in a normal, healthy, non-infected uterus at the correct time will achieve the desired results!
BVD Fact Sheet
Vibriosis (Campylobacteriosis) Information
Infectious Causes of Reduced Fertility in Cattle