How can we best record heat and how can these measures be used to genetically improve the oestrus expression?

Description

The pregnancy rate has impaired in our high-yielding dairy cows. There is evidence suggesting that the heat has become shorter and weaker. When artificial insemination (AI) is used, clear heat signs are important for the detection of heat and for the determination of when to inseminate. This is especially so in countries like Sweden where heat synchronization with hormones is not allowed.
The project will study:

• How much shorter and weaker is oestrus in the high yielding dairy cow of today compared with some decades ago?
• How effective are automatic heat detectors such as activity meters/mounting detectors?
• How much easier can the heat be found if you combine visual heat signs with automatic systems for heat detection and with progesterone determinations?
• How large is the genetic variation in oestrus expression?
• Can registrations from automatic heat detectors be used as measurements to genetically improve oestrus expression? And how can they be combined with other ways to register heat?

Aim

The aim of this study is to provide a basis for improved pregnancy result in cows by examining how to best detect and record heat. Automatic systems for heat detection are expected to become standard in future herds along with increasing herd sizes. The accuracy of these automated systems for heat detection will be investigated and compared with visual (external) heat symptoms, which today is the best way to determine if the cow is in heat or not. The goal is to develop the best way to record and genetically improve oestrus expression and thereby the fertility of cows.