Causes of infertility

(Ovulation takes place between 6 and 10 hours after the end of heat. As the spermatozoa need 12 hours to swim up the genital tract to reach the oviduct where fertilisation takes place, they arrive there just after ovulation.)

(The likelihood of fertilization is smaller than at the end of heat, because the percentage of dead sperm will be higher at the time of ovulation.)

(It is preferable, however, to inseminate between 1 and 3 hours after heat has finished rather than at the start of heat.)

(This is much too late, since ovulation has already taken place.)

(This would correspond with the first half of heat during which fertility is not optimal.)

(The risk is that AI would occur at the same time as or just after ovulation, i.e., too late for optimal fertility.)

(This corresponds with the end of the first hours after oestrus, which is the most appropriate period for optimal fertility.)

(It is better not to make such observations during a period of stress for animals (e.g., feeding, milking, etc.).)

(The best conditions for observation are in fact when the cows are calm. Heat detection can be improved further by carrying out a 3rd daily observation, around midday.)

(It is always difficult to carry out detection during a period of stress for the animals or when they are eating.)

(The length of observation is too short even though it is carried out during an optimal period for heat detection.)

(For this type of animal, the aim is to breed them again with a body condition score of 2.5.)

(On the contrary, results are less satisfactory when calving has taken place less than 60 days previously.)

(In general, the fertility rate in first-time calvers is lower than that in multiparous animals.)

(Results are often better with heifers than with cows.)

(The aim is to bring cows that are calving for the first time into reproduction when their body condition score is 3.)

(The aim for this type of cow is to bring them into reproduction with a body condition score of 2.5; it is not advisable to flush an animal with a good body condition.)

(It is not advisable to flush animals with good body condition.)

(Since heat lasts for between 15 and 20 hours on average, it is difficult for more than 30% of the cows on heat to be detected in one long daily observation period.)

(Since heat lasts for between 15 and 20 hours on average, it is difficult for more than 30% of the cows on heat to be detected in one albeit long daily observation period.)

(2 to 3 20-minute observations per day are necessary, outside milking and feeding times, in order to detect 80% of the cows that are in oestrus.)

(Since heat lasts for between 15 and 20 hours on average, it is difficult for more than 30% of the cows on heat to be detected in one albeit long daily observation period, even if it is carried out by the same person.)

(Assessment should be carried out by palpation.)

(Palpation is essential; a simple observation will not be sufficient.)

(For cows calving for the first time, body condition score should be 3 and for a multiparous cow, 2.5.)

(This score is too high- there could be difficulties with calving. The ideal score is 3.)

(The area around the tailhead and the lumbar spines are the best places to assess body condition.)

(Assessment should always include palpation.)

(It is important to check the body condition at this moment in time so as to enable the breeder to adjust feed rations during the drying out period if necessary.)