Analysis of fertility data is a mainstay of modern veterinary practice. Where making recommendations, it is important that reports are robust, consistent and transparent.
This chart shows the cumulative proportion of the herd that have been served, and became pregnant by days in milk. Around 20% of cows are served before the start of the voluntary waiting period (highlighted in green), though very few of these serves resulted in a successful pregnancy. By 100 days in milk, more than 75% of the herd have been served, but only 35% are pregnant. This increases to 83% served by 200 days and 65% pregnant. By 300 days, 84% have been served (a small increase), and 74% were pregnant. From this chart we can estimate non-fertility culls i.e. cows that calved but were never served, 16%. Fertility culls can be estimated as those cows that were served, but didn’t get pregnant (84% – 74% = 10%).
