Cows in organic production are getting inseminated on more occasions than cows in conventional production. This is shown by Hanna Lomander from SLU in her thesis on factors affecting dairy cow fertility. Today, it takes longer for a dairy cow to become pregnant after calving than it did 20 years ago.
It has been discussed that organic diets can lead to more cows in negative energy balance compared with cows on conventional diets, which in turn results in poor fertility. Therefore, Hanna Lomander compared the number of inseminations on organic and conventional farms. She found that cows in organic herds get 9 percent more inseminations per series than cows in conventional herds and also have lower odds of being pregnant on the first insemination.
Of the total number of 63,561 cows in the study, 2,564 of them were in organic herds, 55,367 in conventional and 1,044 cows in herds that were in conversion from conventional to organic. The selection was based on the crews that had more than 60 cows calving in 2010.
- I have used the number of inseminations per cow as a fertility measure. This should be interpreted with caution because it is the number of inseminations that a cow get regardless to if she becomes pregnant, slaughtered or remain in the herd without being pregnant, says Hanna Lomander.
- A cow with many inseminations does therefore not necessarily have lower fertility than a cow with only a few inseminations. It is not entirely impossible that cows in organic herds generally get more chances to get pregnant compared to cows in conventional herds, says Hanna.
- The odds of pregnancy at first insemination, is a safer measure of cow fertility and there have organic cows lower odds compared to conventional herds, says Hanna.
Providing newly calved cows an energy-rich supplement feed, like glycerol, to reduce the load on the body reserves when they suddenly produce large quantities of milk, is however not the solution to the problem. Read the previous news about this.
Other studies of fertility in Swedish cows in organic herds have, for unknown reasons, shown varying results.