regolith
Well-known member
Inspired by herofan's thread as well as observations in my herd.
Several years back I contacted my vet of the time about long returns to AI, he sent me some information and we established that my herd did have far more than the accepted proportion of long heat intervals.
I don't think it changes that much from year to year. I do think it's probably the biggest thing impacting the fertility of my herd, is cows that are cycling normally, mated, stop cycling and return to heat weeks later - sometimes close enough to 40 - 44 days to suggest a missed heat but I'm also seeing them return at five weeks, seven weeks, eight weeks, thirteen weeks... and I have several years worth of data showing that I miss around 1 - 2% of heats in unmated cycling cows but every year that goes to at least 5 - 6% after they've been mated.
Have never quite got round to kidnapping a very good vet for discussion and problem solving on the issue. Five years ago the herd tested at high BVD antibody levels, two PIs were found and culled, the antibody levels dropped to moderate and over the last two years have returned to extremely high with all PCR milk tests negative for PIs in the herd.
All animals are lepto vaccinated annually; the calves a month earlier and then again along with the rest of the herd.
My first inclination is to think that transient BVD infections may be causing early pregnancy losses, though I'm not getting PIs or obvious BVD calves.
Any other ideas? Interesting to note that my overall open rate is usually slightly better than average, so the long returns seem to be impacting calving spread rather than number of open cows. It would still be nice to shave 2% off the open rate.
A cessation of cycling followed by a return to heat after rain is quite common in a small proportion of cows, but that usually happens towards the end of mating when we're heading into a dry summer & I think is entirely caused by inadequate feed to support cycling through a dry spell.
Several years back I contacted my vet of the time about long returns to AI, he sent me some information and we established that my herd did have far more than the accepted proportion of long heat intervals.
I don't think it changes that much from year to year. I do think it's probably the biggest thing impacting the fertility of my herd, is cows that are cycling normally, mated, stop cycling and return to heat weeks later - sometimes close enough to 40 - 44 days to suggest a missed heat but I'm also seeing them return at five weeks, seven weeks, eight weeks, thirteen weeks... and I have several years worth of data showing that I miss around 1 - 2% of heats in unmated cycling cows but every year that goes to at least 5 - 6% after they've been mated.
Have never quite got round to kidnapping a very good vet for discussion and problem solving on the issue. Five years ago the herd tested at high BVD antibody levels, two PIs were found and culled, the antibody levels dropped to moderate and over the last two years have returned to extremely high with all PCR milk tests negative for PIs in the herd.
All animals are lepto vaccinated annually; the calves a month earlier and then again along with the rest of the herd.
My first inclination is to think that transient BVD infections may be causing early pregnancy losses, though I'm not getting PIs or obvious BVD calves.
Any other ideas? Interesting to note that my overall open rate is usually slightly better than average, so the long returns seem to be impacting calving spread rather than number of open cows. It would still be nice to shave 2% off the open rate.
A cessation of cycling followed by a return to heat after rain is quite common in a small proportion of cows, but that usually happens towards the end of mating when we're heading into a dry summer & I think is entirely caused by inadequate feed to support cycling through a dry spell.
