The use of maldison50/malathion on a regular basis can interfere with fertility and is banned in the European Union, especially Switzerland and Germany due to its cancerogenic effects.
Is is known to accumulate in tissue.
After reading some hours about the effects, I think it might well be the cause of his infertility.
I am still searching for the discussion had about exactly this topic at a different poultry site several years ago.
I will post a link as soon as I find it.
https://de.wikipedia.org/wiki/Malathion
https://www.vetpharm.uzh.ch/clinitox/toxdb/klt_004.htm
https://www.vetpharm.uzh.ch/perldocs/toxsyqry.htm
Is is known to accumulate in tissue.
After reading some hours about the effects, I think it might well be the cause of his infertility.
I am still searching for the discussion had about exactly this topic at a different poultry site several years ago.
I will post a link as soon as I find it.
https://de.wikipedia.org/wiki/Malathion
https://www.vetpharm.uzh.ch/clinitox/toxdb/klt_004.htm
https://www.vetpharm.uzh.ch/perldocs/toxsyqry.htm