Complex sentence: Such methods were an alternative to the common practice of beak trimming, done with a heated blade or infrared beam usually when chicks are one day old, which is effective in reducing injuries due to pecking, but has significant effects on chicken welfare.
Split into simpler sentences: Such methods were an alternative to beak trimming, which is performed with a cold or heated blade, or infrared beam, usually when chicks are 1-d old. This is often effective in reducing pecking injuries, but has significant effects on chicken welfare.