Effect of melatonin administration prior to calving on milk secretion in the next lactation in dairy cows

This study evaluated the effects of melatonin administration 60 days prior to expect calving (drying-off period) on milk yield during the next lactation. Sixty dairy cows were treated with subcutaneous melatonin implants during summer (n=30) or winter (n=30) period. Another 60 animals were not treated and served as the control. There were no differences in the average milk yield between treated and untreated animals (44.5±3.7 and 44.8±5.0 kg/day for melatonin and control cows, respectively). There was an effect of season with a higher winter milk yield than in summer (43.8±5.0 and 47.1±3.0 kg/day for melatonin and control groups, respectively). The interaction between melatonin and season showed no significant effect; however, during winter, milk yield tended to be higher (P=0.06) in control cows than in melatonin treated cows (45.3±3.7 and 49.2±3.0, respectively). This study indicates that treatment with melatonin prior to calving did not modify milk yield during the following lactation. Only a tendency for a reduction in milk yield during winter was observed in melatonin treated cows

Učinak primjene melatonina prije teljenja na izlučivanje mlijeka tijekom laktacije u mliječnih krava

This study evaluated the effects of melatonin administration 60 days prior to expect calving (drying-off period) on milk yield during the next lactation. Sixty dairy cows were treated with subcutaneous melatonin implants during summer (n=30) or winter (n=30) period. Another 60 animals were not treated and served as the control. There were no differences in the average milk yield between treated and untreated animals (44.5±3.7 and 44.8±5.0 kg/day for melatonin and control cows, respectively). There was an effect of season with a higher winter milk yield than in summer (43.8±5.0 and 47.1±3.0 kg/day for melatonin and control groups, respectively). The interaction between melatonin and season showed no significant effect; however, during winter, milk yield tended to be higher (P=0.06) in control cows than in melatonin treated cows (45.3±3.7 and 49.2±3.0, respectively). This study indicates that treatment with melatonin prior to calving did not modify milk yield during the following lactation. Only a tendency for a reduction in milk yield during winter was observed in melatonin treated cows.U ovom istraživanju procjenjivan je učinak primjene melatonina 60 dana prije očekivanog teljenja (razdoblje isušivanja) na proizvodnju mlijeka tijekom kasnije laktacije. Šezdeset mliječnih krava tretirano je potkožnim implantatima melatonina tijekom ljetnog (n=30), odnosno zimskog (n=30) razdoblja. Drugih 60 životinja nije tretirano i one su poslužile kao kontrola. Nije bilo razlika u prosječnoj proizvodnji mlijeka između tretiranih i netretiranih životinja (44,5±3,7 kg/ dan u krava tretiranih melatoninom, odnosno 44,8±5,0 kg/dan u kontrolnih krava). Postojao je učinak sezone, pri čemu je proizvodnja mlijeka bila veća zimi u odnosu na ljeto (43,8±5,0 kg/ dan u krava tretiranih melatoninom, odnosno 47,1±3,0 kg/dan u kontrolnoj skupini). Interakcija između melatonina i sezone nije pokazala značajniji učinak, ali tijekom zimske sezone proizvodnja mlijeka u kontrolnih krava bila je veća (P=0,06) u odnosu na krave tretirane melatoninom (45,3±3,7 u kontrolnoj skupini, odnosno 49,2±3,0 u krava tretiranih melatoninom). Ova studija ukazuje da tretman melatoninom prije teljenja ne mijenja proizvodnju mlijeka tijekom kasnije laktacije. Primijećena je samo tendencija smanjenja proizvodnje mlijeka u zimskoj sezoni u krava tretiranih melatoninom