Effects of photoperiod on mammary development. Concentration of hormones in serum of pregnant dairy heifers

analytical methods biological development blood composition composition du sang composizione del sangue cows fotoperiodismo gestation ghiandole mammarie glande mammaire gravidanza mammary glands melatonin melatonina metodi analitici photoperiodicity pregnancy prolactin prolactina prolactine prolattina sviluppo biologico technique analytique vaca vacche vache