[Artificial lactation induction in 12- to 19-month-old heifers with regard to the behavior of the concentration of sex hormones and lactogenic proteohormones in the blood plasma].
In 24 prepubertal heifers the lactation was artificially induced by two different methods of hormone application. The changes in milk yield and the concentrations of estradiol-17 beta (E), progesterone (P), prolactin, somatotropin and insulin-like growth factor I in blood plasma during the first 55 days of lactation were analyzed. Depending on the age, the animals were divided in three experimental groups (EG) of eight animals each: 12 months old (EG I), 15 months old (EG II) and 19 months (EG III). Four animals of each EG were treated similarly: group E and P, which was injected by estradiol benzoate and P for 7 days, or group E, which received only estradiol benzoate for 10 days. The oldest heifers (EG III) showed an induction rate of 100% with E and P treatment and of 75% with E alone. On the other hand, in heifers of EG I and EG II the induction rate was only 50% irrespectively of the treatment. The animals of EG III had the highest milk yield. The daily milk yield on the 50th day of lactation was 7.0 kg and 4.0 kg in group E and P or group E, respectively. Comparable levels in 15 months old heifers (EG II) were 4.8 kg and 1.4 kg, and in 12 months old heifers (EG I) 2.5 kg and 2.5 kg. The changes of the concentrations of the hormones in blood plasma are demonstrated in diagrams, their effect on the milk production is discussed.
D000818:Animals; D002417:Cattle / Q000097:blood / Q000502:physiology*; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D013006:Growth Hormone / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007774:Lactation / Q000097:blood* / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000097:blood
D012739:Gonadal Steroid Hormones; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D013006:Growth Hormone
Untersuchungen zur künstlichen Laktationsinduktion an 12 bis 19 Monate alten Jungrindern unter Berücksichtigung des Verhaltens der Konzentrationen an Sexualhormonen und laktogenen Proteohormonen im Blutplasma.