Use of a beta 2-adrenergic stimulant (clenbuterol) for eliminating night-time calving.
To determine whether beta 2-adrenergic stimulant (clenbuterol) would exhibit beneficial effects upon the elimination of night-time calving, 42 Holstein Friesian cows and heifers at the first stage of labour were injected intramuscularly twice with clenbuterol; 300 micrograms at 18:00 and 210 micrograms at 22:00. Other 26 cows and heifers of the same breed at the first stage of labour at 18:00 were not treated and served as controls. All of the treated animals, but one, calved after 5:00 in the next morning, showing a peak of parturition between 5:00 and 10:00. In contrast to this, 42% of the control animals calved at night between 22:00 and 5:00. Thus, the double administrations of clenbuterol were shown to be effective for eliminating night-time calving. The cows treated with clenbuterol tended to show lower incidences of dystocia and retained placenta and a higher first insemination conception rate than the control animals. No adverse effects of the treatment on the viability of newborn calves and milk yields were observed.
Nakao
T
T
Department of Veterinary Obstetrics and Gynecology, Rakuno Gakuen University, Hokkaido, Japan.
Sato
K
K
Nakamura
T
T
Taguchi
K
K
Moriyoshi
M
M
Kawata
K
K
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002418:Cattle Diseases / Q000139:chemically induced; D002940:Circadian Rhythm; D002976:Clenbuterol / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D004420:Dystocia / Q000139:chemically induced / Q000662:veterinary; D005260:Female; D005298:Fertility / Q000187:drug effects; D007273:Injections, Intramuscular / Q000662:veterinary; D007743:Labor, Obstetric / Q000187:drug effects*; D007774:Lactation / Q000187:drug effects; D011247:Pregnancy; D011897:Random Allocation
D002976:Clenbuterol