Effects of active immunization against a synthetic peptide sequence of the inhibin alpha-subunit on plasma gonadotrophin concentrations, ovulation rate and lambing rate in ewes.
Thirty adult Mule (Blue-faced Leicester x Swaledale) ewes were actively immunized against a synthetically produced peptide corresponding to the N-terminus of the alpha-subunit of bovine inhibin conjugated to tuberculin purified protein derivative (PPD). Primary immunization in the late anoestrous period was followed by two booster injections at 5 week intervals. Control groups were either not immunized (n = 15) or received PPD only (n = 15). Ten days after the second booster, oestrus was synchronized using progestagen sponges and ovulation rate was assessed by laparoscopy on days 9-10 of the cycle. Blood samples were taken at the time of each immunization and immediately before laparoscopy. Ewes were mated with fertile rams in mid-November and the resulting conception, pregnancy and lambing rates monitored. All inhibin-immunized ewes generated antibodies that bound 125I-labelled native bovine inhibin (M(r) 32,000), and their plasma follicle-stimulating hormone (FSH) concentrations after the second booster were significantly higher than the preimmunization values (30%; P less than 0.001) and the corresponding value in the controls (25%; P less than 0.025). Inhibin immunization was associated with a 90% increase in ovulation rate (P less than 0.005) and had no adverse effect on conception rate (100%), pregnancy rate (100%) or length of gestation (146 days). However, only a 37% increase (P less than 0.05) in lambing rate was recorded for inhibin-immunized ewes, indicating a higher incidence of wastage of ova, or embryos, or both, in these ewes.(ABSTRACT TRUNCATED AT 250 WORDS)
Wrathall
J H
JH
Department of Biochemistry and Physiology, University of Reading, UK.
McLeod
B J
BJ
Glencross
R G
RG
Knight
P G
PG
D000818:Animals; D001724:Birth Weight; D005260:Female; D005313:Fetal Death / Q000209:etiology; D005640:Follicle Stimulating Hormone / Q000097:blood; D006065:Gonadotropins, Pituitary / Q000097:blood*; D007265:Inhibins / Q000276:immunology / Q000502:physiology*; D008098:Litter Size; D007986:Luteinizing Hormone / Q000097:blood; D010060:Ovulation / Q000502:physiology*; D011247:Pregnancy; D012756:Sheep / Q000097:blood / Q000502:physiology*; D014611:Vaccination
D006065:Gonadotropins, Pituitary; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone