Technical note: use of slow-release estradiol and prostaglandin F2alpha to induce pseudopregnancy and control estrus in gilts.
We determined whether a single injection of slow-release estradiol-17beta (SRE2) would induce pseudopregnancy in gilts and whether PGF2alpha would regress the corpora lutea (CL) of pseudopregnancy. Crossbred gilts (n = 40) were induced to ovulate by treatment with 400 IU of hCG + 200 IU of eCG (PG600, Intervet, Millsboro, DE) given at 180 d of age (d = 0). On d 14, gilts were injected i.m. with one of five doses (n = 8 gilts/dose) of SRE2 (0, 12.5, 25, 50, or 100 mg). Blood samples were collected before SRE2 and twice weekly until d 73 to monitor serum progesterone (P4) and estradiol (E2). On d 59, gilts received (i.m.) 10 mg of PGF2alpha (Lutalyse, Pharmacia Upjohn, Kalamazoo, MI) and were checked for estrus for 7 d. On d 62, mammary development was scored (0 = no development; 1 = some development; 2 = teat and gland development) by a neutral observer. Treatment with SRE2 increased (P < .05) peak E2 concentrations, duration of luteal function, and mammary gland score. There were no differences (chi-square, P > .05) among doses of SRE2 in the percentage of pseudopregnant gilts that showed luteolysis after PGF2alpha. We conclude that a single injection of SRE2 can induce pseudopregnancy and that the CL can be regressed with PGF2alpha, providing a simple method for controlling estrus in gilts.
Cushman
R A
RA
Department of Anatomy, Physiological Sciences, and Radiology, North Carolina State University, Raleigh 27606, USA.
Davis
P E
PE
Boonyaprakob
U
U
Hedgpeth
V S
VS
Burns
P J
PJ
Britt
J H
JH
D000818:Animals; D003692:Delayed-Action Preparations; D015237:Dinoprost / Q000008:administration & dosage / Q000494:pharmacology*; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D011555:Pseudopregnancy / Q000139:chemically induced*; D013552:Swine
D003692:Delayed-Action Preparations; D004958:Estradiol; D015237:Dinoprost