EFFECT OF GnRH POST INSEMINATION ON LUTEAL FUNTION IN SHEEP.

FERNANDEZ J; BRUNO GALARRAGA MACARENA; SOTO, A; CUETO MARCELA; DE LA SOTA, R.L.; GIBBONS A,; LACAU, I.M.

Buenos Aires

Jornada; XX JORNADAS ANUALES DE LA SOCIEDAD ARGENTINA DE BIOLOGÍA (SAB), XVII JORNADAS DE LA SOCIEDAD URUGUAYA DE BIOCIENCIAS (SUB)- Segundas Jornadas Rioplatenses de Biología.; 2018

SAB Y SUB

We evaluated the effect of the administrationof gonadotropin-releasing hormone (GnRH) at Day 4 post timed artificialinsemination (TAI) on the formation of accessory corpora lutea (acc CL) and theproduction of luteinizing hormone (LH) and progesterone (P4) insheep. During the breeding season, a total of 24 adult Merino ewes wererandomly assigned to two groups on Day 4 post TAI: GnRH Group (n= 12; 4 µg of Buserelin,i.m., Receptal®, Intervet, Arg.) and Control Group (n= 12; 1 ml ofsaline solution, i.m.). Laparoscopic observation of the ovaries at Days 4, 10and 21 post TAI was performed to determine the presence of ovulatory CL and accCL. Serum P4 concentration was assessed by chemiluminescence on days4, 7, 10, 13, 17, 21, 28 and 35 post TAI. Serum LH concentration was assessedby RIA 2-6 h post treatment. The number of acc CL and LH concentration was analyzedby ANOVA and P4 concentration by a generalized linear model withtime-repeated measurements. Statistical significance was accepted fromP<0.05. The presence of an acc CL was only observed in the GnRH Group (P<0.05).GnRH administration did not increase serum P4 concentration (5.8±0.4ng/ml) compared to the Control group (5.3±0.3 ng/ml) (P>0.05). Moreover,GnRH treated ewes had similar concentration of P4, whatever theydeveloped or not an acc CL (P>0.05). GnRH administration increased serum LHconcentration about 2-6 h after treatment compared to the Control group (10.6±1.2ng/ml and 3.1±1.1 ng/ml, respectively; P <0.05). The increase of LHconcentration was observed only in the ewes that generated acc CL (P<0.05). Administrationof GnRH at Day 4 post TAI increased serum LH concentration and induced theformation of acc CL. However, serum P4 concentration did notincrease.