Efecto de los implantes subcutáneos de melatonina y la suplementación alimentaria, sobre la inducción de la actividad ovárica en ovejas Pelibuey durante la época de anestro

Abstract

T OF MELATONIN IMPLANTS ON OVARIAN ACTIVITY WAS EVALUATED IN SUPPLEMENTED AND NON SUPPLEMENTED PELIBUEY SHEEP DURING THE ANOESTROUS SEASON. THE STUDY WAS CARRIED OUT AT 20O 04"" N UNDER TROPICAL CONDITIONS. THE EXPERIMENTAL FLOCK CONSISTED OF NINETY ANOESTROUS EWES THAT LAMBED IN THE SUMMER. HALF OF THE ANIMALS WERE SUPPLEMENTED WITH A CONCENTRATE (14% CP AND 3 500 KCAL/KG) FROM FEBRUARY TO JUNE. SUPPLEMENTED AND NON SUPPLEMENTED ANIMALS WERE SUBDIVIDED IN TWO GROUPS IN MARCH: ONE OF THEM RECEIVED A SUBCUTANEOUS MELATONIN IMPLANT (18 MG) TO FORM THE FOLLOWING GROUPS: M S (MELATONIN SUPPLEMENTED; N:24), M (MELATONIN-GRAZING; N:23), S (SUPPLEMENTED; N:22) AND C (GRAZING OR CONTROL; N:21). OVARIAN ACTIVITY WAS MONITORED BY MEASURING PROGESTERONE LEVELS, AND BY OESTROUS DETECTION. ONLY 54.4% OF THE ANIMALS SHOWED OESTRUS. THERE WERE NO DIFFERENCES (P >0.05) AMONG GROUPS IN THE OVULATING FEMALES (M S = 84.6%; M P = 72.9%; S = 80.0%, AND THE CONTROL = 55.5%); INCIDENCE OF OESTROUS (M S = 70.8%; M P=47.8%; S = 45.4%, AND THE CONTROL=52.3%); INTERVAL FROM MELATONINE IMPLANT INSERTION TO FIRST INCREASE OF PROGESTERONE (M S = 11.6 ± 2.9 D; M P = 16.5 ± 3.3 D; S = 12.2 ± 1.3D, AND THE CONTROL = 8.0 ± 3.6 D); AND INTERVAL FROM IMPLANT INSERTION TO OESTROUS (M S = 18.8 ± 2.8 D; M P = 14.0 ± 1.9 D; S = 10.4 ± 1.5 D, AND THE CONTROL 11.5 ± 1.9 D). IT IS CONCLUDED THAT NEITHER MELATONIN IMPLANTS, NON SUPPLEMENTATION EXERT AN EFFECT ON THE ONSET OF OVARIAN ACTIVITY IN PELIBUEY ANOESTROUS EWES.