Resumen

NAVARRO, L. M.; YOSTAR, E. J.  y  CAPELLARI, A.. Reproductive performance evaluation in two indics crosses females categories with conventional protocol and J-Synch. Rev. vet. [online]. 2022, vol.33, n.2, pp.208-214. ISSN 1669-6840.  http://dx.doi.org/10.30972/vet.3326183.

The objective of this study was evaluate the reproductive performance of índics cross cows and heifers with a conventional protocol and prolonged proestrus in a breeding system at Chaco. Were used 264 cows without calf and 236 heifers with body condition 4 to 6 (scale 1-9). On day 0 a device with 0.5 g of progesterone (DIB) and 2 mg of estradiol benzoate was applied. Animals were randomly distributed into 2 groups: a) conventional: day 8: DIB was withdrawn, D-Cloprostenol (PG) (150µg) and estradiol cypionate (0.5 mg) were administered. Artificial insemination (AI) was performed 48 to 54 hours after withdrawal DIB. b) J-Synch: day 6 DIB was withdrawn, PG (150 µg) and equine chorionic gonadotropin (eCG) (300 or 400 IU) were applied in heifers and cows respectively. The sacro-coccygeal region was painted to determine estrus manifestation, performing AI on the unpainted ones at 60 h and 72 hand in those that were still painted at 72 h in addition to AI buserelin acetate (10 µg) was applied. Ultrasonography diagnosis was made 40 days post-AI. Using Chi (2) test were compared the effect of treatment (conventional vs. J-Synch without eCG) and category (heifer and cow) on the rates of pregnancy and in J-Synch (without vs. with eCG) in addition to estrus manifestation. No association was found between treatments evaluated with reproductive performance with pregnancies of 43% vs 54% in cows and 59% vs 51% in heifers with conventional and J-Synch respectively. In J-Synch of 52 and 56% in cows (54 vs 62%) and heifers (51 vs 50%) without and with eCG respectively. The general pregnancy was 55% in animals that showed estrus and 44% in those that did not. In conclusion, the cows had a tendency to perform better with J-Synch where the use of eCG had no influence on pregnancy.

Palabras clave : cattle; fixed-time AI; prolonged proestrus; pregnancy rate.

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