Conforto térmico e eficiência da inseminação artificial em tempo fixo em búfalas leiteiras mantidas em sistemas silvipastoris na Amazônia Oriental

Abstract

This experiment was developed in U.P.A. “Senador Álvaro Adolpho”, of Embrapa Eastern Amazon, Belém, Pará (1º25¢ S 48º26¢ W), under hot and humid conditions (Afi). The aim of this research was to evaluate the use of silvopastoral systems (SSP´s) as management tool to provide animal comfort to dairy buffaloes and to increase their reproductive efficiency after fixed time artificial insemination. Two different SSP´s were used during Phase 1 (April to June), characterized by intense rainfall and Phase 2 (September to November), characterized by mild rainfall. Heart rate (HR), respiratory rate (RR), rectal temperature (RT) and ruminal movement (RM) were measured at 9:00 A.M.. Animal Comfort Index (ACI) was calculated as ACI=RT/38.33 + RF/23. Animal received two different treatment for oestrus synchronization: SSP 1/Ovsynch, SSP 2/Ovsynch (Ovsynch based protocol), SSP 1/Prog and SSP 2/Prog (Ovsynch + 1g of intravaginal progesterone). Ovaries of all buffaloes were scanned by ultrasound in D0, D7 and D9. Females were inseminated on D10. The averages of HR were 57.35±8.24 beats/min in Phase 1 and 62.48±7.79 beats/min in Phase 2 (P <0.01). The averages of RF were of 25.66±10.53 mov/min in Phase 1, and 33.38±18.23 mov/min in Phase 2 (P <0.01). Animals kept in SSP 1 presented higher values of RT compared to the SSP 2 (39.02± 0.53 °C and 38.65±0.41 °C, P<0,01). The ACI average ranged from 1.89 to 3.55. During Phase 1, ACI ranged from 1.89 to 2.42 (mean 2.12±0.46); in Phase 2, ACI ranged from 1.91 to 3.55 (mean 2.46±0.79). Significant difference was observed between Phases (P<0,01). Dominant follicle diameter on D9 was higher on progesterone treated animals (10.40±1.22 mm versus 12.21±3.42 mm, P=0.05). Overall pregnancy rate was 48.21%, corresponding to Phase 1 = 56.66% and Phase 2 = 38.46% (SSP1/Ovsynch: 40.0%; SSP2/Ovsynch: 38.46%; SSP1/Prog: 46.66% and SSP2/Prog: 69.23%; P>0,05). These results emphasize importance of physical environment management for buffaloes production at Eastern Amazon; in order to avoid energy expenditure for animal thermoregulation and to allow shifting reproductive rates.