Efeitos de ondas de calor no dia da inseminação de leitoas criadas em ambiente tropical

Abstract

Heat stress negatively affects reproductive performance in gilts. Thus, the aim of the present study was to investigate the effect of heat waves on the day of insemination of gilts in a tropical environment. The study was carried out from reproductive data from a commercial farm from September 2013 to July 2019. Meteorological data were obtained by the National Institute of Meteorology (INMET) with daily information on air temperature and relative humidity at three times: 9:00, 15:00 and 21:00 hours, after which the Temperature and Humidity Index (THI) was calculated. Thus, heat waves were defined as temperature ≥ 25°C and THI > 74 for at least three consecutive days in at least one of the times evaluated. Data from 10051 inseminations were used. Gilts were divided into two groups: without heat waves (4574) and with heat waves (5477) on the day of insemination, where pregnancy and abortion were analyzed. Higher temperatures, THI and consequently heat waves were observed in the months of January, February, March, April, September, October, November and December. The group of gilts inseminated without heat waves had a higher percentage of pregnant gilts (98.78%) when compared to the group of gilts inseminated on the day of heat waves (98.21%) (P = 0.0267). The percentage of gilts that aborted in the group without heat waves (2.16%) and with heat waves (2.68%) on the day of insemination did not differ (P = 0.1065). Gilts housed in sheds with fans and fogging exposed to heat waves on the day of insemination reduces the number of pregnancies, but does not change the number of abortions.