02121naa a2200313 a 450000100080000000500110000800800410001902200140006010000230007424501170009726000090021452011790022365000160140265000280141865000280144665000160147465000110149065000120150165000240151365300200153765300210155765300250157870000250160370000230162870000190165170000240167070000240169477300890171820089102016-01-29       2015    bl uuuu     u00u1 u    #d  a1806-86721 aOLIVEIRA, N. M. de  aEnvironmental effects on reproductive performance of Nellore cows widely raised in the Cerrado/Pantanal ecotone.  c2015  aWe analyzed the pregnancy rate (PR) and birth rate (BR) of Nellore cows raised extensively in the Cerrado/Pantanal during 4 mating seasons (2009?2012), assessing the relationship with the temperature and humidity index (THI) and the effect of the year and breeding season. We used information from 2,116 cows, which were categorized as either multiparous (n = 1430), primiparous (n = 338), or nulliparous (n = 348). In the months of the breeding season (December?February), temperature and relative humidity data were collected to calculate the temperature and humidity index (THI). An ANOVA was performed with a model that included sources of variation from the fixed effects of category of cow and year on PR and BR; and a linear regression analysis and correlation between THI and PR and BR. We observed a significant effect (p &lt 0.05) on PR. We classified the average across breeding seasons as a moderate THI. The THI of the breeding seasons showed high and significant (p &lt 0.05) effects only on the nulliparous BR, and low values in other categories. It is concluded that the seasonal THI was not related to the performance of cows, except BR in nulliparous cows.  abeef cattle  areproductive efficiency  aEficiência Reprodutiva  aGado nelore  aMatriz  aPrenhez  aReprodução animal  aBovino de corte  aEfeito ambiental  aEnvironmental effect1 aREZENDE, M. P. G. de1 aABREU, U. G. P. de1 aROSA, A. do N.1 aSTERZA, F. de A. M.1 aLEÃO FIALHO, A. L.  tActa Scientiarum. Animal Sciences, Maringágv. 37, n. 1, p. 77-82, jan.-mar., 2015.