3.1. Analysis 1
Forty different THI thresholds were determined ranging
from THI of 41 or more to THI of 79 or more. The CR for each
THI threshold from 41 to 79 was calculated from herd
reproductive data. The greatest CR was observed at a mean
daily THI less than 41 (30.4%; n ¼ 12) and the lowest at a
mean daily THI of 78 or more (10.5%; n ¼ 15). Overall, thecoefficient of correlation between THI at the day of
breeding and CR was r ¼ 0.49 (n ¼ 7252 inseminations;
P < 0.01). In the univariable logistic regression models, the
effect of THI thresholds from THI of 56 or more to THI of 76
or more on CR remained significant (Table 1). Odds ratios
decreased as THI increased, indicating a negative effect of
increasing THI on CR