The goal of this study was to determine whether 1 h of trucking stress
before or after artificial insemination (AI) altered the conception r
ate of beef heifers. Estrus was synchronized in heifers with prostagla
ndin F-2 alpha The 3 treatment groups consisted of 1) AI (control heif
ers, n=93); 2) Truck+AI (trucked for 1 h immediately before AI, n=81);
and 3) AI+Truck (trucked for 1 h immediately after AI, n=82). All hei
fers were artificially inseminated by a single technician with semen f
rom a single ejaculate. Blood samples were collected for cortisol meas
urement 1 h before Al, immediately before and after AI, and 1 h after
AI in the AI (n=6), Truck+AI (n=9), and AI+Truck (n=8) groups. Pregnan
cy in heifers was confirmed either at slaughter or by palpation per re
ctum. Trucking before AI elevated (P<0.01) serum cortisol concentratio
ns. Artificial insemination alone increased (P<0.01) serum cortisol co
ncentrations in Al heifers. The increase in serum cortisol concentrati
ons caused by trucking after AI was not significant (P>0.05). Areas un
der the cortisol curves in Truck+AI heifers are greater (P<0.05) than
in Al heifers. The conception rates of AI heifers (50.5%), Truck+AI he
ifers (51.9%) and AI+Truck heifers (58.5%) are not different (P>0.05).
This study demonstrates that 1 h of trucking stress either before or
after AI did not lower the conception rate of heifers.