TRUCKING STRESS AT BREEDING DOES NOT LOWER CONCEPTION RATE OF BEEF HEIFERS

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.