Authors: JUAN GONZÁLEZ MALDONADO, RAYMUNDO RANGEL SANTOS, RAYMUNDO RODRIGUEZ DE LARA, GUSTAVO RAMIREZ VALVERDE
Abstract: This study evaluated the effect of injecting vitamin C (VC) and E (VE) on size of the preovulatory follicle, volume of the corpus luteum, and pregnancy rates in Holstein cows under heat stress conditions (temperature humidity index > 74). Sixty-two cows were randomly assigned to one of four treatments: 1, control, n = 15: cows were not supplemented with vitamins; 2, VCG, n = 15: cows were simultaneously injected i.v. with 500 and s.c. with 2500 mg of VC before and after estrus; 3, VEG, n = 15: cows received an i.m. injection of 3000 IU of VE before estrus; 4, VCEG, n = 17: cows were injected with VC and VE in the same way and doses as in treatments 2 and 3. Treatment did not significantly affect any of the measured variables, despite a numerical increase in pregnancy rates in cows injected with vitamins (7.5 ± 7.3%, 9.6 ± 9.4%, 15.1 ± 10.0%, and 18.34 ± 9.9% for control, VCG, VEG, and VCEG, respectively). In conclusion, injections of vitamin C and E did not affect either the development of the preovulatory follicle and the corpus luteum or pregnancy rates in Holstein dairy cattle under heat stress conditions.
Keywords: Corpus luteum, dairy cattle, heat stress, pregnancy rate, vitamin C, vitamin E
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