Dissertação
Aspectos fisiopatológicos da reprodução de novilhas submetidas a dietas contendo zearalenona com e sem aditivo anti-micotoxina
Fecha
2018-07-31Autor
Parmeggiani, Eliana Burtet
Institución
Resumen
Zearalenone (ZEA) is a mycotoxin produced by several fungi species of the genus Fusarium spp., which can
interferes with the physiology of endogenous hormones and affects the reproductive system of production animals.
Since diets are contaminated with ZEA, the possibility of reducing exposure is through adoption of
decontamination strategies such as use of anti-mycotoxin additive (AAM). Therefore, the aim of the present study
was to evaluate whether the modified bentonite-based anti-mycotoxin additive would reduce the negative effect
of zearalenone-contaminated diets on the clinical, cyclical and conception rate of beef heifers submitted to Fixed-
Time Artificial Insemination (FTAI). Twenty-four heifers (n=24) with average age of 2 years and 271 ± 11.14 kg
of body weight were evaluated through a general and complete gynecological examination. Healthy and cyclic
females were selected and randomly assigned to compose four experimental groups with 6 animals each: T1 -
basal diet (control), T2 - basal diet + 5 mg/kg ZEA, T3 - basal diet + 5 mg/kg ZEA + 2.5 kg/ton AAM and T4 -
basal diet + 5 mg/kg ZEA + 5.0 kg/ton AAM. The research had a total duration of 37 days, being 11 days of
adaptation period, 21 days of experimental period and 5 days of regression period. In the adaptation period, all
heifers received a hormonal protocol for estrus synchronization and ovulation. During the experimental and
regression period were evaluated body weight, vulvar volume, mammary gland edema, blood collection for
estradiol and progesterone hormone dosage, and ultrasonography of the reproductive tract for frequency of uterine
edema and number and diameter of follicles and corpus luteum on days 0, 5, 10, 15, 20 and 25. At the reproductive
season (D67) the heifers were submitted to a FTAI protocol to analyze conception rate after intoxication. Body
weight averages were similar between treatments on the different days evaluated. There was no significant vulvar
edema between treatments on the different days evaluated. The edema of the mammary gland was absent in all
treatments on the different days evaluated. In the assessment of uterine edema, it was observed that at day 0, all
heifers presented uterine edema regardless of the treatment. And on days 5, 10 and 25 uterine edemas were absent
in all heifers regardless of the treatment. On days 15 and 20, uterine edema occurred randomly between treatments.
In the evaluation of the ovaries the averages were similar between treatments, regarding the number and diameter
of follicles and corpora lutea corpus luteum on the different days evaluated. Serum estradiol concentration was
similar between treatments on the different days evaluated. The progesterone levels revealed that there was no
significant difference between treatments on days 0, 5, 10, 15 and 25, except for day 20 (P=0.03), where
concentration was higher in T4. Conception rates after intoxication was 83% for T1, 60% for T2, 67% for T3, 83%
for T4, and the overall rate between treatments was 74%. The use of an anti-mycotoxin additive at a dose of 5
kg/ton reduced the negative effect of diets contaminated with zearalenone by preventing the effects of mycotoxin
on conception rate of heifers submitted to FTAI protocol. The contamination of the diets with 5 mg/kg zearalenone
did not affect the clinical aspects and the cyclicity during days evaluated in the beef heifers, but reduced conception
rate.