EFFECT OF ZINC SUPPLEMENTATION ON THE AREA OF CORPUS LUTEUM AND PROGESTERONE SERUM CONCENTRATION

ANCHORDOQUY J MATEO; ANCHORDOQUY J PATRICIO; GALARZA E; NIKOLOFF N; CARRANZA A; PASCUA AM; FARNETANO NA; FURNUS C

Foz do Iguazu

Simposio; 10th International Ruminant Reproduction Symposium; 2018

International Ruminant Reproduction Symposium Team

Zinc (Zn) is a relevant trace element in the body. The function of Zn involves a wide range of biological processes including cell proliferation, immune function, and defense against free radicals. Zinc is an essential component of Cu/Zn-SOD that plays a key role in the maintenance of a functional corpus luteum (CL), in its morphology and progesterone (P4) production (Kawaguchi et al., 2013). The aim of this study was to evaluate the effect of parenteral Zn supplementation at the beginning of fixed-time artificial insemination (FTAI) on corpus luteum size, P4 and Zn serum concentration. Multiparous Aberdeen Angus cows (n =27) were randomly assigned to two groups: Control (n=16) and Zinc (n=11) group supplemented with 400 mg ZnSO4 injected at the beginning of FTAI protocol (day 0). Follicular waves were synchronized by intravaginal insertion of a CIDR for seven days and an intramuscular (i.m.) injection of estradiol (E2) benzoate (day 0). At day 7, CIDR was removed and a i.m. injection of PGF2α and E2 cypionate was applied. All cows were inseminated on day 9. Blood samples were collected on day 0, 7, 9 and 16. The variables assessed were Zn serum concentration (day 0, 7, 9 and 16), area of preovulatory follicle (APF), and E2 serum concentration (E2SC) at insemination time (day 9), area of corpus luteum (ACL) and P4 serum concentration (P4SC) at day 16 and pregnancy rate (day 40). The statistical analysis was carried out with SAS. Continuous response variables were analyzed with linear models and pregnancy rate (percentage) was analyzed by logistic regression. Serum zinc concentrations (Mean ± SEM) were not affected by Zn supplementation for Control= 92,8 ± 8,3; 130,4± 8,3; 99± 8,3; 89,3± 8,3 µg/dL; and Zinc= 89,6 ± 10; 121,6± 10; 100,8 ± 10; 90,6 ± 10 µg/dL at days 0, 7, 9 and 16 respectively (p> 0.05). These results showed that 66.6 % cows (18/27) had serum Zn deficiency (< 90 µg/dL) at the beginning of FTAI protocol (day 0). Zinc supplementation did not modify APF (Control= 10.1 ± 1.0; Zn= 12.9 ± 1.2 mm2), E2SC (Control= 17.8 ± 1.0; Zn= 16.3 ± 1.2 pg/mL) and ACL (Control= 34.8 ± 2.7; Zn= 38.6 ± 3.7 mm2) when all cows were considered. However, Zn supplementation increased ACL (Control= 32.6 ± 2.9; Zn= 43.5 ± 3.9 mm2; p< 0.05) in Zn deficient cow, and tended to increase APF (Control= 9.7 ± 1.2; Zn= 13.6 ± 1.5 mm2; p= 0.097). The P4SC were increased by Zn supplementation when all cows were considered (Control= 4.2 ± 0.4; Zn= 5.7 ± 0.5 ng/mL; p< 0.05). The P4SC of deficient cow were similar between treatments (Control= 4.1 ± 0.6; Zn= 5.4 ± 0.8 ng/mL; p> 0.05). Pregnancy rates at day 40 was higher but not significantly different for cows injected with Zn respect to Control group (Control= 46.1%, 50%; Zn= 80%, 100%, considering all and deficient cows respectively p> 0.05). In conclusion, Zn supplementation at the beginning of the FTAI protocol in deficient cows increased corpus luteum area, and increase serum progesterone concentrations when all cows were considered in the analyses. This study provide evidence that parenteral Zn supplementation may enhance pregnancy rates, even in those cows that present adequate Zn serum concentrations.