Effect of zinc supplementation on the area of corpus luteum and progesterone serum concentration

GALARZA E; PASCUA, A.M.; ANCHORDOQUY, JP; CARRANZA A; FURNUS, C.C.; ANCHORDOQUY, JM; NIKOLOFF N; FARNETANO, N

Foz do Iguazu

Simposio; International Ruminant Reproduction Symposium.; 2018

Zinc (Zn) is a relevant trace element in the body. The function of Zn involves a wide range of biologicalprocesses including cell proliferation, immune function, and defense against free radicals. Zinc is anessential 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 studywas to evaluate the effect of parenteral Zn supplementation at the beginning of fixed-time artificialinsemination (FTAI) on corpus luteum size, P4 and Zn serum concentration. Multiparous Aberdeen Anguscows (n =27) were randomly assigned to two groups: Control (n=16) and Zinc (n=11) groupsupplemented with 400 mg ZnSO4 injected at the beginning of FTAI protocol (day 0). Follicular waveswere 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 PGF2αand E2 cypionate was applied. All cows were inseminated on day 9. Blood samples were collected on day0, 7, 9 and 16. The variables assessed were Zn serum concentration (day 0, 7, 9 and 16), area ofpreovulatory follicle (APF), and E2 serum concentration (E2SC) at insemination time (day 9), area ofcorpus luteum (ACL) and P4 serum concentration (P4SC) at day 16 and pregnancy rate (day 40). Thestatistical analysis was carried out with SAS. Continuous response variables were analyzed with linearmodels 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 16respectively (P > 0.05). These results showed that 66.6 % cows (18/27) had serum Zn deficiency (< 90μg/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 increasedACL (Control= 32.6 ± 2.9; Zn= 43.5 ± 3.9 mm2; P < 0.05) in Zn deficient cow and tended to increaseAPF (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.