Ispitivanje parametara efikasnosti reprodukcije visokomlečnih krava nakon sinhronizacije estrusa i stimulacije lutealne funkcije

Abstract

Rani embrionalni razvoj kod krava moţe biti negativno pogoĎen nedovoljnom lutealnom proizvodnjom progesterona (P4). Cilj našeg istraţivanja bio je da ispitamo mogući uticaj tretmana gonadotropnim oslobaĎajućim hormonom (GnRH) i/ili humanim horionskim gonadotropinom (hCG), nakon indukcije estrusa tretmanom prostaglandinom F2, na povišeno lučenje P4 i rezultate steonosti krava. Ogled je sproveden na kravama Simentalske rase (n = 110), izmeĎu 3-5 laktacije, sa prosečnom proizvodnjom mleka od 6500L/305 dana, 40-80 dana posle partusa i to na četiri ogledne grupe: 1) krave sa spontanim estrusom (C: kontrolna grupa), 2) GnRH tretman u vreme veštačkog osemenjavanja (VO) (grupa O), 3) GnRH + hCG tretman 7 dana nakon VO (OP grupa), i 4) hCG tretman 7. dana posle VO (P grupa). Sve ţivotinje su dvostruko osemenjene (u vreme otkrivanja estrusa i posle 12±2h). Uzorci seruma i mleka krvi sakupljeni su u estrusu, 14, 21. i 28. dana nakon VO. Serumski P4 i estradiol-17 (E2) su odreĎivani komercijalnim radioimunološkim testom (RIA), a nivo P4 u mleku je odreĎivan pomoću enzimoimunološkig testa (EIA). Dijagnostika steonosti je vršena ultrazvukom izmeĎu 28. i 35. dana nakon VO. Statistička značajnost razlike vrednosti P4 i E2 u serumu, kao i P4 u mleku, kao i procentu steonih krava utvrĎene su pomoću Dunn’s Multiple Comparison test i Z testa za poreĎenje proporcija. Koncentracija P4 u krvnom serumu bila je statistički značajno povišena 14, 21. i 28. dana nakon VO kod ţivotinja tretiranih sa hCG-om (14 dan, P:C, P:O, p<0.001; OP:C, p<0.05; 21 dan, P:C, P:O, p<0.001; P:OP, p<0.05; 28 dan, P:C, P:O, p<0.001; P:OP, p<0.05) što ukazuje na povećanu aktivnost lutealnog tkiva, sa sličnom tendencijom u vrednostima P4 u mleku. Vrednosti E2 u krvnom serumu nisu dale jasne podatke za procenu funkcije jajnika. Tretman sa hCG-om tokom rane lutealne faze takoĎe je doveo do povećanja procenta steonih krava Simentalske rase (P:C i (P+OP+P):C, p<0.05).

Early embryonic development may be negatively affected by insufficient progesterone (P4) production therefore the aim of our study was to increase it by gonadotropin-releasing hormone (GnRH) and/or human chorionic gonadotropin (hCG) treatments after inducing of oestrus by prostaglandin treatment. Lactating Simmental dairy cows (n=110), between 3 to 5 lactations, with average milk production of 6500L/305 days, at 40-80 days postpartum were used and grouped as follows: 1) spontaneous oestrus (C: control group), 2) GnRH treatment at AI (O group), 3) GnRH at AI + hCG treatment at Day 7 after AI (OP group), and 4) hCG treatment at Day 7 after AI (P group). All animals were double inseminated (at the time of oestrus detection and after 12±2h). Blood serum and milk samples were collected at oestrus, 14, 21. and 28. days after AI. Serum P4 and estradiol-17 (E2) were determined using a commercial radioimmunoassay (RIA) test, and milk P4 was determined using enzyme-linked immunoassay (EIA) test. Pregnancy status was confirmed by means of ultrasonography between Days 28. and 35. after AI. Differences of serum or milk P4 and E2 medians, and pregnancy rate were determined using Dunn’s Multiple Comparison Tests and Z test, respectively. Serum P4 medians were significantly higher at Days 14, 21. and 28. after AI in the hCG treated animals (Day 14, P:C, P:O, p<0.001; OP:C, p<0.05; Day 21, P:C, P:O, p<0.001; P:OP, p<0.05; Day 28, P:C, P:O, p<0.001; P:OP, p<0.05), indicating increased luteal activity, with the similar tendency in whole milk P4 values. Blood serum E2 values were unconclusive for the ovarian function estimation. Treatment with hCG during the early luteal phase also induced increased pregnancy rate in the Simmental dairy cows (P:C and (P+OP+P):C, p<0.05).