Ocena varijabilnosti koncentracije testosterona i povezanosti sa primarnim i sekundarnim polnim osobinama i ponašanjem ovnova

Abstract

U savremenom ovčarstvu, reproduktivni procesi ovaca i ovnova uglavnom sekontrolišu od strane odgajivača. U reprodukciji se koristi mali broj ovnova zakontrolisano parenje ovaca ili njihova sperma za osemenjavanje. Mužjak je odgovoranza multiple bremenitosti tokom godine u programima parenja i do stotina hiljadabremenitosti u programima veštačkog osemenjavanja. Poznavanje reproduktivnihprocesa ovaca, a naročito polnog sazrevanja ovnova, je stoga veoma značajno.Osnovni cilj istraživanja u ovoj doktorskoj disertaciji bio je da se ispitavarijabilnost koncentracije testosterona i povezanost sa primarnim i sekundarnimpolnim osobinama i ponašanjem ovnova. U okviru toga sagledani su sledeći parametri:koncentracija testosterona u krvnom serumu ovnova, obim testisa ovnova, telesna masaovnova, kvalitet sperme ovnova, polno ponašanje ovnova u okviru interakcija muškožensko,polno ponašanje ovnova u okviru interakcije muško-muško i rezultati plodnostiovaca.Istraživanja u ovoj doktorskoj disertaciji izvršena su na eksperimentalnojovčarskoj farmi Instituta za stočarstvo u Zemunu. U istraživanjima je bilo uključeno 20ovnova i 76 ovaca Mis populacije. Sva muška grla bila su po tipu rođenja blizanci, istoguzrasta. Grla su uvedena u istraživanje u uzrastu od 3 meseca, a istraživanje je završenou uzrastu ovnova od 18 meseci. Ženska grla uključena u istraživanje bila su starosti od 3do 5 godina.Od momenta uvođenja ovnova u istraživanje, telesna masa i obim testisa merenisu jednom mesečno. Uzorci krvi za utvrđivanje koncentracije testosterona u krvnomserumu uzimani su na svaka dva meseca (u uzrastu od 3 do 17 meseci). Za analizukvaliteta sperme uzorci semena ovnova uzimani su u uzrastu ovnova od 9 do 17 mesecina svaka dva meseca, primenom metode elektroejakulacije. Od parametara kvalitetasperme analizirani su: zapremina ejakulata, koncentracija spermatozoida u ejakulatu,pokretljivost spermatozoida, procenat živih spermatozoida u ejakulatu i procenatpatoloških formi spermatozoida u ejakulatu...

In current sheep production, reproductive processes in ewes and rams are mainlycontrolled by the breeder. A small number of rams is used for controlled breeding ofewes, or their sperm for artificial insemination. The male is responsible for multiplepregnancies during a year within breeding/mating programs and hundreds of thousandsof pregnancies in programs of insemination. Understanding of reproductive processes insheep, and especially the sexual maturity of the rams, is therefore very important.The main aim of the research in this doctoral thesis was to evaluate thevariability of testosterone concentration and its correlation with primary and secondarysexual characteristics and behaviour of rams. The following parameters wereconsidered: testosterone concentration in the blood serum, scrotal circumference, bodymass of rams, semen quality, rams’ sexual behaviour within the male-femaleinteractions, sexual behaviour of rams within male-male interactions and the results ofthe fertility of ewes.Research in this doctoral thesis was carried out on the Experimental sheep farmof the Institute for Animal Husbandry, Zemun. The study included 20 rams and 76 ewesof Mis population. All males were twins according to the type of birth and of the sameage. Animals were introduced to the trial at the age of 3 months, the trial was completedat the age of rams of 18 months. Female animals included in the trial were 3 to 5 yearsold.From the moment of introduction of rams in the trial, body mass and scrotalcircumference were measured once a month. Blood samples for determination of theconcentration of testosterone were taken every two months (from 3 to 17 months ofage). To analyse sperm quality, samples of rams' semen were taken at the age of ramsfrom 9 to 17 months, every two months, using the method of electroejaculation. Thefollowing sperm quality parameters were analysed: ejaculate volume, spermconcentration, sperm motility, percentage of live sperm and the percentage of abnormal forms of spermatozoa...