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 se kontrolišu od strane odgajivača. U reprodukciji se koristi mali broj ovnova za kontrolisano parenje ovaca ili njihova sperma za osemenjavanje. Mužjak je odgovoran za multiple bremenitosti tokom godine u programima parenja i do stotina hiljada bremenitosti u programima veštačkog osemenjavanja. Poznavanje reproduktivnih procesa ovaca, a naročito polnog sazrevanja ovnova, je stoga veoma značajno. Osnovni cilj istraživanja u ovoj doktorskoj disertaciji bio je da se ispita varijabilnost koncentracije testosterona i povezanost sa primarnim i sekundarnim polnim osobinama i ponašanjem ovnova. U okviru toga sagledani su sledeći parametri: koncentracija testosterona u krvnom serumu ovnova, obim testisa ovnova, telesna masa ovnova, kvalitet sperme ovnova, polno ponašanje ovnova u okviru interakcija muškožensko, polno ponašanje ovnova u okviru interakcije muško-muško i rezultati plodnosti ovaca. Istraživanja u ovoj doktorskoj disertaciji izvršena su na eksperimentalnoj ovčarskoj farmi Instituta za stočarstvo u Zemunu. U istraživanjima je bilo uključeno 20 ovnova i 76 ovaca Mis populacije. Sva muška grla bila su po tipu rođenja blizanci, istog uzrasta. Grla su uvedena u istraživanje u uzrastu od 3 meseca, a istraživanje je završeno u uzrastu ovnova od 18 meseci. Ženska grla uključena u istraživanje bila su starosti od 3 do 5 godina. Od momenta uvođenja ovnova u istraživanje, telesna masa i obim testisa mereni su jednom mesečno. Uzorci krvi za utvrđivanje koncentracije testosterona u krvnom serumu uzimani su na svaka dva meseca (u uzrastu od 3 do 17 meseci). Za analizu kvaliteta sperme uzorci semena ovnova uzimani su u uzrastu ovnova od 9 do 17 meseci na svaka dva meseca, primenom metode elektroejakulacije. Od parametara kvaliteta sperme analizirani su: zapremina ejakulata, koncentracija spermatozoida u ejakulatu, pokretljivost spermatozoida, procenat živih spermatozoida u ejakulatu i procenat patoloških formi spermatozoida u ejakulatu...

In current sheep production, reproductive processes in ewes and rams are mainly controlled by the breeder. A small number of rams is used for controlled breeding of ewes, or their sperm for artificial insemination. The male is responsible for multiple pregnancies during a year within breeding/mating programs and hundreds of thousands of pregnancies in programs of insemination. Understanding of reproductive processes in sheep, 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 the variability of testosterone concentration and its correlation with primary and secondary sexual characteristics and behaviour of rams. The following parameters were considered: testosterone concentration in the blood serum, scrotal circumference, body mass of rams, semen quality, rams’ sexual behaviour within the male-female interactions, sexual behaviour of rams within male-male interactions and the results of the fertility of ewes. Research in this doctoral thesis was carried out on the Experimental sheep farm of the Institute for Animal Husbandry, Zemun. The study included 20 rams and 76 ewes of Mis population. All males were twins according to the type of birth and of the same age. Animals were introduced to the trial at the age of 3 months, the trial was completed at the age of rams of 18 months. Female animals included in the trial were 3 to 5 years old. From the moment of introduction of rams in the trial, body mass and scrotal circumference were measured once a month. Blood samples for determination of the concentration of testosterone were taken every two months (from 3 to 17 months of age). To analyse sperm quality, samples of rams' semen were taken at the age of rams from 9 to 17 months, every two months, using the method of electroejaculation. The following sperm quality parameters were analysed: ejaculate volume, sperm concentration, sperm motility, percentage of live sperm and the percentage of abnormal forms of spermatozoa...