Biological and technological background of estrus synchronization and fixed-time ovulation induction in the pig

Abstract

A technology that allows for manipulating of estrus and ovulation, and would then also allow for fixed-time insemination, can be of great benefit for swine farms that operate using sow batch management. Such technology at least in part, saves labor and permits the production of large batches of evenly developed pigs. Thanks to the current knowledge on endocrine regulation of follicle development and ovulation, and the availability of numerous reproductively active substances such a technology is now available. This 'biotechnology of reproduction' will be reviewed. It covers procedures for synchronizing estrus based on the use of altrenogest in gilts and of batch-wise weaning in sows, for stimulating follicle development using eCG and for inducing of ovulation using hCG or LH as well as GnRH analogues. While the procedures for estrus synchronization stand alone, other procedures require additional treatments. If fixed-time insemination is the goal, estrus needs to be synchronized and follicular development and ovulation induced by the use of GnRH analogues and hCG with ovulation occurring within 36-42 hrs. It is a general recommendation to inseminate those animals twice, i.e. 24 and 40 hrs after ovulation induction. However, the aforementioned technology requires healthy animals and a solid management and cannot be used to compensate for poor management.Tehnologija koja omogucava manipulisanje estrusom i ovulacijom, i koja takodje omogucava fiksno vreme osemenjavanja, moze da bude od velike koristi za svinjarske farme koje raspolazu velikim brojem krmaca. Takva tehnologija delimicno stiti porodjaj i omogucava proizvodnju velikog broja svinja istog uzrasta. Zahvaljujuci dosadasnjim saznanjima o endokrinoj regulaciji razvoja folikula i ovulaciji, kao i dostupnim brojnim reproduktivno aktivnim supstancama, ova tehnologija je danas moguca. Ova ?reproduktivna biotehnologija? ce biti prikazana. Ona obuhvata postupke sinhronizacije estrusa zasnovane na upotrebi altrenogesta kod nazimica i velikog broja odlucenih krmaca, za stimulaciju razvoja folikula koristi se eCG a za izazivanje ovulacije koristi se hCG ili LH kao i GnRH analog. Dok su postupci sinhronizacije estrusa pojedinacni, drugi postupci zahtevaju dodatni tretman. Ako je cilj fiksno vreme osemenjavanja, onda estrus treba da bude sinhronizovan a razvoj folikula i ovulacija da budu izazvani upotrebom GnRH analoga i hCG i da se ovulacija javlja nakon 36-42 sata. Opsta je preporuka da se osemenjavanje ovih zivotinja obavlja dvokratno, odnosno 24 i 40 casova nakon izazivanja ovulacije. Medjutim, ova tehnologija zahteva zdrave zivotinje i jak menadzment i ne moze se primeniti kao zamena za los menadzment na farmi.