Ovarian function in dairy cattle after gonadotropin-releasing hormone treatments during perioestrus
نویسنده
چکیده
...................................................................................................... ORIGINAL ARTICLES.................................................................................... ABBREVIATIONS........................................................................................... 10 INTRODUCTION.............................................................................................. REVIEW OF LITERATURE............................................................................. 13 1. Normal oestrous cycle of cattle............................................................... 2. Gonadotropin-releasing hormone............................................................ 13 3. Applications of GnRH for reproductive management............................. 17 4. GnRH treatments during perioestrus and at the time of AI to improve fertility..... ................................................................................................ 18 4.1. The effect of GnRH treatments on pregnancy rate........................ 18 4.2. Mechanisms and factors through which GnRH may modify fertility............................................................................................ 26 5. Possible negative effects of GnRH administered during perioestrus...... AIMS.................................................................................................................. MATERIALS AND METHODS....................................................................... 1. Animals.................................................................................................... 32 2. Experimental design................................................................................ 2.1. GnRH during induced prooestrus (I).............................................. 33 2.2. GnRH during metoestrus (II)......................................................... 2.3. Incidence of short oestrous cycles and oestrous signs after GnRH (III)...................................................................................... 35 2.4. Short oestrous cycles and 15-ketodihydro-PGF2α (IV).................. 3. Ovarian examinations.............................................................................. 36 4. Hormone analyses.................................................................................... 37 4.1. Progesterone................................................................................... 4.2. Oestradiol-17β (I)........................................................................... 38 4.3. 15-Ketodihydro-PGF2α (IV)........................................................... 38 5. Statistical analysis.................................................................................... 39 RESULTS........................................................................................................... 40 1. Effect of PG (I, III, IV)............................................................................ 1.1. Luteolytic effect............................................................................. 1.2. Effect on ovulation......................................................................... 2. Effect of GnRH on size and growth of ovulatory follicle (I, II, IV)........ 3. Effect of GnRH on oestradiol-17β during PG-induced oestrus (I).......... 4. Ovulations induced with GnRH (I, III, IV)............................................. 9 6
منابع مشابه
The effect of administration of gonadotropin releasing hormone analogue at estrus or during luteal phase on reproductive performance of dairy cows maintained under sub-temperate climate
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