Superovulation and embryo transfer in dairy cattle – effect of management factors with emphasis on sex-sorted semen

........................................................................................................... 6 ORIGINAL ARTICLES ......................................................................................... 8 ABBREVIATIONS ................................................................................................. 9 INTRODUCTION ................................................................................................. 10 REVIEW OF LITERATURE................................................................................ 12 1. Superovulation and embryo recovery in cattle ................................................ 12 2. Major animal-related factors affecting the outcome of superovulation .......... 14 2.1. Ovarian follicular waves ......................................................................... 14 2.2. Count of antral follicles ........................................................................... 15 2.3. Age............. ......................................................................................... 16 3. Environmental factors affecting the outcome of superovulation..................... 16 4. Management factors affecting the outcome of superovulation ....................... 17 4.1. Superovulatory treatment ........................................................................ 18 4.1.1. Gonadotropin preparations ................................................................ 18 4.1.2. Administration of gonadotropins ...................................................... 19 4.2. Sex-sorted semen ..................................................................................... 20 4.2.1. Technique of sperm sorting............................................................... 20 4.2.2. AI of single-ovulating females .......................................................... 21 4.2.3. In vivo embryo production ................................................................ 22 4.2.4. Calves produced with sex-sorted semen ........................................... 25 4.3. Nutrition .................................................................................................. 25 4.3.1. Energy balance .................................................................................. 26 4.3.2. Dietary protein .................................................................................. 28 AIMS ..................................................................................................................... 31 MATERIALS AND METHODS .......................................................................... 32 1. Donors, recipients and embryos ...................................................................... 32 2. Experimental design ........................................................................................ 33 2.1. Nutritional protein (I) .............................................................................. 33 2.2. Superovulation using two commercial FSH-preparations (II) ................ 34 2.3. Effect of sex-sorted semen on embryo production (III, IV) .................... 35 2.4. Effect of sex-sorted semen on calf production (V) ................................. 36 3. Statistical analyses ........................................................................................... 36 RESULTS.............................................................................................................. 38