engleski

Artificial Insemination of Dairy Goats

Artificial insemination (AI) is method of improving the genetic base of the herd, diminishing number of bucks on the farm, decrease transmission of diseases and improvement of herd management. If a producer’s objective is only to impregnate the goats, less costly option is to invest in a quality buck. When oestrus and ovulation are induced, does can be inseminated at any time of the year (if frozen-thawed semen is provided). Daylight or photoperiod is the most important factor related to reproduction. Oestrus appears when days get short ; goats cycle every 18-21 days (seasonal polyestrous) until the days become longer or pregnancy occurs. The cycling start in August and end in January. The length of the breeding season is influenced by photoperiod, breed type and nutrition levels. Generally speaking, AI should take place 12-15 hours after onset of oestrus or standing heat (cervical mucus changes from clear to slightly cloudy and stringy) if detected by teaser buck (buck with apron) and reinseminated again 12h later if still in heat. Goats ovulate at late estrous or shortly after the end of standing heat. AI in goats is performed (trans)cervically (very gently! ; better deposit the semen at the cervical entrance then provoke lesions in order to reach deeper). The semen is deposited 1-2cm deep into the cervical canal in a 60% of goats or even into the uterus (10-30% goats). The goat’s hindquarters are elevated. The lubricated vaginal speculum with light source is introduced (perineal region well washed, rinsed and dried). After cervix is visualized, the insemination pipette is introduced into the cervix. The straws are thawed in water bath (37-38°C, 15-30s). The desired number of motile sperm is 200 million sperm in frozen semen (150 fresh). The most standardised procedures for the IA are progestagen based methods. When “long treatment” is performed, sponges are withdrawn 17-21 days after insertion with injection of 400-500 i.u. of PMSG (depending on milk production and seasonal period, doelings half-doses) at sponge removal during breading season or 24-48h before in transition period or out of breading season. Optimal time for fixed-time AI is at 43±2h after sponge removal. Better results are achieved if “short treatment” is used. The sponges are inserted for 11 days and PMSG and a PGF2α (50µg ; 0.2mL) 48h before withdrawal. The heat is detected 28-30h after removal of sponges and AI performed 43±2h after sponge withdrawal. The general fertility rates ranges from 50-70% with higher rates when short treatment is applied. The fertility rates after IA are low (30%) if oestrus appears after 30h after sponge removal. It is important to inseminate only the animals that are confirmed to be in oestrus! The stress should be avoided before, during and after AI!

artificial insemination; dairy goats; synchronisation

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