Marcio Saporski Segui

Comparison between deep intracornual artificial insemination (dIAI) and conventional artificial insemination (AI) using low concentration of spermatozoa in beef cattle

This study aimed to compare the pregnancy rate using the conventional artificial insemination (AI) or deep intracornual artificial insemination (DIAI), with low number of spermatozoa (4.0 million sperm) in 270 Nelore cows. The animals were divided in two groups (G: G1 (135 cows) conventional AI was performed (=semen deposition in the uterine body) and in G2 (135 cows) to DIAI, in ipsilateral horn where the dominant follicle in the ovary had previously been detected, by ultrasound examinations. For both the methods, a single artificial insemination was carried out after visual estrus observation, checked three times a day (morning, afternoon and evening). The pregnancy diagnosis after 45 days was conducted by ultrasound. Results showed a better pregnancy rate in the DIAI group (67.4% - p<0.01), when compared to conventional AI (48.8%) with low spermatozoa concentration.

The effects of intramuscular or intravenous injections of gonadotropin releasing hormone at fixed-time artificial insemination on pregnancy rates of Bos indicus beef cows

The effect of an intramuscular versus intravenous administration of gonadotropin releasing hormone (GnRH) at fixed-time AI (FTAI) on the pregnancy rates of crossbred Bos indicus beef cows was evaluated. Pluriparous nursing calv cows (n=120) were synchronized as follows: d 0 cows received a 2.0 mg injection of estradiol benzoate (EB) and insertion of a controlled intravaginal progesterone releasing device containing 0.558 g of progesterone, d 8 removal of the progesterone device , a 0.15 mg injection of prostaglandin F2α (PGF), a 1.0 mg injection of EB, and 400 IU injection of equine chorionic gonadotropin. Fifty-four hr after PGF, all cows were exposed to FTAI and a 0.084 mg injection of GnRH was administered either via Vena caudalis (n=60), or via Longissimus dorsi (n=60). Cows were inseminated with the same sire and by a single AI technician. Pregnancy was determined by the transrectal ultrasonography on d 40 after AI. Cows receiving the intravenous administration of GnRH had higher (P = 0.04) pregnancy rates than the cows receiving the intramuscular injection of GnRH (65 vs 46.6%, respectively). It was concluded that the intravenous administration of GnRH at the time of AI improved the pregnancy rates of crossbred Bos indicus beef cows submitted to FTAI.

Impact of Equine Chorionic Gonadotropin Associated with Temporary Weaning, Estradiol Benzoate, or Estradiol Cypionate on Timed Artificial Insemination in Primiparous Bos Indicus Cows

This study aimed to determine the impact of equine chorionic gonadotropin (eCG) associated with different timedartificial insemination (TAI) protocols on the pregnancy rate (PR) in Bos taurus indicus previously treated with progesterone (P4). Five hundred and fifty-seven primiparous cows received the following treatments: on day 0 (d0), GeCGTW (group eCG+Temporary Weaning(TW); n=178) received 0.558g intravaginal progesterone (P4)+1.0 mg of estradiol benzoate (EB)(IM); on d8 (P4 removal+0.075 mg D-cloprostenol+400 IU eCG+TW for 48h); on d10, TAI+calf return to dam; GeCGEB (group eCG+EB; n=176) the same as GeCGTW without TW+1.0 mg of EB on d9; GeCGEC (group eCG+EC;n=203), the same as GeCGTW without TW+1.5 mg estrtadiol cypionate (EC) (IM). On d35 after TAI pregnancy diagnosis (PD) was performed. Open cows remained with clean-up bulls for 90 days and then underwent pregnancy diagnosis by ultrasound. Drugs used were from Biogenesis Bago (Curitiba, PR) except eCG (Foligon, MSD, SP) and the EC (Zoetis, SP). The statistical analysis was performed with Chi-square (level of P 0.05) respectively. The PR following clean-up bulls was 88.3, 47.3, and 31.1% (P<0.05). The final PR (TAI+clean-up bulls) of the groups was 94.4, 72.1, and 64.0%, respectively (P<0.05). In conclusion, there were no detectable differences in PR among TAI protocols; PR in the GeCGTW protocol following clean-up bulls was greater compared to others (P<0.05); the overall PR of cows subjected to TAI+clean-up bulls was significantly greater in GeCGTW as compared to other groups.

Pregnancy and repeat breeding rate of high producing dairy cows for morning, evening or night artificial insemination

The study aimed (1) to verify if artificial insemination (AI), performed in the morning, evening or nighttimehas influence on the pregnancy rate on high production dairy cows, and (2) to determine the repeat breedingrate after the AI at intervals of 01-21, 22-43 and 44-65 days. We analyzed 1980 AI data from HolsteinFriesian cows from years 2004 to 2008. The average milk production on this period was 39 kg/milk/day/cow (305 days of lactation). The AI was performed 12 hours after the first detection of estrus. For the dataanalysis one AI was computed. The AI was done based on conventional method. The incidence of the AI in themorning, evening and night was 29.8; 50.4 and 19.8% respectively; and the pregnancy rate 45.7; 44.9 and48.4%. The frequency of the repeat breeding rate at the interval of 1-21 days on morning, evening and nightafter failed AI was 28.0; 22.3 and 19.8% respectively; at the interval of 22-43 days was 52.0; 52.2 and 55.2%,respectively and at interval of 44-65 days was respectively 20.0; 25.5 and 25.0%. Comparing the three timesof the day each other, the cows showed greater repeat breeding on 22-43 days (P<0.05) after the AI. It wasconcluded that times of the day has no influence on the on pregnancy rate; the highest repeat breeding ratetook place between 22 and 43 days after AI, resulting significant delaying of the open period.

Temporary Calf Removal and Equine Chorionic Gonadotropin (Ecg) Administration after Progesterone-Based Protocol Improves the Reproductive Performance of Beef Cattle

This study aimed to evaluate the effects of equine chorionic gonadotropin (eCG) administration and the temporary 48-h calf removal (CR) in a long-term progesterone (P4)based protocol in suckled Nelore cows. In all, 150 cows were randomly submitted to P4 protocol as follows. At day 0 (d 0), an intravaginal device containing 1.9 g P4 was inserted, and 1 mg estradiol benzoate (EB) was injected intramuscularly (im). On d 8, the P4 device was removed, and cows were im injected 500 µg of prostaglandin F group 2 alpha (PGF 2α ). On the same day, 75 cows (eCGCR group) received 400 IU im of eCG and were separated from their calves for 48 h. The other 75 cows (NoeCGCR group) stayed with the calves and did not receive eCG. On d 10, the calves were returned to the eCGCR group. After 8 days, all the cows were observed for estrus. The ovulatory follicle size was measured using ultrasonography at the day estrus was detected, and artificial insemination (AI) was performed 12 h later. Pregnancy was diagnosed 35 days after AI. The respective parameters for the eCGCR and NoeCGCR groups were as follows: pregnancy rate, 74.6% and 50.6% ( p 0.05). Thus, eCGCR after a long-term P4 protocol markedly improved pregnancy rates and estrus induction.