Intensified use of TAI and sexed semen on commercial farms

The livestock sector has achieved many technological advances, which have resulted in continued improvements in animal production systems and in the reproductive efficiency of herds. The associated use of reproductive biotechnology and genetic improvements combined with adequate sanitary and nutritional management are essential conditions for sustainable intensified animal production and financial autonomy within farms. Timed artificial insemination (TAI) represents one of the strategies with the greatest impact of expansion in providing genetic improvements and increased reproductive efficiency at a decreased cost. Despite the high proportion of cows receiving TAI, this market still exhibits considerable potential for expansion. After a TAI procedure, approximately 40 to 60% of females become pregnant. This result can vary depending on such factors as the hormonal protocol employed, female category, body condition score, ovarian status, farm management and aspects related to bulls and semen. The fertility and genetic quality of the bull plays an important role in the herd because a single bull can influence the entire production system. Another important strategy is the use of sex-sorted semen associated with TAI, primarily when associated with management practices to improve the pregnancy rate. This paper presents a review of the intensification of TAI, supplying practical information regarding the implementation of TAI commercial programs.

Intensified use of TAI and sexed semen on commercial farms

The livestock sector has achieved many technological advances, which have resulted in continued improvements in animal production systems and in the reproductive efficiency of herds. The associated use of reproductive biotechnology and genetic improvements combined with adequate sanitary and nutritional management are essential conditions for sustainable intensified animal production and financial autonomy within farms. Timed artificial insemination (TAI) represents one of the strategies with the greatest impact of expansion in providing genetic improvements and increased reproductive efficiency at a decreased cost. Despite the high proportion of cows receiving TAI, this market still exhibits considerable potential for expansion. After a TAI procedure, approximately 40 to 60% of females become pregnant. This result can vary depending on such factors as the hormonal protocol employed, female category, body condition score, ovarian status, farm management and aspects related to bulls and semen. The fertility and genetic quality of the bull plays an important role in the herd because a single bull can influence the entire production system. Another important strategy is the use of sex-sorted semen associated with TAI, primarily when associated with management practices to improve the pregnancy rate. This paper presents a review of the intensification of TAI, supplying practical information regarding the implementation of TAI commercial programs.(AU)

Intensified use of TAI and sexed semen on commercial farms.

The livestock sector has achieved many technological advances, which have resulted in continued improvements in animal production systems and in the reproductive efficiency of herds. The associated use of reproductive biotechnology and genetic improvements combined with adequate sanitary and nutritional management are essential conditions for sustainable intensified animal production and financial autonomy within farms. Timed artificial insemination (TAI) represents one of the strategies with the greatest impact of expansion in providing genetic improvements and increased reproductive efficiency at a decreased cost. Despite the high proportion of cows receiving TAI, this market still exhibits considerable potential for expansion. After a TAI procedure, approximately 40 to 60% of females become pregnant. This result can vary depending on such factors as the hormonal protocol employed, female category, body condition score, ovarian status, farm management and aspects related to bulls and semen. The fertility and genetic quality of the bull plays an important role in the herd because a single bull can influence the entire production system. Another important strategy is the use of sex-sorted semen associated with TAI, primarily when associated with management practices to improve the pregnancy rate. This paper presents a review of the intensification of TAI, supplying practical information regarding the implementation of TAI commercial programs.

Influence of category--heifers, primiparous and multiparous lactating cows--in a large-scale resynchronization fixed-time artificial insemination program.

This study was conducted to evaluate the influence of category (heifers, primiparous or multiparous cows) on pregnancy rates in a large scale resynchronization ovulation program. Nelore heifers (n = 903), primiparous lactating cows (n = 338) and multiparous lactating cows (n = 1,223) were synchronized using a conventional protocol of estradiol/P4-based fixed-time artificial insemination (FTAI). Thirty days after ultrasonography, females who failed the first FTAI were resynchronized with the same hormonal protocol prior to a second FTAI. The pregnancy status of each cohort was evaluated by ultrasonography 30 days after each FTAI. The average conception rate after the first FTAI and resynchronization was 80.5%. Heifers had a higher conception rate (85%) than primiparous (76%) or multiparous cows (78%; p = 0.0001). The conception rate after the first FTAI was similar among heifers (57%), primiparous cows (51%) and multiparous cows (56%; p = 0.193). After the second FTAI, heifers exhibited a higher conception rate (66%) than primiparous or multiparous cows (51%; p = 0.0001). These results demonstrate the feasibility of resynchronization in large beef herds for providing consistent pregnancy rates in a short period of time. We also demonstrated that ovulation resynchronization 30 days after FTAI is particularly effective for heifers, providing a conception rate of up to 66%.

Dinâmica folicular e taxa de prenhez em novilhasreceptoras de embrião (Bos taurus indicus x Bostaurus taurus) tratadas com o protocolo “Ovsynch”para inovulação em tempo fixo / Follicular dynamics and pregnancy rate in embryorecipient (Bos taurus indicus x Bos taurus taurus) treatedwith “Ovsynch” protocol for fixed-time embryo transfer

Objetivou-se avaliar a eficiência da sincronização da ovulação parainovulação em tempo fixo em novilhas Bos taurus indicus x Bos taurustaurus receptoras de embrião. No Experimento 1, a dinâmica folicularfoi acompanhada durante o protocolo “Ovsynch” (G1; n=35) eapós a aplicação de PGF2α (G2; n=34). No Experimento 2, osmesmos tratamentos foram realizados a campo em 168 (G1) e 177(G2) novilhas. No D6, colheu-se sangue para dosagem de P4 e serealizaram exames ultra-sonográficos. No D7, realizou-se ainovulação. No Experimento 1, 45,7% dos animais ovularam após o1º GnRH (P<0,05) e 74,3% após o 2º. A taxa de ovulação foi de58,8% no G2. Foram detectadas em estro 64,7% das novilhas noG2 e 22,9% no Gl (P<0,01). No Experimento 2, observaram-semais receptoras aptas a inovulação no Gl que no G2 (72,6% vs.45,2%; P<0,01). A taxa de concepção foi de 49,2% para o Gl e de56,3% para o G2 (P>0,05). Ao final, a taxa de prenhez no Gl foi de35,7% e no G2 de 25,4% (P<0,05). Foram detectadas em estro53,7% das novilhas do G2 e 33,3% do Gl (P<0,05). Os corposlúteos com maior área determinaram maiores concentrações de P4e taxa de concepção (P<0,05). A sincronização da ovulação parainovulação em tempo fixo aumentou as taxas de ovulação, deaproveitamento e de prenhez em novilhas receptoras de embrião.(AU)

The aim of this study was to evaluate the efficacy of thesynchronization of ovulation for fixed-time embryo transfer incrossbred recipient heifers (Bos taurus indicus x Bos taurus taurus). AtExperiment 1, ovarian ultrasonography was performed to evaluatefollicular dynamics during the “Ovsynch” protocol (G1; n=35) orsingle PGF2α injection (G2; n=34). At Experiment 2, the sametreatments were used at field conditions in 168 (G1) and 177 (G2)heifers. On D6, ovarian ultrasonography and blood collection forP4 assay were performed. On D7, a embryo was transferred. AtExperiment 1, 45.7% of the heifers ovulated after the 1st and 74.3%after the 2nd GnRH injection (P<0.05). The ovulation rate in G2was 58.8%. In G2, 64.7% of the heifers were detected in estrus andin Gl, 22.9% (P<0.01). At Experiment 2, Gl had more selectedheifers for embryo transfer than G2 (72.6% vs. 45.2%; P<0.01).Conception rates were 49.2% and 56.3% in G1 and G2, respectively(P>0.05). Thus, the pregnancy rate in Gl was 35.7% and 25.4% inG2 (P<0.05). Estrus was detected in 53.7% of the recipients in G2and 33.3% in those of the Gl (P<0.05). It was verified that CL withlarger area induced an increase on P4 concentration and on theconception rate of both groups (P<0.05). The synchronization ofovulation for fixed-time embryo transfer increased the ovulation,the selection and the pregnancy rates in recipient heifers.(AU)

Dinâmica folicular e taxa de prenhez em novilhas receptoras de embrião (Bos taurus indicus x Bos taurus taurus) tratadas com o protocolo Ovsynch para inovulação em tempo fixo / Follicular dynamics and pregnancy rate in embryo recipient (Bos taurus indicus x Bos taurus taurus) treated with Ovsynch protocol for fixed-time embryo transfer

Objetivou-se avaliar a eficiência da sincronização da ovulação para inovulação em tempo fixo em novilhas Bos taurus indicus x Bos taurus taurus receptoras de embrião. No Experimento 1, a dinâmica folicular foi acompanhada durante o protocolo "Ovsynch" (G1; n=35) e após a aplicação de PGF2alfa (G2; n=34). No Experimento 2, os mesmos tratamentos foram realizados a campo em 168 (G1) e 177 (G2) novilhas. No D6, colheu-se sangue para dosagem de P4 e se realizaram exames ultra-sonográficos. No D7, realizou-se a inovulação. No Experimento 1, 45,7 por cento dos animais ovularam após o 1° GnRH (P<0,05) e 74,3 por cento após o 2°. A taxa de ovulação foi de 58,8 por cento no G2. Foram detectadas em estro 64,7 por cento das novilhas no G2 e 22,9 por cento no Gl (P<0,01). No Experimento 2, observaram-se mais receptoras aptas a inovulação no Gl que no G2 (72,6 por cento vs. 45,2 por cento; P<0,01). A taxa de concepção foi de 49,2 por cento para o Gl e de 56,3 por cento para o G2 (P>0,05). Ao final, a taxa de prenhez no Gl foi de 35,7 por cento e no G2 de 25,4 por cento (P<0,05). Foram detectadas em estro 53,7 por cento das novilhas do G2 e 33,3 por cento do Gl (P<0,05). Os corpos lúteos com maior área determinaram maiores concentrações de P4 e taxa de concepção (P<0,05). A sincronização da ovulação para inovulação em tempo fixo aumentou as taxas de ovulação, de aproveitamento e de prenhez em novilhas receptoras de embrião.

The aim of this study was to evaluate the efficacy of the synchronization of ovulation for fixed-time embryo transfer in crossbred recipient heifers (Bos taurus indicus x Bos taurus taurus). At Experiment 1, ovarian ultrasonography was performed to evaluate follicular dynamics during the "Ovsynch" protocol (G1; n=35) or single PGF2alpha injection (G2; n=34). At Experiment 2, the same treatments were used at field conditions in 168 (G1) and 177 (G2) heifers. On D6, ovarian ultrasonography and blood collection for P4 assay were performed. On D7, a embryo was transferred. At Experiment 1, 45.7 percent of the heifers ovulated after the 1st and 74.3 percent after the 2nd GnRH injection (P<0.05). The ovulation rate in G2 was 58.8 percent. In G2, 64.7 percent of the heifers were detected in estrus and in Gl, 22.9 percent (P<0.01). At Experiment 2, Gl had more selected heifers for embryo transfer than G2 (72.6 percent vs. 45.2 percent; P<0.01). Conception rates were 49.2 percent and 56.3 percent in G1 and G2, respectively (P>0.05). Thus, the pregnancy rate in Gl was 35.7 percent and 25.4 percent in G2 (P<0.05). Estrus was detected in 53.7 percent of the recipients in G2 and 33.3 percent in those of the Gl (P<0.05). It was verified that CL with larger area induced an increase on P4 concentration and on the conception rate of both groups (P<0.05). The synchronization of ovulation for fixed-time embryo transfer increased the ovulation, the selection and the pregnancy rates in recipient heifers.

Lecirelin and Buserelin (Gonadotrophin releasing hormone agonists) are equally effective for fixed time insemination in buffalo

Buffalo has peculiar reproductive patterns, which make artificial insemination programs a hard and expensive task. Artificial insemination in fixed time is advantaged because females show low incidence of homosexual behaviour and strong dominance relationships, which leads to a poor accuracy in estrus detection. The aim of this experiment was to compare the efficiency of two different GnRH agonists in the GnRH/PGF2alpha/GnRH protocol (Buserelin vs Lecirelin). Two hundred and seventy buffaloes with 45 to 60 days postpartum were synchronized and fixed-time inseminated. The animals were kept on pasture in two farms at Säo Paulo and Mato Grosso do Sul (Brazil). Cows in Group 1 (n = 132) received, intramuscularly, 20 æg of Buserelin at a random day of the estrous cycle and, seven days later, 15 mg of prostaglandin F2alpha. Two days after prostaglandin administration, 10 æg Buserelin were intramuscularly injected. Cows in Group 2 (n = 138) were treated with the same protocol, but with intra-muscular administrations of Lecirelin (50 æg in the first administration and 25 æg in the second). Artificial insemination was performed 16 hours after the last injection in both groups. Pregnancies were diagnosed by ultrasonography (Pie Medical 480, 5.0 and 7.5 MHz linear probe), 30 days after artificial insemination. Conception rates were not influenced by farm (P > 0.05) and were similar in both groups [Group 1: 47.0 percent (62/132); Group 2: 50.0 percent (69/138); P > 0.05]. Results show that Lecirelin is as efficient as Buserelin to synchronize ovulation for fixed-time artificial insemination in buffaloes