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)

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)