Dinâmica ovariana em vacas magras com anestro e taxa de prenhez com IATF em vacas leiteiras mestiças de diferentes escores de condição corporal

• Ano de defesa: 2013
• Autor(a) principal: Almeida Neto, José Rogério Moura de
• Orientador(a): Costa, Eduardo Paulino da
• Banca de defesa: Csermak Junior, Antonio Carlos , Mâncio, Antonio Bento
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Medicina Veterinária
• Departamento: Biotecnologia, diagnóstico e controle de doenças; Epidemiologia e controle de qualidade de prod. de
• País: BR
• Palavras-chave em Português: Dinâmica ovariana; Manejo reprodutivo; Bovinos
• Palavras-chave em Inglês: Ovarian dynamics; Reproductive management; Cattle
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA::REPRODUCAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1463

This study was carried out to evaluate the response obtained from crossbred cows ( Holstein x Zebu) presenting different body condition scores for hormonal induction of the ovarian cyclicity as well as to verify the ovarian dynamics of the lean anestrous cows. Experiment I : During 21 days, the follicular dynamics tests were performed in 18 lactating cows under anestrus, from which the ECC was lower than 2.5. No animal showed estrus, ovulation and follicular luteinization during evaluation of the follicular dynamics, therefore showing all cows to be under anestrus. It was found the follicular dynamics of the lean cows under evaluation to present a pattern with two or three cycles of follicular growth (23.3 and 77.7% for cycles with two and three waves, respectively). Experiment II : One hundred eighty six lactating cows Holstein X Zebu with different blood degrees. The cows were grouped into three experimental groups ( G1 , G2 and G3) according to degree of the Body Condition Score (ECC). In the present experiment, the cows ECC showed high positive correlation with the follicular diameters at placement (P=0.0001; 0.85 ) or at implant removal ( P = 0.0001 , 0.75 .) At seven days after estrus, the luteal was 1.5 , 2.5 and 2.9 cm2 for groups G1 , G2 and G3 respectively. In the present experiment, ECC presented high and positive correlation with ovulation rate ( P = 0.0001; 0.55 ) and pregnancy rate (P=0.0001 ; 0.70 ). The cows with ECC equal or higher than 2.5 (scale 1 to 5) showed higher ovulation rate (P < 0.05) and pregnancy rate (P <0.05 ), as compared to cows with ECC lower than 2.5. In this study, it was observed the ovulation rate to be 53.6 %, 72.1% and 79.6 % for groups G1, G2 and G3 respectively, after hormonal therapy. The result of the group G1 was lower ( P < 0.05 ) than those observed in groups G2 and G3, which were similar (P > 0,05). According to results, the animals of the group G1 presented lower pregnancy rates at IATF , therefore highlighting the importance of the ECC on reproductive " status " of the dairy cattle. The results of this study suggest the ultrasound to be important for selection of the animals with low ECC, as targeting the use of protocols for fixed-time artificial insemination.