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Efeito do diâmetro folicular e da condição corporal sobre a taxa de gestação em vacas Bos indicus sujeitas a programa de inseminação artificial em tempo fixo
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Resumo(s)
Diversos estudos indicam que o tamanho do folículo pré-ovulatório (FPO) no momento da inseminação influencia de forma significativa as taxas de gestação (TG) e a mortalidade embrionária/fetal, em vacas no pós-parto sujeitas a um protocolo de inseminação artificial em tempo fixo (IATF). Para além disso, nos bovinos, o status de energia, particularmente o balanço energético negativo (BEN), tem uma grande influência no desempenho reprodutivo dos mesmos. Dessa forma, o presente trabalho teve como objectivo determinar e compreender a relação existente entre o diâmetro do FPO e os efeitos da condição corporal (CC) sobre a TG, em bovinos Bos indicus (n=376) sujeitos a um programa de IATF. O protocolo utilizado consistiu num protocolo de 3 maneios [Dia 0 (D0) - 2 mg de benzoato de E2 (BE) + dispositivo intravaginal (DIV) com 0,7 g de progesterona (P4); Dia 8 ou D8,5 (D8/8,5) - remoção do DIV de P4 + 1 mg de BE + 0,150 mg de D-cloprostenol (PGF2α) + 300 UI de gonadotrofina coriónica equina (eCG); Dia 9,5 ou D10 (D9,5/10) – IATF]. O diâmetro do FPO (D9,5/10) e a gestação (DG30, DG60, DG100) foram determinados por ultra-sonografia. O score de condição corporal (SCC) foi obtido ao D0 e o cio foi diagnosticado ao D9,5/10, pelo método de pintura da base da cauda. O diâmetro médio do FPO no dia da IATF foi de 15,16 mm. A taxa de gestação média ao DG30, DG60 e DG100 foi, respectivamente, 60,11%, 55,05% e 82,71%. As vacas que apresentaram no dia da IATF FPO de diâmetro superior a 15 mm tiveram uma TG ao DG30 (68,33% vs. 52,55%; p=0,008), DG60 (63,33% vs. 47,45%; p=0,001) e DG100 (85,71% vs. 79,90; p=0,03) estatisticamente superior àquelas com um diâmetro entre os 8,5-15 mm. Em relação ao SCC, as vacas com um SCC ≥5 tiveram uma TG estatisticamente superior ao DG30 (60,94% vs. 55,36%; p=0,05) e DG60 (56,25% vs. 48,21%; p=0,04) em comparação com as de SCC <5. A TG em relação à categoria das fêmeas (primípara vs. multípara), embora sempre superior nas multíparas, apenas ao DG100, revelou um valor com significância estatística (88,42% vs. 64,84%; p=0,01). A perda embrionária foi inferior nos animais com um FPO >15 mm (7,32% vs. 9,71%; p=0,44), nos animais com um SCC ≥5 (7,69% vs. 12,90; p=0,17) e nas fêmeas multíparas (7,43% vs. 11,76%; p=0,65), no entanto, nenhum desses valores revelou significância estatística.
Em conclusão, o diâmetro folicular na altura da IATF e a CC dos animais ao início do protocolo revelaram um efeito estatisticamente significativo na TG de fêmeas Bos indicus, sujeitas a um programa de IATF com P4 e E2.
ABSTRACT - Effect of follicular diameter and body condition on the pregnancy rate in Bos indicus cows submitted to a Fixed Time Artificial Insemination program - Several studies indicate that the size of the pre-ovulatory follicle (POF) at the time of insemination, significantly influences the pregnancy rates (PR) and embryo/fetal mortality in cows subjected to fixed-time artificial insemination protocol (FTAI) after calving. Furthermore, in cattle, the energy status, particularly the negative energy balance (NEB), has a great influence on their reproductive performance. Thus, this study aimed to determine and understand the relationship between the diameter of the POF and the effects of body condition (BC) on the PR in Bos indicus cattle (n = 376) subject to a FTAI program. The protocol used was a 3 protocol managements [Day 0 (D0) - 2 mg of estradiol (E2) benzoate (EB) + intravaginal device (IVD) with 0.7 g of progesterone (P4); Day 8 or D8.5 (D8/8.5) - IVD removal + 1 mg of EB + 0.150 mg of D-cloprostenol (PGF2α) + 300 IU equine chorionic gonadotropin (eCG); Day 9.5 or D10 (D9.5/10) – FTAI]. The diameter of the POF (D9.5/10) and the pregnancy (DG30, DG60 and DG100) were determined by ultrasound. The body condition score (BCS) was obtained at D0 and the heat was diagnosed at D9.5/10, by the method of tail-head paint. The average diameter of the POF on the FTAI was 15.16 mm. The average PR at DG30, DG60 and DG100 was respectively 60.11%, 55.05% and 82.71%. The cows who showed at the FTAI day, POF greater than 15 mm, had a PR at DG30 (68.33% vs. 52.55%, P = 0.008), DG60 (63.33% vs. 47.45%; p = 0.001) and DG100 (85.71% vs. 79.90; p = 0.03) statistically higher, than those with a diameter between 8.5 to 15 mm. Regarding the BCS, animals with a BCS ≥5 had a PR statistically superior at DG30 (60.94% vs. 55.36%; p = 0.05) and DG60 (56.25% vs. 48.21%, P = 0.04) compared with the animals BCS <5. The PR in relation to females category (primiparous vs. multiparous), although always higher at the multiparous, only at DG100, revealed a value with statistical significance (88.42% vs. 64.84%, p = 0.01). The embryonic loss was lower in animals with a POF >15 mm (7.32% vs. 9.71%, p = 0.44), animals with a BCS ≥5 (7.69% vs. 12.90; p = 0.17) and the multiparous females (7.43% vs. 11.76%, P = 0.65), however, none of those values showed statistical significance. In conclusion, the follicular diameter at the FTAI moment and the BC of the animals at the beginning of protocol revealed a statistically significant effect on PR female Bos indicus submitted to a FTAI program.
ABSTRACT - Effect of follicular diameter and body condition on the pregnancy rate in Bos indicus cows submitted to a Fixed Time Artificial Insemination program - Several studies indicate that the size of the pre-ovulatory follicle (POF) at the time of insemination, significantly influences the pregnancy rates (PR) and embryo/fetal mortality in cows subjected to fixed-time artificial insemination protocol (FTAI) after calving. Furthermore, in cattle, the energy status, particularly the negative energy balance (NEB), has a great influence on their reproductive performance. Thus, this study aimed to determine and understand the relationship between the diameter of the POF and the effects of body condition (BC) on the PR in Bos indicus cattle (n = 376) subject to a FTAI program. The protocol used was a 3 protocol managements [Day 0 (D0) - 2 mg of estradiol (E2) benzoate (EB) + intravaginal device (IVD) with 0.7 g of progesterone (P4); Day 8 or D8.5 (D8/8.5) - IVD removal + 1 mg of EB + 0.150 mg of D-cloprostenol (PGF2α) + 300 IU equine chorionic gonadotropin (eCG); Day 9.5 or D10 (D9.5/10) – FTAI]. The diameter of the POF (D9.5/10) and the pregnancy (DG30, DG60 and DG100) were determined by ultrasound. The body condition score (BCS) was obtained at D0 and the heat was diagnosed at D9.5/10, by the method of tail-head paint. The average diameter of the POF on the FTAI was 15.16 mm. The average PR at DG30, DG60 and DG100 was respectively 60.11%, 55.05% and 82.71%. The cows who showed at the FTAI day, POF greater than 15 mm, had a PR at DG30 (68.33% vs. 52.55%, P = 0.008), DG60 (63.33% vs. 47.45%; p = 0.001) and DG100 (85.71% vs. 79.90; p = 0.03) statistically higher, than those with a diameter between 8.5 to 15 mm. Regarding the BCS, animals with a BCS ≥5 had a PR statistically superior at DG30 (60.94% vs. 55.36%; p = 0.05) and DG60 (56.25% vs. 48.21%, P = 0.04) compared with the animals BCS <5. The PR in relation to females category (primiparous vs. multiparous), although always higher at the multiparous, only at DG100, revealed a value with statistical significance (88.42% vs. 64.84%, p = 0.01). The embryonic loss was lower in animals with a POF >15 mm (7.32% vs. 9.71%, p = 0.44), animals with a BCS ≥5 (7.69% vs. 12.90; p = 0.17) and the multiparous females (7.43% vs. 11.76%, P = 0.65), however, none of those values showed statistical significance. In conclusion, the follicular diameter at the FTAI moment and the BC of the animals at the beginning of protocol revealed a statistically significant effect on PR female Bos indicus submitted to a FTAI program.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária
Palavras-chave
Diâmetro folicular Condição corporal Taxa de gestação Bos indicus Inseminação artificial em tempo fixo Follicular diameter Body condition Pregnancy rate Fixed-time artificial insemination
Contexto Educativo
Citação
Rosa, G.M.S.T. (2015). Efeito do diâmetro folicular e da condição corporal sobre a taxa de gestação em vacas Bos indicus sujeitas a programa de inseminação artificial em tempo fixo. Dissertação de mestrado. Universidade de Lisboa, Faculdade de Medicina Veterinária, Lisboa.
Editora
Universidade de Lisboa. Faculdade de Medicina Veterinária