Incidência de atraso de luteólise em vacas holandesas lactantes de alta produção
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Data
2020-01-14
Autores
Santos, Ana Paula Oliveira
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste estudo foi comparar a duração da fase lútea em vacas Holandesas em lactação, que receberam inseminação artificial (IA) ou não (Controle). Vacas não gestantes (n= 1322) foram submetidas após o período de espera voluntário ao protocolo de sincronização de ovulação: um dispositivo intravaginal de progesterona (CIDR), 100 µg de GnRH e 2,0 mg de benzoato de estradiol em d-11, 25 mg de PGF em d -4, remoção do CIDR, 1,0 mg de cipionato de estradiol e PGF em d -2. As vacas foram aleatoriamente distribuídas no d 0 do protocolo para os tratamentos IA ou Controle. Somente vacas observadas em estro (n= 1124), detectadas por monitores de atividade foram incluídas no estudo. Para a análise de duração da fase lútea, apenas as vacas detectadas com corpo lúteo (CL) no d 17 e, posteriormente, não diagnosticadas gestantes foram incluídas na análise. Um mapa de cada vaca foi realizado para avaliar a presença de CL no d 17, 24 e 31. Foram coletadas amostras de sangue para os animais identificados com presença de CL nos dias 17, 24 e 31. Foi considerado como regressão do CL os animais que retornaram ao estro, os com ausência de CL ao exame de US, e os que apresentarem concentrações de P4 <1 ng/ml. Vacas que foram reinseminadas entre os dias 17 e 24 foram consideradas como tendo regressão luteal normal. Vacas que foram reinseminadas entre os dias 24 e 31 foram consideradas como regressão luteal tardia.Vacas com o mesmo CL nos respectivos dias (d 17, 24, 31) que não foram reinseminadas durante o período e não foram diagnosticadas como gestantes no dia 31 foram classificadas como tendo fase luteal longa. As concentrações séricas de PAG foram analisadas e utilizadas como marcadores de gestação e perda embrionária. O escore de condição corporal (ECC) e o escore de tamanho e posição do útero (SPS) foram determinados no d 0 e incluídos nas análises dos fatores de riscos associados à prenhez e à dinâmica do CL. Os dados binomiais foram analisados usando Proc Glimmix (SAS Institute Inc., Cary, NC, EUA) com vaca como unidade de medida aleatória. Os modelos estatísticos incluíram tratamento, paridade, ECC, SPS e interações. As vacas em ambos os tratamentos foram distribuídas de maneira similar pela paridade (P=0,78). A prenhez por IA aos 31 e 60 dias no grupo IA foi de 21,0% e 17,2%, respectivamente. A porcentagem de detecção de estro foi de 48%. O tratamento não afetou a proporção de vacas com regressão de CL e nenhuma das variáveis explicativas foi significativa como fatores de risco para explicar a presença de fases luteínicas longas. Em conclusão, este estudo demonstrou que grande proporção (~ 60%) de vacas Holandesas em lactação não regrediram adequadamente o CL, independente de ter recebido IA ou não e a estimativa de perda de gestação entre 24 e 31 dias foi de 18%.
The aim of this study was to compare the length of the luteal phase in lactating Holstein cows that which received to artificial insemination (AI) or not (Control). Non-pregnant cows (n=1322) were submitted after the voluntary waiting period to a synchronization protocol: An intravaginal progesterone device (CIDR), 100 ug of GnRH and 2.0 mg of estradiol benzoate on d -11, 25 mg of PGF on d -4, CIDR removal, 1.0 mg of estradiol cypionate and PGF on d -2. Cows were then randomly assigned at estrus (d 0) to the AI or the Control (sham) treatments. Only cows observed in estrus (n= 1124), detected by activity monitors were included in the study. For the analysis of length of luteal phase, only cows detected with a corpus luteum (CL) on d 17 and later not diagnosed pregnant were included in the analysis. A map of each individual cow was performance to evaluate the CL presence on d 17, 24 and 31. Blood samples were collect for animals identified with the presence of CL on the days 17, 24 and 31. It was considered as regression of CL, them returned to estrus, animals without CL on US examination, and those with P4 concentrations <1 ng / ml. Cows that were re-inseminated between days 17 and 24 were considered to have normal luteal regression. Cows that were rebreed between days 24 and 31 were considere as late luteal regression. Cows with the same CL on the respective days (d 17, 24 and 31) that were not rebreed during the period and were not diagnosed as pregnant on day 31 were classified as having a long luteal phase. Serum PAG concentrations were analyze and used as markers of pregnancy and embryonic loss. The body condition score (BCS) and a size and position score of the uterus (SPS) were measured at d 0 and included in the analyses of risk factors associated with pregnancy and CL dynamics. Binomial data was analyzed using proc glimmix of SAS with a cow how unit of aleatory measure. Statistical models included treatment, parity, BCS, SPS and interactions. Cows on both treatments were similarly distributed by parity (P=0.78). Pregnancy per AI at d 31 and 60 in the AI group was 21.0% and 17.2%, respectively. The frequency of estrus detected was 48%. Treatment did not affect the proportion of cows with a total regression of CL and none of the explanatory variables was significant as risk factors to explain the presence of long luteal phases. In conclusion, this study demonstrated that a large proportion (~ 60%) of lactating Holstein cows were failed to regression of the CL, regardless of whether they received AI or not and the estimated pregnancy loss betwenn 24 and 31 days was 18%.
The aim of this study was to compare the length of the luteal phase in lactating Holstein cows that which received to artificial insemination (AI) or not (Control). Non-pregnant cows (n=1322) were submitted after the voluntary waiting period to a synchronization protocol: An intravaginal progesterone device (CIDR), 100 ug of GnRH and 2.0 mg of estradiol benzoate on d -11, 25 mg of PGF on d -4, CIDR removal, 1.0 mg of estradiol cypionate and PGF on d -2. Cows were then randomly assigned at estrus (d 0) to the AI or the Control (sham) treatments. Only cows observed in estrus (n= 1124), detected by activity monitors were included in the study. For the analysis of length of luteal phase, only cows detected with a corpus luteum (CL) on d 17 and later not diagnosed pregnant were included in the analysis. A map of each individual cow was performance to evaluate the CL presence on d 17, 24 and 31. Blood samples were collect for animals identified with the presence of CL on the days 17, 24 and 31. It was considered as regression of CL, them returned to estrus, animals without CL on US examination, and those with P4 concentrations <1 ng / ml. Cows that were re-inseminated between days 17 and 24 were considered to have normal luteal regression. Cows that were rebreed between days 24 and 31 were considere as late luteal regression. Cows with the same CL on the respective days (d 17, 24 and 31) that were not rebreed during the period and were not diagnosed as pregnant on day 31 were classified as having a long luteal phase. Serum PAG concentrations were analyze and used as markers of pregnancy and embryonic loss. The body condition score (BCS) and a size and position score of the uterus (SPS) were measured at d 0 and included in the analyses of risk factors associated with pregnancy and CL dynamics. Binomial data was analyzed using proc glimmix of SAS with a cow how unit of aleatory measure. Statistical models included treatment, parity, BCS, SPS and interactions. Cows on both treatments were similarly distributed by parity (P=0.78). Pregnancy per AI at d 31 and 60 in the AI group was 21.0% and 17.2%, respectively. The frequency of estrus detected was 48%. Treatment did not affect the proportion of cows with a total regression of CL and none of the explanatory variables was significant as risk factors to explain the presence of long luteal phases. In conclusion, this study demonstrated that a large proportion (~ 60%) of lactating Holstein cows were failed to regression of the CL, regardless of whether they received AI or not and the estimated pregnancy loss betwenn 24 and 31 days was 18%.
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Palavras-chave
Corpo lúteo, Bovinos de leite, Luteólise