RESUMO

In this study, we aimed to provide a wet laboratory validation for a set of single nucleotide polymorphisms (SNP), which had been identified as candidate functional variants in silico. Genotyping for candidate SNP was performed in Brahman and Tropical Composite cattle. After quality control, 29 SNP were first investigated individually for their association with female reproductive traits and then used as a panel for genomic predictions. The reproductive traits studied were age at first corpus luteum (AGECL; days), post-partum anoestrus interval (PPAI; days), and a binary trait that described if the cow had ovulated before weaning the first calf or not (PW, 0-1). Single nucleotide polymorphisms in six genes (FOXA2, TRAF4, IRF2, IRF1, BPTF, and CPEB1) were found to be significantly associated with reproduction traits . The genomic prediction method used was BayesR, to accommodate the 29 new SNP and compare their performance with predictions based on 50K genotypes (Illumina SNP chip). When new SNP and PLAG1 mutation rs109231213 were included in the genomic predictions for female reproductive traits their accuracies improved. The best predictions were obtained by combining the new SNP and the 50K SNP using BayesR analysis, with a 4% improvement in accuracy. The proportion of the genetic variance explained by the new SNP together was 0.07 for AGECL, 0.03 for PPAI, and 0.02 for PW. It would be favourable to include these new SNP in future versions of bovine SNP chips to target selection for female reproductive traits. These new SNP are likely to improve genomic predictions for female reproductive traits in tropical beef cattle breeds, with varying degrees of Bos indicus content.(AU)

Assuntos

RESUMO

Anestrous postpartum is a state of complete sexual inactivity without estrous manifestations and the return of ovarian activity in postpartum may be negatively affected by several factors, such as negative energy balance (NEB), loss of body condition score (BCS), season in which the calving occurs, nutritional deficiencies, dystocic calving, retained placenta, uterine infections and metabolic diseases. This study aimed to evaluate the effects of BCS and number of days in milk (DIM) on ovarian cyclicity of Holstein dairy cows. Ovarian conditions of 168 cows between 30 to 90 days in milk (DIM) were evaluated twice by ultrasonography with seven days of interval and cows were classified in four categories: ovaries with presence of small follicles (Category 1: up to 10 mm); ovaries with medium follicles (Category 2: 10 to 18 mm); ovaries with large follicles (Category 3: over 20 mm) and ovaries with presence of corpus luteum (CL) (Category 4). The cows classified in categories 1, 2 and 3 were considered in anestrous. Data were analyzed by logistic regression at Minitab (P0.05) of DIM in the percentage of cycling cows, however there was a tendency (P=0.074) that cows with greater BCS (≥ 2.75) had a higher cyclicity rate (74.44% vs. 61.54%) than cows with lower BCS. Days in milk effect was not detected in cyclicity rate in cows between 30 and 90 DIM, but there was a tendency of Holstein cows with greater body condition score to had higher cyclicity rate.

O anestro é um estado de completa inatividade sexual, sem manifestações de cio e o retorno à atividade ovariana no pós-parto pode ser afetado negativamente por diversos fatores, como o balanço energético negativo (BEN), perda de escore de condição corporal (ECC), estação do ano na qual ocorre o parto, deficiências nutricionais, ocorrência de distocia, retenção de placenta, infecções uterinas e doenças metabólicas. Objetivou-se avaliar os efeitos do ECC e donúmero de dias em lactação (DEL) sobre a ciclicidade ovariana de vacas leiteiras Holandesas. A condição ovariana de 168 vacas entre 30 e 90 dias em lactação (DEL) foi avaliada em dois exames de ultrassonografia com intervalo de sete dias, e as vacas foram classificadas em quatro categorias: ovários com presença de pequenos folículos (Categoria 1: até 10 mm); ovários com médios folículos (Categoria 2: 10 a 18 mm); ovários com grandes folículos (Categoria 3: acima de 20 mm) e ovários com presença de corpo lúteo (CL) (Categoria 4). As vacas classificadas nas B. Indústr. Anim., Nova Odessa,v.71, n.1, p.34-38, 2014 categorias 1, 2 e 3 foram consideradas em anestro. Os dados foram analisados por regressão logística usando o programa Minitab (P0,05) de DEL sobre a porcentagem de vacas ciclando (com CL), porém houve uma tendência (P=0,074) das vacas com maior ECC (≥ 2,75) apresentarem maiores taxas de ciclicidade (74,44% vs. 61,54%) do que vacas com baixo ECC. Conclui-se que os dias em lactação não afetam a taxa de ciclicidade de vacas Holandesas, porém há uma tendência das vacas com melhor condição corporal apresentarem maiores taxas de ciclicidade.

Assuntos

RESUMO

Anestrous postpartum is a state of complete sexual inactivity without estrous manifestations and the return of ovarian activity in postpartum may be negatively affected by several factors, such as negative energy balance (NEB), loss of body condition score (BCS), season in which the calving occurs, nutritional deficiencies, dystocic calving, retained placenta, uterine infections and metabolic diseases. This study aimed to evaluate the effects of BCS and number of days in milk (DIM) on ovarian cyclicity of Holstein dairy cows. Ovarian conditions of 168 cows between 30 to 90 days in milk (DIM) were evaluated twice by ultrasonography with seven days of interval and cows were classified in four categories: ovaries with presence of small follicles (Category 1: up to 10 mm); ovaries with medium follicles (Category 2: 10 to 18 mm); ovaries with large follicles (Category 3: over 20 mm) and ovaries with presence of corpus luteum (CL) (Category 4). The cows classified in categories 1, 2 and 3 were considered in anestrous. Data were analyzed by logistic regression at Minitab (P<0.05). As a result 15 cows (8.93%) were in Category 1, 34 (20.24%) in Category 2, 4 (2.38%) in Category 3 and 115 (68.45%) in Category 4. There was no effect (P>0.05) of DIM in the percentage of cycling cows, however there was a tendency (P=0.074) that cows with greater BCS (≥ 2.75) had a higher cyclicity rate (74.44% vs. 61.54%) than cows with lower BCS. Days in milk effect was not detected in cyclicity rate in cows between 30 and 90 DIM, but there was a tendency of Holstein cows with greater body condition score to had higher cyclicity rate.(AU)

O anestro é um estado de completa inatividade sexual, sem manifestações de cio e o retorno à atividade ovariana no pós-parto pode ser afetado negativamente por diversos fatores, como o balanço energético negativo (BEN), perda de escore de condição corporal (ECC), estação do ano na qual ocorre o parto, deficiências nutricionais, ocorrência de distocia, retenção de placenta, infecções uterinas e doenças metabólicas. Objetivou-se avaliar os efeitos do ECC e donúmero de dias em lactação (DEL) sobre a ciclicidade ovariana de vacas leiteiras Holandesas. A condição ovariana de 168 vacas entre 30 e 90 dias em lactação (DEL) foi avaliada em dois exames de ultrassonografia com intervalo de sete dias, e as vacas foram classificadas em quatro categorias: ovários com presença de pequenos folículos (Categoria 1: até 10 mm); ovários com médios folículos (Categoria 2: 10 a 18 mm); ovários com grandes folículos (Categoria 3: acima de 20 mm) e ovários com presença de corpo lúteo (CL) (Categoria 4). As vacas classificadas nas B. Indústr. Anim., Nova Odessa,v.71, n.1, p.34-38, 2014 categorias 1, 2 e 3 foram consideradas em anestro. Os dados foram analisados por regressão logística usando o programa Minitab (P<0,05). Como resultado 15 vacas (8,93%) foram classificadas na Categoria 1, 34 (20,24%) na Categoria 2, 4 (2,38%) na Categoria 3 e 115 (68,45%) na Categoria 4. Não foi detectado efeito (P>0,05) de DEL sobre a porcentagem de vacas ciclando (com CL), porém houve uma tendência (P=0,074) das vacas com maior ECC (≥ 2,75) apresentarem maiores taxas de ciclicidade (74,44% vs. 61,54%) do que vacas com baixo ECC. Conclui-se que os dias em lactação não afetam a taxa de ciclicidade de vacas Holandesas, porém há uma tendência das vacas com melhor condição corporal apresentarem maiores taxas de ciclicidade.(AU)

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RESUMO

La melatonina es una hormona que regula los ciclos circadianos y muchos de los aspectos reproductivos de los mamíferos y es secretada por la glándula pineal en las horas de ausencia de luz. Esta hormona posee receptores de alta afinidad acoplados a proteínas de tipo G, denominados MT1. Un polimorfismo de la secuencia que codifica para estos receptores estaría involucrado en el control de la reproducción estacional de los ovinos. El propósito de este estudio busca determinar la presencia del polimorfismo del receptor MT1 en la oveja criolla Araucana, un ovino local en el que se ha registrado un corto anestro reproductivo. Para poder realizar este trabajo se utilizó la técnica denominada reacción en cadena de la polimerasa para polimorfismo en el tamaño de los fragmentos de restricción PCR-RFLP, para lo cual, se obtuvieron muestras de ADN genómico de 50 ovejas Araucanas, las cuales fueron digeridas con la endonucleasa de restricción Mnl1. Se logró identificar la presencia del polimorfismo del receptor MT1 en la oveja Araucana. Los genotipos se hallaron en una frecuencia de 68 por ciento para el genotipo +/+, 28 por ciento para el genotipo +/- y4 por ciento para el genotipo -/-. Este alto porcentaje de animales con genotipo +/+ podría explicar el corto anestro reproductivo que presenta esta raza.

Melatonin is a hormone that regulates circadian rhythms and many of the reproductive aspects of mammals and is secreted by the pineal gland during the hours of absence of light. This hormone has high affinity receptors coupled to G-like proteins, termed MT1. A polymorphism of the sequence coding for these receptors was involved in the control of seasonal reproduction in sheep. The purpose of this study was to determine the presence of MT1 receptor polymorphism in Araucana creole sheep, a local breed with a short reproductive anestrus. To carry out this work, we used a technique called polymerase chain reaction-restriction fragment lengh polymorphism PCR-RFLP, for which samples were obtained from genomic DNA of 50 Araucana sheep, which were digested with Mnl1 restriction endonuclease. It was possible to identify the presence of MT1 receptor polymorphism in Araucana sheep. The genotypes were found in a genotype frequency of 68 percent for genotype + / +, 28 percent for genotype + / - y4 percent for genotype - / -. This high percentage of animals with genotype + / + could explain the short reproductive anestrus featuring this breed.

Assuntos