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Background: Genetic information is necessary to devise strategic plans aimed to improve the genetic merit of buffalos. Objective: To assess the effect of genetic polymorphisms in GH, Pit-1, GHR, GHRHR, and KCN3 genes on milk production and body weight of Khuzestan water buffaloes. Methods: Blood samples were collected from 60 buffaloes from the Khuzestan province, Iran. Using the PCR-RFLP technique, the amplified and digested fragments of GH/AluI, GHR/AluI, GHRHR/ HaeIII, Pit1/HinfI, and KCN3/HindIII were genotyped. Results: All animals were monomorphic for GHRHR. The frequency of mutant alleles for GH, GHR, KCN3, and Pit1 was 47.5, 74.2, 49.2, and 51.7%, respectively. There were significant differences (p<0.0001) in the genotypic frequencies of GH, GHR, and Pit1 between high and low milk-yielding buffaloes. The GH (p=0.0002), GHR (p<0.0001) and Pit1 (p<0.0001) polymorphisms also had significant effects on body weight. Sequencing results revealed the presence of C496A, G495A, G498A and C1501T SNPs in the GH, and G1702T in the GHR gene of Khuzestan buffalos. Conclusion: This study highlights the importance of GH, GHR, and Pit1 on milk production and body weight of Khuzestan buffaloes. The results suggest that devising an integrated breeding plan in Khuzestan water buffalos can considerably benefit from the very high diversity in candidate genes.Keywords: animal breeding, casein, genetic variation, growth hormone, milk production, SNP. ResumenAntecedentes: La información genética es necesaria para diseñar planes estratégicos con el objeto de mejorar el mérito genético de los búfalos. Objetivo: Evaluar el efecto de los polimorfismos genéticos en los genes GH, Pit-1, GHR, GHRHR y KCN3 sobre la producción láctea y peso corporal de búfalos de agua de la provincia de Juzestán, Iran. Métodos: Se recolectaron 60 muestras de sangre de búfalos de la provincia de Juzestán, en Irán. Los fragmentos amplificados y digeridos de GH/AluI, GHR/AluI, GHRHR/HaeIII, Pit1/HinfI y KCN3/HindIII fueron clasificados genotípicamente, utilizando la técnica PCR-RFLP. Resultados: Todos los animales fueron monomórficos para el gen GHRHR. La frecuencia alélica de alelos mutantes para los genes GH, GHR, KCN3 y Pit1 fue 47,5, 74,2, 49,2 y 51,7%, respectivamente. Se encontraron diferencias significativas (p<0,0001) en las frecuencias genotípicas de GH, GHR y Pit1 entre búfalos de alta y baja producción. El efecto del polimorfismo GH (p=0,0002), GHR (p<0,0001) y Pit1 (p<0,0001) también fue significativo para peso corporal. Los resultados de la secuenciación revelaron la presencia de SNPs C496A, G495A, G498A y C1501T en GH, y G1702T en el gen GHR. Conclusiones: Este estudio resalta la importancia de los genes GH, GHR y Pit1 sobre la producción de leche y el peso corporal de búfalos de Juzestán. Los resultados sugieren que la elaboración de un plan de cruzamiento integrado en búfalos de agua de Juzestán puede beneficiarse considerablemente de la gran diversidad de genes candidatos.Palabras clave: caseína, hormona del crecimiento, producción de leche, reproducción animal, SNP, variación genética. ResumoAntecedentes: Determinação informações genéticas é o passo crítico para elaborar planos estratégicos com o objetivo de melhorar o mérito genético dos búfalos. Objetivo: Avaliar o efeito de polimorfismos genéticos nos genes GH, Pit-1, GHR, GHRHR e KCN3 na produção de leite e no peso corporal dos búfalos de água do Cuzistão, Irã. Métodos: Amostras de sangue foram coletadas de 60 búfalos da província de Cuzistão, no Irã. Utilizando a técnica PCR-RFLP, os fragmentos amplificados e digeridos de GH/AluI, GHR/AluI, GHRHR/HaeIII, Pit1/HinfI e KCN3/HindIII foram genotipados. Resultados: Todos os animais eram monomórficos para o gene GHRHR. A freqüência alélica de alelos mutantes para os genes GH, GHR, KCN3 e Pit1 foi 47,5, 74,2, 49,2 e 51,7%, respectivamente. Uma diferença significativa (p<0,0001) foi encontrada nas freqüências genotípicas de os genes GH, GHR e Pit1 entre búfalos de alta e baixa produção. O efeito do polimorfismo GH (p=0,0002), GHR (p<0,0001) e Pit1 (p<0,0001) também foi significativo para o peso corporal. Os resultados da sequenciação revelaram a presença de SNPs C496A, G495A, G498A e C1501T no GH, e G1702T no gene GHR dos buffalos do Cuzistão. Conclusões: Este estudo destacou a importância da GH, GHR e Pit1 na produção de leite e no peso corporal de buffalos do Cuzistão. Os resultados sugerem que a elaboração de um plano de melhoramiento genético integrado em búfalos de água do Cuzistão pode beneficiar consideravelmente da grande diversidade de genes candidatos.Palavras-chave: caseína, hormônio do crescimento, produção de leite, reprodução animal, SNP, variação genética.

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The myostatin gene (MSTN), which encodes the protein myostatin, is pleiotropic, and its expression has been associated with both increased and decreased adipogenesis and increased skeletal muscle mass in animals. In this study, the polymerase chain reaction, coupled with single strand conformation polymorphism analysis, was utilized to reveal nucleotide sequence variation in bovine MSTN in 410 New Zealand (NZ) Holstein-Friesian × Jersey (HF × J)-cross cows. These cows ranged from 3 to 9 years of age and over the time studied, produced an average 22.53 ± 2.18 L of milk per day, with an average milk fat content of 4.94 ± 0.17% and average milk protein content of 4.03 ± 0.10%. Analysis of a 406-bp amplicon from the intron 1 region, revealed five nucleotide sequence variants (A–E) that contained seven nucleotide substitutions. Using general linear mixed-effect model analyses the AD genotype was associated with reduced C10:0, C12:0, and C12:1 levels when compared to levels in cows with the AA genotype. These associations in NZ HF × J cross cows are novel, and they suggest that this variation in bovine MSTN could be explored for increasing the amount of milk unsaturated fatty acid and decreasing the amount of saturated fatty acid.

Differential equations and advanced statistical models have been used to predict growth phenomena. In the present study, general nonlinear growth functions such as von Bertalanffy, Gompertz, logistic, and Brody, along with hierarchical modeling were applied to investigate the phenotypic growth pattern of Iranian Lori-Bakhtiari sheep. Growth data from 1410 Lori-Bakhtiari lambs were used in the present study. The results showed that the Brody function outperformed the other three nonlinear growth functions. In addition, including hierarchical growth modeling results allowed the adoption of many random effect structures, suggesting that hierarchical growth modeling has a useful role in growth data modeling. This method provides an estimation of growth parameters based on individual animals, improving individual growth selection. The results suggest this approach for growth modeling. Combining the strength of individual growth modeling with general growth modeling, e.g., von Bertalanffy, Gompertz, logistic, and Brody would be deeply appealing in the future. In this regard, dealing with sheep growth phenomenon using pure mathematical models, i.e. grey system theory models that could be new powerful prediction tools for breeders and experts, has not been done yet. However, running the analysis on large datasets will require significantly higher computational power than is ordinarily available.

Abstract. In recent decades, there has been a downward trend in length of productive life (LPL) in Holstein cows across industrial dairy herds. This study examined the factors that might influence LPL and estimated the genetic parameters of LPL in Holstein dairy herds in Isfahan province, Iran. LPL is defined as the number of days between the first calving and the end of recording. Data consisted of 35 137 records of productive life from registered cows that started first calving between 1991 and 2012. Cows that remained alive at the end of the study were considered right-censored. The average lifetime for culled and censored cows was 938 and 1003 days, respectively. A survival analysis was applied using a proportional risk model with a Weibull distribution. Milk production was divided into five groups, where the culling risk of cows with a milk yield of less than 1.5 standard deviations (SD) of the mean was 3.5 times greater than the culling risk of high-producing cows producing more than 1.5 SD above the mean. Results showed that culling risk increased almost linearly beyond the milk production groups. Furthermore, somatic cell count and age at first calving significantly increased the culling risk across the herds. The results for the combined effect of parity × stage of lactation showed a decrease in culling risk during the first calving, and an increase during the further parities. Moreover, a higher age at first calving was observed, reflecting a lower risk of culling. Estimated heritability were 0.074 and 0.18 based on a logarithmic scale and original scale, respectively. According to the results, use of Weibull models showed that the proportional culling risk was higher in low-production cows, but a higher risk ratio was revealed in high-milk-production cows. However, there were some fluctuations in genetic trends, but an overall increase was observed in LPL which will lead to a longer LPL of Holstein cows in Isfahan province.