Genetic parameters for milk yield and reproduction traits in the Chilean Dairy Overo Colorado cattle breed

The objective of this study was to estimate genetic parameters for milk production and reproduction traits using phenotypic and pedigree information from the Dairy Overo Colorado breed from southern Chile. Single- and multi-trait mixed models were used to analyze the data. Analyses were performed using ASReml software. The heritability estimates for milk yield, fat yield, protein yield, fat content, protein content, age at first calving and calving interval were 0.29 ± 0.04, 0.34 ± 0.04, 0.30 ± 0.04, 0.56 ± 0.04, 0.56 ± 0.04, 0.01 ± 0.07 and 0.002 ± 0.02, respectively. The genetic correlations between yield traits were high and positive (≥ 0.81). The genetic correlations of milk yield with fat content (-0.32) and protein content (-0.34) were unfavorable. The genetic correlation estimates between age at first calving and yield traits were negative, ranging between -0.71 and -0.29. The phenotypic correlations between calving interval and milk yield traits were slightly positive (0.06-0.09), suggesting a weak relationship between reproduction and yield in this population. Genetic variation was significantly greater than zero for milk production traits. Genetic improvement for age at first calving and calving interval may be slow because small differences between animals and low reliabilities are expected for estimated breeding values for these traits due to heritabilities close to zero. The design of an efficient breeding program for yield traits based on artificial insemination for this population is feasible using either progeny testing or genomic breeding value prediction to select sires.El objetivo de este estudio fue estimar parámetros genéticos para características de producción de leche y reproducción en la raza Overo Colorado Lechero del sur de Chile. Se utilizaron modelos de una y múltiples características para analizar los datos. Los análisis se realizaron usando el programa ASReml. Los estimados de heredabilidad para producción de leche, producción de grasa, producción de proteína, contenido de grasa, contenido de proteína, edad al primer parto e intervalo entre partos fueron 0.29 ± 0.04, 0.34 ± 0.04, 0.30 ± 0.04, 0.56 ± 0.04, 0.56 ± 0.04, 0.01 ± 0.07 y 0.002 ± 0.02, respectivamente. Las correlaciones genéticas entre las características de producción fueron altas y positivas (≥ 0.81). Las correlaciones genéticas de la producción de leche con el contenido de grasa (-0.32) y el contenido de proteína (-0.34) fueron desfavorables. La correlación genética entre edad al primer parto y las características de producción fueron negativas entre -0.71 and -0.29. Las correlaciones fenotípicas entre el intervalo entre partos y las características de producción de leche fueron ligeramente positivas, (0.06-0.09), lo que sugiere una relación débil entre reproducción y producción en esta población. La variación genética es significativamente mayor a cero para las características de producción de leche. El mejoramiento genético para edad al primer parto e intervalo entre partos será lento, debido a que se esperan pequeñas diferencias entre animales y bajas confiabilidades para los valores genéticos estimados, debido a que los valores de las heredabilidades son cercanos a cero. El diseño de un programa eficiente de mejoramiento genético para características de producción basado en inseminación artificial para esta población es factible usando pruebas de progenie o predicciones del valor genético aditivo usando evaluaciones genómicas para la selección de sementales

Trans-supraorbital approach to supratentorial aneurysms

OBJECTIVE: The trans-supraorbital approach has the advantage of combining the keyhole principle with cranial base surgery. The anatomic fields that can be visualized with the use of this procedure have been demonstrated in cadavers, and the advantages and potential surgical applications of this procedure are described in this report. This article is the first to describe a group of intracranial supratentorial aneurysms. METHODS: We used the trans-supraorbital approach in 22 cases of supratentorial aneurysms. In this technique, an incision is made through the eyebrow, then a 3.5-cm craniotomy is performed with en bloc extension to the orbital arch, complemented by different drilling extensions of the orbital roof according to the surgical objective. We describe the anatomic details of the experimental work as well as the clinical results. RESULTS: The trans-supraorbital technique offers an unlimited wide exposure of neurovascular structures in this microsurgical corridor. The craniotomy extension allows greater exposure than the conventional keyhole supraorbital approach, which makes the technique safe for the patient and comfortable for the surgeon. All patient outcomes were successful; no serious complications from the surgical technique occurred. Our success was achieved through better microscopic illumination in the deep field and by gaining access to the complete supratentorial vascular territory with minimal cerebral retraction and an acceptable cosmetic result. CONCLUSION: The trans-supraorbital approach is effective for gaining access to and treating supratentorial aneurysms. Also, the microsurgical field is more convenient in microscope-assisted surgery because total reliance on the endoscope is not required, and minimal brain retraction is needed. This modification of the keyhole procedure also provides multiple surgical options in this microsurgical corridor, using the principles of minimal invasiveness in cranial base surgery