Estimación de factores de corrección del perímetro escrotal para edad y peso corporal en toros jóvenes de la raza nelore

El presente trabajo estudia los efectos de la edad y peso sobre el Perímetro Escrotal (PE), en toritos de la raza Nelore en el Paraguay; a los efectos de estimar factores de corrección (FC). Las informaciones provinieron de los Registros de Producción de la Asociación Paraguaya de Criadores de Nelore, obtenidos entre 1986 y 1997 de 110 establecimientos, totalizando 7.458 observaciones. Los coeficientes de regresión que permitieron el cálculo de los FCs para PE, fueron estimados por el método de los cuadrados mínimos con ayuda del programa estadístico SAS. El modelo empleado consideró el grupo contemporáneo (animales nacidos en el mismo año, estación, rebaño, evaluados en la misma fecha y del mismo grupo de manejo alimenticio en el destete y a los 18 meses), efecto lineal de la edad en días, y lineal y cuadrático del peso a los 570 días de edad. El efecto de la edad sobre el PE fue de 0,0383(±0,0024) cm/día; y del peso a los 570 días sobre el PE corregido para esa edad fue 0,0708(±0,0049) cm/kg, efecto lineal y, -0,0000413(±0,0000074) cm/kg, efecto cuadrático. La edad y el peso del animal fueron importantes fuentes de variación a ser removidos del PE, como indicativo de la precocidad sexual de toros de año y medio

Análise espermática de perdizes (Rhynchotus rufescens) criadas em cativeiro e suplementadas com selênio

Considerando a importância comercial da perdiz (Rhynchotus rufescens), implantaram-se algumas biotecnologias reprodutivas. Trinta animais, provenientes da FCAV-UNESP/Jaboticabal (2007-2008), foram aleatoriamente distribuídos em grupos: controle (sem selênio orgânico) e tratamento (com 0,2 a 0,8 mg de selênio em 1000 kg de ração ). Coletou-se sêmen por excitação manual, que foi aliquotado em pools com 150 µL. Mensuraram-se volume, motilidade, vigor, número de espermatozoides, concentração e morfologia espermáticas. Diluíram-se 20 µl de sêmen em 300 µl de solução fisiológica para testes complementares (Integridade das membranas acrossomal e plasmática). Contaram-se 200 células, por teste, e classificaram-nas: 1) Acrossomo Íntegro: cor lilás e Não-Íntegro: róseo; 2) Células Vivas (não coradas) e Mortas (coradas). Os dados foram analisados pelo SAS, System for Windows. Os resultados dos pools com e sem selênio foram: as variáveis volume, motilidade, vigor, número de espermatozoides, concentração, integridade acrossomal e integridade da membrana plasmática não apresentaram resultados significantes, porém encontrou-se uma menor porcentagem de espermatozoides com peça intermediária fortemente dobrada, nos animais tratados com selênio em relação aos não tratados (1,33 ± 0,53 vs. 3,78 ± 0,69, respectivamente; p = 0.0107). De fato, sabe-se que o selênio tem papel importante na estrutura dos espermatozoides20. A deficiência de selênio está associada com danos na arquitetura da peça intermediária do espermatozóide10.Due to the commercial importance of the red-winged tinamou (Rhynchotus rufescens), for the past few years, the employment of reproductive biotechnologies has been attempted. Thirty animals were randomly assigned into two groups: control group (no selenium) and treatment group (supplemented with 0,2 a 0,8 mg selenium/ 1000 kg ration). Animals were allocated at the FCAV - UNESP/Jaboticabal (2007-2008). Semen collections were performed by digital manipulation and divided in pools of at least 150 µL. After the immediate evaluation of motility, vigour, concentration and morphology, an aliquot of 20 µL was diluted in 300 µL of physiologic solution in order to test acrosome and membrane integrities, which were performed by counting 200 cells for each test. Cells were evaluated as follows: 1) Intact acrosome: lilac acrosome; Non-intact acrosome: pink acrosome; 2) Live cells: non stained; Dead: stained. Data was statistically analysed using the SAS System for Windows. No differences were found between treatment and control groups for volume, motility, vigour, mean number of spermatozoa per animal, concentration, Intact acrosome, Intact membrane. The difference found on midpiece sperm defect (Se = 1,33 ± 0,53 and control = 3,78 ± 0,69, p = 0.0107) may be due to the damages caused by the selenium deficiency to the architecture of the midpiece, which compromises sperm mobility and fertilization capacity

Use of direct and iterative solvers for estimation of SNP effects in genome-wide selection

The aim of this study was to compare iterative and direct solvers for estimation of marker effects in genomic selection. One iterative and two direct methods were used: Gauss-Seidel with Residual Update, Cholesky Decomposition and Gentleman-Givens rotations. For resembling different scenarios with respect to number of markers and of genotyped animals, a simulated data set divided into 25 subsets was used. Number of markers ranged from 1,200 to 5,925 and number of animals ranged from 1,200 to 5,865. Methods were also applied to real data comprising 3081 individuals genotyped for 45181 SNPs. Results from simulated data showed that the iterative solver was substantially faster than direct methods for larger numbers of markers. Use of a direct solver may allow for computing (co)variances of SNP effects. When applied to real data, performance of the iterative method varied substantially, depending on the level of ill-conditioning of the coefficient matrix. From results with real data, Gentleman-Givens rotations would be the method of choice in this particular application as it provided an exact solution within a fairly reasonable time frame (less than two hours). It would indeed be the preferred method whenever computer resources allow its use