ABSTRACT. In order to better understand vitamin D 3 in cattle metabolism, we quantified 1alpha-HYD and 24-HYD gene expression. In the kidneys of 35 male Nellore cattle, these were divided into a control group and two treatment groups (2 x 10 6 international units of vitamin D 3 administered for 2 or 8 consecutive days pre-slaughter). Vitamin D 3 supplementation resulted in a significant increase in 1alpha-HYD gene expression; however, significantly increased 24-HYD gene expression was only detected in cattle that had 8 days of supplementation. The finding of upregulation of 24-HYD due to vitamin D supplementation is in line with the expected rise in 24,25-di-hydroxy-vitamin D 3 synthesis observed when plasma vitamin D 3 concentrations are high, stimulating excretion by the organism. On the other hand, upregulation of 1alpha-HYD was unexpected, since vitamin D 3 supplementation has been reported to impact these two genes in opposite directions. We conclude that vitamin D 3 metabolism in these animals is more complex than previously reported.
The calpain system is the central player for meat tenderization and the calpastatin activity plays an important role in beef tenderness of Bos taurus indicus cattle. This study investigated whether dietary vitamin D3 induced gene expression of μ-calpain (CAPN1), total calpastatin (CAST T), and their variants (CAST I and II). Animals received none or 2 × 106 IU of vitamin D3 for either 2 or 8 days before slaughter and were submitted to different conditions during feedlot: sun exposure or artificial shade. Steaks from Longissimus lumborum were fabricated, aged for 1, 7, and 21 days post-mortem, and later used for the analyses of shear force and the myofibrillar fragmentation index. Vitamin D3 did not influence mRNA abundance; however, it induced a greater CAST II transcript in animals supplemented 8 days before slaughter. There was a negative association between CAST II abundance and the shear force, which revealed an important modulation of the calpain system expression due to vitamin D supplementation. This result is an important tool for strategies to improve beef tenderness.
RESUMO: Entre os métodos de estabilização utilizados na pavimentação destaca-se a estabilização química, que ocorre através da incorporação de um aditivo ao solo, sendo que um dos mais utilizados na pavimentação brasileira é a cal hidratada. Considerando que em regiões de climas tropicais predominam solos na situação não saturada, torna-se fundamental entender a influência da cal na curva característica solo-água (CCSA). Este trabalho apresenta uma investigação laboratorial do efeito da cal na CCSA de um solo tropical considerando diferentes teores de cal (0; 1,5; 3; 6 e 9%). Foi empregada uma placa de pressão para a obtenção de sucções abaixo de 100 kPa e de um potenciômetro de ponto de orvalho para a obtenção de sucções mais altas. Como resultado obteve-se que para um tempo de cura reduzido a cal tem pouca influência na CCSA, visto que todas as curvas apresentaram um comportamento semelhante.
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