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Objective: To evaluate the effect of the offer level of silage from Avena sativa L., Altoandina variety, on the total dry matter intake of the diet and the productivity of lactating cows under grazing conditions in the Pasto municipality, Colombia. Materials and Methods: Twelve F1 cows (Kiwi cross x Holstein) were used, of 450 kg of average live weight, in a crossover design. Two treatments were established, which corresponded to two silage inclusion levels: 20 (T1) and 35 % (T2) of the total dry matter intake. Periods of 12 days were evaluated, seven of adaptation and five for measurement. Dry matter intake, milk quality and production, as well as the indicators of the metabolic profile (glucose, cholesterol and blood ureic nitrogen) were estimated. The information was processed through a variance analysis and Tukey's mean comparison test. Results: There was significant effect (p < 0,05) for the variables total dry matter intake of the silage (2,8 vs. 1,4 kg/ DM/cow/day for 35 and 20 % of inclusion of oat silage, respectively). The milk production was 14,9 vs. 14,3 kg/cow/ day, for 35 and 20 % of inclusion of oat silage, respectively. The milk ureic nitrogen and blood ureic nitrogen were higher in T1 with regards to T2 (15,8 and 3,1 vs. 14,5 and 2,8, respectively). Conclusions: The introduction in the diet of silage of A. sativa, Altoandina variety (20 and 35 %), affected the total dry matter intake. In addition, the inclusion of 35 % of the silage influenced positively milk production, increasing by 4 %. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of the offer level of silage from Avena sativa L., Altoandina variety, on the total dry matter intake of the diet and the productivity of lactating cows under grazing conditions in the Pasto municipality, Colombia. Materials and Methods: Twelve F1 cows (Kiwi cross x Holstein) were used, of 450 kg of average live weight, in a crossover design. Two treatments were established, which corresponded to two silage inclusion levels: 20 (T1) and 35 % (T2) of the total dry matter intake. Periods of 12 days were evaluated, seven of adaptation and five for measurement. Dry matter intake, milk quality and production, as well as the indicators of the metabolic profile (glucose, cholesterol and blood ureic nitrogen) were estimated. The information was processed through a variance analysis and Tukey's mean comparison test. Results: There was significant effect (p < 0,05) for the variables total dry matter intake of the silage (2,8 vs. 1,4 kg/ DM/cow/day for 35 and 20 % of inclusion of oat silage, respectively). The milk production was 14,9 vs. 14,3 kg/cow/ day, for 35 and 20 % of inclusion of oat silage, respectively. The milk ureic nitrogen and blood ureic nitrogen were higher in T1 with regards to T2 (15,8 and 3,1 vs. 14,5 and 2,8, respectively). Conclusions: The introduction in the diet of silage of A. sativa, Altoandina variety (20 and 35 %), affected the total dry matter intake. In addition, the inclusion of 35 % of the silage influenced positively milk production, increasing by 4 %. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate three ryegrass (Lolium perenne L.) cultivars with dairy cows, in the high tropic of Nariño-Colombia, in two localities: Pasto (PAS) and Cumbal (CUM). In each locality nine cows were used, in a Latin square design (3 x 3) with three treatments (T), corresponding to each cultivar to be evaluated: T1: ryegrass Columbia, T2: ryegrass Samson, T3: ryegrass Ohau. The dry matter intake (DMI) and milk production (MP) were estimated, and samples were collected to analyze: fat, protein, total solids and milk ureic nitrogen (MUN). There was no statistical difference in the DMI among the ryegrasses in the localities. In PAS significant differences were found among cultivars in the variable milk production (p < 0,05); with Samson and Ohau higher production was obtained (17,5 and 17,1 kg/cow/day) with regards to Columbia (15,5 kg/cow/day). In the content of fat and non-fatty solids in the milk, there were no differences among the treatments in any of the two localities. However, significant difference (p < 0,05) was found in the milk protein in PAS (3,48; 3,61 and 3,47 % for Columbia, Samson and Ohau, respectively). For the variable MUN (mg/dL), significant difference (p < 0,05) was observed in the PAS locality. It is concluded that L. perenne showed similar nutritional characteristics in the two localities where they were established. The response in milk production and compositional quality was considered good, taking into consideration that the animals did not receive supplementation and the trial was conducted in the dry season, in which the pasture yields decrease. [ABSTRACT FROM AUTHOR]

The aim of this study is to design a new dynamic mechanical analysis (DMA) measurement system that can operate for shear tests at frequencies as high as 10 kHz with strain amplitudes sufficient for viscoelastic materials operating in high-frequency deformation applications, such as tire rubbers. The available DMA systems in market cannot effectively operate for accurate and direct measurement of viscoelastic material properties for applications dealing with high-frequency deformation of materials. Due to this, the available DMA systems are used for indirect measurements at low frequencies and low temperatures, followed by using time-temperature superposition principle to predict the properties at high frequencies. The goal of this study is to make the range of the test broad enough to eliminate the use of the time-temperature superposition principle in the determination of properties of viscoelastic materials. Direct measurement of viscoelastic material properties and increasing the accuracy of results are the main motivations to design a new DMA system. For this purpose, the state-of-the-art technologies to achieve high frequencies and strain amplitudes as well as instrumentation and control of the system are studied. The design process is presented in this paper. [ABSTRACT FROM AUTHOR]

The repair of atrioventricular valves requires optimal valve exposure through even unconventional surgical approaches. This is especially true in the situation of multiple re-do valve surgeries, where extensive adhesions may prevent adequate valve exposure. When multiple valve surgeries are contemplated, an extensive incisional approach is required without causing damage to any surrounding crucial structures. Re-do surgeries are described in patients with prosthetic valve endocarditis where the correction of all valves involved is necessary, as is the correction of underlying ventricular pathologies such as sinuses and atrioventricular tunnels. As several surgical approaches have been attempted in these situations, a technique is described which involves a superior biatrial approach after transecting the aorta, which addresses the mitral, tricuspid and aortic valves and allows the correction of associated ventricular pathologies.