Effect of two oil types and energy levels on broiler performance, carcass quality and skin pigmentation

This study evaluated different levels of metabolisable energy (ME) and two oil types: crude soybean oil (CSO) and acidulated soybean oil (ASO), in sorghum-soybean meal diets for broilers. One thousand and eight unsexed Ross 308 chicks aged 1 to 49 days old were used in a factorial arrangement design 2x3. The first factor corresponded to the oils (CSO and ASO) and the second factor corresponded to the ME levels (high, medium and low) in the initiation (1-10 days), growing (11-25 days) and finishing (26-48 days) feeds, with a 90 kcal/kg reduction. The treatments were as follows: (1) CSO with 3010, 3175 and 3200 kcal/kg; (2) CSO with 2920, 3085 and 3110 kcal/kg; (3) CSO with 2920, 3085 and 3200 kcal/kg; (4) ASO with 3010, 3175 and 3200 kcal/kg; (5) ASO with 2920, 3085 and 3110 kcal/kg; and (6) ASO with 2920, 3085 and 3200 kcal/kg. The treatments with high and medium levels of ME (P<0.05) were higher. The carcass weight and skin pigmentation when cold were better in broilers fed with high and medium levels of ME (P<0.05). No effect (P>0.05) between oil types was found. It can be concluded that it is feasible to replace CSO by ASO and to reduce 90 kcal/kg of ME from the recommended amount for the breed during the initiation and growing stages, without affecting their performance

Crack initiation and propagation on the polymeric material ABS (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing

Crack initiation and propagation have been investigated on the polymeric material ABS (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing. Three controlled actions were implemented in order to carry out fatigue tests at very high frequency on this material of low thermal conductivity, they are: a) The applying load was low to limit heat dissipation at the specimen neck section, b) The dimensions of testing specimen were small (but fitting the resonance condition), in order to restraint the temperature gradient at the specimen narrow section, c) Temperature at the specimen neck section was restrained by immersion in water or oil during ultrasonic fatigue testing. Experimental results are discussed on the basis of thermo-mechanical behaviour: the tail phenomenon at the initial stage of fatigue, initial shear yielding deformation, crazed development on the later stage, plastic strain on the fracture surface and the transition from low to high crack growth rate. In addition, a numerical analysis is developed to evaluate the J integral of energy dissipation and the stress intensity factor K, with the crack lengt

Cambios económicos, condiciones de bienestar y políticas sociales en México (1970-1991)

Trabajo preparado como parte del proyecto "Prioridades de Investigación sobre Política Social en América Latina

Cambios económicos, condiciones de bienestar y políticas sociales en México (1970-1991)

Trabajo preparado como parte del proyecto "Prioridades de Investigación sobre Política Social en América Latina

Effects of Glycyrrhizic Acid on Productive and Immune Parameters of Broilers

ABSTRACT Considering that glycyrrhizic acid (GRA) has been shown to have in-vitro and in-vivo antiviral activity against a wide range of viruses as well as immunostimulating activity, a trial to evaluate its effects on the performance and the immune response against Newcastle disease of broiler chickens was carried out. The study was performed with one-day-old Ross x Ross broiler chickens. GRA was added to the drinking water throughout the 49-d production cycle at a dose of 0.03%. Sample size of the trial was established in a pilot assay. Results showed that broiler chickens treated with GRA presented better weight gain, final body weight, feed conversion ratio, and lower mortality rate than the non-treated controls. In addition, GRA-treated birds presented higher antibody titers against Newcastle disease virus and more efficient cellular immune response, as demonstrated by the late-hypersensitivity response test. Blood lymphocyte and thrombocyte counts also increased in this group. The histopathological examination of the bursa, spleen, and thymus revealed that only the thymus of the GRA-treated group had a clearly defined increase in cortex thickness on day 49. The bursa showed a higher number of lymphoid lesions in CG on days 21 and 49 compared with the GRA group. These results suggest that GRA has growth promotion properties, which are possibly linked to immune-based effects

Crack initiation and propagation on the polymeric material ABS (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing

Crack initiation and propagation have been investigated on the polymeric material ABS (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing. Three controlled actions were implemented in order to carry out fatigue tests at very high frequency on this material of low thermal conductivity, they are: a) The applying load was low to limit heat dissipation at the specimen neck section, b) The dimensions of testing specimen were small (but fitting the resonance condition), in order to restraint the temperature gradient at the specimen narrow section, c) Temperature at the specimen neck section was restrained by immersion in water or oil during ultrasonic fatigue testing. Experimental results are discussed on the basis of thermo-mechanical behaviour: the tail phenomenon at the initial stage of fatigue, initial shear yielding deformation, crazed development on the later stage, plastic strain on the fracture surface and the transition from low to high crack growth rate. In addition, a numerical analysis is developed to evaluate the J integral of energy dissipation and the stress intensity factor K, with the crack lengt