Genetic and management factors affecting beef quality in grazing Hereford steers

Attributes contributing to differences in beef quality of 206 Hereford steers finished on pasture were assessed. Beef quality traits evaluated were: Warner–Bratzler meat tenderness and muscle and fat color at one and seven days after slaughter and trained sensory panel traits (tenderness, juiciness, flavor, and marbling) at seven days. Molecular markers were CAPN1 316 and an SNP in exon 2 on the leptin gene (E2FB). Average daily live weight gain, ultrasound monthly backfat thickness gain and rib-eye area gain were estimated. Molecular markers effects on meat quality traits were analyzed by mixed models. Association of meat quality with post weaning growth traits was analyzed by canonical correlations. Muscle color and marbling were affected by CAPN1 316 and E2FB and Warner–Bratzler meat tenderness by the former. The results confirm that marker assisted selection for tenderness is advisable only when beef aging is a common practice. The most important sources of variation in tenderness and color of meat remained unaccounted for.EEA BalcarceFil: Melucci, Lilia Magdalena. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Departamento de Producción Animal; ArgentinaFil: Panarace, M. Goyaike SAACIYF. Biotechnology Area; ArgentinaFil: Feula, P. Goyaike SAACIYF. Biotechnology Area; ArgentinaFil: Villarreal, Edgardo Leopoldo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Área de Investigación en Producción Animal; ArgentinaFil: Grigioni, Gabriela Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Tecnología de Alimentos; ArgentinaFil: Carduza, Fernando Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Tecnología de Alimentos; ArgentinaFil: Soria, Liliana A. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Mezzadra, Carlos Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Arceo, Maria E. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Papaleo Mazzucco, Juliana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Área de Investigación en Producción Animal; ArgentinaFil: Corva, Pablo Marcelo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Departamento de Producción Animal; ArgentinaFil: Irurueta, Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Tecnología de Alimentos; ArgentinaFil: Rogberg Muñoz, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Genética Veterinaria; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Miquel, María Cristina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias; Argentin

A systematic study of the effect of the hard end-group composition on the microphase separation, thermal and mechanical properties of supramolecular polyurethanes

This paper reports a systematic study on a series of supramolecular polyurethanes that possess microphase separated morphologies which afford elastic materials at room temperature. Combinations of urea and/or urethane linkers in addition to a phenyl spacer have been used to study the effect of the rigidity of the hard end group segments as well as the hydrogen bonding capability of the urethane-urea linker units. Small angle X-ray scattering (SAXS) experiments have revealed characteristic microphase separated morphologies. Wide angle X-ray scattering (WAXS) was used to probe the lateral packing of the urethane and/or urea within the hard segments. Differential scanning calorimetry (DSC) analysis confirmed that unsymmetrical soft/hard segment phases have been achieved by varying the urethane/urea content. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) determined that a 1-D fibrillar structure was obtained when the hard segment featured ureas whereas a 3-D structure was achieved when a combination of urea and urethane groups was used, giving rise to enhanced elongation properties. Finally, we present mechanical testing data in which oscillatory rheology at a range of frequencies and temperatures has revealed the effect of the connectivity of the hard segments on the relaxation times of the supramolecular chains. Tensile tests showed that end groups with ureas or a combination of a urea and urethane yielded elastic materials with strengths of ca. 5 MPa at room temperature