ABSTRACT
RESUMEN En la producción de carne ovina en Argentina existe escasa tradición para la comercialización de reses de corderos pesados con bajo tenor de grasa. Un nuevo genotipo cuya marca registrada es Magrario (M) fue obtenido en el Campo Villarino de la Facultad de Ciencias Agrarias de la Universidad Nacional de Rosario (33º S, 61º O) por cruzas absorbentes de una raza tradicional en la zona, Ideal (I) (Polwarth), hacia la raza Texel (raza reconocida por producir reses magras). A partir de la población base de la tercera retrocruza se seleccionó a los machos por el Aumento Medio Diario relativo hasta los tres meses de edad y a las hembras por la fertilidad de sus madres. Se verificaron diferencias significativas en la composición de la res en lo referente a depósitos grasos de este nuevo genotipo respecto a la población fundadora I tanto en confinamiento posdestete durante dos meses como en condiciones de cría a campo. También se compararon en confinamiento corderos M con los de la raza Hampshire Down (HD) siendo los depósitos grasos significativamente superiores en esta última raza. También se analizaron cruzamientos de M con HD e I verificando un efecto semi-dominante del nuevo genotipo para reducir tenor de grasa en las cruzas. La reducción de grasa subcutánea en el Longissimus Dorsi de (MxHD) se redujo un 20%. Esta experiencia demostró que Magrario puede ser utilizado como progenitor en cruzamientos si se desea producir corderos con menores depósitos grasos en condiciones de suplementación posdestete.
ABSTRACT Generally there is poor tradition to produce and to commercialize heavy lean lamb carcasses. To achieve a better product for the ovine meat market Ideal (Polwarth) breed ewes were backcrossed to Texel breed rams (breed recognized to reduce carcass fat). Ideal breed (I) is one of the most ordinary breeds in Argentina. However, when their lambs are reared in feedlot conditions, a high fat content is found in their lamb carcasses. After three generations of backcrosses followed by a breeding program for increase male lamb weaning weight and female fertility a new genotype was obtained for the local ovine meat production systems. This new genotype registered as Magrario (M) was obtained at Villarino Field Station of UNR (Zavalla, Santa Fe, 33º S, 61º W). It was verify that M produced more lean meat than I breed under feet lot conditions. M rams were introduced in flocks of Hampshire Down (HD) breed to evaluate lamb crosses with lean meat. Genotype M was compared under feed lot conditions with HD lambs during two months in the post weaning. Also crosses (MxHD), (MxI) and (IxHD) were evaluated in the same conditions. At the end of the experiment ultrasonic methods were used to evaluate fat depot on Longissimus dorsi. The (MxHD) showed a reduction of 20% respecting to HD. These results suggested that M genotype could be a useful paternal genotype to reduce fat depots when the aim is to produce lamb crosses under feed lot conditions in a short period of time.
ABSTRACT
Agro-industrial systems provide large quantities of organic wastes that could imply an important environmental risk. While manures can be easily treated by anaerobic digestion, horticultural fruit wastes generally cannot be processed alone and should be treated by co-digestion. To use organic wastes as fertilizers is fundamental to improve understanding of their impact on soil-plant systems. In this research, cattle manure, poultry litter, pig slurry and onion waste were collected. Animal manures were studied without treatment, treated by anaerobic digestion alone and in co-digestion with onion wastes. To study their effect on soil-plant systems, chemical and spectroscopic characterization of manures and their transformed products were combined with soil biological activity and growth dynamic of lettuce following wastes incorporation to the soil. Anaerobic digestion decreased the C/N ratio, whilst there was an increase in NH4+-N/N ratio and short-chain organic acids. The magnitude of these changes varied depending on the type of organic matter present in each material and the incorporation of onion wastes intensified them. However, the digestates presented similar structural characteristics to each other, independently of the material of origin. Digestate soil application produced a fast and short microbial stimulation (18-34 and 7-11â¯mg CO2 during the first 6â¯h, digestates vs. rest of treatments). The digestate dosage should be done according to the content of NH4+-N given that the vegetal growth is related to it. Soils amended with digestates showed less CO2 emission than soils amended with manures improving overall C balance.
