Caracterización morfológica, de la canal y de la carne, e inferencia de maternidades en ovinos de raza Ripollesa.

Abstract

To be able to implement genetic selection programs in meat-producing sheep breeds, is essential define and evaluate biological traits with economic importance in the production. The Ripollesa sheep breed is an important Spanish local breed mainly located in the Mediterranean mountains and cultivated plains of Catalonia, exploited under semi-extensive production systems and currently intended for meat production. The morphologic characterization of the Ripollesa breed was carried out from the study of 8 flocks representative of different subpopulations. They were differentiated four subpopulations with relevant implications to be taken into account for the breed conservation program. The observed differences could be attributable to geographic location, selective history, flock management, and genetics. The estimated zootechnical indexes classified the Ripollesa sheep breed as a medium-sized and long-shaped body frame, with a marked orientation to meat production and with signs of adaptation to the environment. In sheep flocks, lamb’s parents can be misidentified or confounded due to the plausibility of two or more potential sires or dams. This phenomenon leads to a moderate-to-low percentage of lambs with missing pedigrees, with the subsequent loss of information for the corresponding animal breeding programs and selection schemes. To ascertain the dam of abandoned lambs we adapted a Bayesian model by integrating both genetic and environmental sources of information from phenotypic data and modeling the uncertain dam as an additional unknown parameter. The model performance was evaluated by using simulation data and by assuming seven different scenarios where one to four abandoned lambs had to be assigned to two candidate ewes. The overall average probability of assignment to the right dam was 0.59. Any inference on uncertain dams would reduce further economic costs by allowing to focus genotyping efforts on those lambs with higher probabilities to be offspring from elite ewes. Concern about meat composition and its relationship with human health has increased during the last few decades has been a key point for the actual sheep farming industry. Real-time ultrasound techniques are of great utility to predict carcass characteristics in the live animal in a non-invasive way. With the aim to assess the accuracy of the ultrasound measurements for predicting carcass traits, ultrasound images were taken in ‘pascual’-type lambs, transversal and longitudinal to the vertebral column, and at thoracic and lumbar locations. transversal ultrasound measurements at both thoracic and lumbar levels could be a useful tool for predicting carcass traits in light lambs, contributing with relevant information for light lamb producers worldwide, with a special emphasis in the Mediterranean basin where this kind of production system accounts for an outstanding percentage of the sheep industry. Lamb meat is an important source of different fatty acids with numerous health benefits for the consumer. With the aim of characterize carcass and meat traits in Lacaune, Ripollesa and Lacaune×Ripollesa ‘pascual’-type lambs ultrasound and direct measurements on carcasses were used and laboratory analyses on meat samples. They were not found significant differences between breeds for ultrasound and carcass measures. Carcass yield was better for Lacaune followed by Ripollesa. The meat fatty acid (FA) mostly represented in muscular tissue under examination were: oleic, palmitic and stearic. Differences between breeds for saturated (SFA), monounsaturated and polyunsaturated FA (PUFA) proportions were found. Differences for nutritional ratios were only found for PUFA/SFA ratio. All of this information becomes essential for light lamb producers, a livestock product that has high market demand in the Mediterranean basin.

Date of Award	12 Jul 2012
Original language	Spanish
Supervisor	Jesus Piedrafita Arilla (Director) & Joaquin Casellas Vidal (Director)