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Kominakis, A., Rogdakis, E. and Koutsotolis, K. 1998. Genetic parameters for milk yield and litter size in Boutsico dairy sheep. Can. J. Anim. Sci. 78: 525-532. Lactation and litter size records (n = 2553) of Boutsico dairy sheep were used to estimate direct additive, maternal genetic, maternal and animal's permanent environmental variance components for milk yield and litter size by restricted maximum likelihood under a repeated records animal model. Raw milk yield data were transformed by log and Box-Cox (BC) transformations. Heritability estimates of direct additive effects were between 0.21 and 0.30, 0.18 and 0.24 and 0.21 and 0.27 for untransformed, log transformed and BC transformed data, respectively. Only maternal and animal's environmental effects were important for milk yield. Direct-maternal genetic covariance did not significantly (P > 0.05) influence milk yield. Repeatability for milk yield ranged from 0.32 to 0.38. Only additive genetic effects were important for litter size. Heritability and repeatability for litter size were 0.07 and 0.11, respectively. Genetic and phenotypic correlations between yield and litter size were 0.13 and 0.19, respectively.

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A total of 36 sheep in groups of 4 were inoculated with 9 isolates of Trichinella and euthanized after 10 weeks. Thereafter, numbers of muscle larvae were determined in 13 different muscles/muscle groups. Muscle larvae were found in high numbers in all four sheep inoculated with T. spiralis, in lower numbers in two sheep inoculated with T. pseudospiralis (USA isolate), and in very low numbers in one sheep inoculated with T. pseudospiralis (USSR isolate) and one inoculated with T. britovi. In infections of high and moderate larval intensity, predilection sites of T. spiralis were the masseter muscles, the tongue, and the diaphragm and those of T. pseudospiralis were the masseter muscle and the neck. In low-intensity infections, muscle larvae were detected only in the diaphragm or in pooled muscle samples. For evaluation of the freeze tolerance of the different Trichinella species in sheep-muscle tissue, samples taken from the filet were stored at +5 degrees, -5 degrees, and -18 degrees C, respectively. After exposure for 1 and 4 weeks the tissue was digested and the released larvae were inoculated into mice for determination of the reproductive capacity index (RCI). Larvae of both T. spiralis and T. pseudospiralis survived freezing at -5 degrees and -18 degrees C for 4 weeks.

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