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The aim of this study was to determine the presence of major genes for fiber diameter (FD), SD of FD (SDFD), CV of FD, and comfort factor (CF) in Huacaya (HU) and Suri (SU) Peruvian alpaca breeds. Bayesian segregation analyses with relaxed transmission probabilities were performed using 1,906 and 6,592 available records for SU and HU breeds. Evidence for the presence of major genes was statistically supported when the 95% posterior density did not include zero. Significant major genes were found associated with decreased FD, SDFD, CV values, and increased CF values. Additive effects of the major genes were 4.18 and 4.23 [micro]m for FD, 1.67 and 1.61 [micro]m for SDFD, 3.32 and 3.76% for CV, and 15.03 and 14.90% for CF in HU and SU breeds, respectively. Dominance effects were -1.98 and -2.03 [micro]m for FD, -0.88 and -1.11 [micro]m for SDFD, -1.37 and -2.17% for CV, and 13.0 and 11.8% for CF in HU and SU breeds, respectively. Major gene variance was larger than the polygenic variance for all traits. Major gene allelic frequencies for FD, SDFD, and CV ranged from 0.81 to 0.86 for HU breed and from 0.70 to 0.77 for the SU breed and were 0.24 and 0.36, respectively, for CF. It can be concluded that a major gene affecting these traits could be segregating. Then, molecular identification and monitoring of animals carrying favorable genes throughout the worldwide alpaca population would allow for a quick genetic improvement. Key words: alpaca, fiber, major gene, mixed-inheritance model, segregation analysis doi: 10.2527/jas.2010-2865

The aim of this paper was to estimate the genetic relationships among calving ease (CE), calf survival (CS), and gestation length (GL) to assess the possibility of including this information in beef cattle breeding programs. A total of 35,395 field records were available for CE, 30,684 for GL, and 36,132 for CS from the Asturiana de los Valles beef cattle breed. The 3 traits were analyzed as traits of the calf fitting a multivariate linear mixed model. Estimates of heritability ([+ or -] SE) for the direct genetic effects (CEd, GLd, and CSd) were 0.325 [+ or -] 0.022, 0.331 [+ or -] 0.026, and 0.226 [+ or -] 0.018, respectively, whereas the estimates for maternal genetic effects (CEm, GLm, and CSm) were 0.066 [+ or -] 0.018, 0.066 [+ or -] 0.017, and 0.034 [+ or -] 0.011. The estimates for the ratio of permanent environmental variance to phenotypic variance were CEc 0.090 [+ or -] 0.011, GLc 0.066 [+ or -] 0.011, and CSc 0.024 [+ or -] 0.007. Genetic correlations between direct, maternal genetic, or permanent environmental effects involving CE and GL were, in general, positive and moderate, whereas those involving CE and CS were high. All were significant except for the pair CEm-GLm (0.277 [+ or -] 0.172). Correlations between GL and CS were nonsignificant. Genetic correlations for CEd-CEm, GLd-GLm, and CSd-CSm were negative and high, ranging from -0.461 [+ or -] 0.120 for GLd-GLm to -0.821 [+ or -] 0.145 for CSd-CSm. The genetic correlations for CEd-CSm and for CSd-CEm were negative, significant, and high, whereas that for GLd-CEm was moderate (-0.323 [+ or -] 0.124) and that for GLd-CSm was nonsignificant. The genetic correlations for GLm with the direct effects of the other traits were non-significant. Strong selection for CE will result in a significant correlated response in CS. Therefore, CE can be considered an early indicator of CS performance. The benefit of using GL as a correlated trait in a genetic evaluation with CE and CS seems limited. Key words: beef cattle, calf survival, calving ease, genetic correlation, genetic parameter, gestation length doi: 10.2527/jas.2009-2066

The mating policy for Spanish Purebred horses encourages the same or closely related stallions to be used for reproduction across studs differing in environments. Stallions may perform differently across studs, and if so, adjustment for the sire x stud (ss) interaction is recommended. However, there are no studies available that analyzed the influence of ss interaction on estimation of genetic parameters in horses. This research is aimed at assessing the implications of including ss interaction in models fitted for the estimation of genetic parameters for traits under selection using 8 body measurements in Spanish Purebred (Andalusian) horses: height at withers, height at chest, leg length, body length, width of chest, heart girth circumference, knee perimeter, and cannon bone circumference. Body measurements were available for 11,894 horses. Genetic parameters and EBV were estimated using animal models by REML. The inclusion of the ss interaction gives reduced estimates of heritability. Generally, the genetic correlations estimated using the models including the ss interaction were greater than those obtained using the simpler model. Estimates for the ss variance as a proportion of the total phenotypic variance ranged from 0.02 (height at withers) to 0.11 (width of chest). Estimates between the ss interaction correlations associated with each body measurement were positive, significant, and from moderate to low. The range of EBV estimated using the model including the ss interaction decreased with respect to those estimated using the simpler model, and the EBV ranking order was affected. The models including ss interaction fitted significantly better. Therefore, the genetic parameters estimated using the ss interaction may be more realistic, and the obtained (co)variances may be assumed to be closer to the true population parameters. This interaction may result from selective decisions or preferential management practices causing greater similarity between the progeny of a sire in the same stud. It is therefore advisable to include it in genetic models used in horse breeding schemes. Key words: genetic parameter, genotype x environment interaction, horse breeding, zoometry

The aim of this note is to describe a reliable, fast, and cost-effective real-time PCR method for routine genotyping of mutations responsible for most coat color variation in horses. The melanocortin1 receptor, Agouti-signaling peptide, and membrane-associated transporter protein alleles were simultaneously determined using 2 PCR protocols. The assay described here is an alternative method for routine genotyping of a defined number of polymorphisms. Allelic variants are detected in real time and no post-PCR manipulations are required, therefore limiting costs and possible carryover contamination. Data can be copied to a Microsoft Excel spreadsheet for semiautomatic determination of the genotype using a macro freely available at http://www.igijon.com/personales/fgoyache/software_i.htm (last accessed February 26, 2007). The performance of the method is demonstrated on 156 Spanish Purebred horses. Key words: horse, real-time polymerase chain reaction, coat color, melanocortin-1 receptor, Agouti-signaling peptide, membrane-associated transporter protein

The aim of this paper was to estimate direct and maternal genetic parameters for calving ease (CE), birth weight (BrW), weaning weight (WW), and calving interval (CI) to assess the possibility of including this information in beef cattle improvement programs. Field data, including a total of 59,813 animals (1,390 sires and 1,147 maternal grand sires) from the Asturiana de los Valles beef cattle breed, were analyzed with a multivariate linear model. Estimates of heritability for direct genetic effects (CED, CID, BrWD, and WWD) were 0.191 [+ or -] 0.019, 0.121 [+ or -] 0.013, 0.390 [+ or -] 0.030, and 0.453 [+ or -] 0.035, respectively, whereas those for maternal genetic effects (CEM, BrWM, and WWM) were 0.140 [+ or -] 0.015, 0.208 [+ or -] 0.020, and 0.138 [+ or -] 0.022, respectively. Genetic correlations between direct or maternal genetic effects across traits were, in general, positive and moderate to low. However, genetic correlation for the pair CED-BrWD was positive and high (0.604 [+ or -] 0.064). Genetic correlations between the direct and maternal genetic effects within a trait were negative and moderate (-0.219 [+ or -] 0.097 for CE, -0.337 [+ or -] 0.080 for BrW, and -0.440 [+ or -] 0.102 for WW). Genetic correlations for CED-BrWM and CED-WWM were -0.121 [+ or -] 0.090 and -0.097 [+ or -] 0.113, respectively. The genetic correlation for CEM-CID was unfavorable (0.485 [+ or -] 0.078), and those for CEM-BrWD (-0.094 + 0.079) and CEM-WWD (-0.125 [+ or -] 0.082) were low and negative. The genetic correlation between CID and WWM was favorable (-0.148 + 0.106). Overall, the data presented here support the hypothesis that maternal effects for CE and BrW are not the same and that the genetic relationships between CI and maternal effects for WW in beef cattle follow a similar pattern to that reported between CI and milk yield in dairy cattle. Moreover, the need to include direct and maternal breeding values in beef cattle selection programs is suggested. Key words: calving ease, cattle, genetic correlation, genetic parameter, maternal effect

Recent studies have proposed the use of molecular coancestry coefficients as a measure of genetic variability and as a useful tool for conservation purposes. Using simulated data, molecular coancestry has been shown to become constant very quickly after separation of populations, leading to population diversity remaining constant. However, the use of molecular coancestry information to study the genetic relationships between breeds has not yet been widely explored. Here we analyze the polymorphism of 14 microsatellites in 222 unrelated individuals belonging to seven native Spanish breeds to ascertain the usefulness of molecular coancestry-based methodologies in providing information on their genetic relationships. Average kinship distance ([D.sub.k]) and average molecular coancestry coefficients ([f.sub.ij]) were compared with well-known genetic distances, such as between-breed Reynolds' distance ([D.sub.R]), Nei's standard distance ([D.sub.s]), and shared allele distance ([D.sub.AS]). Kinship distance and [f.sub.ij] have moderate to low correlations with the other genetic distances, showing that they provide different information: both [D.sub.k] and [f.sub.ij] account for the allele frequencies in the founder population, whereas [D.sub.R], [D.sub.s], and [D.sub.AS] characterize the short-term evolution of the populations. Furthermore, [D.sub.k] and [f.sub.ij] were only moderately correlated (-0.500). The present study used field data to confirm previous research pointing out the ability of molecular coancestry coefficients to assess genetic differentiation of an ancestral origin. In this respect, molecular coancestry-based parameters may be used with classical genetic parameters to obtain information on population dynamics in livestock breeds. This study additionally presents reliable evidence on the history of these sheep breeds. Key Words: Genetic Distance, Microsatellite, Molecular Kinship, Sheep Breeds

Although many research papers have studied diversity and differentiation within livestock species, genetic relationships among neighboring populations remain poorly understood. Here we apply recent methodologies to analyze the polymorphism of 14 microsatellites in 238 unrelated individuals belonging to six sheep breeds from Northern Spain to ascertain their historical relationships and the relative genetic contributions existing between populations. Individual genetypes were analyzed to assess the existence of an underlying genetic structure. Long-term and recent migration rates were estimated to identify patterns of relative genetic contribution among breeds. The complete data set showed a strong population structure derived from both different ancestral origins and some geographical patterns of recent gene flow. Two of the analyzed breeds (Black-faced Latxa and Churra) had a marked genetic background, supporting the hypothesis that, regardless of their phenotypical similarities, they have different ancestral origins. Some of the more presumably related breeds had negative long-term admixture coefficients, showing that they diverged only recently. In addition, we show how methodologies for estimation of long-term gene flow and recent patterns of migration are complementary, providing information about migration rates on different timescales. Key Words: Admixture, Microsatellite, Migration Rate, Population Structure, Sheep