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A total of 88,727 individual BW records of Spanish Merino lambs, obtained from 30,214 animals between 2 and 92 d of age, were analyzed using a random regression model (RRM). These animals were progeny of 546 rams and 15,586 ewes raised in 30 flocks, between 1992 and 2002, with a total of 45,941 animals in the pedigree. The contemporary groups (animals of the same flock, year, and season, with 452 levels), the lambing number (11 levels), the combination sex of lambs with type of litter (4 levels), and a fixed regression coefficient of age on BW were included as fixed effects. A total of 7 RRM were compared, and the best fit was obtained for a model of order 3 for the direct and maternal genetic effects and for the individual permanent environmental effect. For the maternal permanent environmental effect the best model had an order 2. The residual variance was assumed to be heterogeneous with 10 age classes; the covariance between both genetic effects was included. According to the results of the selected RRM, the heritability for both genetic effects ([h.sup.2.sub.a] and [h.sup.2.sub.m]) increased with age, with estimates of 0.123 to 0.186 for [h.sup.2.sub.a] and of 0.059 to 0.108 for [h.sup.2.sub.m] .The correlations between direct and genetic maternal effects were -0.619 to -0.387 during the first 45 d of age and decreased as age increased, until reaching values from -0.366 to -0.275 between 45 to 75 d of age. Important changes in ranking of the animals were found based on the breeding value estimation with the current method and with the random regression procedure. The use of RRM to analyze the genetic trajectory of growth in this population of Merino sheep is highly recommended. Key words: genetic parameter, growth, Merino sheep, random regression model

Monthly test-day records of milk yield and composition in Murciano-Granadina (MG) and Payoya (PYA) dairy goats were combined with weather data from meteorological stations, to analyse the effects of heat stress on dairy traits, measured with an index of temperature and relative humidity (THI). A 'repeatability animal model' and a 'reaction norm animal model' were used to estimate genetic (co)variance components. Estimates obtained with both models were very similar. The h2 of daily yields in MG did not vary throughout the THI scale, but the pattern of variation of content traits showed negative trends for increasing THI values. In PYA, a slight positive tendency throughout the THI scale was observed for the same traits. The genetic correlations between subsequent points in the THI scale were lower than 0.80 when they were computed between low and high THI points. The same reaction norm was observed for all traits. Using the 'reaction norm animal model', it was possible to identify those animals that show the same performance throughout the THI trajectory (robust) and those with varying performances (tolerant and non-tolerant to heat stress). Results in this study also show that heat tolerance decreases, while the genetic level for milk traits increases. Losses because of heat stress were equivalent to 1.9 and 3.1% in the yearly yield of fat and protein for MG and PYA, respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we give an algorithm that detects real singularities, including singularities at infinity, and counts local branches and multiplicities of real rational curves in the affine -space without knowing an implicitization. The main idea behind this is a generalization of the -resultant (see [van den Essen, A., Yu, J.-T., 1997. The -resultant, singularities and the degree of unfaithfulness. Proc. Amer. Math. Soc. 25 (3), 689–695]) to rational functions. This allows us to find all real parameters corresponding to the real singularities between the solutions of a system of polynomials in one variable. [Copyright &y& Elsevier]

Abstract: In the lactating mammary gland, prolactin (PRL) stimulates the synthesis of lactose as well as fatty acid uptake, lipogenesis, and triacylglycerol synthesis. Associations between bovine PRL receptor (PRLR) genotype and fat yield have been reported, which illustrates the role of PRL in conveying lipids toward the udder as well as in stimulating their local synthesis during lactation. Conversely, and to the best of our knowledge, the effects of PRLR genotype on milk fatty acid content have not been studied so far in any mammalian species. In this study, we sequenced most of the coding region of the caprine PRLR gene in several individuals from the Malagueña and Murciano-Granadina breeds. This approach allowed us to identify 2 long and short mRNA isoforms, produced by alternative splicing, and 4 single-nucleotide polymorphisms (SNPs), namely, c.177T>C, c.1131G>A, c.1201G>A and c.1355C>T. Two of these SNPs are nonsynonymous and involve G401R (c.1201G>A) and T452I (c.1355C>T) amino acid substitutions in the cytoplasmic domain of PRLR, which plays a fundamental role in signal transduction. Performance of an association analysis with milk composition traits in a Murciano-Granadina goat population revealed highly suggestive effects on palmitoleic acid content, whereas suggestive effects were detected for other fatty acids, such as palmitic and linoleic. These results are consistent with the pleiotropic effects of PRL on mammary gland lipid metabolism and milk composition. [Copyright &y& Elsevier]

An analysis of the genetic connections among the herds constituting the selection nucleus of the mutton type of Merino sheep in Spain has been carried out in order to improve the reliability of the genetic evaluations. Four climatic variables, registered in weather stations located near the farms, and 16 variables (10 of them related to the production and managing systems and other six related to production traits), registered in 23 farms, were subjected to a discriminant analysis, resulting in seven eigenvectors explaining 78.3% of the variance and four groups (clusters) of farms with similar values for formerly mentioned variables. The relative efficiency of the genetic evaluation models including these clusters of herds in respect to the conventional models including single herd effects was estimated through the analysis of 50,503 weights of lambs at 75 days of age (near weaning) using the method of Criterion of Admission to the Group of Connected Herds ( CACO ), which compares the average coefficients of determinations (CD) of the herds, which is a measure of the degree of connection among herds through common ancestors. Results obtained showed that the values of the contrasts of the CD of the herds were between 2.3% and 14.9% higher (depending on the heritability of the trait) when the model with the clusters was used. When other heritability estimates of weights at other ages were simulated, the increments of these contrasts ranged between 4.1% and 24.9%. These results suggest defining these new clusters grouping herds with similar climatic, managing and production environments is a good alternative to improve the connections and, consequently, may improve the reliability of the estimates of breeding values when connections among herds are poor due to the absence of artificial insemination. [ABSTRACT FROM AUTHOR]

Milk fatty acid (FA) composition is important for the goat dairy industry because of its influence on cheese properties and human health. The aim of the present work was to evaluate the feasibility of NIRS reflectance (oven-dried milk using the DESIR method) and transflectance (liquid milk) analysis to predict milk FA profile and groups of fats in milk samples from individual goats. NIRS analysis of milk samples allowed to estimate FA contents and their ratios and indexes in fat with high precision and accuracy. In general, transflectance analysis gave better or similar results than reflectance mode. Interestingly, NIRS analysis allowed direct prediction of the Atherogenicity and Thrombogenicity indexes, which are useful for the interpretation of the nutritional value of goat milk. Therefore, the calibrations obtained in the present work confirm the viability of NIRS as a fast, reliable and effective analytical method to provide nutritional information of milk samples. [ABSTRACT FROM AUTHOR]

Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. Whereas the endocrine and neural systems are activated in response to the metabolic status and the circulating levels of specific blood metabolites, glutamate receptors have been reported at hepatic level. This study evaluated the possible effect of glutamate supplementation upon changes in serum concentrations across time for total protein (TP), urea (UR) and cholesterol (CL) around the onset of puberty in goats. Prepuberal female goats (n =18) were randomly assigned to: (1) excitatory amino acids group, GLUT, n =10; 16.52±1.04kg live weight (LW), 3.4±0.12 body condition score (BCS) receiving an i.v. infusion of 7mgkg−1 LW of l-glutamate, and (2) Control group, CONT, n =8; 16.1±1.04kg LW, 3.1±0.12 BCS. General averages for LW (23.2±0.72kg), BCS (3.37±0.10 units), serum TP (65.28±2.46mgdL−1), UR (23.42±0.95mgdL−1), CL (77.89±1.10mgdL−1) as well as the serum levels for TP and UR across time did not differ (P >0.05) between treatments. However, while GLUT positively affected (P <0.05) both the onset (207±9 vs. 225±12 d) and the percentage (70 vs. 25%) of females showing puberty, a treatment×time interaction effect (P <0.05) was observed in the GLUT group, with increases in serum cholesterol, coincident with the onset of puberty. Therefore, in peripuberal glutamate supplemented goats, serum cholesterol profile could act as a metabolic modulator for the establishment of puberty, denoting also a potential role of glutamate as modulator of lipid metabolism. [ABSTRACT FROM AUTHOR]