Genetic and environmental factors affecting some reproductive traits of Holstein cows in Cuba

International audienc

Random regression model of growth during the first three months of age in Spanish Merino sheep

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 (ha2 and hm2) increased with age, with estimates of 0.123 to 0.186 for ha2 and of 0.059 to 0.108 for hm2. 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

The importance of genotype x environment interaction for selection and breeding programmes in tropical conditions.

International audienc

GM 24. Creole cattle of Guadeloupe performance - Analysis of fifteen years of work

In order to analyse the animal production of the Creole cattle of Guadeloupe, a general review of the data collected in an experimental station was conducted. The cows used pastures of natural savannas or irrigated and fertilized pangola grass. The reproduction was conducted by natural mating during 60 days, at two seasons. After weaning at 205 days, young males and heifers were fed in different fattening systems or on pastures. Different linear model analysis were performed, according to the data collected. The Creole cows exhibit a high fertility (82.6 %), slightly influenced by their body condition score. They show also a good lifetime production, with a mean of 5 calvings. All the factors had highly significant effects on growth before weaning, with coefficients of determination varying between 36.5 % and 60.1 %. The higher production is obtained with cows at their sixth calving, with weaning weight and growth rate to weaning 13 % higher than the first calving (153.8 kg and 612 g/d). After weaning, males maintained on pastures reached 317 kg at 18 month, with an average daily gain of 503g/d. Heifers, in different conditions, weighted 243 kg at 20 months. These results suggest the interest of this local breed, for its adaptation to tropical conditions

Variabilidad genética para variables maternas en la raza vacuna Asturiana de la Montaña

Genetic variability parameters of traits related to maternal ability (age at first calving–CA1, first calving interval– CI1, and weaning weight–WW) were estimated in an autochthonous beef cattle breed (Asturiana de la Montaña) reared under harsh conditions. The data set comprised 50,749 births on 378 farms from 1994 to 2008. Heritability for CA1 was moderately high (0.22); heritability for CI1 was 0.10. Genetic correlation between these traits was 0.54, and thus favourable to simultaneously selection. Results for WW gave a direct heritability of 0.20 and a maternal heritability of 0.10; the genetic correlation between additive direct effects and additive maternal effects was –0.60 and thus antagonistic, a situation frequently found in similar populations. The change of additive direct values (BVa) for the lapse considered was almost null until 1997, and increased regularly since that year at 0.092 kg yr–1. It should be noted that, at the same time, additive maternal effects (BVm) showed a significant negative tendency of –0.089 kg yr–1. In order to conveniently combine the knowledge on both genetic effects, taking into account the adverse genetic correlation between them, we propose that selection should be based on a global genetic merit index (BVtm) defined as 1⁄2 BVa + BVm. Correlations between BVa and BVtm, and between BVm and BVtm were 0.22 and 0.56, respectively.Se estimaron parámetros de variabilidad genética para variables relacionadas con el carácter materno (edad al primer parto–CA1, primer intervalo entre partos–CI1, y peso al destete–WW) en una raza autóctona de ganado vacuno de aptitud cárnica (Asturiana de la Montaña) que se explota bajo condiciones climáticas duras. Los datos comprendían 50.749 nacimientos en 378 explotaciones entre 1994 y 2008. La heredabilidad estimada para CA1 resultó moderadamente elevada (0,22); para CI1 la heredabilidad fue de 0,10. La correlación genética entre ambos caracteres fue de 0,54, y por tanto favorable para la selección simultánea. Para la variable WW, la heredabilidad directa fue de 0,20 y la maternal de 0,10; la correlación genética entre efectos aditivos directos y maternos fue de –0,60 y por tanto antagónicos, situación descrita con frecuencia en poblaciones similares. El cambio en los valores aditivos directos (BVa) durante el periodo de estudio fue prácticamente nulo hasta 1997, y desde entonces se incrementó progresivamente en 0,092 kg año–1. En el mismo intervalo, los efectos aditivos maternos (BVm) mostraron una tendencia significativamente negativa de –0,089 kg año–1. Para combinar adecuadamente la información sobre ambos valores genéticos, tomando en consideración la correlación adversa entre ellos, se propone que la selección debería basarse en un índice de mérito genético global (BVtm) definido como 1⁄2 BVa + BVm. Las correlaciones entre BVa y BVtm, entre BVm y BVtm fueron de 0,22 y 0,56, respectivamente

Comparative Study to Estimate Weights at Typical Preweaning Ages of Creole Meat-Type Goats

A model, in which weight and growth performances of suckling ruminants are recorded, is necessary when setting up a breeding program. In France, such a model was developed for sheep, but not for suckling goats. In this study, the standard methodology used for meat-type sheep was applied to the robust Creole goats of French Antilles. Growth data up to weaning of 6211 kids were used; the data had been recorded for nearly 20 years at the experimental farm of Gardel in Guadeloupe. Various methods for weight estimation were tested at the typical ages of 10, 30 and 70 days and compared to the standard method developed for suckling lambs in France. Finally, the variability of growth performances was specified and the first elements to test Creole goat growth were determined. Conditions and limitations of the models applied to Creole goats are discussed