Breeding strategies for the Italian Jersey

Jersey dairy cows were introduced in Italy in the early 1980’s, and in 1991 the Italian Jersey Herd book was established. During the last decade the number of registered cows has doubled and nowadays there are more than 5000 registered cows from 488 herds. Most herds have Jersey and Holstein cows even if some “only-jersey” herds do exist. Nevertheless, the Italian Jersey population is, from a genetic point of view, the result of independent breeders’ decisions with regard to importation rather than the result of a national selection program with genetic goals clearly defined. As a result of the growing interest of the breeders, national genetic breeding value estimation......

Impact of areas and sire by herd interaction on heritability estimates for somatic cell count in Italian Holstein Friesian cows

The aim of the paper was to estimate variance components for somatic cell scores for Italian Holsteins using data from three different areas of the country. A total of 2,202,804 first-parity test-day records, collected from 1990 to 1997 in three areas of Italy (Mantova, Milano, and Parmigiano cheese area), were available for study. The areas differ in herd size, feeding systems and especially in milk use. A minimum standard of quality is also required by some specific methods of cheese production, as for example from the Parmigiano Reggiano cheese chain. These reasons, taken together, affect the attention given to the quality of milk production in herds, and, therefore, to the sanitation levels. A pedigree file was extracted from the national database of Holstein Friesian breed. For computational reasons, eight samples of the data were extracted per area. Variance components were estimated by sample using two different test-day repeatability models. The first model included fixed effects of herd-test date, days in milk (30-d intervals) and calving month, and random effects of permanent environment, additive genetic and residual error. Estimated heritabilities in the first model ranged from 0.06 to 0.09 and repeatabilities from 0.36 to 0.45. Only small differences were detected among areas. In the second model, a random sire x herd interaction effect was added. Including the sire x herd effect resulted in heritability estimates ranging between 0.05 and 0.08 and repeatabilities from 0.35 to 0.45. The analysis revealed that only a small fraction of the total variance (0.35 to 1.5€could be explained by sire x herd interaction effect. Based on this research, it appears that parameter estimates for somatic cell count do not differ by region, and inclusion of a sire x herd interaction effect is unnecessary

Relationship between somatic cell count and functional longevity assessed using survival analysis in Italian Holstein-Friesian cows

The relationship between somatic cell scores (SCS) and longevity was assessed for Italian Holstein–Friesian dairy cows using survival analysis. The data of somatic cell count (SCC) test day information of 512 979 cows were provided by nine provinces from Northern Italy. Pedigree information was extracted from the national herd book. Two survival models were run: a model similar to the one used for genetic evaluation on length of productive life, and a second one adding the phenotypic level of ten classes of test-day SCS of the cow. A cow with a test-day in the highest class of phenotypic level for SCS had more than three times greater risk of being culled when compared to risk for the class with the lowest SCS level. The genetic correlation between the risk of being culled and SCS was estimated to be 0.31, based on the correlation between sire EBV. The rank of bulls resulting from the genetic evaluation on survival did not change significantly with the inclusion of SCS in the model (rank correlation of 0.98). It is concluded that the phenotypic level of SCS plays an important role in culling decision of farmers of Italian Holstein–Friesian dairy cows and SCS is genetically associated to the functional longevity of cows

Parametros geneticos de las caracteristicas morfologicas de ganado Carora

Sixteen (16) morphological traits from 3867 Carora cows in Venezuela were studied. Genetic parameters were analyzed using a multiple trait animal model. Fixed effects of herd- year of evaluation interaction, month evaluation, age, stage of lactation classifier, within herd were considered, genetic parameters were obtained from REML estimates of covariance components. The highest heritability was found for stature (0.47) and for body depth (0.27), whereas the lowest values were found for foot angle (0.03). Udder traits showed low heritability estimates ranging from 0.06 for rear with to 0.13 for de udder balance. Higher estimations were found for tea placement side (0.16) and teat length (0.26). Genetic correlations among stature, body depth, strength and rump width were high and ranged from 0.76 to 0.86. Fore udder attachment was positively associated with rear udder height (0.46), udder depth (0.53), teat placement (0.17) and length (0.18) while a negative correlations with udder balance (-.028). Negative estimates genetic correlations were found between rump angle (-0.45), rear-legs rear view (-0.50), udder balance (-0.68), udder support (-0.32) y la angularity. Angularity was positively associated with rear udder height 0.62. Small correlations were estimated between foot angle and most traits. Negative genetic correlations between body development and udder traits suggested that selection to increase body size could not improve the udder conformation. Selection should be oriented towards animals of medium size dairy characteristics