Browsing by Subject "Herd effects"

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    Quantitativ-genetische und genomische Analysen zu den Merkmalen perinataler Saugreflex und Trinkverhalten bei Kälbern der Rasse Braunvieh
    (2020) Dreher, Clarissa Susanne; Bennewitz, Jörn
    A healthy sucking behavior is important for newborn calves to ensure sufficient colostrum intake in the first few hours postpartum. This is essential for the passive immunization of newborn calves and provides the foundation for raising vital and well developed animals. Insufficient colostrum intake not only results in developmental disorders and increased susceptibility to certain diseases, but also inherits the risk of increased postnatal mortality. Therefore, an insufficient colostrum intake is an animal welfare problem and it also leads to economic losses for the farmers. Brown Swiss breeders are more likely to experience the problem of non-sucking calves (incidence: 10%) than is apparent in other breeds. Studies in the Italian Brown Swiss population have already identified a genetic component with mid-range heritabilities for erroneous perinatal sucking behavior. This indicates that the trait sucking behavior is partly influenced by the genes of the animals and thus breeding for this trait might lead to a selection response. Therefore, the characterization of the genetic background of perinatal sucking reflex and sucking behavior in neonatal calves in the Brown Swiss population was carried out in this work. For this purpose, data were collected on more than 220 dairy cattle farms located in Baden-Württemberg. In addition to an evaluation of the husbandry and feeding management of the farms, the phenotype data of more than 10,000 calves were collected to carry out pedigree-based genetic analyzes using univariate and multivariate sire threshold models. In addition, the collection of tissue samples from over 3,000 calves was carried out for the performance of genomic analyzes. Using high-density marker maps, genome-wide association mapping was performed using both single-marker models and Bayesian multi-marker models. Tissue samples of approximately 900 mothers were also collected and their 50K-genotypes were analyzed. Based on the maternal marker genotypes, maternal genetic effects on an erroneous sucking reflex of the calves were investigated. Low heritabilities for the traits sucking behavior and sucking reflex could be determined. These ranged from 0.06 to 0.23, depending on the trait, the trait coding used and the models used. The heritability estimates for sucking behavior were slightly higher in the univariate model as well as in the multivariate model than for sucking reflex. The GWAS results clearly showed a quantitative-genetic background of both traits. From these findings, it can be deduced for practical breeding strategies that improving the problem by means of genetic tests, as is the case, for example, with monogenic hereditary diseases, would not be expedient. Instead, breeding progress through the use of genomic selection is recommended. A constant trait recording is required for this purpose. The sucking behavior of the calves should be recorded within the first 12 hours postpartum. The results of gene annotation using GO terms and pathway analysis revealed the overrepresentation of genes with functions in the development of the central nervous system, neurogenesis, and signal transduction. In order to effectively estimate maternal genetic effects on calf sucking weakness, both the marker density of 50K was too low and the data set too small. A highly significant farm effect on the investigated traits was found. However, the evaluations carried out with regard to specific influences of the housing and feeding environments on farms did not show any significant differences.