Effect of bull selection for somatic cell count in first lactation on cell counts and pathogens in later lactations
| Autor: | R.D. Politiek, G.E. Shook, W.J. Koops, U. Vecht, G. Grootenhuis, D.G. Groothuis |
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| Rok vydání: | 1985 |
| Předmět: |
Male
medicine.medical_specialty media_common.quotation_subject Cell Count Biology Animal Breeding and Genomics Genetic correlation Animal science Pregnancy Internal medicine Lactation Genetics medicine Life Science Animals Fokkerij en Genomica Selection Genetic Mastitis Bovine Selection (genetic algorithm) media_common Daughter Heritability medicine.disease Mastitis medicine.anatomical_structure Endocrinology Animal Science and Zoology Cattle Female Somatic cell count Food Science |
| Zdroj: | Journal of Dairy Science 68 (1985) Journal of Dairy Science, 68, 2995-3003 |
| ISSN: | 0022-0302 |
| Popis: | Somatic cell counts were measured one time on Meuse-Rhine-Ijssel cattle in The Netherlands. Experiment 1 involved 1,741 first lactation daughters of 31 bulls. Eleven bulls with daughters with either high or low average cell count were selected for further study of their daughters in third and fourth lactation. Cell counts and bacteriological tests were performed on 684 of the older daughters. A second experiment was conducted to measure daughters in second lactation and to obtain additional daughters in first lactation. This experiment recorded cell counts of 1,071 daughters of 10 of the bulls selected in Experiment 1. Heritability of the natural logarithm of cell count in first lactation was .081 based on daughters of 31 bulls in Experiment 1. Geometric daughter averages ranged from 206 to 700×10 3 cells/ml. Transmitting ability of bulls was estimated by the regressed least squares method. Ranking of bulls on first lactation cell count was different between the two experiments. Management factors and stage of lactation effects could be responsible for these differences. Within Experiment 2, the ranking of bulls on cell counts was nearly identical between first and second lactation. Daughter groups with low average cell count in first lactation in Experiment 2 had low averages in third and fourth lactation although some changes in ranking did occur. These results are consistent with a low to moderate genetic correlation between lactations for cell count. In general, daughter groups with higher average cell count had higher percentage of quarters with mastitis pathogens. |
| Databáze: | OpenAIRE |
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