Γενετική μελέτη της μαστίτιδας στα γαλακτοπαραγωγά πρόβατα ; Genetic study of mastitis in dairy ewes
Aristotle University Of Thessaloniki (AUTH) ; Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης (ΑΠΘ), 2015
Online
Hochschulschrift
Zugriff:
The overall objectives of this study was to investigate the relationship between mastitis and milk production, to estimate genetic parameters of mastitis related traits and validate the effects of previously discovered SNP on these traits in of Greek Chios dairy sheep population. The study was carried out in four commercial farms of purebred Chios dairy ewes. A total of 609 ewes in 1st or 2nd lactation were used. Milk samples from individual ewes were collected in monthly intervals for the first five months of lactation. Each sample was subjected to cytological examination using California mastitis test (CMT). Tests were also performed in the laboratory to assess somatic cell count (SCC) and total viable bacterial count (TVC). Ewes having milk with SCC≥ 500,000/ml and CMT score ≥2 were subjected to bacteriological examination. All animals were genotyped with a customized 960 SNP DNA. All data analyses were performed using SPSS 20©. The results showed that 638/2436 samples (26.1%) were considered positive for subclinical mastitis, but the microbiological tests confirmed only 349 samples (72.55%). Coagulase negative staphylococci (66.2%), Staphylococcus aureus (22.6%) and Streptococcus spp. (7.7%) were the prevalent bacteria. Mastitis had an adverse effect on daily milk yield. The negative effect of mastitis on milk production was justified (about 66ml/ewe/day). The second stage of our research was about genetic parameters and genomic markers associated with mastitis resistance. Each trait (MY, SCC, CM, CMT and TVC) was analyzed separately with a univariate random regression model. The ASREML software was used for statistical analyses. Individual monthly records were adjusted for the fixed effects of flock, year-season of lambing, lactation number, age at lambing and week of lactation. Residuals and de-regressed estimates of the animal effects were used as phenotypes in genome wide association studies (GWAS). The software GEMMA was used to run the GWAS analyses based on a mixed model that included the genomic ...
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Γενετική μελέτη της μαστίτιδας στα γαλακτοπαραγωγά πρόβατα ; Genetic study of mastitis in dairy ewes
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Autor/in / Beteiligte Person: | Bramis, Georgios ; Μπράμης, Γεώργιος |
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Veröffentlichung: | Aristotle University Of Thessaloniki (AUTH) ; Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης (ΑΠΘ), 2015 |
Medientyp: | Hochschulschrift |
DOI: | 10.12681/eadd/40113 |
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