title: Assessment of genetic variation for pathogen-specific mastitis resistance in Valle del Belice dairy sheep.
abstract: BACKGROUND
  Mastitis resistance is a complex and multifactorial trait, and its expression depends on both genetic and environmental factors, including infection pressure. The objective of this research was to determine the genetic basis of mastitis resistance to specific pathogens using a repeatability threshold probit animal model.
  
  
  RESULTS
  The most prevalent isolated pathogens were coagulase-negative staphylococci (CNS); 39 % of records and 77 % of the animals infected at least one time in the whole period of study. There was significant genetic variation only for Streptococci (STR). In addition, there was a positive genetic correlation between STR and all pathogens together (ALL) (0.36 ± 0.22), and CNS and ALL (0.92 ± 0.04).
  
  
  CONCLUSIONS
  The results of our study support the presence of significant genetic variation for mastitis caused by Streptococci and suggest the importance of discriminating between different pathogens causing mastitis due to the fact that they most likely influence different genetic traits. Low heritabilities for pathogen specific-mastitis resistance may be considered when including bacteriological status as a measure of mastitis presence to implement breeding strategies for improving udder health in dairy ewes.
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università degli Studi di Palermo, Viale delle Scienze, Palermo, 90128, Italy. marco.tolone@unipa.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Tolone
authors.affiliation: Faculty of Veterinary and Animal Sciences, University of Chile, Av. Santa Rosa, La Pintana, Santiago, 11735, Chile.
authors.forename: Cristian
authors.initials: C
authors.lastname: Larrondo
authors.affiliation: Faculty of Veterinary and Animal Sciences, University of Chile, Av. Santa Rosa, La Pintana, Santiago, 11735, Chile.
authors.forename: José M
authors.initials: JM
authors.lastname: Yáñez
authors.affiliation: Genus plc, Hendersonville, TN, 37075, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Newman
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università degli Studi di Palermo, Viale delle Scienze, Palermo, 90128, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Sardina
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università degli Studi di Palermo, Viale delle Scienze, Palermo, 90128, Italy.
authors.forename: Baldassare
authors.initials: B
authors.lastname: Portolano
mesh_terms: D000818:Animals; D001947:Breeding; D003612:Dairying; D060467:Disease Resistance / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D008413:Mastitis / Q000235:genetics / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000235:genetics* / Q000382:microbiology* / Q000517:prevention & control; D013290:Streptococcal Infections / Q000235:genetics / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D013291:Streptococcus / Q000235:genetics / Q000302:isolation & purification
keywords: Ewes; Mastitis; Pathogen; Resistance