title: Genetic parameters for rennet- and acid-induced coagulation properties in milk from Swedish Red dairy cows.
abstract: Milk coagulation is an important processing trait, being the basis for production of both cheese and fermented products. There is interest in including technological properties of these products in the breeding goal for dairy cattle. The aim of the present study was therefore to estimate genetic parameters for milk coagulation properties, including both rennet- and acid-induced coagulation, in Swedish Red dairy cattle using genomic relationships. Morning milk samples and blood samples were collected from 395 Swedish Red cows that were selected to be as genetically unrelated as possible. Using a rheometer, milk samples were analyzed for rennet- and acid-induced coagulation properties, including gel strength (G'), coagulation time, and yield stress (YS). In addition to the technological traits, milk composition was analyzed. A binary trait was created to reflect that milk samples that had not coagulated 40min after rennet addition were considered noncoagulating milk. The cows were genotyped by using the Illumina BovineHD BeadChip (Illumina Inc., San Diego, CA). Almost 600,000 markers remained after quality control and were used to construct a matrix of genomic relationships among the cows. Multivariate models including fixed effects of herd, lactation stage, and parity were fitted using the ASReml software to obtain estimates of heritabilities and genetic and phenotypic correlations. Heritability estimates (h(2)) for G' and YS in rennet and acid gels were found to be high (h(2)=0.38-0.62) and the genetic correlations between rennet-induced and acid-induced coagulation properties were weak but favorable, with the exception of YSrennet with G'acid and YSacid, both of which were strong. The high heritability (h(2)=0.45) for milk coagulating ability expressed as a binary trait suggests that noncoagulation could be eliminated through breeding. Additionally, the results indicated that the current breeding objective could increase the frequency of noncoagulating milk and lead to deterioration of acid-induced coagulation through unfavorable genetic associations with protein content (0.38) and milk yield (-0.61 to -0.71), respectively. The outcome of this study suggests that by including more detailed compositional traits genetically associated with milk coagulation or by including milk coagulation properties directly within the breeding goal, it appears possible to breed cows that produce milk better suited for production of cheese and fermented products.
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, PO Box 124, SE-221 00 Lund, Sweden. Electronic address: frida.gustavsson@food.lth.se.
authors.forename: F
authors.initials: F
authors.lastname: Gustavsson
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, PO Box 124, SE-221 00 Lund, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Glantz
authors.affiliation: Department of Food Science, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, PO Box 50, DK-8830 Tjele, Denmark.
authors.forename: N A
authors.initials: NA
authors.lastname: Poulsen
authors.affiliation: Department of Building Materials, Lund University, PO Box 118, SE-221 00 Lund, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Wadsö
authors.affiliation: VikingGenetics, PO Box 64, SE-532 21 Skara, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Stålhammar
authors.affiliation: Department of Food Science, BioCenter, Swedish University of Agricultural Sciences, PO Box 7051, SE-750 07 Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Andrén
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, PO Box 124, SE-221 00 Lund, Sweden; LRF Dairy Sweden, Ideon Science Park, SE-223 70 Lund, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Lindmark Månsson
authors.affiliation: Department of Food Science, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, PO Box 50, DK-8830 Tjele, Denmark.
authors.forename: L B
authors.initials: LB
authors.lastname: Larsen
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, PO Box 124, SE-221 00 Lund, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Paulsson
authors.affiliation: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, SE-750 07 Uppsala, Sweden.
authors.forename: W F
authors.initials: WF
authors.lastname: Fikse
mesh_terms: D000818:Animals; D001947:Breeding; D002364:Caseins / Q000235:genetics; D002417:Cattle / Q000235:genetics* / Q000502:physiology; D012085:Chymosin / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005838:Genotype; D007774:Lactation / Q000235:genetics; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D010298:Parity; D010641:Phenotype; D011247:Pregnancy; D013548:Sweden
chemical_list: D002364:Caseins; C025350:rennet; D012085:Chymosin
keywords: genetic correlation; heritability; milk coagulation; noncoagulating milk