title: Seasonal changes in the technological and compositional quality of ewe's raw milks from commercial flocks under part-time grazing.
abstract: Rennet coagulation parameters, curd texture and gross compositional variables were studied in ewes' raw milk samples from nine commercial flocks using different concentrate:forage ratios and grazing times. From early lactation to March flocks were fed concentrate pellets and hay whereas from April to the end of lactation flocks were allowed to graze from 6 to 19 h/day receiving concentrate supplementation in the morning and evening. Milk from late-lactation flocks, when allowed to graze, showed higher content of fat, dry matter, protein, casein, soluble protein, total calcium, curd firmness and curd resistance to compression than the milk from early lactation flocks. Higher total calcium content and lower fat content were found when the early lactation flocks were fed high concentrate:forage ratio than when the flocks were fed low ratio. Curd firmness were lower for milk from flocks fed high concentrate:forage ratio, and the curd resistance to compression was greater, than for milk from flocks fed low ratio. At late lactation, when flocks grazed for a long time per day the total calcium content was higher than when the flocks grazed for a short time per day. Principal component analysis showed that protein and fat content were highly correlated with coagulum and curd firmness, whereas total calcium content was highly correlated with curd resistance to compression, and milk pH with rennet coagulation time.
authors.affiliation: Tecnología de Alimentos, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Paseo de la Universidad 7, Vitoria-Gasteiz 01006, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Nájera
authors.forename: Luis J R
authors.initials: LJ
authors.lastname: Barron
authors.forename: Patricia
authors.initials: P
authors.lastname: Ribeiro
authors.forename: Fanny
authors.initials: F
authors.lastname: Pèlissier
authors.forename: Eunate
authors.initials: E
authors.lastname: Abilleira
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Pérez-Elortondo
authors.forename: Marta
authors.initials: M
authors.lastname: Albisu
authors.forename: Jesús
authors.initials: J
authors.lastname: Salmerón
authors.forename: Juan C
authors.initials: JC
authors.lastname: Ruiz de Gordoa
authors.forename: Mailo
authors.initials: M
authors.lastname: Virto
authors.forename: Luis
authors.initials: L
authors.lastname: Oregi
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruiz
authors.forename: Mertxe
authors.initials: M
authors.lastname: de Renobales
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002364:Caseins / Q000032:analysis; D012085:Chymosin / Q000008:administration & dosage / Q000378:metabolism; D004032:Diet; D005223:Fats / Q000032:analysis; D005260:Female; D005524:Food Technology; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis; D012621:Seasons; D012756:Sheep
chemical_list: D002364:Caseins; D005223:Fats; D008894:Milk Proteins; C025350:rennet; D012085:Chymosin; D002118:Calcium