title: Milk traits of lactating cows submitted to feed restriction.
abstract: Data from five experiments with dairy cows where feed was restricted to 0, 40, and 50% of the ad libitum amount, with 259 observations, were subjected to multivariate analyses to determine the effects of severity and duration of feed restriction on production, physical-chemical characteristics, ethanol stability, and somatic cell score of milk. A negative relationship was seen between the severity and duration of feed restriction with milk production, lactose content, titratable acidity, and milk stability to the ethanol test. The milk stability to the ethanol test, protein content, milk yield, and somatic cells score were the most important attributes retained by the discriminant analysis. Milk stability to the ethanol test, live weight, days in restriction, and pH were the most important characteristics explaining the variance within the different levels of feed restriction. Milk production and ethanol stability were significantly lower in both levels of feed restriction compared with the group fed ad libitum. When feed restriction was followed by refeeding, the difference observed in ethanol stability was the first discriminant variable, followed by the difference in unstable milk frequency and titratable acidity. Increments in the severity and duration of feed restriction negatively affect milk production and milk ethanol stability.
authors.affiliation: Department of Animal Science, Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Alexandre Mossate
authors.initials: AM
authors.lastname: Gabbi
authors.affiliation: Faculdade de Agronomia e Medicina Veterinária, Universidade de Brasília, Brasília, DF, Brazil.
authors.forename: Concepta Margareth
authors.initials: CM
authors.lastname: McManus
authors.affiliation: Centro Nacional de Pesquisa de Clima Temperado, Embrapa, Pelotas, RS, Brazil.
authors.forename: Maira Balbinotti
authors.initials: MB
authors.lastname: Zanela
authors.affiliation: Instituto de Ciências Biológicas, Universidade de Rio Grande, São Lourenço do Sul, RS, Brazil.
authors.forename: Marcelo Tempel
authors.initials: MT
authors.lastname: Stumpf
authors.affiliation: Embrapa Semiárido, Petrolina, PE, Brazil.
authors.forename: Rosângela Silveira
authors.initials: RS
authors.lastname: Barbosa
authors.affiliation: Empresa de Assistência Técnica e Extensão Rural, EMATER, Erechim, RS, Brazil.
authors.forename: Vilmar
authors.initials: V
authors.lastname: Fruscalso
authors.affiliation: Centro de Ciências Agroveterinárias, Universidade do Estado de Santa Catarina, Lages, SC, Brazil.
authors.forename: André
authors.initials: A
authors.lastname: Thaler Neto
authors.affiliation: Centro de Ciências Agroveterinárias, Universidade do Estado de Santa Catarina, Lages, SC, Brazil.
authors.forename: Fernando André
authors.initials: FA
authors.lastname: Schmidt
authors.affiliation: Department of Animal Science, Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. vivinha.fischer@hotmail.com.|, Av. Bento Gonçalves, 7712, Porto Alegre, RS, 91540-000, Brazil. vivinha.fischer@hotmail.com.
authors.forename: Vivian
authors.initials: V
authors.lastname: Fischer
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D007774:Lactation / Q000502:physiology*; D007785:Lactose / Q000032:analysis; D008892:Milk / Q000737:chemistry; D064067:Rho Guanine Nucleotide Exchange Factors
chemical_list: C577228:ARHGEF5 protein, human; D064067:Rho Guanine Nucleotide Exchange Factors; D007785:Lactose
keywords: Dairy cattle; Ethanol stability; Milk components; Milk production; Nutrient limitation