Effects of intramammary infection on whey proteinograms of sheep during lactation

Abstract

RESUMO.-[Efeitos da infecção intramamária no proteinograma de ovinos durante a lactação.] Este estudo teve como objetivo identificar potenciais biomarcadores de infecção na glândula mamária de ovelhas Santa Inês. Foram monitorados rebanhos comerciais de ovinos, submetidos ao mesmo manejo higiênico-sanitário e nutricional, criados em sistemas de produção semi-intensivo durante as várias fases de lactação e avaliados aos 15, 30, 60 The study aimed to identify potential biomarkers of mammary gland infection in Santa Inês sheep. Commercial flocks of sheep provided the same hygiene, sanitary, and nutritional management under semi-intensive production systems were monitored during the lactation stage-and assessed 15, 30, 60, and 90 days after delivery (through the end of lactation and weaning). The California Mastitis Test (CMT) was performed on the mammary glands. Milk was collected for bacterial examination and protein analysis. Bacterial culture and biochemical characterization of the samples were performed. Forty-two milk samples from healthy glands (negative CMT and bacterial testing) and 43 milk samples from infected glands (positive CMT and bacterial testing) taken at the predefined time points were assessed. A rennin solution was used to obtain the whey. The proteins analysis was performed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which allowed for the quantification of nine whey proteins produced in healthy glands: serum albumin, lactoferrin, IgA, IgG heavy-chain (IgG HC), IgG light-chain (IgG LC), total IgG (IgG HC + IgG LC), α-lactalbumin, β-lactoglobulin, protein with MW 15.000 Da, protein with MW 29.000 Da and eleven whey proteins secreted by infected glands, including haptoglobin and α-1-acid glycoprotein. A comparison of whey proteins between healthy and infected glands showed increases (P<0.05) in the secreted and total contents of all proteins, except for IgG LC and α-lactoalbumin. The most significant changes were observed in α-1-acid glycoprotein, lactoferrin and haptoglobin, which showed three-, five-, and seven-fold increases in secretion, respectively. This study showed that haptoglobin, α-1-acid glycoprotein, lactoferrin, albumin, and the IgA and IgG immunoglobulins may serve as potential biomarkers for mammary gland infection in sheep. CMT). O leite foi coletado para aná-lise bacteriana e análise de proteínas. Foi realizada a cultura bacteriana e a caracterização bioquímica das amostras. Foram selecionadas 42 amostras de leite provenientes de glândulas sadias (CMT negativo e teste bacteriológico negativo) e 43 amostras de leite de glândulas infectadas (CMT positivo e teste bacteriológico positivo). O soro lácteo foi obtido por meio da adição de renina. A proteína total no soro lácteo foi mensurada utilizando o método do biureto e a identificação das proteínas empregando-se eletroforese em gel de poliacrilamida com dodecil sulfato de sódio (SDS-PAGE), permitindo a quantificação de nove proteínas no soro lácteo das glândulas sadias: albumina, lactoferrina, IgA...

Mammary Defences and Immunity against Mastitis in Sheep

“…Also, it contributes to bacterial killing and promotes adhesion and aggregation of neutrophils to the endothelial surface, as well as being involved in activation of the complement system via the alternative pathway and in antigen-processing by cells of the reticuloendothelial system and in antibody production [4]. Mean lactoferrin concentrations in infected ovine mammary glands have been shown to be up to 4.8 times higher than those in healthy ones, demonstrating its role in the natural defence mechanisms against mammary gland inflammation in sheep [105]. Moreover, recent work performed in ewes, has indicated that presence of lactoferrin genotype AA was associated with lower prevalence of subclinical mastitis [106].…”

Quantitative Determination of Whey Protein to Casein Ratio in Infant Formula Milk Powder

“…Nowadays, due to its simple operation, fast detection speed, and low cost, it is often used for the qualitative and quantitative detections of biological macromolecules ( Restani et al, 1995 ; Aludatt et al, 2017 ). But when this method is used to detect whey protein in infant formula milk powder, the detected electrophoresis band will change, thus affecting the detection result, which might be caused by the complicated process under high temperature and high pressure in the production process of the infant formula ( Lemos et al, 2015 ; Krause and Goldring, 2019 ). As one of the most commonly used detection methods, HPLC separates and analyzes the components in the mixture according to their difference in retention time.…”