Lactoperoxidase potential in diagnosing subclinical mastitis in cows via image processing.

This report describes how image processing harnessed to multivariate analysis techniques can be used as a bio-analytical tool for mastitis screening in cows using milk samples collected from 48 animals (32 from Jersey, 7 from Gir, and 9 from Guzerat cow breeds), totalizing a dataset of 144 sequential images was collected and analyzed. In this context, this methodology was developed based on the lactoperoxidase activity to assess mastitis using recorded images of a cuvette during a simple experiment and subsequent image treatments with an R statistics platform. The color of the sample changed from white to brown upon its exposure to reagents, which is a consequence of lactoperoxidase enzymatic reaction. Data analysis was performed to extract the channels from the RGB (Red-Green-Blue) color system, where the resulting dataset was evaluated with Principal Component Analysis (PCA), Multiple Linear Regression (MLR), and Second-Order Regression (SO). Interesting results in terms of enzymatic activity correlation (R2 = 0.96 and R2 = 0.98 by MLR and SO, respectively) and of somatic cell count (R2 = 0.97 and R2 = 0.99 by MLR and SO, respectively), important mastitis indicators, were obtained using this simple method. Additionally, potential advantages can be accessed such as quality control of the dairy chain, easier bovine mastitis prognosis, lower cost, analytical frequency, and could serve as an evaluative parameter to verify the health of the mammary gland.

Involvement of matrix metalloproteinases and their inhibitors in Staphylococcus aureus chronically infected bovine mammary glands during active involution.

The aim of this study was to characterize the protein expression of matrix metalloproteinase-2 (MMP-2) and -- 9 and their inhibitors (TIMP-1 and -2) in mammary tissue of dairy cows with naturally occurring chronic S. aureus intramammary infections (IMI) during active involution. Moreover, the gelatinolytic activity of MMP-2 and -9 in mammary secretions was evaluated. Cows in late lactation that were either uninfected or with chronic naturally acquired S. aureus IMI were included in this study. Protein expression of MMP-2 and -9 in mammary tissues was significantly higher in S. aureus-infected than uninfected quarters at day 14 and 21 of involution. Protein expression of TIMP-1 and -2 was significantly higher in S. aureus-infected than uninfected quarters at day 7, 14 and 21 of involution. The MMP-2/TIMP-1, MMP-2/TIMP-2, MMP-9/TIMP-1 and MMP-9/TIMP-2 ratios were significantly higher in S. aureus-infected compared with uninfected quarters at day 14 of involution. The MMP-2 activity was significantly higher in mammary secretions from S. aureus-infected compared with uninfected quarters at day 1, 2, 7 and 14 of involution. The MMP-9 activity was significantly higher in mammary secretions from infected quarters compared with uninfected quarters at day 7, 14 and 21 of involution. The increased expression of MMP-2 and -9 in mammary tissue as well as the high levels of activity observed in mammary secretion from infected quarters compared with uninfected quarters during active involution, strongly suggests that these gelatinases could contribute to degradation of mammary tissue components during chronic S. aureus IMI. The MMPs/TIMPs imbalance could lead to greater proteolysis and potentially more damage to mammary tissue in S. aureus-infected quarters.

Relationship between milk production system and milk traits and somatic cell counts in Brazilian Murrah buffaloes: a multivariate analysis

The purpose of this study was to evaluate the monthly milk production and quality of buffaloes from two milk production systems in the Brazilian northeast using the multivariate analysis: principal component analysis (PCA). A total of 2,506 individual milk recordings were performed in two production systems, containing information on milk production (kg day-1), fat, protein, lactose and total solids counts and somatic cell count (SCC). There were positive correlations between the fat content and the contents of total solids (TS) and protein, and of TS and protein. From the PCA, two main components (PC1 and PC2) were identified, explaining 67.71% of the total variation. The fat, protein, lactose and ST level, represented by PC1, explain 46.18% of the total variance, and were an indicator of milk nutritional quality. The CP2, composed of milk production, SCC and production systems, explains 21.53% of the total variance, and was indicative of herd health. PCA results may be useful in dairy buffalo breeding programs, and a reduced number of variables are necessary to assess the nutritional quality of milk and herd health.(AU)

Relationship between milk production system and milk traits and somatic cell counts in Brazilian Murrah buffaloes: a multivariate analysis

The purpose of this study was to evaluate the monthly milk production and quality of buffaloes from two milk production systems in the Brazilian northeast using the multivariate analysis: principal component analysis (PCA). A total of 2,506 individual milk recordings were performed in two production systems, containing information on milk production (kg day-1), fat, protein, lactose and total solids counts and somatic cell count (SCC). There were positive correlations between the fat content and the contents of total solids (TS) and protein, and of TS and protein. From the PCA, two main components (PC1 and PC2) were identified, explaining 67.71% of the total variation. The fat, protein, lactose and ST level, represented by PC1, explain 46.18% of the total variance, and were an indicator of milk nutritional quality. The CP2, composed of milk production, SCC and production systems, explains 21.53% of the total variance, and was indicative of herd health. PCA results may be useful in dairy buffalo breeding programs, and a reduced number of variables are necessary to assess the nutritional quality of milk and herd health.

Polymorphisms of the ATP1A1 gene associated with mastitis in dairy cattle.

Mastitis affects the concentrations of potassium and sodium in milk. Since sodium-potassium adenosine triphosphatase (Na(+), K(+)-ATPase) is critical for maintaining the homeostasis of these two ions, and is involved in cell apoptosis and pathogenesis, we presumed that polymorphism of the ATP1A1 gene, which encodes the bovine Na(+), K(+)-ATPase α1 subunit could be associated with mastitis. The ATP1A1 gene was analyzed in 320 Holstein cows using PCR low ionic strength single-strand conformation polymorphism (PCR-LIS-SSCP) and DNA sequencing methods. A C/A SNP was identified at nucleotide position -15,739 in exon 17 of the ATP1A1 gene, but it did not induce any change in amino acids. We examined a possible association of polymorphism of the ATP1A1 gene with somatic cell score and 305-day milk yields. Individuals with genotype CC in ATP1A1 had significantly lower somatic cell scores and 305-day milk yields than those with genotype CA. We also examined changes in Na(+), K(+)-ATPase activity of red cell membranes. The Na(+), K(+)-ATPase activity was significantly higher in dairy cows with genotype CC compared to the other two genotypes, and the Na(+), K(+)-ATPase activity of the resistant group was significantly higher than that of the susceptible group in dairy cows. We conclude that this polymorphism has potential as a marker for mastitis resistance in dairy cattle.