Effect of Different Combinations of Dietary Vitamin A, Protein Levels, and Monensin on Inflammatory Markers and Metabolites, Retinol-Binding Protein, and Retinoid Status in Periparturient Dairy Cows.

The objective of this study was to determine the effect of feeding different combinations of dietary vitamin A supplementation (0 or 110 IU/kg body weight), protein (10.3% or 12.2%), and an ionophore (monensin at 0 or 400 mg/day) on retinoid metabolism and immune function of dairy cows. Eighty multiparous Holstein dairy cows were studied from d -35 to +21 relative to expected parturition in a complete randomized block design with a 2 × 2 × 2 factorial arrangement of treatments. The significance of treatments was declared at p ≤ 0.05. Dairy cows receiving high crude protein (CP) diets with monensin had a greater retinol-binding protein serum concentration than cows receiving high CP diets without monensin (p = 0.04). Animals supplemented with vitamin A showed lower SCC (p = 0.04) and a higher thiobarbituric acid reactive substances concentration (p = 0.06) than cows non-supplemented. Moreover, cows receiving low crude protein diets had a greater haptoglobin concentration (p = 0.01). In addition, cows fed a high crude protein diet had a greater TNF-α expression in peripheral blood mononuclear cells (p = 0.04). Animals fed diets without monensin had a greater serum haptoglobin on day 3 postpartum than those fed monensin (p = 0.01). Moreover, dietary vitamin A increased serum 13-cis retinoic acid postpartum. We conclude that vitamin A, crude protein levels, and monensin fed during the close-up period affect milk somatic cell count, some vitamin statuses, and inflammatory markers during early lactation.

Molecular basis for recognition of the Group A Carbohydrate backbone by the PlyC streptococcal bacteriophage endolysin.

Endolysins are peptidoglycan (PG) hydrolases that function as part of the bacteriophage (phage) lytic system to release progeny phage at the end of a replication cycle. Notably, endolysins alone can produce lysis without phage infection, which offers an attractive alternative to traditional antibiotics. Endolysins from phage that infect Gram-positive bacterial hosts contain at least one enzymatically active domain (EAD) responsible for hydrolysis of PG bonds and a cell wall binding domain (CBD) that binds a cell wall epitope, such as a surface carbohydrate, providing some degree of specificity for the endolysin. Whilst the EADs typically cluster into conserved mechanistic classes with well-defined active sites, relatively little is known about the nature of the CBDs and only a few binding epitopes for CBDs have been elucidated. The major cell wall components of many streptococci are the polysaccharides that contain the polyrhamnose (pRha) backbone modified with species-specific and serotype-specific glycosyl side chains. In this report, using molecular genetics, microscopy, flow cytometry and lytic activity assays, we demonstrate the interaction of PlyCB, the CBD subunit of the streptococcal PlyC endolysin, with the pRha backbone of the cell wall polysaccharides, Group A Carbohydrate (GAC) and serotype c-specific carbohydrate (SCC) expressed by the Group A Streptococcus and Streptococcus mutans, respectively.

The effects of elevated subcutaneous fat stores on fatty acid composition and gene expression of proinflammatory markers in periparturient dairy cows.

During the periparturient period, elevated circulating nonesterified fatty acids (NEFA) from excessive lipid mobilization affect not only the circulating fatty acid (FA) composition, but also that of the peripheral blood mononuclear cells (PBMC) and polymorphonuclear leukocytes (PMNL). However, the changes to specific lipid fractions remain unknown. We hypothesized that elevated lipid mobilization will alter FA profiles and gene expression of selected proinflammatory mediators in PBMC and PMNL. Starting -28 d relative to expected calving (d 0), treatment cows (n = 18) received a dry cow ration plus an additional 10 kg of corn/head per day, while the control cows (n = 16) received the dry cow ration (no additional corn) supplemented with 400 mg of monensin/head per day to minimize lipid mobilization. Postpartum, treatment cows were feed deprived for 8 h on d +3. For FA analysis, serum was collected on d -28 and -7 relative to expected parturition and d +1, +3, +6, +15, and +21 postpartum, in addition to milk samples. Immune cells, PBMC and PMNL, were isolated on d -28, +3, +12, and +21 for FA analysis and gene expression analysis by reverse-transcription PCR. Serum, PBMC, and PMNL lipids were fractionated into NEFA and phospholipids (PL). The FA composition of milk, serum, PBMC, and PMNL was analyzed by gas chromatography. Data were analyzed as repeated measures ANOVA using mixed model procedures in SAS (9.3) with significance declared at P ≤ 0.05. Several FA varied by treatment and across time and parity. Within the serum PL fraction, FA associated with altered immune function, C18:3n-6, C20:4, C20:5, total n-3, and the ratio of n-6 to n-3 varied significantly by a treatment × parity × time interaction. Overall, FA composition of NEFA and PL fractions from PBMC and PMNL did not significantly reflect FA of serum. Gene expression for IL-1ß in PBMC was greater for control, whereas ICAM, IL-1ß, IL-6, and TNF-α were greater in primiparous than multiparous cows, without a detectable treatment effect. Whereas gene expression of CASP, IL-8R, and SELL in PMNL changed over time, no treatment effect was detected. In summary, high-energy prepartal diets altered FA profile in serum, milk, PBMC, and PMNL lipids; however, gene expression of selected proinflammatory mediators was not significantly affected.