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Background: Neonatal period in bovine presents important variations in hematologic and immunologic parameters, and the resulting mortality rates may be due to increased susceptibility to disease. Race, age, environmental, climate and management factors are sources of CBC's parameters variation in cattle. The objective of this study is to evaluate and compare the CBC variables and concentrations of total protein (PTP) and plasma fibrinogen calves of Criolo Lageano Breed variety hornless and Aberdeen Angus (Red Angus) in the first six months of life, which are produced under extensive management at the Planalto Serrano Catarinense (southern Brazil). Materials, Methods & Results:Two groups were selected, comprising 11 calves of Hornless Criolo Lageano and 14 calves of the Aberdeen Angus breed (Red Angus). Blood samples were collected for complete blood count and determination of total protein concentrations, and plasma fibrinogen in the periods between 24 h and 36, 15, 30, 60, 90, 120, 150 and 180 days of life. The statistical analysis was performed using analysis of variance for repeated measures (ANOVA) and Tukey's test (P < 0.05). During the experimental period infestations by ticks in both races were observed. In the first month of life, blood smears revealed the presence of blood parasites of the genus Babesia spp. and Anaplasma sp. The fluctuations seen for erythrocyte in the neonatal period (30 days), although not significant, consisted of raising the number of values of erythrocytes, hemoglobin (Hb) and packed cell volume (PCV), and reduction in mean corpuscular volume values (MCV). From 90 days of age there was a significant reduction in number of red blood cells and VG values, and elevated MCV values and mean corpuscular volume (MCHC) for the Aberdeen Angus (Red Angus). For the WBC, the neonatal period was marked by increase in the number of lymphocytes and decrease in neutrophil ratio: lymphocyte (N, L) with respect to the inversion of 15 days. In the age group 90 days of life was evident increase in the number of leukocytes and lymphocytes in both races. The plasma fibrinogen concentrations showed no significant variations during the trial period. The plasma total protein (PTP), had higher values on the second day of life, with reductions up to 60 days and gradual increase in subsequent times. Discussion: The fluctuations related to the values of erythrocyte variables in the neonatal period are consistent with results reported by other authors in calves of other races. Changes in erythrocyte values observed from 90 days of age on race Aberdeen Angus (Red Angus) can be attributed to infection by blood parasites and consequent hemolysis. As for the leucocyte count, increasing the number of lymphocytes and inversion of N:L is the neonatal period in a physiological variation and confirms observations made by other authors in calves of other races. In the age group 90 days, leukocytosis by lymphocytosis was related to natural premonition against Babesia spp. and Anaplasma spp., which is documented in cattle i...

The objective of this observational study was to compare the metabolic status of dairy cows during the last 6 wk of gestation based on colostrum volume and Ig content. For this, healthy Holstein cows were randomly selected from 3 commercial herds in Michigan. In each farm, four cohorts of 21 cows (one per season), stratified by parity, were enrolled (n=228). Cows were blood sampled weekly during the last 6 wk of gestation, and biomarkers related to nutrient utilization, oxidant status, and inflammation were quantified in serum. Cows were milked within 6 h of calving and the volume of colostrum produced was recorded and an aliquot collected. Concentration of IgG, IgA, and IgM were measured by radial immunodiffusion. Cows were grouped into high colostrum producer (HCP) or low (LCP), high IgG (HIG) or low (LIG), high IgA (HIA) or low (LIA), and high IgM (HIM) or low (LIM). For volume category, we arbitrarily defined 6 L of colostrum (4 L for first and 2 L for second feeding of calves) as the cut-off point, whereas for IgG we used the industry standard of ≥ 50g/L. To create groups of low and high IgM or IgA, we used the median of these Ig as the cutoff point. Colostrum volume was lowest in winter, but no differences were observed among parity groups. Conversely, colostrum IgG concentration was highest in fall and winter, but colostrum IgM was lowest at these seasons. However, colostrum Ig content only showed a negative weak correlation with volume (Spearman rho < -0.28). Compared to LCP, HCP cows had higher concentrations of antioxidant potential, BHB and lower cholesterol and oxidant status index. HIG cows showed higher concentrations of glucose compared to LIG. HIA cows had higher concentrations of cholesterol, reactive oxygen and nitrogen species, oxidant status index, and total protein, while BHB, and glucose were lower compared with LIA. Biomarkers of metabolic stress were not significantly different between HIM and LIM. Nevertheless, the differences observed did not result in differences in inflammatory status between animals in any of the colostrum variable categories analyzed, suggesting that physiological homeostasis was not disrupted during late gestation in association with the colostrum variables studied. Overall, the great variability observed in colostrum variables suggests that colostrogenesis is a complex and multifactorial process. However, our results suggest that greater availability of antioxidants during late gestation could support the production of higher volumes of colostrum, which needs to be explored in future trials.INTERPRETIVE SUMMARYChanges in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume and immunoglobulins content.By Rossi et al., page XXXX. We investigated associations between metabolic stress during the last 6 wk of gestation and the volume and immunoglobulin content of the colostrum produced. We observed that cows producing more than 6 L of colostrum exhibited increased metabolic activity during late gestation. Also, a greater blood antioxidant activity throughout late gestation was observed in cows with higher yields of colostrum, suggesting that greater availability of antioxidants might support the production of higher volumes of colostrum. Therefore, further studies should evaluate whether supplementation with additional antioxidants supplement during late gestation can improve colostrum yield.