Impact of volume, immunoglobulin G concentration, and feeding method of colostrum product on neonatal nursing behavior and transfer of passive immunity in beef calves.

One-third of beef calves fail to achieve adequate transfer of passive immunity (TPI) through timely ingestion of colostrum, which substantially increases their risk of preweaning morbidity and mortality. Two randomized clinical trials were designed to assess the impact of volume, immunoglobulin G (IgG) concentration, and feeding method of colostrum product on neonatal nursing behavior and TPI. In Trial 1, 47 calves were randomly assigned to receive one of three colostrum interventions by oro-esophageal tube feeder (OET): 1 L with 100 g/L IgG, 1.4 L with 70 g/L IgG, or 2 L with 100 g/L IgG. In Trial 2, 29 calves were randomly assigned to be fed 1 L of colostrum product with 100 g/L IgG by either nipple bottle (NB) or OET. Colostrum intervention (i.e. feeding of colostrum product) occurred within 60 minutes of birth. Cow-calf pairs were monitored by video surveillance in individual stalls for 24 h. Dam colostrum was collected at 10 minutes and calf serum was collected at 24-36 h after birth to assess IgG concentration. Differences among colostrum intervention groups on latency to stand and nurse were analyzed using Kaplan-Meier survival curves and Cox proportional hazard models. The impact of colostrum intervention group on TPI was assessed using multivariable linear regression modeling. In Trial 1, calves fed 1.4 L with 70 g/L IgG by OET nursed from their dams statistically significantly earlier compared to calves fed 1 L with 100 g/L IgG (P = 0.003) and calves fed 2 L with 100 g/L IgG (P = 0.008). Six of the 15 calves in the NB group in Trial 2 refused to consume part of the colostrum feeding offered by bottle and required follow-up tube feeding of the remaining volume. These calves were analyzed as a separate group (NB + OET). Calves fed 1 L by NB stood and nursed statistically significantly earlier than calves fed by OET (P = 0.005) or a combination of NB + OET (P = 0.003). Calf serum IgG concentrations were not statistically significantly different among colostrum intervention groups (P > 0.1). Overall, the colostrum interventions assessed in this study led to only one calf with failed TPI. While statistically significant differences in serum IgG concentrations were not detected in this study, subsequent nursing behavior did vary and was improved by feeding a moderate volume (1.4 L with 70 g/L IgG) of colostrum when using an OET, and by using the NB when feeding a smaller volume (1 L with 100 g/L IgG).

Oligosaccharide concentrations in colostrum, transition milk, and mature milk of primi- and multiparous Holstein cows during the first week of lactation.

The objective of this study was to characterize the oligosaccharide (OS) profile of colostrum and transition milk from primiparous (Pp, n = 10) and multiparous (Mp, n = 10) Holstein cows. The experiment was conducted on a commercial dairy farm, where cows were assigned to the study at calving. Colostrum (milking 1) was collected at 5.3 ± 0.7 h after parturition, followed by collection of milkings 2 through 6, milkings 8, 10, 12, and 14 at 0500 and 1600 h each day. Samples were analyzed for OS concentrations using liquid chromatography-mass spectrometry and for IgG and milk components. Concentration of IgG was highest in colostrum and milking 2. Colostral IgG concentration was less in Pp cows than in Mp cows (82.1 ± 3.1 vs. 106.1 ± 16.2 mg/mL). Colostrum and milkings 2 and 3 had 3'-sialyllactose and 6'-sialyllactose concentrations greater than those of mature milk (milkings 8+). For colostrum and milking 2, 6'-sialyllactosamine concentrations were higher than all other milkings, while disialyllactose was only higher in colostrum. In addition, 3'-sialyllactose was the most abundant OS in colostrum and milkings 2 and 3 compared with all other OS. A parity difference was observed for 6'-sialyllactosamine, with Mp having a higher concentration over the first 7 d in milk than Pp (46.4 ± 8.7 vs. 16.9 ± 3.2 µg/mL). Similar results were observed between milkings for OS yields. Parity differences were detected for 3'-sialyllactose, 6'-sialyllactose, and 6'-sialyllactosamine yield, with Mp yield being greater than Pp over the first 7 d in milk. These findings demonstrate that colostrum and transition milk contain elevated concentrations of certain OS compared with mature milk and suggest further research should be conducted regarding the potential benefits of OS in colostrum and transition milk when fed to newborn calves.

Preweaned heifer management on US dairy operations: Part II. Factors associated with colostrum quality and passive transfer status of dairy heifer calves.

Passive transfer of immunity is essential for the short- and long-term health of dairy calves. The objective of this study was to evaluate factors associated with colostrum quality and passive transfer status of US heifer calves. This study included 104 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,972 Holstein heifer calves from birth to weaning. Multivariable mixed linear regression models were selected using backward elimination model selection after univariate screening to determine which factors were associated with colostrum IgG and serum IgG concentrations. The mean colostrum IgG concentration was 74.4 g/L with 77.4% of colostrum samples having IgG concentrations >50 g/L. The final model for colostrum IgG included colostrum source and a categorized temperature-humidity index value (cTHI) for the month before calving. Mean colostrum IgG concentrations were highest for dams in third and higher lactations (84.7 g/L) and lowest for commercial colostrum replacers (40.3 g/L). Colostrum IgG concentrations were highest for cTHI ≥70 (72.6 g/L) and lowest for cTHI <40 (64.2 g/L). The mean serum IgG concentration was 21.6 g/L, with 73.3% of calves having serum IgG concentrations >15 g/L. The final model for serum IgG concentration included region, heat treatment of colostrum, colostrum source, timing to first feeding, volume of colostrum fed in the first 24 h, age of the calf at blood sampling, and colostrum IgG concentration. Mean serum IgG concentrations were highest for calves that received colostrum from first-lactation dams (25.7 g/L) and lowest for calves fed commercial colostrum replacer (16.6 g/L). Serum IgG concentrations were higher for calves fed heat-treated colostrum (24.4 g/L) than for calves fed untreated colostrum (20.5 g/L). Serum IgG concentration was positively associated with the volume of colostrum fed in the first 24 h and colostrum IgG concentration, and negatively associated with the number of hours from birth to colostrum feeding and age (days) at blood collection. Dairy producers should be encouraged to measure the quality of colostrum before administering it to calves and to measure serum IgG or a proxy such as serum total protein or Brix to evaluate passive immunity and colostrum management programs.

Effect of delaying colostrum feeding on passive transfer and intestinal bacterial colonization in neonatal male Holstein calves.

The objective of this study was to investigate the effect of time of first colostrum feeding on the passive transfer of IgG and on bacterial colonization in the intestine of neonatal dairy calves. Twenty-seven male Holstein calves were randomly assigned to 1 of 3 treatments at birth: calves were fed colostrum at 45 min (0 h, n = 9), 6 h (n = 9), or 12 h after birth (n = 9). Calves were fed pooled, heat-treated colostrum (62 g of IgG/L) at their respective feeding times at 7.5% of birth body weight and fed milk replacer at 2.5% of birth body weight per meal every 6 h thereafter. Blood samples were taken every 3 h using a jugular catheter and were analyzed for determination of serum IgG by radial immunodiffusion. At 51 h after birth, calves were euthanized for collection of tissue and digesta of the distal jejunum, ileum, and colon. Quantitative real-time PCR was used to estimate the prevalence of Bifidobacterium spp., Lactobacillus spp., Fecalibacterium prausnitzii, Clostridium cluster XIVa, and total Escherichia coli. Delaying colostrum feeding by 6 h (35.6 ± 1.88%) and 12 h (35.1 ± 3.15%) decreased the maximum apparent efficiency of absorption of IgG compared with feeding colostrum immediately after birth (51.8 ± 4.18%) and delayed the time to maximum serum IgG concentration (24 h vs. 15 h, respectively). Moreover, 12-h calves tended to have a lower prevalence of Bifidobacterium spp. (0.12 ± 0.017%) and Lactobacillus spp. (0.07 ± 0.019%) associated with the colon mucosa compared with 0-h calves (1.24 ± 0.648% and 0.26 ± 0.075%, respectively). In addition, 6-h (0.26 ± 0.124%) and 12-h (0.49 ± 0.233%) calves had a lower prevalence of total E. coli associated with ileum mucosa compared with 0-h calves (1.20 ± 0.458%). These findings suggest that delaying colostrum feeding within 12 h of life decreases the passive transfer of IgG and may delay the colonization of bacteria in the intestine, possibly leaving the calf vulnerable to infections during the preweaning period.

Effects of prepartum stocking density on innate and adaptive leukocyte responses and serum and hair cortisol concentrations.

Objectives were to evaluate the effects of prepartum stocking density on innate and adaptive leukocyte responses, serum cortisol and haptoglobin concentrations and hair cortisol concentration of Jersey cows. The cows (254 ± 3d of gestation) were balanced for parity (nulliparous vs. parous) and previous lactation projected 305-d mature equivalent milk yield and assigned to one of two treatments: 80SD=80% stocking density (38 animals/48 headlocks) and 100SD=100% stocking density (48 animals/48 headlocks). Pens (n=4) were identical in size and design and each pen received each treatment a total of 2 times (4 replicates; 80SD: n=338; 100SD: n=418). A sub-group of cows (n=48/treatment per parity) was randomly selected on week 1 of each replicate from which blood was sampled weekly from d -14 to 14 (d 0=calving) to determine polymorphonuclear leukocyte (PMNL) phagocytosis, oxidative burst, and expression of CD18 and L-selectin, and hemogram. The same sub-group of cows was treated with chicken egg ovalbumin on d -21, -7, and 7 and had blood sampled weekly from d -21 to 21 for determination of serum IgG anti-ovalbumin concentration. Blood was sampled weekly from d -21 to 21 to determine glucose, cortisol, and haptoglobin concentrations in serum. Hair samples collected at enrollment and within 24h of calving were analyzed for cortisol concentration. The percentage of leukocytes classified as granulocyte and the granulocyte to the lymphocyte ratio were not affected by treatment. Treatment did not affect the percentage of PMNL positive for phagocytosis and oxidative burst or the intensity of phagocytosis and oxidative burst. Similarly, treatment did not affect the percentage of PMNL expressing CD18 and L-selectin or the intensity of expression of CD18 and L-selectin. Concentration of IgG anti-ovalbumin was not affected by treatment. Serum concentrations of haptoglobin and cortisol were not affected by treatment. Similarly, hair cortisol concentration at calving was not affected by treatment. According to the current experiment, a target stocking density of 80% did not improve leukocyte responses compared with 100% target stocking density.

Supplementing fresh bovine colostrum with gut-active carbohydrates reduces passive transfer of immunoglobulin G in Holstein dairy calves.

High concentrations of coliform bacteria in maternal colostrum (MC) have been associated with reduced IgG absorption in calves. Mannan-oligosaccharide, a gut-active carbohydrate (GAC) derived from yeast cell wall, has been shown to adsorb pathogens expressing type-1-fimbriae, reducing their ability to colonize the gastrointestinal tract. The objective of this study was to investigate if addition of a GAC to colostrum would result in increased IgG absorption in newborn calves. Newborn Holstein heifer and bull calves were enrolled in summer 2012 at a commercial transition cow facility in western Wisconsin. Each day, 7.6-L pools of fresh, first milking MC were created, split into 3.8-L aliquots, and refrigerated until feeding. Eligible newborn calves were removed from the dam 30 to 60min after birth, weighed, and randomly assigned to be fed either 3.8 L of the MC pool (control) or 3.8 L of the MC pool with 30 g of GAC mixed in immediately before feeding. Duplicate 10-mL samples of colostrum were collected and frozen at -20°C before feeding (and before addition of GAC) for bacterial culture and IgG determination. A 10-mL venous blood sample was collected from calves before feeding colostrum and 24 h after colostrum feeding, for laboratory determination of serum IgG using radial immunodiffusion analysis. Colostrum and calf characteristics, including colostrum IgG concentration (g/L), colostrum bacteria counts (log10, cfu/mL), calf dystocia scores (1 to 4), birth weights (kg), and age at first feeding (min) were not different between the group fed GAC (n=47) and the control group (n=48). Mixed linear regression analysis showed that calves fed colostrum supplemented with 30 g of GAC had lower mean (standard error) apparent efficiency of absorption of IgG and lower serum IgG concentrations at 24 h [23.9% (1.0); IgG=24.0 (1.1) g/L] than did control calves [30.4% (1.0); IgG=30.8 (1.0) g/L]. Given the negative effect observed in this study, it is not recommended that fresh colostrum be supplemented with 30 g of GAC.

Addition of gut active carbohydrates to colostrum replacer does not improve passive transfer of immunoglobulin G in Holstein dairy calves.

The primary objective of this study was to investigate the effects of supplementing a commercial colostrum replacer (CR) with gut active carbohydrates (GAC) on passive transfer of IgG in commercial dairy calves. A secondary objective was to evaluate the effect of treatment on preweaning health and growth. A total of 240 newborn Holstein dairy calves on a commercial dairy farm were enrolled in this study. Newborn heifer and bull calves were weighed and then randomly assigned to either the treated group [GAC: 30g of GAC mixed into 1.5 doses (150g of IgG) of commercial colostrum replacer; n=119] or the control group [CON: 1.5 doses (150g of IgG) of CR; n=121]. The assigned CR treatment was fed within 3.5h of birth using an esophageal tube feeder. Venous blood samples were collected at 0 and 24h of age and used to measure serum IgG (mg/mL) and serum total protein (g/dL) concentrations and to estimate the apparent efficiency of absorption of IgG (%). The 129 heifers calves enrolled (CON=60; GAC=69) were also followed until weaning to assess the effect of GAC addition on preweaning health and growth. Multivariable linear regression showed that the addition of GAC to CR did not influence passive transfer of IgG, as measured by apparent efficiency of absorption at 24h of age (CON=54.0 vs. GAC=54.3%), serum IgG (CON=20.3 vs. GAC=20.2mg/mL), and serum total protein (CON=5.69 vs. GAC=5.68g/dL). Although study sample sizes were not originally derived to evaluate health outcomes, treatment had no effect on weight gain or incidence of health events (diarrhea, pneumonia, mortality) for heifer calves between birth and 7 wk of age.

Evaluation of a Brix refractometer to estimate serum immunoglobulin G concentration in neonatal dairy calves.

The objective of this study was to evaluate the utility of a digital Brix refractometer for the assessment of success of passive transfer of maternal immunoglobulin compared with the measurement of serum total protein (STP) by refractometry. Blood samples (n = 400) were collected from calves at 3 to 6d of age. Serum IgG concentration was determined by radial immunodiffusion (RID), and STP and percentage Brix (%Brix) were determined using a digital refractometer. The mean IgG concentration was 24.1g/L [standard deviation (SD) ± 10.0] with a range from 2.1 to 59.1g/L. The mean STP concentration was 6.0 g/dL (SD ± 0.8) with a range from 4.4 to 8.8 g/dL. The mean %Brix concentration was 9.2% (SD ± 0.9) with a range of 7.3 to 12.4%. Brix percentage was highly correlated with IgG (r = 0.93). Test characteristics were calculated to assess failure of passive transfer (FPT; serum IgG <10 g/L). The sensitivity and specificity of STP at 5.5 g/dL were 76.3 and 94.4%, respectively. A receiver operating characteristic curve was created to plot the true positive rate against the false positive rate for consecutive %Brix values. The optimal combination of sensitivity (88.9%) and specificity (88.9%) was at 8.4% Brix. Serum total protein was also positively correlated with %Brix (r = 1.00) and IgG (r = 0.93). Dairy producers can successfully monitor their colostrum management and the overall success of passive transfer using a digital Brix refractometer to estimate IgG concentration of colostrum and calf serum.

Colostrum replacer feeding regimen, addition of sodium bicarbonate, and milk replacer: the combined effects on absorptive efficiency of immunoglobulin G in neonatal calves.

Eighty Holstein and Holstein cross dairy calves were blocked by birth date and randomly assigned to 1 of 8 treatments within each block to examine the effect of a colostrum replacer (CR) feeding regimen, supplementation of CR with sodium bicarbonate (NaHCO3), and provision of a milk replacer (MR) feeding on IgG absorption. Calves were offered a CR containing 184.5g/L of IgG in either 1 feeding at 0h (within 30 min of birth), with or without 30g of NaHCO3, with or without a feeding of MR at 6h of age, or 2 feedings of CR (123g of IgG at 0h with or without 20g of NaHCO3 and 61.5g of IgG at 6h with or without 10g of NaHCO3), with or without a MR feeding at 12h. Therefore, treatments were (1) 1 feeding of CR; (2) 2 feedings of CR; (3) 1 feeding of CR + 30g of NaHCO3; (4) 2 feedings of CR + 30g of NaHCO3; (5) 1 feeding of CR + MR feeding; (6) 2 feedings of CR + MR feeding; (7) 1 feeding of CR + 30g NaHCO3 + MR feeding; and (8) 2 feedings of CR + 30g NaHCO3 + MR feeding. Blood samples were obtained at 0, 6, 12, 18, and 24h after birth and were analyzed for IgG via radial immunoassay. Results indicated that CR feeding schedule, MR feeding, and the interactions CR × Na, CR × MR, and CR × Na × MR were similar for 24-h serum IgG, apparent efficiency of absorption, or area under the curve. Serum IgG at 24h, apparent efficiency of absorption, and area under the curve were decreased with addition of NaHCO3 compared with calves not supplemented with NaHCO3. These data indicate that supplementation of CR with NaHCO3 is not beneficial to IgG absorption and feeding MR within 6h of CR feeding does not affect IgG absorption.

Short communication: Evaluation of serum immunoglobulin G concentrations using an automated turbidimetric immunoassay in dairy calves.

The absorption of maternal antibodies associated with colostrum feeding is critical to the health of calves. Multiple assays have been described to assess serum immunoglobulin G (IgG) concentrations in calves. However, none are ideal for routine use on farms. The purpose of this study was to evaluate the reliability of a new commercially available immunoassay and portable analyzer for measuring serum IgG concentrations in dairy calves. Serum from 100 Holstein calves that had received colostrum was collected for this study. Immunoglobulin G concentrations were run on each calf using both the rapid immunoassay method and radial immunodiffusion assay. Serum IgG concentrations in calves from this study ranged from 460 to 3,640 mg/dL (mean ± SD: 1,515 ± 71) as measured by radial immunodiffusion and 402 to 3,586 mg/dL (mean 1,473 ± 70) as measured by the immunoassay. Based on regression analysis, the automated results closely paralleled those obtained by radial immunodiffusion with a coefficient of determination value of 0.98. Based on the results of this study, the immunoassay technique using the portable analyzer represents a reliable method that can be run within 15 min and provide an accurate serum IgG level. Although the cost is not insignificant, this assay could be easily implemented on a dairy farm to help monitor transfer of passive immunity.

Addition of sodium bicarbonate to either 1 or 2 feedings of colostrum replacer: effect on uptake and rate of absorption of immunoglobulin G in neonatal calves.

Forty Holstein dairy calves were blocked by birth date and sex, and randomly assigned to 1 of 4 treatments within each block to elucidate the effect of feeding regimen and sodium bicarbonate (NaHCO3) supplementation on absorption of IgG from colostrum replacer (CR). Calves received CR containing 191.4 g of IgG fed either in 1 feeding at 0 h (within 45 min of birth), with or without 30 g of NaHCO3, or in 2 feedings (127.6 g of IgG at 0 h, with or without 20 g of NaHCO3, and 63.8 g of IgG at 6 h, with or without 10 g of NaHCO3). The treatments were (1) 1 feeding of CR+0 g of NaHCO3; (2) 1 feeding of CR+30 g of NaHCO3; (3) 2 feedings of CR+0 g of NaHCO3; and (4) 2 feedings of CR+30 g total of NaHCO3. Only calves born with no dystocia were used on this study. Blood samples were taken at 0, 6, 12, 18, and 24h postpartum and were analyzed for IgG using a radial immunoassay. Results indicated that, individually, feeding regimen and NaHCO3 treatments had no effect. However, the interaction was significant for 24-h IgG and area under the curve, and showed a trend for apparent efficiency of absorption. Absorption rate data indicated that, for calves fed within 45 min of birth, most IgG absorption occurred in the first 6 h after birth. From 6 to 12 h postpartum, IgG absorption started to decrease; however, IgG absorption remained higher for calves fed in a single feeding than in 2 feedings. These data indicated that NaHCO3 may increase IgG absorption when calves are fed colostrum in a single feeding but is not beneficial when colostrum is fed in 2 feedings.

Short communication: Addition of varying amounts of sodium bicarbonate to colostrum replacer: effects on immunoglobulin G absorption and serum bicarbonate in neonatal calves.

Fifty-two dairy calves were blocked by birth date and, within each block, randomly assigned to 1 of 4 treatments to investigate the effects of incremental levels of sodium bicarbonate (NaHCO(3)) on IgG metabolism. Treatments were (1) colostrum replacer (CR)+0 g of NaHCO(3) (control); (2) CR+15 g of NaHCO(3); (3) CR+30 g of NaHCO(3); or (4) CR+45 g of NaHCO(3). Calves were fed colostrum replacer (>200 g of IgG) in one feeding within 45 min of birth (0 h) and 2 L of milk replacer at 12, 24, 36, and 48 h. Only calves born in calving pens from multiparous cows with no dystocia were used in this study. Blood samples were taken at 0, 6, 12, 24, and 48 h postpartum, and serum was analyzed for IgG using radial immunoassay and bicarbonate using spectrophotometry. Feeding increasing levels of sodium bicarbonate had negative linear effects on IgG concentration, IgG apparent efficiency of absorption, and IgG area under the curve, primarily due to the effect of the highest dose of NaHCO(3) (45 g). Sodium bicarbonate treatments had no effect on serum bicarbonate concentration. However, area under the curve of serum bicarbonate increased linearly with the amount of NaHCO(3) fed.

Short communication: improving passive transfer of immunoglobulins in calves. III. Effect of artificial mothering.

The objective of this study was to investigate the effect of artificial mothering, simulated by verbal and physical stimulation of the newborn, on passive transfer of IgG in the dairy calf. Newborn heifer calves born without dystocia were removed from the dam before suckling and randomly assigned to 1 of 2 treatment groups: no tactile or verbal stimulation other than that required for feeding (group 1; n=20), or artificial mothering, consisting of 15 min of vigorous physical and verbal stimulation conducted within 1 to 2h of birth at the time of colostrum feeding and repeated 1 to 2h later (group 2; n=21). All calves were fed 2.25 L (150 g of IgG) of a commercially available colostrum replacement using an esophageal tube feeder. Blood samples collected at 24h of age showed that serum IgG levels and the apparent efficiency of absorption of the IgG were similar in both groups of calves. Artificial mothering by physical and verbal stimulation had no significant effect on IgG passive transfer in dairy heifers born without dystocia.

Anionic salts in the prepartum diet and addition of sodium bicarbonate to colostrum replacer, and their effects on immunoglobulin G absorption in the neonate.

The objectives of this experiment were to determine whether feeding anionic salts to prepartum Holstein cows affected their calf's colostral IgG passive transfer and whether adding sodium bicarbonate to a colostrum replacer (CR) would increase the efficiency of IgG absorption. Forty Holstein cows and their resulting calves were assigned to a 2 x 2 factorial arrangement of treatments in a randomized complete block design based on expected date of calving. Three weeks before the projected due date, cows were placed on 1 of 2 treatments: a diet without anionic salts (dietary cation-anion difference of +77 mEq/kg) or a diet with anionic salts (dietary cation-anion difference of -100 mEq/kg). Within 45 min after birth, all calves received 1 dose of a commercially available CR (132g of IgG) without or with supplemental sodium bicarbonate (19.5 g/dose). A half-dose of CR (66g of IgG) and sodium bicarbonate (9.75g) was fed at 6h of age. Calves received milk replacer at 12, 24, 36, and 48h. Blood samples were obtained from calves at 0, 6, 12, 24, and 48h and were analyzed for IgG concentration. Cows fed the diet supplemented with anionic salts had lower DMI on d 8, 5, 4, and 1 and lower urine pH 2 and 1 wk before parturition compared with cows fed the diet without supplemental anionic salts. Calves born from dams receiving anionic salts had similar IgG concentrations (15.1 vs. 14.4g/L) and apparent efficiency of absorption values (29.2 vs. 28.2%) compared with calves born from dams not fed anionic salts. Calves receiving supplemental sodium bicarbonate in the CR had higher serum IgG concentrations at 12 (14.4 vs. 12.0g/L), 24 (16.3 vs. 13.2g/L), and 48h (14.6 vs. 11.2g/L) and higher apparent efficiency of absorption values (31.2 vs. 26.1%) than calves that did not receive sodium bicarbonate in the CR. Calves receiving sodium bicarbonate also had greater area under the curve values for IgG absorption compared with calves not receiving sodium bicarbonate. There was a trend for an interaction with calves born from dams fed anionic salts having a greater area under the curve when fed supplemental sodium bicarbonate. Of the 40 calves in the study, 90% obtained adequate passive transfer (serum IgG > or = 10g/L). This study indicates that feeding anionic salts to the dam has no effect on passive transfer, whereas adding sodium bicarbonate to the CR increased IgG uptake in calves.

Immunohistochemical expression of vascular endothelial growth factor and vascular endothelial growth factor receptor in canine cutaneous fibrosarcomas.

The expression of five markers associated with tumour angiogenesis, proliferation and apoptosis was studied in 24 canine cutaneous fibrosarcomas. Tumours were assigned histological grades and were immunohistochemically evaluated for the expression of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-2). Additionally, intra-tumour microvessel density (iMVD) was assessed by immunohistochemical labelling for expression of von Willebrand factor (vWf) and tumour proliferation index (PI) was measured following labelling of Ki-67 antigen. Finally, tumour apoptotic index (AI) was determined by application of the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP end-labelling method (TUNEL). VEGF and VEGFR-2 expression were detected in 22/24 (92%) and 24/24 (100%) of fibrosarcomas, respectively. There was correlation between VEGF and VEGFR-2 expression (r = 0.51) and between histological grade and PI (r = 0.82). A significant difference in PI between tumours of different histological grade was found (P < 0.05). The median PI in grade 2 and 3 tumours (30.6 and 54.7, respectively) was significantly higher than in grade 1 tumours (6.4). Therefore, only PI correlates significantly with the histological grade of canine cutaneous fibrosarcomas. The potential for autocrine activity for VEGF exists in canine cutaneous fibrosarcomas, as VEGF and VEGFR-2 expression was found in most tumours.

Improving passive transfer of immunoglobulins in calves. I: dose effect of feeding a commercial colostrum replacer.

The objective of this study was to describe the effects of feeding 1 or 2 doses of a commercially available colostrum-derived colostrum replacer (CR) on passive transfer of immunoglobulins (Ig) in newborn dairy calves, including IgG, IgG1, IgG2, IgA, and IgM. Newborn calves were removed from the dam before suckling and randomly assigned to 1 of 3 treatment groups: group 1 were fed 1 package (100 g of IgG) of CR product, group 2 was fed 2 packages (200 g of IgG) of the same CR product, and group 3 was fed 3.8 L of maternal colostrum. All colostrum treatments were fed using an esophageal tube feeder within 2 h of birth. Blood samples collected before colostrum feeding and at 24 h of age were tested for serum total protein and Ig concentrations. Mean 24-h serum total protein (TP) and IgG concentrations were significantly lower for calves in group 1 (n = 24; TP = 4.9 g/dL, IgG = 9.6 mg/mL) compared with calves in groups 2 or 3. There was no difference in 24-h serum TP or IgG concentrations between calves in group 2 (n = 23; TP = 5.5 g/dL, IgG = 19.0 mg/mL) and calves in group 3 (n = 22; TP = 5.7 g/dL, IgG = 20.7 mg/mL). Fifty-four, 100, and 91% of calves in groups 1, 2 and 3 achieved acceptable passive transfer (24-h serum IgG > or =10 mg/mL), respectively. Statistically significant but numerically small differences existed between calves in groups 2 and 3 for some 24-h serum Ig classes and subclasses (mean serum concentrations of IgG2, IgA, IgM) and for the relative percentages of Ig classes and subclasses (IgA, IgM, and IgG as a percentage of total Ig; IgG1 and IgG2 as a percentage of total IgG).

Improving passive transfer of immunoglobulins in calves. II: interaction between feeding method and volume of colostrum fed.

The objective of this study was to investigate the effect of method of feeding (nipple bottle vs. esophageal tube feeder) on passive transfer of immunoglobulin (Ig) G when either a large or small volume of colostrum was fed. Newborn bull calves were removed from the dam before suckling and randomly assigned to 1 of 4 colostrum replacer (CR) treatment groups: 1.5 L (100 g of IgG) of CR fed using a nipple bottle (group 1; n = 24); 1.5 L (100 g of IgG) of CR fed using an esophageal tube feeder (group 2; n = 24); 3.0 L (200 g of IgG) of CR fed using a nipple bottle (group 3; n = 24), or 3.0 L (200 g of IgG) of CR fed using an esophageal tube feeder (group 4; n = 25). Blood samples collected at 24 h of age showed that serum IgG levels were significantly greater in calves fed large (3 L) volumes of CR compared with calves fed small (1.5 L) volumes of CR, regardless of feeding method. These differences were attributed to the larger mass of IgG ingested by calves fed 3 L of CR (200 g of IgG) compared with calves fed 1.5 L of CR (100 g of IgG). For calves fed small (1.5 L) volumes of colostrum, serum total protein (TP, g/dL), serum IgG (IgG, mg/mL), acceptable passive transfer rates (APT, %), and apparent efficiency of absorption of IgG (AEA, %) were significantly greater for calves fed with a bottle (TP = 5.3 g/dL; IgG = 12.5 mg/mL; APT = 100%; AEA = 51.1%) compared with calves fed with an esophageal tube feeder (TP = 5.0 g/dL; IgG = 9.8 mg/mL; APT = 41.7%; AEA = 40.5%). However, for calves fed large (3 L) volumes of colostrum, there was no difference in passive transfer indices for calves fed with a bottle (TP = 5.8 g/dL; IgG = 19.7 mg/mL; APT = 100%; AEA = 41.1%) compared with calves fed with an esophageal tube feeder (TP = 5.9 g/dL; IgG = 18.7 mg/mL; APT = 100%; AEA = 39.0%).

Immunohistochemical expression of vascular endothelial growth factor and vascular endothelial growth factor receptor associated with tumor cell proliferation in canine cutaneous squamous cell carcinomas and trichoepitheliomas.

The expression of 5 markers associated with angiogenesis was studied in canine squamous cell carcinomas (SCCs) (n = 19) and canine trichoepitheliomas (TCPs) (n = 24). SCCs were assigned histologic grades, and tissue sections from both tumor types were immunohistochemially stained for the expression of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor-2 (VEGFR-2), as well as intratumoral microvessel density (iMVD), tumor proliferation index (PI), and tumor apoptotic index (AI), using antibodies against VEGF, VEGFR-2, von Willebrand's factor, Ki-67 antigen, and the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate end-labeling method (TUNEL), respectively. VEGF and VEGFR-2 were detected in 17/19 (89.4%) and 19/19 (100%) SCCs and in 17/24 (70.8%) and 20/24 (83.3%) TCPs, respectively. In SCCs, there was substantial correlation between histologic grade and PI (r = 0.51); and moderate correlation between VEGF and histologic grade (r = 0.43), VEGFR-2 and histologic grade (r = 0.47), VEGF and PI (r = 0.47), and VEGFR-2 and PI (r = 0.47) (Spearman rank correlation coefficient). In TCPs, there was substantial correlation between VEGF and PI (r = 0.51) and a moderate correlation between VEGFR-2 and iMVD (r = 0.36). The median iMVD of SCCs (15.5) was significantly higher than the median iMVD of TCPs (9.05) (P value < .05). It was concluded that VEGF and VEGFR-2 may promote tumor cell proliferation in TCPs and SCCs. An autocrine pathway for VEGF probably operates in canine SCCs and TCPs, as VEGF and VEGFR-2 expression was found in most tumors and was associated with evidence for tumor cell proliferation.

The immunohistochemical detection of Mycoplasma bovis and bovine viral diarrhea virus in tissues of feedlot cattle with chronic, unresponsive respiratory disease and/or arthritis.

The purpose of this study was to determine the frequency of selected pathogens in the tissues of a group of feedlot cattle with chronic disease (most often respiratory disease and/or arthritis). Samples of lung and joint tissues from 49 feedlot animals that had failed to respond to antibiotic therapy were tested by immunohistochemical staining for the antigens of Mycoplasma bovis, Haemophilus somnus, Pasteurella (Mannheimia) hemolytica, and bovine viral diarrhea virus (BVDV). Mycoplasma bovis was demonstrated in over 80% of cases, including in 45% of joints and 71% of lungs tested. Mycoplasma bovis was the only bacterial pathogen identified in the joints. Haemophilus somnus and Pasteurella (Mannheimia) haemolytica were found in 14% and 23% of cases, respectively, and were confined to the lungs in all instances. Infection with BVDV was demonstrated in over 40% of cases. Mycoplasma bovis and BVDV were the most common pathogens persisting in the tissues of these animals that had failed to respond to antibiotic therapy.

Diverged evolution of recent equine-2 influenza (H3N8) viruses in the Western Hemisphere.

We reported previously that equine-2 influenza A virus (H3N8) had evolved into two genetically and antigenically distinct "Eurasian" and "American" lineages. Phylogenetic analysis, using the HA1 gene of more recent American isolates, indicated a further divergence of these viruses into three evolution lineages: A South American lineage, a Kentucky lineage, and a Florida lineage. These multiple evolution pathways were not due to geographic barriers, as viruses from different lineages co-circulated. For the Kentucky lineage, the evolution rate was estimated to be 0.89 amino acid substitutions per year, which agreed with the previously estimated rate of 0.8. For the South American lineage, the evolution rate was estimated to be only 0.27 amino acid substitutions per year. This low evolution rate was probably due to a unique alternating Ser138 to Ala138 substitutions at antigenic site A. For the Kentucky lineage, there was a preference for sequential nonsynonymous substitutions at antigenic site B, which was also a "hot spot" for amino acid substitutions. Convalescent sera had minimal cross-reactivity to viruses of different lineages, indicating antigenic distinctions among these viruses. In contrast to human H3N2 viruses, our results suggested that the evolution of equine-2 influenza virus resembled the multiple evolution pathways of influenza B virus.