Objective—To determine whether vaccinating cows during late gestation against Mycoplasma bovis will result in adequate concentrations of M bovis–specific IgG1 in serum, colostrum, and milk.
Animals—78 dairy cows.
Procedures—Serum samples were obtained 60 and 39 days prior to expected parturition in vaccinated and control cows from a single herd. Serum and colostrum samples were also obtained at parturition. Milk samples were obtained 7 to 14 days after parturition. Samples were analyzed for anti–M bovis IgG1 concentrations.
Results—Prior to vaccination, control and vaccinated cows had similar anti–M bovis IgG1 concentrations. After initial vaccination and subsequent booster and at parturition, there was a significant difference between the 2 groups, with vaccinated cows having higher IgG concentrations. Colostrum from vaccinated cows had higher anti–M bovis IgG1 concentrations, compared with control cows; however, IgG1 concentrations in milk did not differ between the 2 groups.
Conclusions and Clinical Relevance—Vaccination of late-gestation cows resulted in increased concentrations of anti–M bovis IgG1 in colostrum. However, ingestion of colostrum by calves may not guarantee protection against M bovis infection.
Objective—To determine whether prepartum intramammary
treatment of dairy heifers with pirlimycin
hydrochloride would reduce the prevalence of intramammary
infection (IMI) and lower the somatic cell
count (SCC) during early lactation or improve 305-day
mature equivalent milk production.
Design—Prospective clinical trial.
Animals—183 Holstein-Friesian heifers (663 quarters)
from 2 dairy farms.
Procedure—Heifers were assigned to treatment and
control groups. Treated heifers received a single 50-mg
dose of pirlimycin in each mammary quarter approximately
10 to 14 days prior to parturition. Prepartum
mammary gland secretions and postpartum milk samples
were collected for bacterial culture. Postpartum
milk samples were also collected for determination of
SCC or California mastitis testing and were tested for
pirlimycin residues. Mature equivalent 305-day milk
production data were recorded.
Results—Treated heifers in herd A had a higher overall
cure rate, higher cure rates for IMI caused by coagulase-negative staphylococci (CNS) and Staphylococcus
aureus, lower SCC, and lower prevalence of chronic
IMI, compared with control heifers. Treated heifers in
herd B had a higher overall cure rate and cure rate for
IMI caused by CNS, compared with control heifers, but
postpartum California mastitis test scores and prevalence
of chronic IMI did not differ between groups.
Mature equivalent 305-day milk production did not differ
between herds or treatment groups. No pirlimycin
residues were detected in postpartum milk samples.
Conclusions and Clinical Relevance—Results suggest
that prepartum treatment of dairy heifers with pirlimycin
may reduce the prevalence of early lactation
IMI, particularly IMI caused by CNS, without causing
pirlimycin residues in milk. (J Am Vet Med Assoc 2005;227:1969–1974)
Objective—To determine the amount of colostral IgG required for adequate passive transfer in calves administered colostrum by use of oroesophageal intubation and evaluate the impact of other factors on passive transfer of colostral immunoglobulins in calves.
Animals—120 Holstein bull calves.
Procedures—Calves were randomly assigned to specific treatment groups on the basis of volume of colostrum administered and age of calf at administration of colostrum. Colostrum was administered once by oroesophageal intubation. Equal numbers of calves received 1, 2, 3, or 4 L of colostrum, and equal numbers of calves received colostrum at 2, 6, 10, 14, 18, or 22 hours after birth. Serum samples were obtained from calves 48 hours after birth for IgG determination by radial immunodiffusion assay. Effects of factors affecting transfer of colostral immunoglobulins were determined by use of a stepwise multiple regression model and logistic regression models.
Results—A minimum of 153 g of colostral IgG was required for optimum colostral transfer of immunoglobulins when calves were fed3Lof colostrum at 2 hours after birth. Substantially larger IgG intakes were required by calves fed colostrum > 2 hours after birth.
Conclusions and Clinical Relevance—Feeding 100 g of colostral IgG by oroesophageal intubation was insufficient for adequate passive transfer of colostral immunoglobulins. At least 150 to 200 g of colostral IgG was required for adequate passive transfer of colostral immunoglobulins. Use of an oroesophageal tube for administration of 3 L of colostrum to calves within 2 hours after birth is recommended.
Objective—To determine sensitivity and specificity of 4 methods to assess colostral IgG concentration in dairy cows and determine the optimal cutpoint for each method.
Animals—160 Holstein dairy cows.
Procedures—171 composite colostrum samples collected within 2 hours after parturition were used in the study. Test methods used to estimate colostral IgG concentration consisted of weight of the first milking, 2 hydrometers, and an electronic refractometer. Results of the test methods were compared with colostral IgG concentration determined by means of radial immunodiffusion. For each method, sensitivity and specificity for detecting colostral IgG concentration < 50 g/L were calculated across a range of potential cutpoints, and the optimal cutpoint for each test was selected to maximize sensitivity and specificity.
Results—At the optimal cutpoint for each method, sensitivity for weight of the first milking (0.42) was significantly lower than sensitivity for each of the other 3 methods (hydrometer 1, 0.75; hydrometer 2, 0.76; refractometer, 0.75), but no significant differences were identified among the other 3 methods with regard to sensitivity. Specificities at the optimal cutpoint were similar for all 4 methods.
Conclusions and Clinical Relevance—Results suggested that use of either hydrometer or the electronic refractometer was an acceptable method of screening colostrum for low IgG concentration; however, the manufacturer-defined scale for both hydrometers overestimated colostral IgG concentration. Use of weight of the first milking as a screening test to identify bovine colostrum with inadequate IgG concentration could not be justified because of the low sensitivity.
Objective—To determine the effects of pasteurization
of colostrum on serum lactoferrin concentration and
neutrophil oxidative function by comparing values
from calves given pasteurized (76 C, 15 minutes)
colostrum versus calves given fresh frozen colostrum.
Animals—8 Holstein bull calves were used to study
the effects of pasteurization of colostrum on the
absorption of lactoferrin and neutrophil oxidative burst.
Three additional calves were used to study the effect
of exogenous lactoferrin on neutrophil oxidative burst.
Methods—Calves were fed fresh frozen or heat pasteurized
colostrum (76 C for 15 minutes) via
esophageal feeder within 4 hours of birth. Neutrophils
were isolated from whole blood samples. Neutrophil
oxidative burst was induced by phorbol ester (300
ng/ml) stimulation of cells (1 × 106 cells) at 37 C.
Serum lactoferrin concentrations were compared,
using immunoblot analysis. Serum IgG concentrations
were determined by radial immunoassay.
Comparisons were made between the use of the 2
types of colostrum in calves by measuring subsequent
serum IgG and lactoferrin concentrations and
neutrophil superoxide production.
Results—Serum IgG and lactoferrin concentrations
increased more in calves receiving fresh frozen
colostrum. Neutrophil superoxide production was higher
in neutrophils prepared from calves receiving fresh
frozen colostrum. Colostral lactoferrin addition to neutrophil
incubations resulted in increased oxidative burst.
Conclusions and Clinical Relevance—Compared
with calves given fresh frozen colostrum, calves given
pasteurized colostrum had decreased serum IgG and
lactoferrin concentrations and neutrophil superoxide
production 24 hours after administration. These
results suggest that pasteurizing bovine colostrum at
76 C for 15 minutes has substantial effects on passive
transfer of proteins and neutrophil function. (Am J Vet
Objective—To evaluate the effect of lactoferrin on lipopolysaccharide (LPS)-induced proliferation of bovine peripheral blood mononuclear cells (PBMCs), gene expression of inflammatory mediators, and production of prostanoids in vitro.
Sample Population—PBMCs isolated from 15 Holstein bull calves.
Procedures—Mixed populations of PBMCs were isolated by differential centrifugation. Proliferation assays were conducted in 96-well plates designed to allow addition of lactoferrin (200 ng/mL) with and without LPS (1 μg/mL) in a checkerboard design. Incorporation of 3H-thymidine was used to determine proliferation of PBMCs. Prostaglandin E2 production was determined in culture-conditioned medium by use of enzyme immunoassay. Effects of lactoferrin on LPS-induced gene expression of cyclooxygenase (COX)-2 and matrix metalloproteinase (MMP)-9 were monitored by use of PCR assays.
Results—Lactoferrin supplementation significantly reduced LPS-induced incorporation of 3H-thymidine and production of prostaglandin E2 by PBMCs. Lactoferrin reduced LPS-induced expression of COX-2 and MMP-9 mRNA.
Conclusions and Clinical Relevance—Lactoferrin reduced LPS-induced cellular proliferation, inflammatory mediator gene expression, and prostaglandin E2 production by bovine PBMCs in vitro. These effects may be beneficial in reducing the impact of endotoxemia in neonates.