T. van Werven

Increased risk of abortion following neospora caninum abortion outbreaks: a retrospective and prospective cohort study in four dairy herds

Explosive abortion outbreaks in 4 Dutch dairy herds during 1992 to 1994 are reported. In 50 of 51 fetuses submitted during the first 3 wk of the outbreaks characteristic histological lesions compatible for infection with Neospora caninum were seen. Diagnosis of infection was confirmed by immunohistochemistry in 40 fetuses (78%). No evidence for other abortifacients was found. The abortion risk of the herds was investigated in a prospective and retrospective cohort study. The prospective study showed that cows aborting during the outbreaks and N. caninum seropositive nonaborting cows had a two- to three-fold increased risk of abortion compared with N. caninum seronegative cows. Retrospective examination showed that seropositive nonaborting cows had an increased risk of abortion before the outbreaks, which may indicate that these animals were infected with N. caninum prior to the outbreaks. It is concluded that serostatus can be used for selective culling of cows to decrease future risk of abortion in dairy herds.

Production loss due to new subclinical mastitis in Dutch dairy cows estimated with a test-day model

Milk, fat, and protein loss due to a new subclinical mastitis case may be economically important, and the objective of this study was to estimate this loss. The loss was estimated based on test-day (TD) cow records collected over a 1-yr period from 400 randomly selected Dutch dairy herds. After exclusion of records from cows with clinical mastitis, the data set comprised 251,647 TD records from 43,462 lactations of 39,512 cows. The analysis was carried out using a random regression test-day modeling approach that predicts the cow production at each TD based on the actual production at all previous TD. The definition of new subclinical mastitis was based on the literature and assumed a new subclinical case if somatic cell count (SCC) was >100,000 cells/mL after a TD with SCC <50,000 cells/mL. A second data set was created by applying an adjustment to correct low SCC for the dilution effect when determining if the previous test-day SCC was <50,000 cells/ mL. Thereafter, the loss was estimated for records with SCC >100,000 cells/mL. The production (milk, fat, or protein) losses were modeled as the difference between the actual and predicted production (milk, fat, or protein) at the TD of new subclinical mastitis, for 4,382 cow records, and 2,545 cow records after dilution correction. Primiparous cows were predicted to lose 0.31 (0.25-0.37) and 0.28 (0.20-0.35) kg of milk/d at an SCC of 200,000 cells/mL, for unadjusted and adjusted low SCC, respectively. For the same SCC increase, multiparous cows were predicted to lose 0.58 (0.54-0.62) and 0.50 (0.44-0.56) kg of milk/d, respectively. Moreover, it was found that the greater the SCC increase above 100,000 cells/mL, the greater the production losses. The estimated production losses were more precise than previously reported estimates.

The effects of duration of retained placenta on reproduction, milk production, postpartum disease and culling rate.

Abstract The effects of various durations of placental retention (6, 8, 12, 23, 47 and 71 hours) on reproductive performance, milk production, postpartum disease and culling rate were measured to determine a definition of retained placenta. Data from 1010 calvings on 21 commercial Dutch dairy herds were analyzed by parity groups. The reproductive performance of first calf heifers and of second and third parity cows was not significantly affected by the duration of placental retention. However, fourth parity and higher cows showed the best reproductive performance when they expelled their placenta within 6 hours. Retention of the placenta for longer than 6 hours resulted in an increase of 17 days to the first service and 26 additional days open. Older cows showed decreased milk production with an increase in the duration of retention. For first calf heifers there was no cut-off point at which delayed expulsion of the placenta became detrimental to overall performance. Second and third parity cows as well as fourth parity and higher cows demonstrated the highest overall performance in all the parameters tested when they expelled their placentas within 6 hours after parturition.

Cow-specific treatment of clinical mastitis: An economic approach

Under Dutch circumstances, most clinical mastitis (CM) cases of cows on dairy farms are treated with a standard intramammary antimicrobial treatment. Several antimicrobial treatments are available for CM, differing in antimicrobial compound, route of application, duration, and cost. Because cow factors (e.g., parity, stage of lactation, and somatic cell count history) and the causal pathogen influence the probability of cure, cow-specific treatment of CM is often recommended. The objective of this study was to determine if cow-specific treatment of CM is economically beneficial. Using a stochastic Monte Carlo simulation model, 20,000 CM cases were simulated. These CM cases were caused by Streptococcus uberis and Streptococcus dysgalactiae (40%), Staphylococcus aureus (30%), or Escherichia coli (30%). For each simulated CM case, the consequences of using different antimicrobial treatment regimens (standard 3-d intramammary, extended 5-d intramammary, combination 3-d intramammary+systemic, combination 3-d intramammary+systemic+1-d nonsteroidal antiinflammatory drugs, and combination extended 5-d intramammary+systemic) were simulated simultaneously. Finally, total costs of the 5 antimicrobial treatment regimens were compared. Some inputs for the model were based on literature information and assumptions made by the authors were used if no information was available. Bacteriological cure for each individual cow depended on the antimicrobial treatment regimen, the causal pathogen, and the cow factors parity, stage of lactation, somatic cell count history, CM history, and whether the cow was systemically ill. Total costs for each case depended on treatment costs for the initial CM case (including costs for antibiotics, milk withdrawal, and labor), treatment costs for follow-up CM cases, costs for milk production losses, and costs for culling. Average total costs for CM using the 5 treatments were (US)

Increased surface expression of CD11b receptors on polymorphonuclear leukocytes is not sufficient to sustain phagocytosis during Escherichia coli mastitis in early postpartum dairy cows.

224,

Meta-analysis of dry cow management for dairy cattle. Part 1. Protection against new intramammary infections.

247,

The relationship between oxidative damage and vitamin E concentration in blood, milk, and liver tissue from vitamin E supplemented and nonsupplemented periparturient heifers.

253,

The effect of subclinical mastitis on milk yield in dairy goats

260, and

Vitamin E supplementation during the dry period in dairy cattle. Part I: Adverse effect on incidence of mastitis postpartum in a double-blind randomized field trial

275, respectively. Average probabilities of bacteriological cure for the 5 treatments were 0.53, 0.65, 0.65, 0.68, and 0.75, respectively. For all different simulated CM cases, the standard 3-d intramammary antimicrobial treatment had the lowest total costs. The benefits of lower costs for milk production losses and culling for cases treated with the intensive treatments did not outweigh the higher treatment costs. The stochastic model was developed using information from the literature and assumptions made by the authors. Using these information sources resulted in a difference in effectiveness of different antimicrobial treatments for CM. Based on our assumptions, cow-specific treatment of CM was not economically beneficial.

Bulk milk somatic cell counts are related to bulk milk total bacterial counts and several herd-level risk factors in dairy goats

Phagocytosis, CD11a and CD11b adhesion receptor expression, O2-production and maturity of circulating polymorphonuclear leukocytes (PMN) were studied during acute coliform mastitis in early postpartum dairy cows to obtain a better insight in the role of neutrophils in the pathology of this disease. The mammary gland of twelve newly calved high-yielding dairy cows was experimentally infected with Escherichia coli. Variability in clinical signs of mastitis and inhibition of milk production among cows was very high. There was a significant negative correlation between the number of circulating neutrophils immediately before infection and severity of mastitis represented by the decrease in milk production of non-infected quarters two days after infection. Pre-infection phagocytosis of E. coli, CD11a and CD11b receptor expression, phorbol myristate acetate (PMA)-induced O2-production and maturity of neutrophils on a per cell basis were not related to severity of mastitis. However, significant correlations between severity of mastitis and the total number of phagocytic PMN and mature PMN in blood immediately before infection were found. PMN characteristics responded differently to mastitis depending on the severity of the disease. Neutrophil functions from cows classified as severe (S) and moderate (M) responders to infection of the mammary gland were compared. Surface expression of CD11a receptors on PMN was decreased in all cows 24 h after infection, and this decrease was long-continued in S responders. A biphasic upregulation of the number of CD11b receptors on PMN was observed with a more pronounced response in S cows. PMN phagocytosis was decreased 12 h after infection in S cows and 18 h after infection in S and M cows and was normalized 24 h post-infection. The decrease of phagocytosis coincided with the first peak of CD11b receptor expression. Phorbol myristate acetate (PMA)-induced production of O2-by PMN was decreased for three days after infection in S responders compared to only one day in M responders and was followed by an upregulation. These data demonstrate a complexity in alterations of PMN functions during mastitis and suggest the involvement of differences in systemic factors dependent on severity of mastitis.