Biomedical subjects
F J Grommers
Publications and source records attributed to F J Grommers.
The influence of mononuclear leukocytes on the chemotactic responsiveness of polymorphonuclear leukocytes of bovines.
Polymorphonuclear leukocytes (PMN) isolated from the blood of bovines which do not react with an influx of cells into the milk upon intramammary administration of low doses of endotoxin (Group II), show a diminished chemotactic activity in vitro as compared to PMN of bovines which do respond to intramammary endotoxin administration (Group I; 8). The purpose of the present study was to determine whether other immune cells affected the chemotactic activity of PMN of Group I and II bovines. Mononuclear leukocyte suspensions of Group I animals had no effect on the migration of PMN of Group I animals. In contrast, the distance migrated by Group II PMN was diminished in the presence of Group II mononuclear leukocytes. As a consequence, this phenomenon resulted in a much larger difference in chemotactic activity of PMN in vitro between Group I and Group II bovines. It can be concluded that the chemotactic activity of PMN of animals which are more susceptible for mastitis as indicated by non-responsiveness to intramammary endotoxin-infusions, was further down-regulated by mononuclear leukocytes.
Population dynamics of bulk milk somatic cell counts.
The population dynamics for bulk milk SCC in 27,000 Dutch dairy farms was studied over 6 yr; SCC declined markedly in 1984 and 1985. This coincided with the introduction of the quota system in the European Community. The CV of SCC was .36, ranging from .15 to .89. Month of year had a significant effect on SCC with the highest SCC in October and the lowest in April. The dynamics of the annual SCC were modeled with a state transition model. Farmers managing herds with a fairly low SCC (less than 450,000) had a reasonable chance to remain in these states. Herds with a higher annual SCC were much more variable. The model simulated, the potential reactions of the farmers to the decrease of the SCC limit from 750,000 to 500,000 starting January 1, 1989. The simulations showed a further decrease in mean annual SCC, although the number of farms in the category with a very low SCC (less than 150,000) is not likely to increase. In all simulations an increased number of farmers will receive a penalty due to the more strict regulations of the European Community.
Risk factors for clinical mastitis in herds with a low bulk milk somatic cell count. 1. Data and risk factors for all cases.
The incidence rate of clinical mastitis in 125 herds with a low annual bulk milk SCC (less than 150,000 cells/ml) was modeled using a Poisson regression model. The rate of clinical mastitis was significantly associated with some variables that increased the exposure to environmental microorganisms: poor cubicle cleanliness increased the mastitis rate; rubber mats in cubicles were associated with a higher incidence; and drinking water from sources other than public water also increased the rate of mastitis. Other variables may be associated with host resistance: an increasing percentage of cows leaking milk increased the rate of mastitis; postmilking teat disinfection was associated with a higher incidence of clinical mastitis; and a high frequency of cubicle disinfection was also associated with more mastitis. Three other variables were associated with the rate of mastitis: breed (Holstein-Friesian had a lower incidence than the Meuse-Rhine-Yssel breed); use of sugar beet pulp in the ration increased the mastitis rate; and in herds with high milk production a higher incidence of mastitis was observed. These items are discussed in respect to their causal relation to clinical mastitis.
Polymorphonuclear leucocyte function: relationship between induced migration into the bovine mammary gland and in vitro cell activity.
Low doses of 10(-7) mg Escherichia coli endotoxin applied as intramammary infusion into single bovine quarters induced a rise in milk cell count without other inflammatory signs. Significantly fewer quarters responded in early lactation than in mid lactation. Maximum cell count was also somewhat later and less pronounced in early lactation. The rise in milk cell count after infusion of E. coli endotoxin was related to in vitro chemotactic activity of blood polymorphonuclear leucocytes (PMN). PMN isolated from cows which did not respond with a rise in milk cell count upon endotoxin infusion showed a diminished chemotactic activity in vitro as compared to PMN isolated from animals which did respond to an intramammary endotoxin infusion with a rise in milk cell count. No differences in phagocytic and metabolic activity were observed in vitro between the PMN isolated from the two groups of animals.
Intramammary infections and risk factors for clinical mastitis in herds with low somatic cell counts in bulk milk.
Ten herds with low somatic cell counts in bulk milk had an incidence of clinical mastitis of only 2.2 per 100 cows whereas 10 other herds with similarly low cell counts had an incidence of 53.6 per 100 cows. The major pathogens in the herds with a high incidence were Escherichia coli, Streptococcus uberis, Staphylococcus aureus and the coagulase-negative staphylococci. The percentage of uninfected quarters in the herds with a high incidence of clinical mastitis was 21.4 per cent compared with 12.2 per cent in the herds with a low incidence of clinical mastitis. The prevalence of coagulase-negative staphylococci, Corynebacterium bovis and Micrococcus species was higher in the herds with a low incidence of clinical mastitis. There was a significant linear relationship between the percentage of uninfected quarters and the incidence of clinical mastitis in the herds with a high incidence of clinical mastitis. In herds with a low incidence of clinical mastitis significantly less teat disinfection after milking was practised. The results suggest that infections with minor pathogens tend to protect cows against mastitis, and that teat disinfection after milking may increase the percentage of uninfected quarters and lead to an increased risk of clinical mastitis in herds with low somatic cell counts in bulk milk.
Incidence of clinical mastitis on farms with low somatic cell counts in bulk milk.
A total of 1140 clinical cases of mastitis, with at least one inflamed quarter, were reported on 125 farms with somatic cell counts in bulk milk less than 150,000/ml. The average annual incidence was 17.9 cases per 100 cows and ranged from none to 80 cases per 100 cows. The microorganisms most frequently isolated were Escherichia coli (16.2 per cent), coagulase negative staphylococci (13.0 per cent), Staphylococcus aureus (9.6 per cent) and Streptococcus uberis (8.0 per cent). Only two cases of Streptococcus agalactiae were found. As the incidence of clinical mastitis increased, the proportion of S aureus also increased, while the proportions of E coli, S uberis and Streptococcus dysgalactiae remained about the same. Most of the clinical cases of mastitis occurred in early lactation, in November, December and January. However, after correction for the number of calvings per month, the incidence of mastitis was highest in the early summer months.
The relationship between phagocytic activity of polymorphonuclear leukocytes and mastitis in cattle.
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Effect of freezing on bacteriologic culturing of mastitis milk samples.
The objective was to determine the effect of freezing and length of freezing in a commercial freezer on the qualitative results of bacteriologic culturing of milk collected from glands of cows with clinical or subclinical intramammary infections. A total of 182 milk samples from cows with clinical mastitis and 55 milk samples of cows with subclinical mastitis were taken from four problem herds. Samples were split into four equal sub-samples. Three of these were frozen immediately at -20 degrees C and 1 was submitted fresh for bacteriologic analysis. At 4, 8, and 16 wk after collection, samples were thawed and submitted for bacteriologic culturing. Freezing and increased length of storage resulted in 1) a decrease in the number of samples that had cultures of Escherichia coli or Actinomyces pyogenes; and 2) an increase in the number of samples that had cultures of coagulase-negative staphylococci. Freezing had no effect on streptococci and Staphylococcus aureus.
[The effect of subclinical and clinical mastitis on milk production in cattle].
Subclinical mastitis may cause a decrease in production in the infected quarters, particularly in heifers. Investigations on monozygotic twins in New Zealand showed that this decrease in production of the infected quarter is compensated by an increased production of the normal parallel quarters in secundiparous and older cows. It can be concluded from these findings that a decrease in milk production should be calculated on the basis of cow production rather than on that of quarter production. From the point of view of loss of milk production, particular attention should be paid to heifers in the prevention of mastitis.
[Intersuckling by cattle: a literature review].
The literature on intersucking in cattle is reviewed. The following features are described: incidence, moments of appearance, relationship between herd mates, environmental factors (housing system, size of herd, area per animal, feeding places available, feed ration, nutrient deficiencies, housing and feeding practices during the rearing period), animal factors (genetic predisposition, social bonds, imitation), consequences (pathological changes, milk loss), and forms of symptomatic treatment (mechanical devices, surgery). It is concluded that rearing methods (bucket feeding of milk, early group housing) and genetic predisposition are likely to be the most important factors in the aetiology of intersucking in mature dairy cattle. As methods of symptomatic treatment are not successful in every case and are subject to ethical dispute, it is advisable not to treat intersucking cattle regardless of the symptomatic approach. This is the more important because there is clear evidence of genetic predisposition. The mode of inheritance is still unknown, but is likely to act through sucking motivation or drive at an early age. In problem herds more attention should be paid to rearing methods and selection of (A.I.) bulls. There also is a need for further research into the aetiology, particularly by longitudinal studies in which a large number of animals are studied from birth to first lactation.
[Bacterial count of milk, pin-points and udder health in dairying herds].
The pin-point colonies in bacterial counts of bulk milk were examined for the causative agents of mastitis. Udder health in herds showing unduly high bacterial counts as a result of pin-points was found to be reduced. There was no relationship between the organism isolated from the pin-points and the most important udder pathogen in the herd. The dairy farmers should be informed of the presence of pin-points when the bacterial counts are too high because of their presence.
Duration of bovine intramammary infections in commercial dairy herds.
Data on the infection status of cows on seven commercial dairy farms were collected over 492 full lactations. Foremilk samples were taken at an average interval of five weeks. A total of 249 streptococcal and 433 staphylococcal infections were diagnosed. Spontaneous elimination occurred in 49 per cent of all streptococcal infections and in 54 per cent of Staphylococcus aureus infections. The average duration of spontaneously eliminated infections was 10.8 weeks for Streptococcus agalactiae, 9.9 weeks for Strep dysgalactiae, 10.4 weeks for Strep uberis and 12.8 weeks for Staph aureus. The average duration of infections persisting until drying off was 19.3 weeks for Strep agalactiae, 18.7 weeks for Strep dysgalactiae, 18.5 weeks for Strep uberis and 25.2 weeks for Staph aureus. The method and rate of elimination of infection as found in this analysis are of value for estimating new infection rates and selecting quarters for dry cow therapy.
[Results of mastitis control programmes in dairy cows (author's transl)].
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[Incidence of udder infection in bovine primiparae and milking order (author's transl)].
On four farms taking part in a mastitis prevention programme, milking primiparous animals first failed to result in a significant decrease of the level of udder infection during the first half of lactation. This result may nevertheless be regarded as positive, as there was a rise in infection level among the older animals of the experimental group and a decline in the controls at the same time.
Comparison of dairy cows with low or high rate of udder infection.
Within farms, animals with low and high rate of udder infection were selected from data of a mastitis-prevention field experiment during 3.5 years. Differences between the groups in udder conformation and milkability appeared to be small but were consistently to the disadvantage of the high infection rate group. In the course of a least three preceding lactations the percentage of quarters infected at any time was 53 per cent in the low and 91 per cent in the high infection rate group. The number of infections per quarter infected was 1.53 for the low infection rate group and 2.53 for the high infection rate group. As compared with infection-free quarters it was shown that the duration of infections with udder pathogens was significantly shortened if a quarter was already infected with secondary, i.e. less or non-pathogenic, bacteria. It was not possible to demonstrate differences in cell count or immunoglobulin levels in infection-free quarters between the low and high infection rate groups.
[Relationship between the presence of meconium in newborn lambs and postnatal pH and blood gas tension levels (author's transl)].
The pH of the blood and blood gas tension (PO2 and PCO2) were estimated in thirty-two lambs. Blood was taken from the umbilical vein during labour and blood was collected from the left ventricle after birth (1, 10 and 60 minutes). The findings in twenty-one lambds were used to determine the relationship between the presence of meconium on the fleece and the postnatal changes in pH and blood gas tension. pH, blood gas tension and vitality were found to be identical both in the meconium-stained and in the unstained lambs. Within this experiment, there was no relationship between the length of parturition and pH and blood gas tension levels. The pH, PO2 and PCO2 as determined in the umbilical blood showed that the lambs (both meconium-stained and unstained) continue to be in good condition throughout a normal parturition. Postnatal adjustment is rapid and, following normal ventilation, pH, PO2 and PCO2 respectively attain levels of 7.379; 54.7 and 43.7 within sixty minutes. Diminished vitality, resulting from pathological factors, was observed in four lambs.