Drinking water for dairy cattle: always a benefit or a microbiological risk?

Drinking water can be considered an essential nutrient for dairy cattle. However, because it comes from different sources, its chemical and microbiological quality does not always reach accepted standards. Moreover, water quality is not routinely assessed on dairy farms. The microecology of drinking water sources and distribution systems is rather complex and still not fully understood. Water quality is adversely affected by the formation of biofilms in distribution systems, which form a persistent reservoir for potentially pathogenic bacteria. Saprophytic microorganisms associated with such biofilms interact with organic and inorganic matter in water, with pathogens, and even with each other. In addition, the presence of biofilms in water distribution systems makes cleaning and disinfection difficult and sometimes impossible. This article describes the complex dynamics of microorganisms in water distribution systems. Water quality is diminished primarily as a result of faecal contamination and rarely as a result of putrefaction in water distribution systems. The design of such systems (with/ without anti-backflow valves and pressure) and the materials used (polyethylene enhances biofilm; stainless steel does not) affect the quality of water they provide. The best option is an open, funnel-shaped galvanized drinking trough, possibly with a pressure system, air inlet, and anti-backflow valves. A poor microbiological quality of drinking water may adversely affect feed intake, and herd health and productivity. In turn, public health may be affected because cattle can become a reservoir of microorganisms hazardous to humans, such as some strains of E. coli, Yersinia enterocolitica, and Campylobacter jejuni. A better understanding of the biological processes in water sources and distribution systems and of the viability of microorganisms in these systems may contribute to better advice on herd health and productivity at a farm level. Certain on-farm risk factors for water quality have been identified. A practical approach will facilitate the control and management of these risks, and thereby improve herd health and productivity.

[Changes in blood concentrations of bone-specific biomarkers, osteocalcin and C-telopeptide, in third or higher parity sows after administration of calcium and vitamin D]. / Verloop van de botspecifieke biomarkers osteocalcine en C-telopeptide in bloed van derde en oudere worps zeugen na gelijktijdige verstrekking van extra calcium en vitamine D.

Changes in blood concentrations of bone-specific biomarkers, osteocalcin and C-telopeptide, in third or higher parity sows after administration of calcium and vitamin D The study had two objectives: 1, to measure levels of two bone-specific biomarkers, with a view to identifying sows with leg problems; 2, to evaluate the effect of additional vitamin D/ monocalcium phosphate on the two bone-specific biomarkers and the number of stillborn piglets. Of 272 third or higher parity sows, 136 were randomly selected to receive a high dose (33 times the normal dose) of vitamin D (as depot) 1 to 5 days before parturition plus 20 g monocalcium phosphate 3 days before and 3 days after parturition. The sows in the control group received no treatment. The housing and feeding conditions of the two groups of sows were identical. Blood samples were taken from five sows per group just before parturition, 2-3 days after parturition, 3 weeks after parturition, and 1 week after weaning for the measurement of osteocalcin (bone formation, osteoblastic activity) and C-telopeptide (CTX, bone degradation, osteoclast activity), calcium, and phosphorus. The total number of piglets born, stillborn piglets, and weaned piglets were registered per group. The bone metabolism of sows is comparable with that of mice, sheep, and goats. CTX levels increased and osteocalcin levels decreased after parturition, and the reverse pattern was seen after weaning, with a decrease in CRX levels and an increase in osteocalcin levels. Thus these two bone-specific biomarkers can be used to monitor bone metabolism in sows. Serum calcium and CTX levels were clearly correlated. Blood calcium levels increased significantly after treatment with vitamin D/monocalcium phosphate in sows with low calcium levels at the start of the study but not in sows with normal calcium levels at the start of the study. Treatment with vitamin D/monocalcium phosphate did not influence the number of stillborn piglets or the number of weaned piglets.

[Selenium requirements of dairy goats]. / Seleenbehoefte van melkgevende geiten.

Selenium is an essential part of the enzyme glutathione-peroxidase (GSH-Px) and plays an important role in the intracellular aspecific immune defence. Reference values for blood levels of GSH-Px are not available for dairy goats. The EU has authorized the addition of selenium (as E), in the form of sodium selenite or sodium selenate, to animal feeds, to a maximum of 0.5 mg selenium/kg complete feed. Dairy goats given feed containing the maximum level of selenium (0.5 mg/kg) had GSH-Px levels of more than 1000 U/g Hb. The reference values for GSH-Px in cattle, horses, and pigs are between 120 and 600 U/g Hb. Newborn kids had GSH-Px levels between 350 and 400 U/g Hb, comparable with those ofnewborn calves. In conclusion, the addition of selenium to feeds for dairy goats in amounts authorized by the EU leads to blood GSH-Px levels that are substantially higher than those in other species, such as horses, cattle, and pigs. Thus the maximum level of supplemental selenium in feeds for dairy goats should be less than 0.5 mg/kg.

Analyses of the results of different test systems in the 2005 global proficiency testing schemes for infectious bursal disease virus and Newcastle disease virus antibody detection in chicken serum.

The results of global proficiency testing schemes (PTS) for serological tests to detect antibodies against infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) in chicken serum, in which 125 and 120 laboratories, respectively, participated from Africa, Asia, Europe, Central and South America, were used to analyse the performances of different antibody test systems such as virus neutralization tests, haemagglutination inhibition tests, enzyme-linked immunosorbent assays and agar gel precipitation tests. All laboratories were asked to carry out their routine diagnostic tests for the detection of IBDV and NDV antibodies as usual. This global ring trial provided a large amount of data on variation within and between laboratories and test systems used worldwide. The data showed that the variation between the quantitative test results of different laboratories (R(between)) using the IBDV virus neutralization tests and the NDV haemagglutination inhibition test was higher (about double) compared with the variation within commercial enzyme-linked immunosorbent assay systems. Although both tests are often referred to and used as the "gold standard" in experimental and scientific studies, official procedures and for the validation of tests, this study shows that there is an urgent need for a global implementation of recommended test procedures and/or the inclusion of international reference sera in these studies.

[Measurement of the status of trace elements in cattle using liver biopsy samples]. / Het bepalen van de status van de spoorelementenvoorziening bij rundvee met behulp van leverbiopten.

Serum, plasma, or urine samples are usually used for the measurement of the trace elements copper; zinc, iron, selenium, because these samples are easy to obtain; however; these samples are not always appropriate. For example, it is not possible to measure molybdenum, the major antagonist of copper; in blood or urine. Therefore measurement of trace elements in liver tissue is considered the gold standard. For the assessment of selenium the method of choice remains determination of glutathion peroxidase in erythrocytes and for the assessment of magnesium determination of magnesium in urine. We determined the accuracy and repeatability of measuring trace elements in liver biopsies and whole liver homogenates. The levels of trace elements measured were similar in both preparations (92% agreement). Liver biopsy in live animals is a relatively simple procedure but not common in The Netherlands. Reference levels of trace elements, classified as too low, low, adequate, high, and too high, were established on the basis of our research and information in the literature. In a second study we investigated the practical aspects of obtaining liver tissue samples and their use. Samples were collected from cattle on a commercial dairy farm. Liver biopsy provided additional information to that obtained from serum and urine samples. We prepared a biopsy protocol and a test package, which we tested on 14 farms where an imbalance of trace minerals was suspected. Biopsy samples taken from 4 to 6 animals revealed extreme levels of trace elements.

[Suckling calves with symptoms of swayback]. / Het beeld van swayback bij zoogkalveren.

Within a 1-year period, three calves from the same herd developed ataxia of the hind limbs and urinary incontinence at about 6 months of age. Signs progressed and the calves were slaughtered 1-8 months after the onset of signs. The calves belonged to a suckling beef herd of 35 cattle. Blood samples from 11 cattle of different ages were collected and glutathione peroxidase and copper levels were measured. Glutathione peroxidase levels were below the normal range in all cattle and copper levels were below the normal range in 7 of ll cattle. Pathological examination of an affected calf revealed a Wallerian type of degeneration of myelinated nerve fibres in the lateral and ventral spinal cord tracts. In addition, the hepatic copper content was very low. Copper deficiency is a well-known cause of swayback in young sheep and goats. To our knowledge, this is the first report of a possible association between a swayback-like syndrome and copper deficiency in calves.

[Stillbirth/perinatal weak calf syndrome in dairy heifers: results of a pilot study]. / Doodgeboren kalveren bij vaarzen op melkveebedrijven: resultaten van een oriënterend onderzoek.

A pilot study of 10 Dutch dairy herds was performed to investigate possible causes of stillbirth/perinatal weak calf syndrome in heifers. Possible causes and advice for further investigations on farms affected by this syndrome are discussed based on the results of investigations of blood and urine from pregnant young stock, postmortem examination of still-born calves, and a questionnaire held among farmers. Infections with Neospora caninum, Salmonella spp. or Leptospira hardjo, or a deficiency of iodine could be excluded.

[Suffocating, slow calves with a thick neck. Iodine deficiency in cattle]. / Benauwde, slome kalveren met een dikke hals. Jodiumdeficiëntie bij rundvee.

On a dairy farm situated 200 km from the sea on sandy soil an increasing problem arose during 3 years with new-born calves showing a thickness over the larynx. The calves and close-in heifers proved to be severely deficient in trace elements. The new born calves had goitre. The clinical picture, diagnosis and therapy/prevention are discussed.

Shortfalls using second-generation anticoagulant rodenticides.

Second-generation anticoagulant rodenticides can give rise to unexpected casualties in nontarget species in zoos. The first two offspring of a pair of turkey vultures (Cathartes aura) died of brodifacoum toxicosis. The adult birds fed rodenticide-killed mice to their offspring. There are previous case reports of small carnivorous birds (Dacelo novae-guinae and Tockus deckeni) killed eating poisoned (difenacoum and brodifacoum) mice. Even a granivorous species (Rollulus roulroul) died, probably by contamination of its food by cockroaches that transported the rodenticide.

Accidental fenitrothion intoxication in young broilers.

Death from fenitrothion intoxication in young broiler chicks has never been reported. The mortality in this instance was 16.4% in the first week. The dead birds were found lying in a ventral position resting their heads on the floor. Prior to death dyspnea and paralysis occurred. A concentration of 120 mg fenitrothion/kg of litter (dry weight) was found.

The phytohaemagglutinin (PHA) skin test as an indicator of stress-induced changes in immune reactivity in pigs.

The present study describes two experiments to standardize the phytohaemagglutinin (PHA) skin test as an indicator of lymphocyte reactivity in pigs after exposure to stressful situations in practical pig husbandry. The first experiment was a dose-response experiment. No time dose interaction was found, so the pattern of the reaction was the same for all doses used, although the magnitude of the reaction differed. The second experiment was carried out to determine stress-induced changes in lymphocyte reactivity. One half of a group of 48 pigs was exposed to stress (mixing, moving, and an increased stocking density). The immune reactivity to intradermally injected PHA of stressed animals differed significantly (P < 0.01) from that of unstressed controls. The reaction of stressed animals can be characterized by a delayed reaction with a lower peak. It can be concluded that frequent measurements are preferable to single measurements when the effects of stress on immunological processes are studied.

[Selenium deficiency without clinical symptoms in young cattle on a dairy farm]. / Seleendeficiëntie zonder klinische symptomen bij jongvee op een melkveebedrijf.

On a dairy farm a selenium deficiency was diagnosed on the basis of the blood chemistry of heifer calves. Of ten heifers, aged five to fourteen months, six animals had a glutathione peroxidase (GSH-PX) activity lower than 10 U/gHb. A good correlation was found between this low GSH-Px-activity and the selenium concentration in the blood. The animals had no symptoms of selenium deficiency nor elevated CPK levels. On the basis of the vitamin E-concentration in the blood it is postulated that the lack of symptom is mainly caused by the amount of vitamin E in the ration (grass and grass silage).

Haematology and biochemistry reference values for sows kept under modern management conditions.

The data presented here were obtained using blood samples from 159 healthy, conventionally managed sows from 37 breeding herds. Sows were sampled at weaning and at 4-5 weeks gestation. Paired blood samples were analysed from sows that had a normal pregnancy and subsequently farrowed. The mean values of serum total protein, albumin and gamma globulin concentration were lower in the blood samples obtained at weaning compared with those obtained at 4-5 weeks gestation. Leucocyte count was higher, mostly as a result of a higher segmented neutrophil count, in the blood samples obtained at weaning compared with those obtained at 4-5 weeks gestation.

Changes in the composition of cervical mucus of the cow during the estrous cycle as parameters for predicting potential fertility.

Four experiments were conducted to test the hypothesis that the composition of cervical mucus can be used as an indicator of reproductive efficiency in the cow. In Experiment 1, biochemical changes were studied in cervical mucus during the estrous cycle. Sorbitol concentration was observed to be highest at 1 to 3 days prior to estrus and lowest on Days 6 to 12 (P<0.001) of the estrous cycle. Cholesterol and protein concentrations were highest at Day 6 of the estrous cycle and lowest on the day of estrus (P<0.001). In Experiment 2, the relationships between the biochemical characteristics of cervical mucus and fertility were studied. It was shown that the embryo transfer recipients which exhibited a high concentration of sorbitol (>1.5 mMol/l) at 1 to 3 days before estrus; a low concentration of protein (< 2 units); and a low concentration of cholesterol (<0.1 mMol/l) on the day of estrus had a higher level of fertility than their counterparts. The predictive ability of these criteria was tested using embryo transfer recipients (n=294) in Experiment 3. Significantly more of the animals predicted to have high potential fertility became pregnant than those predicted to have low potential fertility (70.7 vs 45.6%; P<0.001). A similar difference in pregnancy rate for cows (n=56) presented for artificial insemination was observed in Experiment 4 (59.1 vs 27.2%; P<0.10). These results suggest that the composition of cervical mucus may be a useful indication of potential fertility in cattle.

[The effect of feeding mangel-wurzels on blood beta-hydroxybutyrate level of milk-producing cows]. / Invloed van het voeren van voederbieten op de concentratie van beta-hydroxybutyraat in serum van melkgevende runderen.

The effect of feeding dairy cattle mangel-wurzels on the serum increased concentration of beta-hydroxybutyrate was investigated in serum is normally indicative of an increased catabolism of fats in the liver as a result of an energy shortage. Feeding cattle large amounts of mangel-wurzels can cause the serum beta-hydroxybutyrate concentration to increase above normal reference values, thus seemingly indicating that there is a (sub)clinical acetonaemia. In fact the increased concentration of beta-hydroxybutyrate is probably the result of an increased production of butyrate in the rumen.

Haematological and clinicochemical blood profiles in slaughter pigs.

In a cohort study, 40 pig finishing herds were selected: twenty pig herds with a low and twenty pig herds with a high prevalence of several pathological lesions recorded at slaughter in a six-month period before the start of the study. Blood samples were taken from 20 pigs per herd at the end of the finishing period to investigate haematological and clinicochemical profiles. There was only a significant difference in serum albumin concentration between the low and high lesion prevalence groups. There were distinct differences in blood profiles between pig herds, but also between batches of pigs within a herd, housed in different compartments. Differences between castrated males and gilts were also demonstrated with respect to mean values of the blood variables haemoglobin, iron, copper, beta-globulin, eosinophils and segmented neutrophils. However, the differences were not of a biologically important magnitude. The mean values of the blood variables pepsinogen and lymphocytes differed significantly between pig herds from the two participating integration groups. Pigs with a higher albumin concentration, a lower gamma-globulin concentration, a higher copper concentration and a higher creatine kinase activity in serum showed a higher daily weight gain.