Discussion and conclusion

Calves without diarrhoea (%)

Cryptosporidium spp. 55/178 (30.9) 496/1 788 (27.7) Eimeria spp. 86/178 (48.3) 860/1 759 (48.9) Giardia intestinalis 102/176 (58.0) 1 017/1 788 (56.9)

2.3.6 Discussion and conclusion

The preliminary findings of this study are mainly in accordance with studies performed in Sweden and in the United Kingdom (Angen, Ø., 2006; Bjorkman et al., 2003; Reynolds et al., 1986), as well as with a previous survey done in Norway (Valheim et al., 2002) .

51 The present investigation confirms that rotavirus and Cryptosporidium spp. are common diarrhoea-associated pathogens in Norwegian calves, while enterotoxigenic E. coli F5 (K99) only was detected in small a number of animals with diarrhoea. Other pathogenic bacteria, like various enterotoxigenic E. coli (ETEC), as well as other enteric viruses may also contribute to the diarrhoea-complex in calves and young stock in Norway. This is yet to be investigated.

Coronavirus was not detected in any of the samples from calves with diarrhoea which may be due to the virus not being present at the time of sampling, or possible low sensitivity of the assay.

Coccidia are of some importance in calves from approximately two weeks of age (data from post-mortem examinations in project herds) but the prevalence in samples from animals without diarrhoea is also very high (48.9 %). This seems to be the case for Cryptosporidium spp. and Giardia intestinalis as well.

In contrast to most other countries, Salmonella spp. are rarely detected in samples from calves with diarrhoea in Norway and Sweden. From Denmark and the UK prevalences of 4.2-14.6 % and 12 % have been reported, respectively (Angen, Ø., 2006; Reynolds, D. J. et al., 1986).

Infection with bovine virus diarrhoea virus is also relevant in most countries while Norway was declared free of BVDV in November 2006.

In the majority (73.6 %) of diarrhoeal samples no probable etiologic agent was detected by antigen ELISA, suggesting other aetiological agents not included in the assay, dietetic or environmental factors. Some samples may also have been misclassified leading to an underestimate of the true prevalence of the pathogens in calves with disease.

The current findings of this investigation indicate that it may be appropriate to sample several animals with clinical diarrhoea in a herd when investigating a herd problem. The application of quantitative or semi-quantitative methods to detect probable disease causing organisms may aid the clinician when interpreting the test results.

2.3.7 Literature

Angen, Ø. 2006. Diarrhoea in Calves caused by E. coli and Salmonella. The Swedish Animal Health Service Conference 2006, Halmstad, Sweden.

Bendali, F. et al. 1999. Pattern of diarrhoea in newborn beef calves in south-west France.

Vet.Res. 30.1: 61-74.

Bjørkman, C. et al. 2003. Cryptosporidium parvum and Giardia intestinalis in calf diarrhoea in Sweden. Acta Vet.Scand. 44.3-4: 145-52.

Daugschies, A. and Najdrowski, M. 2005. Eimeriosis in cattle: current understanding.

J.Vet.Med.B Infect.Dis.Vet.Public Health 52.10: 417-27.

de Verdier, Klingenberg K. and L. Svensson. 1998. Group A rotavirus as a cause of neonatal calf enteritis in Sweden. Acta Vet.Scand. 39.2: 195-99.

Hoet, A. E. et al. 2003. Association of enteric shedding of bovine torovirus (Breda virus) and other enteropathogens with diarrhoea in veal calves. Am.J.Vet.Res. 64.4: 485-90.

Lie, K, Gulliksen, S, Jor, E., Nafstad, O., Sviland, S., Løken, T., Simensen, E., and Østerås, O. 2005. Calf Health in Norway. Husdyrforsøksmøtet 2005, Lillestrøm.

Maddox-Hyttel, C. 2006. Protozoan parasites of young calves. The Swedish Animal Health Service Conference 2006, Halmstad, Sweden.

Reynolds, D. J. et al. 1986. Microbiology of calf diarrhoea in southern Britain Vet.Rec. 119.2:

34-39.

Valheim, M. et al. 2002. Sjukdomsfremkallende agens ved diaré hos kalv.

Husdyrforsøksmøtet 2002, Lillestrøm.

52 Wise, A. G. et al. 2004. Molecular characterization of noroviruses detected in diarrheic stools

of Michigan and Wisconsin dairy calves: circulation of two distinct subgroups. Virus Res. 100.2: 165-77.

53 2.4 Seroprevalence of Selected Respiratory Infectious Agents

in Norwegian Calves and Youngstock.

Norwegian School of Veterinary Science, Oslo, Norway ,

2

TINE BA, Oslo, Norway,

3

National Veterinary Institute, Oslo, Norway

2.4.1 Abstract

In this paper, preliminary results of the ongoing research project “Calf Health in Norway” are presented. Serum from randomly selected calves in randomly selected herds were examined with respect to antibodies against Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza virus 3 (PIV-3), Bovine corona virus (BCoV) and Mycoplasma bovis. In addition the occurrence of respiratory disease in the projects dairy herds was recorded using the Norwegian Dairy Herd Recording System (NDHRS). The results showed that 22.5%, 43.3%

and 23.2% of the calves were serologically positive for BRSV, PIV-3 and BCoV respectively.

Of the farms included, 52.2%, 79.0% and 57.0% had at least one animal that were seropositive for these agents. All animals tested with respect to Mycoplasma bovis were negative. The most frequent diseases reported in calves in the participating dairy herds were enteritis and respiratory disease which made up about ¾ of all diseases reported.

2.4.2 Sammendrag

I det følgende presenteres foreløpige resultater fra det pågående forskningsprosjektet ”Kalve- og ungdyrhelse i Norge”. Serum fra tilfeldig utplukkede kalver i tilfeldig utplukkede besetninger ble undersøkt med tanke på antistoffer mot Bovint Respiratorisk Syncytial Virus (BRSV), Parainfluensa virus 3 (PIV-3), Bovint corona virus (BCoV) og Mycoplasma bovis. I tillegg ble det innsamlet data vedrørende forekomst av klinisk luftveissjukdom gjennom den norske helsekortordningen (Kukontrollen). Resutatene viste at 22,5%, 43,3% og 23,2% av kalvene var seropositive for henholdsvis BRSV, PIV-3 og BCoV. Av de inkluderte besetningene hadde 52,2% 79,0% and 57,0% ett eller flere dyr som var positive for disse virusene. Alle dyrene som ble testet med tanke på Mycoplasma bovis var negative.

Helsekortdata fra deltakerbesetningene viste at mage-/tarmbetennelse og luftveissjukdommer var de vanligste problemene da disse utgjorde nærmere ¾ av all registrert sjukdom.

2.4.3 Introduction

Besides diarrhoea, respiratory disease is found to be the most common and economically important disease in calves (Autio et al., 2007; Olsson et al.,1993, Svensson et al., 2003;

Svensson et al., 2006). The nature of the disease is often multifactorial, caused by an unfortunate combination of infectious micro organisms, environment and stress (Roy, 1990).

Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza virus 3 (PIV-3), Bovine corona

54 virus (BCoV), Bovine viral diarrhoea virus (BVDV) and Bovine herpes virus 1, are found to be the most important viral agents involved in respiratory disease complexes in calves and young stock (Autio et al, 2007). An increasing prevalence of Mycoplasma bovis is reported in several countries (Byrne et al., 2001).

EFTA Surveillance Authority (ESA) has recognised Norway as free from Infectious Bovine Rhinotraceitis (IBR) since 1994, and Norway was declared free of Bovine viral diarrhoea virus (BVDV) in 2005, with only one positive herd left after going through a national eradication program (Annual report, The National Veterinary Institute, 2005) . In spite of this, according to the Norwegian Dairy Herd Recording System (NDHRS), respiratory disease was the most frequently reported disease event in dairy calves, both bulls and heifers, in 2006.

Cattle production in Norway has gone through many changes the last 10-20 years, and is at present changing rapidly. The herds are getting larger, the number of cooperatives is increasing, and the authorities demand all cattle being housed in free stalls by 2024. These changes will probably increase the risk of disease and mortality in calves and young stock in Norway. The aims of the present study were to estimate the prevalence of selected respiratory agents in Norwegian dairy and beef herds.