Fiftynine cases of abomasal displacement were registered during a 10 year period in a veterinary district in Norway with a dairy cow population of approx. 2500. Of these, 88% were left displacements and 12% right displacements. Ten per cent recovered spontaneously without subsequent relapse. Corrective surgery was performed on the remainder, and 92% of these recovered completely. Surgery was, in most cases, performed on the same day as the diagnosis of abomasal displacement was made. The displacements occurred at all times of the year: 86% of cases involved cows in third or subsequent lactation 95% were diagnosed within the period 4--64 days after calving, and 70% of the cows had been treated for other illness with disturbance of digestion during the week immediately prior to the demonstration of the displacement. In a further 25%, ketosis was diagnosed at the same time as the displacement. Etiology and pathogenesis are discussed.
The aim of this study was to investigate differences in disease incidence between organic and conventional herds. The study was based on data from the Norwegian Dairy Herd Recording, which includes the Norwegian Cattle Health Recording System. All herds certified for organic farming in 1994 with a herd size of more than five cow-years were included. Conventional herds were matched on size and region, and from these, three herds were randomly selected for each organic herd. This resulted in a study group of 31 organic and 93 conventional herds with data from 1994 through 1997. The study unit was the cow within a lactation. Factors influencing disease incidence were studied by means of a generalized linear model approach. Management system had a highly significant effect on disease incidence. Odds ratios for organic compared with conventional herds were as follows: mastitis, 0.38; ketosis, 0.33; and milk fever, 0.60. Other significant factors that emerged in modeling the three diseases were year and lactation category for mastitis; lactation category, maximum milk yield, and season for ketosis; and lactation category and milk yield for milk fever. There was no marked difference in milk somatic cell count (SCC) between organic and conventional herds. However, cows in organic herds had lower SCC in lactation two and greater counts in lactations six and higher.
The results are based on the Norwegian Cattle Health Recording System, which has been in place for the entire country since 1975. The dairy breeds in Norway consist of 94% Norwegian Red and 4% crossbreeds with Norwegian Red. No other breed consists of more than 0.5% of the total population. During the past 30 yr, there have been 11,563,692 dairy cows within the recording system, corresponding to 8,633,532 cow-years and 8,632,516 calvings. This population consisted of 3,038,675 first-calving cows. Altogether, 8,435,704 different diagnoses were recorded from 4,444,485 different cows each year. The general trend for all recordings was an increase in the incidence rate of all cases from 0.74 per 365 d at risk (cow-year) in 1976 to 1.36 in 1990, and then a decrease to 0.62 in 2002. The corresponding figures for cows treated per cow-year were 0.44 up to a maximum of 0.82, and then a decrease to 0.46 per cow-year in 2002. The most common diseases were acute (severe to moderate) clinical mastitis, chronic (mild) clinical mastitis, ketosis, milk fever, teat injuries, retained placenta, silent heat or anestrous, indigestion, cystic ovaries, and metritis. Clinical mastitis increased from 0.15 cows treated per cow-year in 1975 to 0.44 in 1994, and then decreased to 0.23 in 2002. Ketosis began at 0.10 in 1975, increased to 0.24 in 1985, and then decreased to 0.05 in 2005. For several of the most common diseases, there was a reduction of more than 50% from the 1990s to the years after 2000. Validation processes confirmed that this fluctuation reflected the general trend in the population. The disease recording system also reflected the known outbreaks of bovine respiratory syncytial virus during 1976, 1989 to 1990, and 1995. A marked increase in malformation diagnoses could be seen in 1986 and in 1989 and 1990. These could be related to the Chernobyl nuclear power plant accident in April 1986. The diagnosis that showed the most stability throughout these 30 yr was retained placenta. The 3 main reasons for the large fluctuation for many of the diseases could be the following: a breeding effect, an effect of preventive work, and an effect of changing the therapeutic attitude. Many of the actions taken to bring about improvements would not have been possible without a functioning and practical recording system. Our experience is that an organ-related diagnosis system with up to 60 or 70 different diagnoses will meet the needs of the dairy industry.