Original article(s)

The objective of the present study was to determine factors that are associated with the birth size ofHolstein calves. A retrospective cross-sectional study was set up, and data of 1594 calf births from fourdairy herds in Belgium and one in Germany were analyzed. Of the variables offered to the offspringbirth weight (BW) model in heifers, calf gender, gestation length, season of calving, age at calving andheart girth, wither height and diagonal length of the dam were retained as significant. The BW wassignificantly lower in heifers that calved at a very old age (25.5 to 37.3 months) (P < 0.001). Calvesborn out of young (20.3 to < 22 months) and old (23.3 to 25.5 months) heifers were lighter than calvesborn out of intermediately aged (22 to < 23.5 months) heifers. Of the variables offered to the offspringBW model in cows, calf gender, season of calving, gestation length, parity, length of the dry periodand the milk production during gestation (MGEST) were significant. For cows having the same heartgirth, the BW of the calves was 0.97 and 1.11 kg higher in cows with low (1,400 to < 5,400 kg) andhigh (6,500 to < 7,200) MGEST, respectively, than in cows with very high MGEST (7,200 to 11,600kg) (P < 0.05). The negative effects of young and older age at calving in heifers and of very highmilk production levels during gestation in cows on the BW of their calves, provide a basis for furtherresearch in nutritional and managerial interventions to improve the long-term health and productivityof the offspring.

Fertility data derived from of 3,108 lactation periods in nine high-yielding dairy herds in Flanders were analyzed to determine the incidence and importance of preservice postpartum anoestrous. In 1,291 (42%) of all studied lactation periods studied, no heat was observed within 60 days after calving. Of the cows observed to be in heat within the first 60 days after calving (n=1,817), 622 (34%) had to be examined during regular herd health visits because they had not been observed in heat at the time insemination should be started. Hence, in total, 1,913 (62%) of all lactation periods were identified as having suffered from one or another kind of preservice postpartum anoestrous. Cows not observed in heat within 60 days after calving as well as cows suffering from cessation of cyclicity, both had a significant (P<0.001) increase in days open (26 and 24 days respectively) and a significantly (P<0.05) increased risk of being culled as compared with their normal herdmates (Odds Ratio: 1.41 and 1.44 respectively). There was a significant (P<0.001) variation among the herds in the lactational incidence rate (LIR) both for cows not observed in heat during the first 60 days after calving and for cows with cessation of cyclicity, the former ranging from 21% to 67%, and the latter from 14 to 48% among the herds. Besides significant herd influences, the season of calving was also of major importance. The LIR for cows not observed in heat in the first 60 days after calving was highest for cows calving in April and lowest for cows calving in September (P<0.001). In conclusion, the authors stress the importance of the preservice postpartum anoestrous problem in dairy herds, and explain the need for further investigation of this problem with a view to taking preventive measures.

A retrospective study was performed on 2,264 horses presented with colic at the University of Ghent (Belgium) in the period 1986-1994. In this article, parameters not directly related to a specific type of colic are discussed. Approximately 31.8% of all horses admitted to the clinic of Internal Diseases were presented because of colic. The colic pathology was observed mainly during the spring. A significantly great number of mares and warmblood riding horses were presented, and a significantly lower number of stallions and halfblood horses. The prevalence of colic increased with age, stagnating around the age of 13. One thousand one hundred sixty-eight exploratory laparotomies were performed on 1,069 horses. During the period 1986-1994 the number of surgical interventions gradually increased. The short-term survival rate also increased progressively: by the end of the period studied, it had reached 86.8% for conservative treatment and 73.1% for surgical correction. A variable success rate after surgery was observed among the different surgeons. The determining factors for this variable success were the surgeon’s individual experience in abdominal surgery and the period in which the exploratory laparotomies were performed. The success rate after non-invasive or minimally-invasive surgical techniques was significantly better than after the use of invasive techniques. The most commonly observed postoperative complications were thrombophlebitis, diarrhoea, wound infection and laminitis.

In 1998 a questionnaire was sent to 2280 dairy cattle farmers in Flanders, Belgium, to investigate whether the pasture management included measures to control gastrointestinal nematodes, whether chemoprophylaxis was applied and whether chemoprophylaxis and grazing management were integrated, rather than superimposed. Information was also gathered on the control measures against lungworm and liver fluke. On 82% of the farms, the grazing management included preventive measures against gastrointestinal nematodes, such as rotational grazing (21.8%), grazing on aftermath (57.0%), or late turnout (26.1%). Nevertheless, the calves received preventive anthelmintic treatment on 69.9% of the farms. At least on 18.3% of the farms preventive pasture management was combined with intensive chemoprophylaxis, which may be ‘overprotective’. On the other hand, on 7.4% of the farms no protective measures against gastrointestinal nematodes were taken. Only 15.1% of the farmers vaccinated their calves against Dictyocaulus. Cattle were treated against liver fluke on 12.1% of the farms.

One hundred and thirty-five cows were surgically treated for correction of right displaced abomasum (RDA) using the right flank omentopexy technique. In 33 cows an abomasal dilatation was diagnosed. Abomasal volvulus was found in 99 animals and omaso-abomasal volvulus in 3. In-hospital mortality was 15% (n = 20). None of the cows with abomaso-omasal torsion survived. Ninety-seven percent (n = 32) of the cows with abomasal dilatation and 84% (n = 83) of the cows with abomasal volvulus were discharged from the clinic. Six months after surgery, 94% of the cows with abomasal dilatation had survived. This percentage fell to 88.5% after another half year. For cows with abomasal volvulus, these survival rates were 74% and 62%, respectively. Regardless of the type of abomasal dislocation, 77% of the total group of animals survived after six months and 66% after one year. Six months after surgery, good milk production was reported in 67% (n = 58) of the surviving cows; this figure rose to 91% of the surviving cows (n = 63) after 12 months.

Three different feeding systems were applied for each of which the protein content decreased differently in time. Urine and faeces were collected separately in metabolism cages without volatilisation of ammonia to determine the daily amount of nitrogen retained and excreted. In the stable the litter was collected after ammonia volatilisation. The samples were analysed for nitrogen. The three feeding systems did not differ in growth, feed conversion or carcass composition. The nitrogen retention was higher in gilts than in barrows. The percentage nitrogen emission through urine increased with age; the faecal nitrogen emission stayed unchanged. The reduction of feed nitrogen reduced the total nitrogen emission by the decrease of the urinary nitrogen emission. As a consequence, the potential ammonia-emission was reduced. The supply of protein-poor feed and multi-phase feeding is a valid option to lower nitrogen and ammonia emissions in growing pigs.

The prevalence of circovirosis in 158 young racing pigeons necropsied in the Avian Diseases Clinic of Ghent University (Belgium) between January and August 1999 was 19%. The highest incidence was observed between March and May. The frequency and nature of concurrent infections, lesions and clinical signs were identical in pigeons that were positive and pigeons that were negative for circovirus infection, though mortality was significantly higher in the former. Findings indicate that circovirosis is an infection that is frequently associated with mortality in young pigeons. Clinical indications for the immunosuppressive effects of circovirus were not found.

A survey to determine the prevalence of anthelmintic resistance of cyathostomes was carried out on 13 horse farms distributed over five different Belgian provinces. Based on faecal egg count reduction tests, resistance to mebendazole (a benzimidazole) was demonstrated on 12 (92%) of these 13 farms. The efficacy ranged from 0% to 100%. The efficacy of pyrantel could be evaluated on only three farms, where the faecal egg count reduction varied from 83% to 96%, which suggested a reduced efficacy of this drug on one farm. The very high prevalence of mebendazole resistance in this study shows that drugs of the (pro-)benzimidazole family should not be used to control cyathostome infections. This survey also demonstrates that the efficacy of anthelmintics used for cyathostome control programmes on horse farms should be routinely evaluated.

Only 19% of 84 Staphylococcus intermedius strains isolated between 1997 and 1999 from skin lesions in dogs showed normal sensitivity to antibiotics. Most resistances involved penicillinase-labile penicillins (64%), tetracyclines (53%) and sulphonamides (44%), combined in dual or multiple resistance patterns. Other frequently occurring resistances included macrolide- and lincosamide cross-resistance. The resistance percentages are compared in a table with those found in 1982 and 1986 in a similar study. The increase of macrolide lincosamide crossresistance from 11 to 33% was the most striking finding.

A set of two biochemical analysers which is commercially available for use in animals was evaluated for the determination of alanine aminotransferase, albumin, alkaline, phosphatase, amylase, aspartate aminotransferase, calcium, cholesterol, creatine kinase, creatinine, gamma-glutamyltranspeptidase, globulin, glucose, inorganic phosphate, lactate dehydrogenase, lipase, total bilirubin, total protein, triglycerides, urea nitrogen, uric acid, sodium, potassium and chloride concentrations in pigeon plasma. The results indicated that the analysers are reliable for use in this bird species. Reference values for all parameters were established through examination of healthy pigeons.