Influence of negative energy balance on the reproductive performance after treatment of cystic ovarian disease with gonadotrophin-releasing hormone in dairy cows.

The aim of this study was to investigate whether a significant relation exists between the presence of a negative energy balance (NEB) in cows early in lactation and the reproductive performance after treatment with gonadotrophin-releasing hormone of cows with clinical cystic ovarian disease. Reproductive performance after treatment was assessed from the interval between treatment and first insemination (ITFI) and the interval between treatment and conception (ITC). Based on the outcome of the daily change of milk fat yield (Deltafatg) between the first and second milk recordings post-partum, cows were considered to have passed the NEB nadir (positive Deltafatg) or not (negative Deltafatg). Lactations (n = 430) were divided into four groups according to the interval between calving and first milk recording (ICMR): (i) 0-9 days; (ii) 10-19 days; (iii) 20-29 days; (iv) 30-49 days. The relation between a NEB-proxy parameter (Deltafatg) and reproductive performance was determined. A significant interaction existed for groups 1 and 3 (ICMR on 0-9 and 20-29 days post-partum respectively) with an increased and a decreased probability of being inseminated the first day after treatment (ITFI) respectively. However, no significant interaction was found between Deltafatg and the groups with regard to ITC.

Fertility parameters of dairy cows with cystic ovarian disease after treatment with gonadotrophin-releasing hormone.

Fertility data were collected every four weeks for 10 years from 40 herds of Holstein-Friesian dairy cattle. The data collected during 925 lactations from cows with cystic ovarian disease which were treated with 500 microg gonadorelin were compared with data from a control group of 13,869 normal lactations. The intervals between parturition and first insemination and between parturition and conception were significantly shorter (P<0.001) in the normal cows, but the interval between first insemination and conception was not. The overall conception rate tended to be higher (P<0.10) in the normal cows, but the conception rate after the first insemination was significantly higher (P<0.001) and the number of services per conception was significantly lower (P=0.008) in the normal cows.

[Analysis of symptoms associated with bovine herpesvirus 1 vaccination]. / Analyse van gezondheidsklachten na BHV1 vaccinatie.

Between 1 May 1998 and 22 February 1999, it was compulsory for Dutch cattle farmers to take measures against bovine herpesvirus 1 (BHV1). Cattle on farms that were not certified as infectious bovine rhinotracheitis (IBR)-free had to be vaccinated twice a year. During the vaccination programme, both farmers and veterinarians reported side-effects of the vaccine. These reports were collected by the Stichting IBR/BVD Schade (SIS; Foundation for IBR/BVD Damage) in order to draw up a damage report. In 1999 in total 6977 cattle farmers lodged complaints which they considered to be related to the vaccination against BHV1. On these farms, 15,150 herd vaccinations had been performed, 10,269 of which were associated with one or more symptoms. During the compulsory vaccination period, 13% of the herd vaccinations led to symptoms and complaints. In March 1999, a number of vaccine batches were found to be contaminated with bovine virus diarrhoea (BVD) virus. For the purposes of this analysis, a 'known contaminated' herd vaccination was defined as one in which at least one 'known contaminated' batch or lot of vaccine was used. In total, 987 of 1007 herds vaccinated with 'known contaminated' vaccines developed one or more symptoms compatible with acute BVD. There were no commonly seen combinations of symptoms. For this reason, and because the start and end dates were not reported for 55% of the symptoms, it was not possible to detect a symptom pattern. Therefore there were no 'suspect' batches of vaccine which, although not contaminated with BVD virus, gave rise to symptoms. The number of BVD symptoms was determined for those herds with vaccination-related symptoms. There was no difference in the distribution frequency between batch numbers or between 'known contaminated' batches and 'non-suspect' batches. The farmers' definition of chronic wasting was used in this investigation, with the inevitable large differences in definition. The symptom chronic 'wasting' was reported for 3209 of the 10,269 herds with vaccination-related symptoms. On 161 farms (164 herd vaccinations) 'chronic wasting' accounted for more than 20% of the symptoms. As expected, other symptoms were reported in addition to wasting. The symptom 'chronic wasting' was reported more often on forms where a 'known contaminated' vaccine was used. Inactivated vaccine was used for 154 herd vaccinations. In 34 cases, one or more symptoms of acute BVD were reported. The frequency was the same as that for live vaccines. The frequency of reported symptoms tended to be lower with the inactivated vaccine. On the basis of the SIS data, no relationship was found between vaccine batch and reported symptoms. This may be because (i) the classification of a vaccine as 'known contaminated', 'non-suspect', and 'not known' may not have been in keeping with the real status of the vaccine, (ii) farmers may have reported symptoms selectively, and (iii) there is no relationship with vaccination against BHV1.