Effect of ß-hydroxybutyric acid, parity, and body condition score on phenotype and proliferative capacity of colostral mononuclear leukocytes of high-yielding dairy cows.

In neonatal calves, the ingestion of colostrum is imperative for preventing infectious diseases. Investigations into the transfer of passive immunity of cattle have primarily focused on the importance of colostral immunoglobulins, with a recent increase in focus on understanding the role of colostral leukocytes. The main objective of the present study was to measure the influence of parity, body condition score, serum nonesterified fatty acids, and serum ß-hydroxybutyrate concentrations of periparturient cows on phenotype and mitogen- and antigen-induced proliferative capacity of bovine colostral leukocytes. Holstein-Friesian cows (n=141) were intramuscularly vaccinated at 60 and 30 d before the expected parturition date with a tetanus toxoid vaccine. Of these 141 animals, 28 primiparous and 72 multiparous cows were sampled immediately after parturition. Colostrum mononuclear cell populations were identified by flow cytometry using bovine cluster of differentiation markers, and the proliferative capacity of these cells was determined using a (3)H-thymidine proliferation assay. Under-conditioned cows had a significantly higher percentage of colostral macrophages than normal-conditioned animals, whereas over-conditioned cows had significantly more colostral B-lymphocytes. Serum ß-hydroxybutyrate was significantly associated with higher numbers of colostral T-lymphocytes and macrophages. Heifers had significantly higher mitogen- and antigen-induced proliferation of their colostral leukocytes than third parity or older cows. In conclusion, body condition score, parity, and serum ß-hydroxybutyrate concentration of periparturient high-yielding dairy cows were shown to influence the number of colostral macrophages or the mitogen- and antigen-induced proliferation of colostral leukocytes, possibly influencing the cellular immunity of the newborn calf.

Evaluation of a protocol to reduce the incidence of neonatal calf diarrhoea on dairy herds.

Calf diarrhoea causes substantial economic losses in cattle herds worldwide. Neonatal calves are particularly sensitive to infections with enteropathogens. The present study focused on prevention against the main infectious causes of neonatal calf diarrhoea i.e. Escherichia coli, rota- and coronavirus, and Cryptosporidium parvum. Dairy herds (n=24) with a high percentage of neonatal calves scouring (>10%) were included and calves were sampled for the presence of these four enteropathogens. To decrease diarrhoea problems among neonatal calves, a standard protocol was tested on 13 herds (treatment group) where both C. parvum and either E. coli or rota- or coronavirus were identified as being involved, the other 11 herds served as control group. The protocol consisted of 2 points of action: preventive vaccination of dams against E. coli, rota- and coronavirus, and preventive administration of halofuginone lactate to newborn calves. The average percentage of calves suffering from neonatal diarrhoea (39.7% versus 14.3%, P<0.01) and the average percentage of faecal samples positive for C. parvum (34% versus 11%, P<0.05) differed significantly between control herds and treatment herds after implementation of the protocol. No significant differences between control and treatment group were observed in the percentage of calves excreting E. coli, rotavirus and coronavirus, both before and at the end of the trial. Furthermore, risk factors potentially associated with the development of neonatal calf scours were determined. Non-significant results were obtained for the effect of the protocol on duration of diarrhoea and the effect of the colostral IgG quantity on the risk of diarrhoea. Passive immunity transfer status of the calves, measured both before the onset and at the end of the study, were non-significant between groups.

Two atypical cases of granulosa cell tumours in Belgian Blue heifers.

This paper describes two atypical cases of granulosa cell tumours (GCTs) in Belgian Blue heifers. In the first case, an 18-month-old heifer died after ovariectomy, and a granulosa-theca cell tumour was diagnosed post-mortem. The second heifer (31 months of age) was near term and was successfully treated surgically for a malignant granulosa cell tumour. Unfortunately, no further reproductive data are available, as the heifer was sold for slaughter. This is the first report describing GCTs in Belgian Blue beef cattle.