Financial analysis of East Coast fever control strategies on beef production under farm conditions.

This study provides a financial analysis of an East Coast fever immunisation trial conducted on a farm in the Coast Province of Kenya. The objective of the trial was to assess the effects of immunisation by the infection and treatment method, under different acaricidal treatments, on the productivity of beef cattle. Eighty beef cattle were immunised and an equal number acted as controls. The immunised and unimmunised groups were divided into four subgroups of 20 animals. Two subgroups, one from the immunised and one from the unimmunised group, were sprayed with acaricide twice a week; a second pair of subgroups was sprayed once every three weeks; a third pair had prolonged release acaricide-impregnated ear-tags inserted into each ear; and a fourth pair had no tick control treatment. Financial analysis revealed that the immunised subgroups were more profitable, owing to lower mortality and higher weight gains than the unimmunised subgroups. Of the immunised subgroups, the best was that sprayed with acaricide twice a week; it yielded a marginal rate of return of 244 per cent and maximised financial benefits to the farmer in this trial. However, further trials under different production circumstances would be required before the method could be recommended for widespread adoption.

The effect of East Coast fever immunisation and different acaricidal treatments on the productivity of beef cattle.

A trial was performed on a farm in the Coast Province of Kenya to study the effects of East Coast fever immunisation and different acaricidal treatments on the productivity of immunised and unimmunised beef cattle. Eighty cattle were immunised against Theileria parva parva (Marikebuni) by the infection and treatment method and a similar group was left as an unimmunised control. Immunisation had no deleterious effect on the cattle. After immunisation, the immunised and control groups were each subdivided into four groups of 20 and each subgroup was managed under a different tick control regimen. The tick control regimen were, acaricidal spraying twice a week or once every three weeks, the application of acaricide-impregnated ear-tags, and no tick control. During a nine-month exposure period there were 18 cases of East Coast fever among the 80 immunised cattle, three which were severe and the others mild. Among the 80 unimmunised cattle there were 57 cases of East Coast fever, 50 of which were severe. The highest morbidity and mortality occurred in the groups under limited tick control or without tick control. Overall weight gain in the immunised cattle, irrespective of the tick control regimen, was better than the weight gain in the unimmunised groups. Within the immunised groups, the weight gain of the cattle sprayed twice weekly was comparable to the weight gain of the animals with acaricidal ear-tags and was significantly higher than the weight gains in the groups sprayed once every three weeks or with tick control. Preliminary cost/benefit analysis showed that it was uneconomical to maintain unimmunised cattle under limited or no tick control.(ABSTRACT TRUNCATED AT 250 WORDS)

Cryopreservation of Theileria-infected lymphoblastoid cells with functional assessment of viability.

Bovine lymphoblastoid cell cultures infected with Theileria annulata were frozen to -60 degrees C in a programmable cooling apparatus using continuous cooling rates of 1 degree C/min, 10 degrees C/min and 120 degrees C/min and a two-step cooling rate with an equilibration period of 20 min at -30 degrees C. The cryopreservative was DMSO at concentrations of 5, 10 and 15%. Aliquots of cryopreserved material were stored in the vapour phase of a liquid nitrogen refrigerator and resuscitated by rapid thawing in a 40 degrees C water bath. The efficiency of the freezing methods was compared by assessing the viability and plating efficiency of cells after resuscitation, dilution and equilibration in cell culture medium. A significant correlation was recorded between the results obtained by these two methods which showed that the two-step method yielded cells with viability of 95 to 97% and a plating efficiency equal to that of unfrozen cells. It was concluded that such a freezing method would be ideal for the cryopreservation and storage of banks of Theileria annulata-infected cells for vaccine purposes.