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Oukessou, M., Hossaini, J., Zine-Filali, R. & Toutain, P.L. Comparative benzylpenicillin pharmacokinetics in the dromedary Camelus dromedarius and in sheep. J. vet. Pharmacol. Therap. 13, 298–303. Benzylpenicillin pharmacokinetics were compared in the dromedary Camelus dromedarius (n=5) and in sheep (n=5) after administration of a single intravenous injection of benzylpenicillin. The data were described by an open three-compartment model with elimination from the central compartment. Body clearance (Clb) was 4.87±0.63 ml/min/kg in the dromedary and 9.17±1.39 ml/min/kg in sheep, the steady-state volumes of distribution (Vss) were 0.151±0.023 l/kg and 0.165±0.038 l/kg and the mean residence times (MRT) 27.34±1.38 min and 14.95±4.16 min in the dromedary and in sheep, respectively. It was concluded that benzylpenicillin elimination occurs more slowly in the dromedary dian in sheep and that use of the same dosage regimen for the two ruminant species may lead to significant differences in plasma concentrations and therapeutic efficacy. P. L. Toutain, INRA Station de Pharmacologie-Toxicologie, 180 chemin de Tournefeuille, Toulouse, France.

Camels thrive in arid and semiarid areas, although food and water frequently are scarce. However, the mechanisms enabling camels to withstand food deprivation are poorly understood. In this study four female camels were totally deprived of food for 4 days. Their body weight decreased by 6%. Food deprivation caused no change in total plasma protein concentration in the camel, indicating that no alterations in plasma volume occurred. When the first meal was withheld water intake was unchanged. Next day the camels showed signs of hydration with a decreased plasma Na+ concentration and an increased excretion of diluted urine. In the afternoon water intake decreased. Urine K+ excretion fell the first day and urine volume and Na+ excretion from the third day. No activation of the renin-angiotensin-aldosterone system (RAAS) was observed. Plasma and urine urea concentration increased during food deprivation. Plasma glucose concentration and plasma cortisol and thyroxine levels did not change. Body temperature decreased during food deprivation. After refeeding, total plasma proteins increased temporarily by 12%, and a threefold increase in RAAS was seen, implying that both plasma volume and RAAs changed rapidly. Our results show that fluid balance was only slightly affected in the food-deprived camel. We suggest that strategies for the camel to endure food deprivation include maintenance of plasma volume and glucose concentration and a lowering of the body temperature.

Bovine spermatozoa were separated into different density subpopulations utilizing water insoluble hydrocarbon and silicone gels of defined specific gravity. Sperm density profiles were generated for 13 bulls. The separations were found to be repeatable and characteristic of the bull examined. Considerable density variation among animals was demonstrated. Analysis of the separated spermatozoa, before and after freezing, demonstrated that good motility and aerosomal integrity of spermatozoa were maintained. When the least dense fraction of spermatozoa was used for insemination, conception rates were similar to those obtained routinely by artificial insemination with unfractionated spermatozoa. Therefore, this system may be useful in separating spermatozoa of various densities and for removing extraneous matter from semen. However, the sex ratio, among 51 60-day-old fetuses recovered from heifers inseminated with the lowest density fraction of spermatozoa, was 26 males: 25 females.