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Cage position preferences of rats
by Matti Heikkilä, Riina Sarkanen, Hanna-Marja Voipio, Satu Mering & Timo Nevalainen

Polycarbonate and stainless steel are commonly used cage body materials for laboratory rodents. The aim of this study was to assess preference of rats for the cage material. Altogether 64 male rats were used, 32 in two different facilities. The study cages were made of either stainless steel with a polycarbonate false inner half (Kuopio) or polycarbonate with a steel false inner half (Oulu). There were four different options for alignment of false cage halves and food hopper, and likewise two options for which end of the cage faced the wall. A video camera with time lapse recording of one second each minute was used. Weekly recording started at 16.00 and ended at 01.30, and each cage was recorded when the rats were aged four, five, six, seven and eight weeks. The results were processed separately for both facilities and for day and night. Statistical analysis was done with ANOVA using alignment of food hopper to false inner cage half and direction to the wall as the main effects. During the daytime the location of the rats in nontransparent steel body cages is largely governed by the light intensity created by cage walls and hopper, but stainless steel was clearly preferred in three of four possible combinations. During the night the element of light direction became less important, but again hopper and steel combination was more attractive than the hopper and polycarbonate combination. In polycarbonate cages with false steel inner half cages, the light intensity difference had a less prominent role. However, during the day, placing the feed hopper with steel was preferred. During the night, the even distribution was indicative of a slight preference to the familiar wall material, polycarbonate. In conclusion, in both study sites stainless steel was favored in 3 out 4 possible combinations during the day. During the dark, when transparency of the material was less critical, animals accustomed to a stainless steel cages preferred steel over polycarbonate, but for animals raised in polycarbonate cages neither steel nor polycarbonate was favored.

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Probiotics in gnotobiotic mice: Short-chain fatty acids production in vitro and in vivo by by Maria E. Cardona, Tore Midtvedt & Elisabeth Norin

Several bacterial strains are currently used as probiotics. Sixteen of them belonging to the genera: Bifidobacterium, Enterococcus, Lactobacillus and Streptococcus, were selected to test short-chain fatty acids (SCFAs) production in vitro and/or in vivo. The probiotic strains were monocultivated in specific media and/or monoassociated with NMRI-KI germfree (GF) mice. The individual and total amounts of SCFAs were measured in the media and in the large intestinal content of the ex-GF mice. All the samples were assayed by gas-liquid chromatography. We found that commercially available media contain detectable amounts of acetic and propionic acids. When cultivated in vitro, none of the probiotic strains was able to increase the amounts of SCFAs present in the medium. Rather, a tendency to lowering the concentration of SCFAs following cultivation, was observed. We also found that commercially available laboratory rodents chow contained detectable amount of all SCFAs. When the probiotics were monoinoculated to GF animals, nine out of sixteen groups of mice showed higher amount of intestinal SCFAs than in the GF control group. Acetic acid was the dominant one. In all cases, however, the values of the SCFAs were far from those found in conventional mice. The results clearly underline the importance of working with laboratory animals with a known flora, i. e. gnotobiotic animals, when the biochemical "profile" of a probiotic is worked out.

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The telemetric monitoring of heart rate during copulatory behavior in the male rat
by T.R. Saito, R. Hokao, M. Terada, K.W. Takahashi, H. Tsubone & S. Sugano

We have studied the physiological and behavioral responses in male rats to copulation and exercise. For this purpose, electrocardiographys (ECGs) were recorded from conscious and unrestrained rats using radiotelemetry system. Heart rate during copulation rose sharply following the induction of a receptive female, showed a peak of about 520 bpm during each ejaculation series, and then rapidly decreased. To compare the rate of decrease after ejaculation with that following vigorous exercise, we run male rats on a motor wheel until heart rate became to the same value during ejaculation. Following the cessation of exercise, heart rate decreased gradually. The possible role of the autonomic nervous system in the changes of heart rate during copulation and exercise is discussed.

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Occlusion prevents the use of vascular loops for blood sampling and dosing in minipigs
by Hrund Larusdottir, Aage Kristian Olsen, Hanne Gamst-Andersen, Marianne Olholm Larsen & Axel Kornerup Hansen

Continous blood sampling and intravenous dosing are difficult in pigs, especially minipigs. A skin loop containing the jugular vein or the carotid artery has been used for solving this problem in other species of animals, but it has never been attempted in the pig. In this study eight such skin loops were made on minipigs, which technically caused only a few problems. Shortening the loop and widening the distance between the two parallel incisions reduced problems of necrosis and improper wound healing. A juvenile pig did not show such problems. However, in all loops excessive formation of fibrotic tissue occluded the vessel after approximately six days. We, therefore, conclude that although the surgical technique is possible, further modification, e.g. by insertion of a rigid artificial vessel or an in-dwelling catheter, is necessary, before vascular loops can be used as a method for continuous sampling and dosing in minipigs.

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Meet another Member Association of FELASA: NVP

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Summary of Discussions from the Scanbur Workshop Seminar March 2001 "Improving Welfare for Animals and Staff"
by T.C. Krohn,

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Meetings