A study of free-running rhythms in sheep.

Free-running rhythms for eating, drinking, standing and walking activities were studied in two experiments with four cross-bred rams. In the first experiment the rhythms were entrained to a LD (12:12) (300:0) regimen. Following a change to continuous dim light (less than 2 lux) there was a suggestion of free-running activity for about three days in some of the variables. By the fourth day, however, the previously entrained rhythms had been damped out and were replaced by random patterns of activity in all variables. In the second experiment, two entraining agents were used: LD (12:12) (300:0) and restriction of feed to the light period only. There was again some indication of free-running activity for the first few days of continuous dim light (less than 2 lux) but by the fourth day only random patterns of activity were evident.

Electrocardiograms of male rats fed rapeseed oil.

Frontal plane electrocardiograms (standard limb leads) were recorded on male Sprague-Dawley rats fed for 14 weeks on semisynthetic diets containing 20% (by weight) of Brassica napus cv. Tower or B. campestris cv. Span rapeseed oil or fractions isolated from Span rapeseed oil. Control diets were rat Chow or semisynthetic diets containing 20% (by weight) of either safflower oil or corn oil. The amplitude of the P, Q, R, S, and T waves, the duration of the P wave, QRS complex, and P-R interval, and the cardiac rate were measured in the electrocardiograms and differences between groups compared statistically. While there were statistically significant differences in the amplitude of some of the wave forms, there were no consistent differences which could be attributed to the feeding of rapeseed oil or its fractions. The duration of the P wave and the QRS complex were significantly longer in some of the control groups than those in most of the treated groups. There was no correlation between the presence of a Q wave and the incidence of myocardial lesions in any group. Cardiac rate was essentially the same in all groups.

A system for studying biorhythms in domestic sheep in confinement.

A system is described for studying biorhythms in domestic sheep. One animal in each of four temperature and light controlled rooms can be studied in pens designed to permit continuous monitoring of eating, drinking, walking, resting, body temperature and cardiac rate. Automated data acquisition, including analog-to-digital conversion, is controlled with a minicomputer. Digitized data are recorded on magnetic and punched paper tape. Data processing on large scale computers includes editing, summarisation, machine plotting and time-series statistical analysis of the period, amplitude and phase of the biorhythms.

Vaginal temperature rhythms in sheep.

Six ovariectomized adult sheep were tethered in a temperature--and light--controlled room and given feed and water ad lib. Vaginal temperatures were recorded at 10m intervals for 12 or 17d. Hourly means were calculated and subjected to statistical anlayses by time--series procedures. Initial analysis revealed a positive linear trend in most animals suggesting a low frequency rhythm with a period greater than the 17d experimental period. All subsequent analyses were, therefore, conducted on data adjusted for a linear trend. The periodogram, correlogram and spectral density analyses revealed a predominant circadian rhythm in 5 of the 6 animals. Ultradian rhythms, with periods of 12 and 8h, were also present in some animals. The magnitude of the rhythmic change in vaginal temperature, as estimated from the amplitude of the circadian component, varied from 0.05 degrees to 0.16 degrees C. Calculation of the external acrophase indicated that the daily maximum temperature occurred between 0851 and 1727.

The development of dermal lesions and alopecia in male rats fed rapeseed oil.

For 8 weeks 10 male weanling Sprague-Dawley rats were fed a semisynthetic diet containing by weight either 20% corn oil or rapeseed oils containing different amounts of erucic acid (Brassica napus var. Zephyr, 0.6%; B. napus var. Oro, 1.8%; B. campestris var. Span, 4.8%; or B. campestris var. Echo and Arlo, i.e., regular rapeseed oil, 23.6%). At 4-5 weeks after the experiment began, rats receiving the diets containing rapeseed oil showed evidence of alopecia and developed scaly, hemorrhagic, and necrotic tails, as well as scaliness of the feet, similar to the lesions described in essential fatty acid (EFA) deficiency. This condition became most severe between 5 and 8 weeks and had disappeared by 14 weeks. Fatty acid analysis of the diets and tissues of the animals did not reveal any evidence of EFA deficiency. It is suggested that these symptoms observed might be related to a possible inhibition of prostaglandin biosynthesis in rats fed rapeseed oils.