104 Abstracts

12. Time spent in shelter in relation to weather by two free-ranging thoroughbred yearlings during winter

P. Michanek and M. Bentorp

Swedish University of Agricultural Sciences, Department of Farm Buildings, Box 945, S-220 09 Lund, Sweden

Two free-ranging thoroughbred fillies, S-10 months old, were used to study the utilization of a straw-bedded shelter in winter in the south of Sweden. During the experiment, temperature varied between + 10°C and - 10°C and wind-speed ranged from 0 to 30 m/s. No natural wind or rain protection was available.

The interior of the shelter was video-taped for a total of 27 24 h periods. Temperature, wind and precipitation were recorded twice a day, at 07.00 and 17.00. The exact time spent inside the shelter was determined from the video recordings.

The horses spent an average of 7 h and 25 min per 24 h period inside the shelter. They lay down for a total of 4 h and 40 min. There were significant differences between day (06.00-18.00) and night (18.00-06.00) observations. During daytime the horses spent an average of 2 h 56 min inside the shelter, with 1 h 21 min in the lying position. The correlation between total time and time spent lying was 0.61. Rain significantly increased the time spent standing in the shelter and increasing wind was also associated with more time spent standing in the shelter during day-time. During the night, an average of 4 h 30 min was spent in the shelter with 3 h 20 min in the lying position. There was a 0.91 correlation between time spent in shelter and time spent lying. No significant correlation with weather was found.

It was concluded that the need for a comfortable lying place was the main motive for the horses to use their shelter. Rain and strong winds increased the use of the shelter, but the need for weather protection was probably secondary to behavioural needs. Interpretation of these findings is not straightforward.

On the one hand one might conclude that weather protection in winter for well-fed horses is not strongly needed, since they chose to leave their shelter during hard weather in the night, in order to perform apparently pointless behaviours like grazing a practically nonexistent winter pasture. From another point of view it might be argued that if the behavioural needs are strong enough to make the horses leave their shelter during severe weather, there is good reason to question traditional indoor keeping of horses in individual boxes.

13. Genetic influences on psychobiological responses to the environment

P. Mormede’, C. Desautes’, S. Garcia-Belenguer4, V. Perreau’, A. Sarrieau’, M. Moisan’, J.C. Caritez’ and Y. Levreton3

‘Genetique du Stress, Insenn-INRA, Bordeaux, France *Domaine du Magneraud, INRA Surgeres, France 3Station du Recherches Porcines, Rennes, France 4Facultad de Veterinaria, Zaragoza, Spain

The response to environmental challenges involves both behavioural changes and neuroendrocrine adjustments. All the components of this response display a large range of interindividual variation.

Abstracts 105

It has been clearly shown that heredity plays a large part in the control of adaptive responses. The goal of our studies is the detection of the genes involved in this control. When compared to the European Large White breed, Chinese Meishan pigs have an hyperactive adrenocortical axis, as shown by their high circulating levels of cortisol, and the resistance of their pituitary-adrenal system to dexamethasone suppression. The analysis of these neuroendocrine characteristics suggests that the adrenal gland is hyperactive to ACTH. Furthermore, very low levels of both type I and type II receptors were found in the hippocampus of these animals. On the other hand, Meishan pigs also show a low behavioural reactivity to stress, as shown for instance by their reduced struggling response to handling, or their low locomotor response in a novel environment. The pigs from the Fl crossing (LW x MS) have an intermediate phenotype and we use the animals from the segregating F2 crossing to analyse the genetic correlations between different traits of psychobiological reactivity (is there a common control of behavioural and neuroendocrine characters), between stress reactivity and production traits, and finally to detect at the molecular level the genes involved in the control of stress responses.

14. Sheep health, disease and welfare in southern New Zealand

M. Orr

Invermay Health Laboratory, Mosgiel, New Zealand

In southern New Zealand, sheep farms range from about 200 hectares with around 13 sheep (usually Romney types) per hectare on lowland grassland farms, to over 1000 ha with < 4 sheep (often Merino types) per hectare in remote high country areas. ‘Extensive’ is a relative term, but compared with European farming systems, all sheep farming in this region could be considered to be extensive.

Sheep in New Zealand are remarkably disease free. This can be attributed to factors such as the geographic isolation of the country, its relatively recent colonisation, its temperate climate and insect vector-free status and of course its extensive farming systems. The temperate climate allows pasture to grow for most of the year, and most livestock to be farmed outdoors all year round.

There is a long list of diseases exotic to New Zealand, including bluetongue, jaagsiekte, maedi-visna, chlamydial abortion, scrapie and the vesicular diseases (such as foot and mouth disease). This healthy state of affairs is something we safeguard with stringent border controls and disease control and surveillance systems.

Animal welfare is closely bound to animal health and disease. Freedom from disease is one of the five ‘freedoms’ we try to ensure in the good management of domestic animals.

Johne’s disease in sheep is not uncommon in the southern half of the South Island. Fortunately there is an effective vaccine available for use on problem farms. Other diseases that once caused significant production losses can also be controlled by the use of effective vaccines-these diseases include abortions caused by Campylobacter spp. and Toxoplasma gondii; clostridial diseases (which now occur at a low prevalence) and salmonellosis (which can cause significant outbreaks of disease in ewes).

The diseases that cause most production losses in New Zealand’s relatively extensive farming systems are probably trace element deficiencies, gastro-intestinal parasitism and foot problems.

The stress of bad weather can predispose to a variety of disease. In sheep, the most significant of these in the region are the metabolic diseases: acetonaemia, hypomagnesaemia and hypocal- caemia.