Welfare and the intensive production of rabbits.

Rabbit production in Europe is concentrated largely in the "Latin" countries of Italy, France and Spain, in which animal protectionist attitudes are considered moderate. However, in the case of rabbits, the intensification of husbandry necessitates strict observance of physiological, behavioural and health requirements, in view of the very special needs of the species and the sensitivity of rabbits to environmental conditions. Rabbits are described as anxious, timid and emotional, with unusual arrangements for reproduction (induced ovulation) and digestion (caecotrophy). Therefore, these animals could not be reared intensively until the completion of extensive research, which has been conducted over the past twenty years, into the environmental and nutritional needs of rabbits, and the selection of lines having a calm temperament and maternal aptitude. This research was required to meet the welfare needs of this species. These concepts are perfectly integrated into the current operation of intensive units, and should not be brought into question on the basis of fragmentary observations by some researchers who would wish to see a return to rearing on litter. A discussion of rabbit welfare conducted in 1992 by specialists of the German branch of the World Rabbit Science Association approved modern methods of keeping rabbits on wire grids, provided that some changes were made to current procedures.

Hepatitis of viral origin in Leporidae: introduction and aetiological hypotheses.

In less than ten years, two very serious viral hepatic diseases have spread through Leporidae populations (rabbits and hares) in numerous countries. In May 1989, the Office International des Epizooties designated this new disease of rabbits "viral haemorrhagic disease" and entered it as a List B disease in the International Animal Health Code. Clinically, the disease is very similar to the European brown hare syndrome. However, numerous uncertainties prevail today on the true nature of the viruses of the two species. Although they are related, the viruses appear to be different and cross infection between species has given contradictory results. Hepatitis of Leporidae have probably existed in Europe for several years, although their viral aetiology has been demonstrated only recently. The acute form has occurred in hares in Northern Europe since approximately 1980, while the inapparent (or ignored) form has been present in rabbits in Czechoslovakia since 1975. These diseases of Leporidae are true viral hepatitis which, in their fulminating forms, bear a remarkable resemblance to human viral hepatitis (B and non-A non-B) with regard to clinical symptoms, pathological lesions and mode of transmission. The dominant faecal-oral transmission observed for types A and E hepatitis would explain the particular susceptibility of family-kept rabbits, as they are fed potentially contaminated fodder. As the clinically similar fulminating hepatitis in human beings is caused by a diversity of viruses (both RNA and DNA), the disease in Leporidae might also be caused by different viruses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal welfare and the intensive production of bovine meat.

After a brief review of the legal framework of animal protection applicable to cattle--including Council of Europe and European Union legislation, as well as French law--the main features of husbandry systems used in the intensive husbandry of veal calves and young cattle are analysed. For veal calves, the standards proposed at the European level do not take into account major differences in the age, weight and quality of veal produced by different Member States. In the case of red meat, the production of baby beef in intensive units leads to some behavioural anomalies, which could be remedied within economic restrictions compatible with the interests of producers and consumers.

Antibody response to rabbit viral hemorrhagic disease virus in red foxes (Vulpes vulpes) consuming livers of infected rabbits (Oryctolagus cuniculus).

Six red foxes (Vulpes vulpes) were given oral doses of homogenized liver from rabbits (Oryctolagus cuniculus) that died from rabbit viral hemorrhagic disease (RVHD) and four control foxes were given liver from uninfected rabbits. Antibodies to RVHD virus were monitored over 6 months. There was a pronounced antibody response 7 days after exposure which persisted to 14 days and then diminished. Low titers still were evident in three foxes at the end of the experiment. Based on these results, fox serum may be useful as an index of the prevalence of RVHD in sympatric rabbit populations.

Evaluation of some risks factors in bovine salmonellosis.

Previous work has given evidence of the frequency of Salmonella carriage by healthy dairy cows, the increased excretion of Salmonella by talent carriers at the calving time, and the frequency of clinical salmonellosis during that period. From this the authors evaluated the relevance of 3 risks factors supposed to play a role in the triggering clinical salmonellosis, namely: metabolic and hepatic parameters; Fasciola hepatica infestation; and bovine virus diarrhoea (BVD) infection. The prevalence of F hepatica and BVD, identical in infected and control herds, suggested that flukes and BVD did not play a significant role in the development of salmonellosis in the conditions of the present work. Although the mean values of metabolic and hepatic parameters were not different between healthy animals within infected herds and controls, the sequential monitoring performed in 2 reference herds gave evidence of important modifications at the calving time and during the early stages of milk production. If not formally demonstrated in this study, it is suggested that metabolic and hepatic changes observed during the peripartum, could result in a disruption of the intestinal ecosystem (pH, volatile fatty acids, NH3, peristalsis) and in the emergence of a Salmonella population. The excretion of considerable amounts of Salmonella by the first sick animals allows it to spread to the others, especially those with impaired hepatic functions.

Effect of cage area, cage height and perches on feather condition, bone breakage and mortality of laying hens.

1. The health of 2 flocks of 896 ISA Brown laying hens were studied successively over the years 1995 and 1996 under different caging conditions. Hens were kept in groups of 4 in a total of 224 cages. The treatments (7 different types of cages) differed in area per hen (450, 600 or 800 cm2) and height (40 or 60 cm). In the large (800 cm2/hen) and high (60 cm cage) treatment, half of the cages were equipped with perches (20 cm/hen). Each study lasted 48 weeks. 2. Feather condition was found to be independent of cage type. 3. No differences were apparent between the 7 treatments in tibia breaking strength (using the 3-point breakage technique). A significant increase in humerus breaking strength was observed in the high cages. The frequency of broken wings recorded after slaughter was lower in high cages (23%) than in low ones (36%). 4. Mortality was different between treatments. This was explained by a higher proportion of birds killed by 'body cannibalism' in the 60 cm high cages, and by a higher proportion of birds killed by 'vent cannibalism' in the cages with perches.

Viral haemorrhagic disease of rabbit: purification and characterization of a strain isolated in France.

The causative agent of rabbit viral haemorrhagic disease (VHD) was purified by CsCl density gradient centrifugation from liver homogenates of rabbits infected with a strain of VHD virus isolated in France. Electron microscopy observations revealed that the virions were icosahedral with a diameter of 33-35 nm, and with an average buoyant density of 1.33. Structural proteins were investigated by SDS-polyacrylamide gel electrophoresis and western blotting. The results indicated the presence of a major structural protein of 64 kDa and other minor proteins of molecular weight of 43, 36 and 32 kDa, the last presumably resulting from the proteolytic degradation of VP 64. These results correspond with the description made by the different authors who identify the VHD virus as a member of the Caliciviridae family.

Influence of stocking density on some behavioural, physiological and productivity traits of broilers.

In order to investigate the influence of stocking density on broiler welfare, 17,616 Ross chickens were assigned to three different treatments: T1, T2 and T3 with a final stocking density of 27, 35 and 43 kg/m2, respectively (corresponding to an initial density of 12, 16 and 20 birds/m2). Animal welfare was assessed by measuring behavioural, physiological and productivity traits. Behavioural observations included the disturbance frequency of resting birds by other birds, the duration of the lying bouts and the standing/lying ratio. The heterophil/lymphocyte ratios were assessed from blood collected before departure to the slaughterhouse. Main productivity traits were the final live weight and carcass degradation due to foot and pad dermatitis and breast blisters. Most of the observed parameters were adversely affected by the highest density (P < 0.05). Between T1 and T2, some traits tended to demonstrate that a better degree of bird welfare existed in T1 (higher standing/lying postures ratio and final live weight, lower frequency of pododermatitis and hock lesions; P < 0.05) whereas other traits showed no differences (frequency of disturbances by other birds during resting, heterophil/lymphocyte ratio). In conclusion, a stocking density of 43 kg/m2 seemed to induce poor bird welfare whereas it was not clearly demonstrated that 27 kg/m2 was better than 35 kg/m2.

Influence of stocking density on behavioural, health and productivity traits of turkeys in large flocks.

1. The effect of stocking density on welfare traits of turkeys was studied in 2 experiments. In each experiment 2,633 sexed BUT turkey poults were assigned to 3 rooms, 135 m2 with 1 treatment per room. Because of the large flock size (675,878 and 1080 birds in T1, T2 and T3 respectively) treatments were not replicated 2. Floor space allowances varied according to treatment; for the males: 24 dm2, 18.5 dm2 and 15 dm2 until week 12 and 40 dm2, 31 dm2 and 25 dm2 from week 12; for the females: 16 dm2, 12.3 dm2 and 10 dm2. 2. The scan sampling method in experiment 1 and the focal sampling method in experiment 2 were used to record behaviour at week 6, 9, 12 (males and females), and 16 (males). Birds' ethogram was divided into 7 mutually exclusive behaviours: standing/walking, resting, feeding, drinking, pecking at the environment, pecking at another bird, and preening. Position changes in the pen and the frequency of disturbances of resting birds by other birds were recorded in experiment 2. 3. Gait was assessed at week 12 (females) and week 16 (males). Prevalence of lesions, breast (males), hip and foot (males and females), were recorded at slaughter. Birds were weighed at week 12 (males and females) and week 16 (males). 4. Stocking density had little influence on behaviour except on the frequency of disturbances of resting birds by other birds, which tended to be more frequent at the highest density. 5. Gait deteriorated as stocking density increased. Hip and foot lesions were more frequent at the highest density. Bodyweight decreased significantly with decreasing floor space. 6. The results suggest that turkey welfare was poorer at the highest density than at the 2 lower stocking densities.

Influence of stocking density, artificial dusk and group size on the perching behaviour of broilers.

1. Perching behaviour of Ross broiler chickens was studied in order to increase the available space at the floor level. Pens (36 m2) were equipped with wooden perches mounted 20 and 33 cm above the litter (5 cm perch length per bird). 2. The influences of stocking density (22 vs 11 birds/m2, experiment 1) and of a 10 min artificial dusk (17 birds/m2, experiment 2) were tested in a 2x2 factorial design (n=4 by treatment) including control pens without perches. In experiment 3, perching behaviour between 2 different group sizes (1020 vs 4590 birds, 17 birds/m2, no replicates) was compared. 3. The percentage of perching birds (PPB) was assessed by scan sampling observations during the 20 to 22 h light period (8 observations per d, 5 d a week, from week 3). In experiment 2, infra-red video recording was performed at the time lights were dimmed and during the dark period. In experiment 1, carcase lesions were noted. In experiment 2, tibia breaking strength of frequently perching birds was compared with controls. Birds were weighed before slaughter and food conversion was calculated. 4. PPB increased with age and density (P<0.01) and was highest at the 22 birds/m2 density during week 6 (mean=10.6%, maximum=13.5%). PPB was not influenced by a 10-min artificial dusk. In experiment 3, PPB was slightly lower during weeks 5 and 6 in the large group size compared to the small group size (6.8% vs 7.9% respectively in week 6). 5. Prevalence of carcase lesions and tibia breaking strengths were unrelated to perch usage. Final body-weights were not influenced by the presence of perches except at the 22 birds/m2 density where males were slightly heavier in the control pens compared with males in pens equipped with perches (2096 g vs 2051 g, P=0.015). Food conversion was independent of the presence of perches.

Molecular epidemiology of rabbit haemorrhagic disease virus outbreaks in France during 1988 to 1995.

In order to evaluate genetic variation between rabbit haemorrhagic disease virus (RHDV) isolates and to derive phylogenetic relationships, 56 virus isolates collected from various parts of France over a 7 year period (1988 to 1995) were examined. Analyses were carried out by direct nucleotide sequencing of PCR fragments of three genomic regions encoding the capsid protein (VP60) (regions A and B) and a non-structural protein (region C). Multiple sequence alignments revealed maximum nucleotide divergence of 7.6, 9.4 and 8.7% for regions A, B and C, respectively, indicating a high level of conservation between isolates. Irrespective of the genomic region analysed, phylogenetic analyses carried out using various methods allowed the identification of three genogroups; distribution of isolates within these genogroups appears to be more related to the year of their collection than to their geographical origin. The possible evolution of RHDV is discussed.

Environment and gastro-enteritis.

Pathologists are always tempted to account for the occurrence of diseases by the presence or absence of some specific microbiological agent. It is the case when a major infectious agent is in contact with a receptive animal. When the Transmissible Gastro-enteritis virus is introduced into a susceptible herd, the results of the infection are calamitious. Nevertheless, the relationship between the infection and the disease is rarely simple. It is necessary to distinguish two kinds of diseases: --the monofactorial diseases (T.G.E....) --the multifactorial diseases (Colibacillosis especially after the weaning...). For these multifactorial diseases the clinical signs and the lesions are induced by an infectious agent which can be considered as a final "effector" whose multiplication depends on factors in the farm which disturb physiological or immunological mechanisms of regulation (humoral immunity, clearance, intestinal motility...). The herd system can be defined by 6 variables which could be considered as limiting factors responsible for the onset of digestive disorders: food, building, management, animal with specific and non-specific resistance, microbism and the farmer who plays a main role in the control of these variables. The disease has to be considered not only as the result of the multiplication of the microbe which is often the last actor of a morbid process but also as the disharmony of the variables defining the structure of the herd.