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The age at which piglets are separated from the sow has been identified as an animal welfare risk in current swine production systems. Animal welfare gains of a minimal disease state must be objectively balanced against the welfare costs of early weaning. Veterinary practitioners should continue to participate in the development and validation of humane animal production methods.

Allotransplantation of organs is one of the most prominent medical achievements of this century. The success of allotransplantation has, however, provoked a problem or organ shortage. In order to overcome these problems, the possibility of using animals as potential donors for humans (xenotransplantation) is considered. Many investigators recently proposed the pig as an alternative source of organs. Pigs are easy to breed, have anatomical and physiological characteristics compatible with humans, and are well studied for several pathogens potentially transmissible to humans. Moreover transgenic pigs can be obtained expressing human proteins in order to resist hyperacute rejection. Caesarean-derived piglets can easily be maintained gnotobiotics or specified-pathogen free. The pig being nowadays the best candidate for xenotransplantation, this paper will focus on the potential public health risk linked to the use of this species as a source of organs, and the general rules to follow in order to manage it, (risk management).

In the first part of this paper, the authors discuss the growing concern of consumers for farm animal welfare, and the attitude adopted by veterinarians to cope with this new and more humanitarian concept of intensive husbandry. The effects of intensification of pig production on the ability of pigs to adapt, and the behavioural, husbandry and health consequences of the principal stress factors in pig rearing are reviewed and illustrated by examples from recent research. In conclusion, the authors discuss the importance of constructive integration of welfare into pig production, in training courses and in actual application.

This paper reviews experimental data on exogenous pST administration effects on growth and carcass performances in pigs to show the importance pST could have for pigs breeding in Africa. In Europe and USA pST breeding conditions induced growth rate increase (+18.7%) and a decrease of the feed intake (-14.6%) and the feed/gain ratio (-26.5%). The carcass muscle percentage was increased (+17.8%) and the fat rib was decreased (-25.6%) in treated animals compared to controls. pST induced a generalised thoracic and abdominal organs hypertrophy which can partly explain the slight decrease of dressing percentage. On the meat quality pST didn't have any pronounced detrimental effect. According to these interesting results, pST effects must be tested in Africa breeding conditions.

Innovation, quality, variety and flexibility of production require simultaneously an improvement of professional skills and an increase in cooperation. However, this cooperation should not be reduced to a mere data exchange, but must extend to a co-construction of new representations and new action schemes. In this way, health advising integrates production and knowledge apprenticeship, which we studied using a didactic approach (from the knowledge point of view). In this article, we will establish that animal ecopathology, by the standardization of the breeding description through diagnostic activity, has contributed to the strengthening of the cooperation between the breeder and the practicien.

An experimental model representing the pollution background in a pigpen was constructed in order to study the toxicology of pig respiratory air pollutants. Temperature, relative humidity, air-flow rate, total dust, total viable particles, endotoxins in respirable dust (< 5 microns) and ammonia were measured in a 1.9 m3 environmental chamber designed for piglets. The activity of 1 piglet was recorded on video. Temperature and relative humidity were respectively 23.9 +/- 1.3 degrees C and 70.5 +/- 8.3% (mean +/- SD). Air flow rate was 10 m3/h. Dust, viable particles, endotoxin and ammonia concentrations were respectively 7 +/- 2 particles/ml, 3.4 x 10(4) +/- 2.9 x 10(4) BCFP (bacterial colony-forming particles)/m3, 4.8 +/- 1.5 ng/m3 and 6 +/- 0.8 ppm (mean +/- SD). All these parameters were comparable to the lowest values recorded in pigpens.

Food intake enhances the release of intestinal cholecystokinin (CCK) in the pig but the contribution of individual nutrients to the CCK response has not yet been established in this species. Six hogs (mean weight 50 kg) were fitted with a duodenal fistula for instillation of nutrients and with portal (PV) and carotid (CA) catheters for blood sampling. After a 24-h fast, the animals received 1,000 ml of isotonic solution containing 440 kcal of carbohydrate (starch hydrolysate), or of protein (casein hydrolysate) or fat (Intralipid) or a control saline solution by 60-min intraduodenal perfusion after a 60-min control period during which the animals received saline. Portal and peripheral blood samples were collected at 15-min intervals for CCK radioimmunoassay. Intraduodenal perfusion of fat provoked a sharp increase in CCK-Like immunoreactivity (CCK-LI) in PV (peak 76.6 +/- 12.2 pM from basal 10.8 +/- 1.2 pM) and in peripheral blood (peak 46.7 +/- 8.4 pM from basal 9.1 +/- 1.0 pM). The protein hydrolysate induced a transient increase in plasma CCK-LI during the first 30 min of intestinal perfusion (PV: peak 40.1 +/- 5.0 pM from basal 11.9 +/- 1.4 pM; CA: 31.8 +/- 4.0 pM from basal 8.5 +/- 0.8 pM). The transient effect of proteins on CCK release might reflect the consequence of somatostatin release from intestinal stores. Starch hydrolysate promptly raised plasma CCK-LI level to a plateau value (PV: 52.5 +/- 13.1 pM from basal 11.9 +/- 1.4 pM; CA: 35.4 +/- 8.0 from basal 8.5 +/- 0.8 pM).(ABSTRACT TRUNCATED AT 250 WORDS)

50-kg pigs fed a purified wheat starch and casein diet were fitted with a gastric cannula. Gastric emptying was studied by checking the residual gastric contents at 30 min and 1, 2, 4 and 7 hrs after feeding. Five of the 25 pigs were used as controls; 5 were submitted to total vagal deafferentation including removal of the left nodose ganglion, right truncal vagotomy at the diaphragm and resection of the interconnecting branches between the two vagi on their intrathoracic course; 5 were submitted to total contralateral vagal deafferentation; 5 only underwent left truncal vagotomy and resection of the connectives; 5 were submitted to the contralateral operation. Total vagal deafferentation, suppressing bilateral afferences originating below the diaphragm, resulted in much higher residual gastric contents at all times studied after the meal. Significant gastric retention was also observed after unilateral truncal vagotomy as compared to the controls. Nevertheless, this retention was significantly lower than after total deafferentation. The reduced emptying rate after total vagal deafferentation was a result of the loss of all afferences, while the simultaneous reduction of efferences was of little importance. The mechanisms responsible for gastric retention have been discussed in relation with the sustained antral hyperactivity previously found in deafferented pigs and with the various controls of gastric emptying. Several factors may be involved, including both motor and secretory changes. The prolonged postprandial activity of the gastric antrum seemed to be a consequence of gastric retention.

Postnatal mortality rate of piglets increases in relation to the number of suckled piglets and decreases when piglet birth weight increases. Moreover it is lower with second parity sows independently of prolificacy. Higher mortality rate observed with first parity sows seems related to lower piglet birth weight.

Effects on reproduction of feed restriction during different periods of growth were investigated in 76 Large-White gilts given one of 3 treatments between 79 days of age (27.9 kg) and puberty. The control gilts (group 1) were fed ad libitum during the experimental period, and those in group 2 received 12% less feed from 61 kg of liveweight until puberty. The gilts in group 3 received 33% less feed before 61 kg and were then pair-fed with the gilts in group 1. All the gilts were mated at first estrus and received 2.4 kg of feed per day during pregnancy. They were laparotomized at 38 days after mating and slaughtered at 105 days of pregnancy to measure early and late embryonic mortality. Contrary to group 3 (age at puberty: 256 days), no difference was found in age at puberty between group 1 and 2 gilts (232 and 226 days, respectively). Early undernutrition delayed age at first estrus, even when followed by normal feeding after 61 kg of liveweight. The gilts in group 2 had less backfat (backfat depth 24 vs 31 mm) and weighed less at puberty than the others (111 kg vs 124 kg). Severe undernutrition tended to increase early embryonic mortality (21.1, 18.8 and 33% in groups 1, 2 and 3, respectively) but the reverse was observed thereafter so that there was no difference in total embryonic mortality at 105 days of gestation (32.6, 30.6 and 36.5% in groups 1, 2 and 3, respectively).

Blood samples as well as mesenteric fat for measurement of biochemical parameters were taken from 51 wild boars (36 males, 15 females) slaughtered over a period of one year. The relative weight of the mesenteric adipose tissue as well as its lipid content showed a maximum in the autumn and regularly decreased until the end of the next summer. The lipid content thus ranged from 39 to less than 10% at the end of the summer. Variations in the blood levels of some metabolites measured in the plasma were compared with the nutritional status of the animals. The values showed a high glycaemia (158 mg/dl) that varied little with the season. In contrast, the cholesterol level decreased from the autumn till late winter with a minimum value in March (89 to 50 mg/dl). The level of total proteins, which was low from February to September, increased during the autumn-winter period, independently of the albumin content which seemed to be constant. The urea content was highly variable thus masking possible seasonal variations. The creatinine level showed a minimum in the autumn (2.0 mg/dl) and a maximum in the summer (2.9 mg/dl), a period with little abundant food supplies. Thus, the wild boar exhibits large seasonal variations of its metabolism and constitutes body reserves which are mobilised during periods of reduced food availability. The mesenteric fat weight as well as the blood levels of cholesterol and creatinine seem to characterize rather well the nutritional status of this animal.

Qualitative and quantitative changes in pig lymphocyte sub-populations (T, B, L and nulls) were studied in the mammary gland of primiparous sows, as well as the appearance and development of plasma cells in relation to the 3 phases of mammary development: gestational, colostral and lacteal phases. Results showed: 1) An early colonisation of mammary epithelium from the beginning of the gestation phase by the three T, B and L lymphocyte subpopulations; 2) The presence of activated T lymphocytes, especially during the colostral phase; 3) The appearance of plasma cells during the colostral phase and their increase during the lacteal phase; 4) Not only the T, B and L lymphocyte subpopulations increased during the lactation but there was also a special increase in null lymphocyte subpopulation. These results give new data which are particularly important in allowing us to envisage immunization schemes for the pregnant sows, with the aim of enhancing local mammary or lactogenic immunity by transfer of antibodies and lymphocytes to the newborns.

The exploratory behavior of pigs was studied in two successive daily 20-mn sessions in a two-compartment box by counting the number of crossings from one compartment to the other and observing the activity patterns. Injection of 1 mg/kg diazepam before the first session increased the number of crossings without affecting the temporal decline of activity within the session; treated pigs did not attempt to escape the experimental situation and tended to be more perseverative in their activity patterns than control pigs. Injected before the second session, diazepam did not modify the exploratory behavior. There was no evidence of a state-dissociation effect in experimental groups for which the treatment condition differed from one session to the other. These results are discussed with respect to current theories about the behavioral effects of benzodiazepines.

Feeding behavior has been analyzed in Large-White and Chinese pig breeds. Maximally automatized apparatuses, especially adapted to animal size, were used. Besides the usual parameters measured such as food intake, meal size, meal duration, meal frequency, intermeal intervals and postprandial correlation, these apparatuses also permitted us to measure the rate of intake during the meal. This rate was constant throughout the meal in ad libitum conditions and after 24-hour deprivation. A positive correlation between meal size and length of the postmeal interval was found in only half of the animals. During this work, we began to study the mechanisms initiating food intake.

Sexual steroids are involved not only in the triggering of sexual activity but also in sex-linked social behaviour (aggressiveness etc.) The use of anabolic agents (particularly steroids) raises the problem of their possible interference with these mechanisms. In the normal male, an injection of androgen does not alter the level of sexual activity, which seems to be determined by nervous mechanisms. On the contrary, by feed-back in the hypothalamo-hypophysial mechanisms it exerts a depressive effect on the endogenous secretion. Female hormones have an inhibiting effect which works both by reducing the actual secretion of androgen and by direct action at two levels: the nervous receptors and the target organs of the genital apparatus. In the female, injections of exogenous hormones may interfere with the mechanisms regulating the oestrous cycle, e.g. inhibition of oestrous and of ovulation by progestagens, and luteotrophic or luteolytic action in the case of the estrogens. In an ovariectomized female the injection of testosterone propionate causes the appearance of sexual receptivity. The behaviour induced in this way is completely normal and free from any abnormal male component. The importance of this action has led to the presumption of a role played by the androgens in the normal triggering off of female sexual behaviour. It therefore seems that the nervous system of the female, but not of the male, possesses a potential bisexuality. The rate at which the hormone passes into the circulation appears to be more important than the actual type of hormone (estrogen or androgen) in causing the appearance in the female of sexual behaviour of one or the other sex. It has been suggested that estrogens might be the active steroid form necessary at the nervous structure level for initiating sexual behaviour in the two sexes, while the androgens would have to undergo aromatization in order to acquire their effectiveness at that level. Aggressiveness depends on the sexual hormones; the androgens are normally responsible for the high level of aggressiveness in males. On the other hand, in some species the characteristic aggressiveness of the female is explained by the presence of progesterone (e.g. hamsters). The territorial marking typical of the male of, for example, the dog, cat and rabbit species etc. is also due to the androgens. The pheromones usually depend on the sexual hormones (pheromones of sexual attraction which promote or inhibit aggression, etc.) A "sexualization" of the nervous system exists---e.g. of the hypothalamus---which is refelcted not only in the modes of hypophysial secretion but also in the type of sexual behaviour. This sexualization occurs through the loss of the possibility of a female-type reaction that occurs in the male under the influence of the androgenic secretions of the foetal or neonatal testicle. Therefore this action appears at an early stage and is conclusive...

This paper presents a study of the metabolic and contractile types of 34 samples from 30 muscles in five crossbred Pietrain-Large White pigs 6 to 7 months old. The activity of the following enzymes was measured: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase using high (LDH-h) or low (LDH-b) pyruvate concentrations in the reaction medium, citrate synthase (CS), and myofibrillar Ca-Mg activated ATPase. Haeminic iron and ultimate pH (pHu) were measured on the same samples. The results showed a negative, rather linear relationship between GAPDH, LDH and ATPase activities on the one hand and CS and haeminic iron on the other. Rather high correlations (r = 0.7 to 0.8) were observed between metabolic and contractile criteria and pHu; the red (slow) muscles had the highest pHu.

This study describes the instruments used in recording the feeding patterns of 21 pigs of three different breeds fed ad libitum from weaning to adulthood. The feeding behavior of the pigs was characterized by 1) the presence of well individualized meals, and 2) the circadian distribution of food intake: whatever the breed, the animals preferred to eat in the daytime. This diurnal character of food intake was accentuated gradually with age. The frequency of the daily food intake decreased progressively from a mean of 9.5 meals after weaning to usually 3 at adulthood when growth was finished (2 meals in the daytime and 1 at night).

Bile salt output and digestive utilization of a high-lipid diet were studied in pig bile collected from the common bile duct and infused into the duodenum then into the distal ileum of the animal. Five Large-White pigs of 50 kg body-weight were fitted with three permanent fistulae, one in the common bile duct for complete collection of bile secretion, and the other two in the duodenum and the ileum (at about 80 cm from the ileo-caecal valve) for returning the secretion to the animal. The diversion of the bile into the distal ileum led to a significant 82 p. 100 decrease in daily bile acid output and a 36 p. 100 decrease in apparent digestibility of dietary energy when compared with values obtained when bile was infused into the duodenum. The latter decrease was mainly due to a marked diminution ( - 60.4 p. 100) of the digestive utilization of the dietary lipids. The results show the role of the pig small intestine in maintaining an efficient enterohepatic circulation of bile acid as a result of optimal utilization of the dietary lipids.

Social isolation and exposure to a new environment induce hyperactivity, vocalizations and ACTH release in weaned Piglets acutely submitted to this stress. These reactions are increased by pretreatment with morphine (0.5 and 1 mg/kg) and decreased by naloxone (1 mg/kg), suggesting that endogenous opiates modulate emotional behaviour in Pigs.