Antibiotics have long been of great benefit for people, both in the medical treatment of human disease and in animal food where they improve the growth performance and feed utilization during animal production. Antibiotics as in-feed supplements affect all stages of pork production, including the gestation, nursing, growing, and finishing stages, although the effects show stage-dependent differences. However, the use of antibiotics in animal feed has become a worldwide concern. This review describes why sub-therapeutic levels of antibiotic additives in animal feed have become an integral part of animal feeding programs for more than 70 years, particularly in pork production. It also discusses the threat of the long-term use of sub-therapeutic levels of antibiotics in pork production. In recent years, the effectiveness of in-feed antibiotics has tended to decrease. This review analyzes this change from various perspectives. First, the equipment used at pig farms has improved dramatically and is more sanitary. Worldwide, more pig farms use pig farrowing crates, gestation crates, piglet nursery crates, flooring devices, piggery ventilation and cooler systems, automatic pig feeders, piggery heating equipment, and artificial insemination systems. In addition, scientists have replaced the use of antibiotics with organic acids, fermented mash, probiotics, prebiotics, minerals, oligosaccharides, enzymes, herbs/flavors, and protein/amino acids, and have improved management and husbandry techniques. In addition, animal welfare legislation has been aimed at improving the quality of the floors and living space, ensuring that animals have permanent access to fresh water, and setting a minimum weaning age. Finally, the prospects and the possibility of replacing antibiotics in pork production are described, in line with recent research results.

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ABSTRACT. Growth hormone (GH) is secreted in a pulsatile manner, but the underlying mechanisms of GH pulse generation remain to be resolved. In the present study, we investigated the relationship between GH pulses in the peripheral circulation and GH-releasing hormone (GHRH) and somatostatin (SRIF) profiles in the cerebrospinal fluid (CSF) of male goats. The effects of an intracerebrovent ricular (icv) injection of neuropeptide Y (NPY), galanin and ghrelin were also analyzed. Blood and CSF samples were collected every 15 min for 8 hr from the jugular vein and third ventricle, respectively. GH pulsatility in the goat was found to consist of distinct large pulses of 5 hr periodicity and small pulses of 1 hr periodicity. GHRH and SRIF in the CSF fluctuated in a pulsatile manner with 1 hr periodicity, and most of the descending phase of SRIF pulses were associated with the initiation of GH pulses. Icv injections of NPY, galanin and ghrelin stimulated GHRH release without affecting SRIF release. In addition, NPY suppressed, and galanin and ghrelin induced large GH pulses, although ghrelin was much more effective than galanin. These results suggest that an hourly fall in SRIF is involved in generating intrinsic circhoral rhythm of GH pulsatility. The mechanisms underlying the generation of large GH pulses of 5 hr periodicity remain unknown, while direct action of NPY and/or ghrelin on the pituitary might be involved. KEY WORDS: ghrelin, growth hormone, growth hormone-releasing hormone, NPY, somatostatin.J. Vet. Med. Sci. 66(9): 1071-1078, 2004 Growth hormone (GH) is secreted in a pulsatile manner in all mammalian species studied to date, and this pulsatility plays an important role in the regulation of somatic growth and metabolism [7,10,15,20]. Knowledge of the exact mechanisms underlying the generation of GH pulses is, therefore, of physiological and pathophysiological importance. It is generally accepted that GH pulses are governed by two hypothalamic peptides, GH-releasing hormone (GHRH) and somatostatin (SRIF), which are stimulatory and inhibitory for GH secretion, respectively [15,29,34,41]. Most studies on the neuroendocrine regulation of GH pulsatility have been performed in male rats, in which GH secretion is characterized by a strikingly regular ultradian rhythm with large secretory bursts of every 3-4 hr [15,41]. In the rat, indirect studies such as passive immunizations against GHRH and SRIF suggested that GH pulses depend on GHRH discharge in combination with a decrease in SRIF secretion [29,41]. However, the secretory profiles of GHRH and SRIF under physiological conditions in this species remain to be elucidated because of the technical difficulties involved in collecting pituitary portal blood from unanesthetized animals. On the other hand, direct measurement of GHRH and SRIF in the portal blood from conscious animals has been reported in the sheep [4,12,44]. According to these studies, GH pulsatility in the sheep seemed less regular and the secretory patterns of GHRH and SRIF seemed more complex than ...

AIM: To investigate the mechanism underlying intestinal barrier function damage after severe trauma and the therapeutic effect of glutamine. METHODS:Burned patients, and animal models of severe trauma replicated by hemorrhagic shock combined with endotoxin infusion and burn injury, were included in a serial experiment. Effects of oral glutamine on intestinal barrier function were observed in scalded rats. Parameters measured in these experiments were as follows: plasma levels of diamine oxidase (DAO), tumor necrosis factor (TNFα α α α α), endotoxin (LPS), and lactate as well as D-lactate by biochemical methods, lactose/mannitol (L/M) ratio in urine by SP-3400, and pathological examination of intestinal mucosa under light microscopy. RESULTS: INTRODCTIONIt is generally accepted that the intestine may serve as an important organ in the development of severe complications under critically ill conditions, including trauma, burns, shock, etc.[1-3] Hemorrhagic shock and/or gut ischemia-reperfusion injury commonly occur in the early stage after acute insults, leading to gut-derived sepsis as a result of gut barrier dysfunction [4][5][6][7][8][9][10] . In order to investigate the mechanism underlying intestinal barrier function damage and its potential interventional measures, burned patients and animal models of severe trauma were employed in our current experiments [6,[11][12][13][14][15] . MATERIALS AND METHODS Animal modelsAnimal models of severe trauma were replicated by hemorrhagic shock combined with endotoxin infusion. Male Wistar rats, weighing 190g-230g, were anaesthetized with intraperitoneal injection of 30g·L -1 barbitone sodium (35mg·kg -1 ), and the femoral artery and jugular vein were cannulated under aseptic conditions. The rats were then bled via the jugular vein catheter until a mean arterial pressure of 30-35 mmHg (4.6 kPa) was reached. At the end of shock, endotoxin (E.coliO55 B5, Sigma) was infused through tail vein at a dose of 2mg·kg -1 . A goat model of hemorrhagic shock combined with endotoxin challenge was established according to the previous report(n=20) [5] . Animals received E.coliO26 B6 endotoxin via portal vein 24h after the recovery from shock, and the dosage was 30 ng·kg -1 ·min -1, which was given in a continuous infusion lashing for 5d. Wistar rats were divided randomly into three groups: normal controls, early feeding with standard feed plase Gln 0.5g after scalding, and animals (except control group) sustained a 30% TBSA fullthickness scald covering the back and flanks [6] . Determination of plasma diamine oxidase in 21 burned patients (17 male and 4 female) at the age of 33±10 years, with burn area (64±21)%, and (35±20)% 0. Plasma DAO activity was determined on day 1, 3, 7, 14 and 21 postburn.Blood and intestinal DAO levels were tested according to our previous report [17] . Plasma lactate and Dlactate concentrations were determined by biochemical methods as described by Brandt et al [18] . Microassay for quantitation of endotoxin in blood was made with new PCA treatment...