Resorption and incorporation of radioactive-labeled amino acids during the administration of various protein carriers in rats. 2. Uptake of radioactivity by tissues of the gastrointestinal tract after intragastric administration of 14C-L-U-leucine and 3H-glycine]

Male Albino rats (weighing 90-100 gms) were fed ad libitum for 14 days with limited periods of access to food. Powdered whole egg (V), fish meal (F), yeats (H), and gelatine (10% protein in dry matter) used as protein sources. Additionally, one group of rats received a protein-free (e). Radioactive tracers were administered by intragastric infusion of 25 mu Ci 3H glycine and 5 mu Ci 14C L-leucine per 100 gm of body weight 2 hrs after the feeding of 2 gm of the experimental diet per 100 gms of body weight. The level of uptake of radioactive tracers from the different sections of the gastro-intestinal tract was measurels of 3H and 14C labelling in intestinal tissues were observed 3 hrs and 7 hrs after infusion. The level of 14C labelling was found to be negatively correlated and the level of 3H labelling was positively correlated with the biological value of the diet. Intestinal tissues are capable of storing considerable amounts of 14C radioactivity. So, 72 hrs after infusion, the following levels of 14C radioactivity (expressed as percentage of the total dose of radioactivity) were found in tissues of the gastro-intestinal tract: whole egg: 8.4%, fish meal: 9.6%, yeast: 13.1%, gelatine: 14.9%; protein-free diet; 14.2%. The quotients correlating the levels of radioactivity from the intestinal contents with that found in the intestinal wall suggest that the walls of the small intestine possess a high capacity for absorption. At all times of radioactive measurements the walls of the small intestine were found to contain higher levels of both 14C and 3H radioactivity than the contents of small intestine.     

Resorption and incorporation of radioactive-labeled amino acids during administration of various protein carriers in rats. 3. Uptake of radioactivity by blood plasma, liver and muscular tissue and incorporation into tissue proteins after intragastric administration of 14C-leucine and 3H-glycine]

Growing male rats received diets of varying biological value (protein sources: powdered whole egg (V); fish meal (F); yeast (H); gelatine (G); protein-free diet (e)) for a 14-day feeding period. Subsequently, 14C leucine and 3H glycine were administered intragastrically. The level of uptake of 14C and 3H radioactivity into blood plasma, liver and muscular tissue and the rate of incorporation of the radioactive tracers into the proteins of these tissues was examined. A negative correlation was found to exist between the incorporation of radioactivity into liver proteins and the biological value of dietary proteins, the former being mainly dependent on the level of incorporation into the liver. For muscular proteins the rate of incorporation decreases with the decreasing biological value of the dietary proteins. This may be attributed to the fact that with poor protein nutrition the rate of protein synthesis in the skeletal muscles is also reduced. Comparative studies on the specific 14C radioactivity from free leucine made in the group on the protein-free diet and in the group receiving the whole egg diet showed that the leucine pool of the skeletal muscles was markedly redueced in animals fed a protein-deficient diet while the leucine pool in the liver remained comparatively constant.     

Studies on the secretion of amino acids and of urea into the gastrointestinal tract of pigs. 3. Secretion of urea determined by continuous intravenous infusion of 15N-urea

Three pigs, of 34 kg live weight, were each fitted with re-entrant cannulas both in the duodenum and terminal ileum and catheters in the jugular vein and in the carotid artery. Pigs received a diet based on wheat and dried skimmed milk in equal amounts at 12 h intervals. During the preliminary period the digesta flowing from both duodenal and ileal cannulas were collected over 12 h after feeding on two consecutive days and half of them were reintroduced into the gut and half were stored at -20 degrees C. During the experimental period 15N-urea was infused into the jugular vein for 12 hours starting with the morning meal. Total amount of urea infused was 5 g containing 1.22 g 15N-excess. The digesta from both proximal duodenal and ileal cannulas were collected and stored, while the digesta from the preliminary period were reintroduced into the respective distal cannulas. Blood samples were taken at different time of infusion. At the end of infusion period the animals were sacrificed and samples of the contents of the digestive tract and tissues were taken. Urea flux calculated according to atom-% 15N-excess of urea N in plasma was 1.23 to 2.37 g/kg body weight/day. In the duodenal digesta 94.5 +/- 0.2 and in ileal digesta 57.1 +/- 7.39 per cent of 15N were in the TCA soluble fraction. The total amount of 15N in the duodenal digesta was 1.7 to 6.3 times greater than in the ileal digesta. Only small amount of 15N was found in the caecum and almost none in the contents of colon and rectum. It is concluded that urea is secreted into all parts of the digestive tract, the main sites of urea secretion being pancreatic juice and/or bile as well as the small intestine. The total amount of urea secreted is assumed to be similar to the daily urea excretion.     

Preparation of monoclonal antibodies against cell surface antigens in cattle

The BALB/c mice were immunized three times with bovine lymphocytes and thrombocytes in vivo. Besides, dissociated spleens of the mice were immunized with bovine lymphocytes in vitro. Hybridomas producing monoclonal antibodies were formed as a result of the fusion of the spleen cells with the murine myeloma cells. On the whole, four fusions were performed after immunization in vivo and three fusions after immunization in vitro, and 70 stable hybridoma clones were obtained. Five monoclonal antibodies exhibited an identical specific reaction only with bovine thrombocytes, two antibodies reacted only with a certain limited population of bovine spleen cells. The remaining monoclonal antibodies exhibited no tissue specificity and were bound to the lymphocytes of peripheral blood, lymph nodes, thymus, and spleen, to thrombocytes, liver cells, and spermatozoa, but never to erythrocytes. As for the amount of the obtained hybridomas and specific antibodies, no significant difference was observed in the effectiveness of in vivo and in vitro immunization.     

Pulmonary bacterial deposition and clearance during ascarid larval migration in weanling pigs.

Pulmonary deposition and clearance of bacteria were measured in weanling pigs, half of which had been inoculated at age 31 days with larvated Ascaris suum ova. Seven days later, when breathing signs of larval migration were pronounced, all pigs were exposed to aerosolized Escherichia coli (strain B). Then, either immediately after aerosol exposure (for deposition assessment) or immediately after a 120 minute period in filtered air (for clearance), bacteria in the pigs' lungs were counted. Ascarid ova-inoculated pigs did not differ significantly from control pigs for number of bacteria in the lungs after aerosol exposure, but after the 120 minute clearance period they had 7.2 times more than did the control pigs. Thus, in weanling pigs, the breathing-pattern changes that were evident during ascarid-larval migration did not affect pulmonary deposition of inhaled bacteria significantly, but the presence of ascarid larvae in the lungs was associated with impaired pulmonary bacterial clearance.     

疾病对世界家禽业的影响

疾病问题一直就是家禽业的一个部分。一些疾病很容易被控制，而另一些疾病应值得更多关注。家禽业的集约化看来正在付出代价。     

Effect of exogenous corticosterone in genetically fat and lean chickens

1. The effects of daily injections of corticosterone (1 or 5 mg/bird) on growth, fat deposition, liver lipid and plasma concentrations of uric acid, glucose, insulin and growth hormone were studied using genetically selected lines of fat (FL) and lean (LL) chickens. 2. Both doses of corticosterone depressed body weight gain and increased the liver lipid and the abdominal fat to the same extent in both lines. 3. In both lines, corticosterone caused a dose-dependent increase in the plasma concentrations of uric acid, glucose and insulin in the fasted and refed states. 4. In untreated birds, plasma concentrations of growth hormone (GH) were slightly higher in FL than in LL chickens and slightly decreased during refeeding. The response was not modified by injection of 1 mg corticosterone. Injections of 5 mg decreased plasma GH in both lines in the fasting state and in LL chickens during refeeding. In contrast, the same dose increased GH in FL chickens during refeeding. This contradiction remains unexplained. 5. The results suggest that corticosterone sensitivity is not involved in difference of fattening between FL and LL chickens.     

Nitrogen metabolism in the large intestine of ruminants. 3. Microbial utilization of intracecally administered 14C- and 15N-marked urea in the large intestine of sheep in simultaneous intracecal administration of partially hydrolyzed straw meal

Two experiments were performed on sheep, receiving on maintenance level a pelleted straw ration high in crude fibre (straw, 70.5%; dried sugar beet pulp, 12%; cereals, 10%; urea, 2%; ammonium hydrogen carbonate, 3%; minerals 2,5%). The animals were fitted with ileo-caecal re-entrant cannulas. The effects of the introduction of HC1-partly hydrolysed straw meal into the digesta of the large intestine on the digestion processes in that segment were studied. Under these conditions the metabolism of 14C and 15N labelled urea, which was given into the caecum, was estimated. In experiment 1 (E 1; 2 animals) unlabelled, precollected digesta were hourly reintroduced together with 14C and 15N labelled urea via the caecal cannula. In experiment 2 (E 2; 3 animals) the digesta were supplemented with partly hydrolysed straw meal (10% of the mean daily DM-intake with the ration). The supplement of partly hydrolysed straw meal caused an increase of the 15N excretion with faeces from 13.4% (E 1) to 19.8% (E 2) of the dose. The 15N was mainly incorporated in the bacterial fraction (98% E 1; 96% E 2). As a reason for the increased 15N incorporation into the bacterial fraction of 106.4 mg15N' in E 2 vs. 67.3 mg15N' in the experiment without straw meal supplement the higher supply of energy as fermentable carbohydrates was assumed.