Fatty acids and coccidiosis: effects of dietary supplementation with different oils on coccidiosis in chickens.

This study was undertaken to investigate the effects of dietary oils on coccidiosis of chickens infected with Eimeria tenella. Five hundred and four 1-day-old male Arbor Acres chicks were randomly assigned to seven groups. Seven diets were supplemented with poultry oil at 25 and 45 g/kg, corn oil at 25 and 45 g/kg, fish oil at 25 and 45 g/kg, and without oils, respectively, from 1 to 42 days of age. Chickens were inoculated by gavage with 3 x 10(5) sporulated oocysts at 21 days of age. Diets supplemented with oils at 45 g/kg resulted in higher body weight gain than with oils at 25 g/kg or without oils. The packed cell volume in chicks fed with diets supplemented with poultry oil was lower than that in chicks fed with diets supplemented with fish oil, corn oil and without oil. Chickens fed with diets supplemented with poultry oil had higher mortality than that of chickens fed with diets without oil. At 7 days post infection, the chickens consuming fish or corn oil diets had lower levels of plasma carotenoids than those fed with poultry oil supplement or without oils. Fish oil supplementation increased serum interleukin-6 levels in chickens compared with poultry oil at 25 and 45 g/kg and corn oil at 25 g/kg. Fish oil or corn oil enhanced secretory IgA levels in the lumen of the caecum, and oil supplementation tended to decrease serum IgG levels. In conclusion, the diets supplemented with saturated fatty acids aggravated mortality in chickens infected with E. tenella. The deleterious effects on coccidiosis of the diets supplemented with poultry oils might be related to the decreased levels of caecal E. tenella antigen-binding-specific secretory IgA or serum IgG.     

Relationship between the intestinal permeability to macromolecules and invasion of septicemia-inducing Escherichia coli in neonatal piglets.

The influence of age and diet on the invasion of septicemia-inducing Escherichia coli and the endocytotic activity of the small intestinal epithelium were examined in colostrum-deprived conventional and gnotobiotic piglets orally infected with E. coli 078. The piglets infected at birth and the animals fed glucose-amino acids solution and infected at 3 days after birth soon suffered from septicemia caused by the invasion of E. coli 378. The piglets fed artifical milk and infected at 3 days after birth, however, showed resistance to the invasion of E. coli in the absence of passively acquired serum gamma globulin. The endocytotic activity of the small intestinal epithelium was more intense in the former than in the latter piglets. Some of the ileal epithelial cells of the piglets infected at birth contained organisms, although these cells were morphologically intact and showed intense endocytosis. The present results suggest that the intestinal permeability to macromolecules, which depends on the endocytotic activity of the small intestinal epithelium, might predispose neonatal piglets to colisepticemia.     

Effect of ambient temperatures on multiplication of attenuated transmissible gastroenteritis virus in the bodies of newborn piglets.

Newborn piglets were found to be more resistant to infection with attenuated transmissible gastroenteritis virus when maintained at higher temperatures. This was attributed to a decreased rate of virus propagation and spreading in the bodies of the infected animals. The highest virus levels were detected in the tissues of piglets maintained at 8 to 12 C. In contrast, no virus was recovered from piglets maintained at 35 to 37.5 C. The virus was found only in the lymph nodes and respiratory organs in the piglets maintained at 20 to 23 C.     

Aspergillus hyphae in infected tissue: evidence of physiologic adaptation and effect on culture recovery

Microbiologic cultures of fungi are routinely incubated at ambient temperatures in room air, and the rate of recovery of Aspergillus species from clinical specimens is poor. Failure of current culture methods to mimic the physiologic temperature and low-oxygen environment found in hypha-laden infected tissue may underlie this poor recovery. Experiments were performed to compare the recovery of Aspergillus spp. incubated at 35 degrees C in 6% O(2)-10% CO(2) with that at 25 degrees C in room air. The samples tested included Aspergillus-infected tissue specimens from a dog model and human autopsies, experimental anaerobically stressed Aspergillus inocula, and 10,062 consecutive clinical specimens. Culture at 35 degrees C in 6% O(2)-10% CO(2) significantly enhanced the recovery of Aspergillus spp. from the infected autopsy tissue samples. Incubation at 35 degrees C alone resulted in approximately 10-fold-improved culture recovery from the experimentally stressed hyphae, and the 6% O(2)-10% CO(2) atmosphere independently favored growth under temperature-matched conditions. Finally, incubation at 35 degrees C (in room air) improved the overall recovery of Aspergillus spp. from clinical specimens by 31%. Culture at 35 degrees C in a microaerobic atmosphere significantly enhances the recovery of Aspergillus spp. from various sources. Aspergillus hyphae growing in infected tissue appear to be adapted to the physiologic temperature and hypoxic milieu.     

Temperature regulation and oxygen consumption in the developing macropod marsupial Setonix brachyurus.

1. When kept at ambient temperatures of 17-5 and 24 degrees C the colonic temperatures of joeys younger than 166 days declined to near ambient temperature. Pouch joeys of 166 days and older were however able to maintain their colonic temperatures at about 35 degrees C. 2. Joeys first developed the ability to sustain high O2 consumption rates in response to cooling, when aged between 144 and 169 days. Only when this latter facility was fully developed in ontogeny could body temperature be maintained in a cool environment. 3. When joeys older than 130 days were kept in a metabolism chamber at pouch temperature (37-5 degrees C) and at high humidity their body temperatures quickly rose to lethal levels, demonstrating the need for cooling mechanisms whilst still contained within the pouch.     

The dependence of the temperature response to pyrogens on the ambient temperature and the initial body temperature

The dependence of the temperature response to injection of Freund's complete adjuvant (FCA) containing killed and dried Mycobacterium butyricum on ambient temperature within 8-10, 14-16, 20-22, 26-28 degrees C ranges and initial body temperature was studied in experiments on rats, guinea pigs, and rabbits. The duration of the hyperthermic response was maximal at an ambient temperature 14-16 degrees C, and its dynamics can be divided in 2 phases, initial febrile and subsequent subfebrile. An increase in rectal temperature after application of the agent was the higher the lower was its initial value and vice versa. The hyperthermic response to FCA did not occur at 8-10 degrees C.     

Effect of dietary energy on lipogenesis in turkey hens prior to and after sexual maturity

An experiment was conducted with 208 Diamond Hybrid Small White turkey hens to determine the role of dietary energy on in vitro lipid metabolism. Young turkey hens were fed diets containing either a high (3100 kcal metabolizable energy) or low (2400 kcal metabolizable energy) energy level from 12 to 30 weeks of age. Both diets contained 12% protein and were fed on an ad libitum basis. Hens were then maintained under a constant (21 degrees C) or cyclic (12 to 27 degrees C) daily temperature regime and fed either a high (47% of the total energy) or low (8% of the total energy) fat diet for a 100-day egg collection period. Hens were killed at the end of the growing phase, after 1 week of receiving the breeder diets and after 2 weeks of stimulatory light (14 hr/day). Hens were also killed following a 100-day egg collection period. In vitro lipid metabolism and enzyme activities were determined at these periods. In vitro fatty acid synthesis was greater (P less than .05) in hens fed the high-energy prebreeder diet although total energy intakes for both groups of birds were similar. Transferring both groups of hens to individual cages in the breeder house decreased (P less than .05) fatty acid synthesis; however, lipogenic rates were higher (P less than .05) after 2 and 18 weeks of stimulatory light. The high-fat diet decreased (P less than .05) in vitro lipogenesis, fatty acid synthesis, malic enzyme and esterification of palmitate. Acetate utilization in the presence of pyruvate was one-half the rate in the absence. Diets fed prior to sexual maturity did not affect egg production or in vitro lipogenesis of mature hens.     

Effects of glycinin and β-conglycinin on enterocyte apoptosis,proliferation and migration of piglets

Glycinin and β-conglycinin have been identified as major food/feed allergens. But effects of glycinin and β-conglycinin on enterocyte migration in piglets are scare. Fifteen weanling (7.06±0.18 kg) General No. 1 barrows, weaned at 28 days, were used. The piglets were randomly allotted to three (A, B and C) treatments with five replicates. The piglets in the A group (control group) were fed diets without ingredients originating from leguminous products, while the piglets in the B or C groups were fed the diets containing purified glycinin or β-conglycinin, which replaced protein in Group A by 4%. All the experimental periods were followed for 7 days. Five-micrometre thick sections of small intestinal tissue were stained with the TUNEL method to assess apoptotic activity, and with Ki-67 immunohistochemistry to assess cellular proliferation. The results indicated that glycinin or β-conglycinin increased proliferative index and apoptotic index in duodenum for piglets (P<0.05).     

Adaptations to ambient temperature in growing pigs

1. Pigs were weaned at 8--10 dyas of age and littermate pairs were raised in individual cages at ambient temperatures of 25 degrees C or 35 degrees C to 8 weeks of age. 2. Pigs reared at the higher temperature had longer extremities and less hair than controls even though body weights were similar. 3. On exposure to an ambient temperature of 45 degrees C, thce as quickly as their littermates. 4. When the scrotum was heated locally to 42 degrees C animals reared in the warmer environment began to pant at a lower ambient temperature than the controls. 5. Heating the hypothalamus by means of an implanted thermode at an ambient temperature of 35 degrees C was accompanied by an increase in respiratory frequency in pigs reared at 25 degrees C. The pigs reared at 35 degrees C already had a slightly elevated rate of breathing and heating the hypothalamus caused no change. 6. The rate of blood flow in the tail was higher in pigs reared at 25 degrees C than those kept at 35 degrees C when measured at ambient temperatures between 20 degrees C and 35 degrees C. When the hypothalamus was cooled the slope of the line relating blood flow to the temperature of the thermode was similar in both groups. 7. The critical temperature as determined from measurements of oxygen consumption was higher in the pigs reared at 35 degrees C than in controls. But the effect of cooling the hypothalamus on metabolism was similar in both groups. 8. There was no difference between the two groups in the rate of cutaneous water loss.     

Temperature dependent attraction by goldfish to a chemical feeding cue presented alone and in combination with heated water

An eight cell multiple-choice experiment was used to investigate the influence of temperature on the locomotor response of goldfish (Carassius auratus) to a chemical feeding cue. When a food extract was infused into a single cell at ambient temperatures of 26, 28, 30, 32, and 34 degrees C (ambient temperature=acclimation temperature) the goldfish spent more time in the extract cell than three similarly outfitted dummy cells at all temperatures, but the intensity of their attraction varied over the thermal interval. Attraction was highest at 28 degrees C and gradually declined to its lowest level by 34 degrees C. Goldfish acclimated and tested at 26 degrees C spent more time visiting a combination of food extract and heated water (H+E) than either food extract (E) or heated water (H) alone. The preference for H+E over H and E increased with the temperature differential between heated and ambient waters. Successive increased in acclimation/ambient temperature (30, 32, and 34 degrees C) extinguished the differences between H+E and H and E but did not eliminate the attraction for the thermal and chemical stimuli, per se. The importance of temperature in the variability of chemoreceptive behavior and the interaction between chemical and thermal stimuli are discussed.     

Elevated environmental temperature enhances immunity in experimental Chagas'' disease.

C3H mice are highly susceptible to the Brazil strain of Trypanosoma cruzi. These mice usually die during the acute phase of infection and develop a profound immunosuppression to heterologous and parasite antigen. In this study, we confirmed earlier reports that infected mice maintained at elevated environmental temperature (36 degrees C) are significantly more resistant to T. cruzi than are mice kept at 20 to 24 degrees C. To determine whether the benefits of increased environmental temperature were due to alterations in the host immune system, the production of antibody to heterologous antigen and the development of parasite-specific T-helper cells were examined in noninfected and T. cruzi-infected mice. Mice were immunized with either sheep erythrocytes (SRBC) or trinitrophenyl groups (TNP) conjugated to fixed culture forms of T. cruzi, and the splenic direct plaque-forming cell (DPFC) responses to SRBC and to TNP-conjugated SRBC were determined. The DPFC response to SRBC from infected mice maintained at elevated environmental temperature was much higher than the suppressed response of infected mice held at room temperature and slightly higher than the response of age-matched noninfected control mice. Likewise, maintaining infected mice at 36 degrees C significantly enhanced the parasite-specific responses of T-helper cells, as reflected by anti-TNP DPFC responses of mice immunized with TNP-conjugated TC.     

Establishment of latency in vitro with herpes simplex virus temperature-sensitive mutants at nonpermissive temperature

This report describes a latency model using human embryo lung cells that were infected with herpes simplex virus type 1 (HSV-1) temperature-sensitive (ts) mutants and cultivated at nonpermissive temperature (40.5 degrees C). ts mutants tsG8 (parental strain HSV-1 KOS) and tsG5 (parental strain HSV-1 13) could be maintained in a latent state at 40.5 degrees C for at least 40 days without exhibiting virus infectivity. During this time, viable virus could be reactivated by reducing the incubation temperature to the permissive level (34 degrees C). Virus replication could be detected 2 to 6 days after temperature reduction and the virus reactivated from the latent state seemed to retain the same ts phenotype as the input virus for at least 14 days.     

Effects on growth and endocrine status of maintaining obese and lean Zucker rats at 22 degrees C and 30 degrees C from weaning

Lean and genetically obese Zucker rats were maintained from 21 to 34 days of age at an ambient temperature of 22 degrees C or 30 degrees C. Maintenance at 30 degrees C normalised the lower rectal temperature of obese rats. At 30 degrees C obese rats reduced their food intake compared with obese animals at 22 degrees C but they were still hyperphagic compared with non-obese animals at 30 degrees C. At 30 degrees C obese rats accumulated as much lipid in their carcase, but deposited less protein than obese animals at 22 degrees C. Obese rats were hyperinsulinemic compared with non-obese animals at either temperature. Plasma T3 and T4 levels did not differ between phenotypes and T4 levels were lower in both phenotypes at 30 degrees C. Plasma corticosterone levels were higher in obese rats at both temperatures and this phenotypic difference was larger at 30 degrees C. In a second experiment rats were maintained at 22 degrees C from 21-34 days of age and obese rats pair-fed to the ad lib intake of non-obese animals. Obese rats still became more obese than non-obese animals and deposited less protein than either non-obese or ad lib fed obese animals. Pair-fed obese rats were hyperinsulinemic and had higher plasma corticosterone concentrations than non-obese animals. These findings suggest that the raised plasma corticosterone concentrations of obese rats kept at 30 degrees C, or not allowed to express their greater appetite, may cause reduced protein deposition.     

Temperature enhancement of syncytium formation by HIV and Sendai virus.

Syncytium formation, the characteristic cytopathic effect (CPE) of the human immunodeficiency virus (HIV) and cell fusion by Sendai virus, is accelerated by increasing the ambient temperature to values at which normal metabolic activity is inhibited. Uninfected C8166, CEM, and H9 cells were absorbed at 4 degrees C onto monolayers of H9 cells chronically infected with HIV and incubated subsequently at either 37 degrees C or 45 degrees C. Similarly chick and human erythrocytes and Hela cells were agglutinated with Sendai virus at 4 degrees C before incubation at temperatures of up to 50 degrees C. With both viruses the rate of cell fusion was directly related to temperature. Since membrane fluidity is dependent on the phase-transition temperature points of the membrane lipids it is proposed that sufficient membrane fluidity is essential for cell fusion to occur. The implication of these observations on the cytopathology of HIV is discussed.     

Beta-lactoglobulin as a potential modulator of intestinal activity and morphology in neonatal piglets

Studies were conducted to determine the effects of the whey protein beta-lactoglobulin (blg) on the intestinal development and intestinal morphology in neonatal piglets. Two trials (5 and 28 days) were conducted on piglets in three separate groups. One group served as a control group while the remaining two were experimental groups based on diets. The two experimental diets were a bovine colostrum powder, one with supplementation with blg and the other without. The control group remained suckling on a sow. All groups were weaned on day 20 and placed onto a solid commercial piglet diet. Enzymatic activity, total DNA synthesis, crypt depth, and villus height were all parameters used to evaluate the effect of blg. Piglets fed a diet supplement with blg had the greatest total DNA after 5 days. Sow-reared piglets had the greatest intestinal morphology development with regards to villus height. No significant differences were found in enzymatic activity between treatments.     

The effect of noradrenaline, injected into the hypothalamus, on thermoregulation in the cat.

1. Noradrenaline (NA) was microinjected into the anterior hypothalamic/preoptic area(AH/POA) of unanaesthetized cats held at ambient temperatures of 10, 22 or 35 degrees C. Loci in which injection of NA caused body temperature changes were also found to be sensitive to the febrile action of PGE1. 2. At all ambient temperatures, NA caused a dose-dependent fall in body temperature. However the mechanisms by which these temperature changes were brought about varied at different ambient temperatures. In cats maintained at the higher ambient temperature, NA activated heat loss mechanisms whereas in the cats maintained in the 10degrees C environment, the major effect of NA injection was an inhibition of heat conservation and heat production mechanisms. 3. We conclude that NA acts in cats not only as an inhibitor of heat conservation and production, but also acts in an excitatory manner on an active heat loss pathway within the AH/POA.     

Critical levels of extracellular glutamate mediating gerbil hippocampal delayed neuronal death during hypothermia: brain microdialysis study.

When the brain temperature was lowered by 2 degrees C from normothermic temperature, a protective effect on postischemic neuronal death was exhibited and levels of extracellular glutamate were attenuated to about half of those at normothermic brain temperature in the gerbil hippocampus. Hypothermia has been reported to confer a protective effect on ischemia-induced delayed neuronal death. The present study was carried out to quantify this protective effect of hypothermia on the degree of alteration in extracellular release of glutamate during ischemia and the final histopathological outcome in the hippocampus. Extracellular glutamate levels were measured by microdialysis. In gerbils whose brain temperature was maintained at normothermia (37 degrees C), glutamate increased during ischemia and the early period of recirculation (by 15-fold), and CA1 neurons were consistently damaged. In animals whose brain temperature was maintained at 35 or 33 degrees C during ischemia, the release of glutamate was significantly attenuated to half or a quarter, respectively, at 37 degrees C. In animals whose brain temperature was maintained at 31 degrees C during ischemia, the release of glutamate was slightly lower than that at 33 degrees C. No CA1 ischemic neuronal damage was seen in 60% of gerbils at 35 degrees C and none was seen in any gerbils at 33 and 31 degrees C. In animals whose brain temperature was maintained at 39 degrees C during ischemia, the release of glutamate was slightly higher than that at 37 degrees C, and a high mortality rate of animals (75%) was observed. Our results reinforce other recent evidence suggesting that one of the mechanisms by which lowering of the brain temperature by only a few degrees during ischemia exerts a protective effect in the hippocampus, involves the reduction of ischemia-induced glutamate release.     

Virulence of Streptococcus mutans: a sensitive method for evaluating cariogenicity in young gnotobiotic rats.

Gnotobiotic rats infected with Streptococcus mutans 6715 at 19 days of age and fed a purified diet (305) containing 5% sucrose developed extensive caries lesions on all molar surfaces within 16 days (35 days of age). Approximately twice as many lesions developed when infected rats were maintained until 45 days of age, whereas noninfected rats did not develop caries when fed diet 305. Gnotobiotic rats infected with S. mutans 6715 and fed a purified diet containing no sucrose (300) until day 25 and subsequently fed diet 305 for 10 days developed lesions similar to rats fed diet 305 for 16 days. Furthermore, rats infected with S. mutans 6715 and fed diet 300 until 45 days of age developed approximately one-half the smooth surface lesions as infected rats fed diet 305 for the same length of time. The level of caries on buccal and proximal molar surfaces in 45-day-old gnotobiotic rats varied when animals were infected with S. mutans AHT, BHT, NCTC 10449, 6715, or LM-7. Animals infected with S. mutans AHT showed more severe lesions on the buccal surfaces than those observed in animals infected with the other strains of S. mutans tested, whereas S. mutans 6715 caused significantly more caries on proximal surfaces. On the other hand, rats infected with S. mutans LM-7 exhibited the lowest level of caries on all molar surfaces of the five strains of S. mutans tested.     

Effects of Exposure to High Temperature and Feeding Level on Regional Blood Flow and Oxidative Capacity of Tissues in Piglets

To determine to what extent exposure to high ambient temperature and feeding level affect tissue energy metabolism in piglets, regional blood flow and oxidative capacity of tissues were evaluated in sixteen 21.8 +/- 2.8 kg pigs. At 5 weeks of age, littermates were divided into three groups and acclimated to the treatment for 25 days. One group was reared at 33 degrees C and fed ad libitum (33AL, n = 6) while the other two groups were maintained at 23 degrees C and either pair-fed on the basis of the food consumption of their 33AL littermates (23PF, n = 5), or fed ad libitum (23AL, n = 5). Regional blood flow was determined in conscious pigs by injection of coloured microspheres, which were recovered in different tissues after slaughter. Activities of cytochrome oxidase and cytochrome aa(3) content were measured in tissue homogenates of heart, longissimus dorsi and rhomboideus muscles, liver and small intestine. There was decreased blood flow to internal adipose tissue (42 %) and increased blood flow to peripheral tissues (skin, 44 %) and tissues implicated in respiratory evaporative heat loss (diaphragm, 45 %, lungs, 59 %) at 33 degrees C compared to 23 degrees C, which can be viewed as an effective mechanism for increasing heat loss at high temperature. In addition, the concomitant decrease in blood flow (49 %) and slight reduction of oxidative capacities in both muscles at 33 degrees C might contribute to the reduction in thermogenesis, but these effects were also observed when the feeding level was reduced at thermal neutrality (23PF group). In the viscera (intestine, liver), blood flow was decreased in the two groups on a restricted food intake (about 50 % of 23AL), independently of environmental temperature. The results suggest that most of the mechanisms associated with the reduction in energy expenditure during warm acclimation are related to the adaptive reduction in food intake. Experimental Physiology (2001) 86.1, 83-91.     

Growth of cytomegalovirus at supra-optimal temperatures.

An isolate (Mira) of cytomegalovirus is shown to replicate in human embryonic lung fibroblasts at supra-optimal temperature (40 degrees C). The ability of the Mira isolate to grow at 40 degrees C decreased as a function of age of cells in which the virus was grown. The unusual morphology of the lesions in late passage cells infected and maintained at 40 degrees C is illustrated.