Pathogenesis of rotavirus infection in various age groups of chickens and turkeys: pathology

Various age groups of turkeys, White Leghorn chickens, and broiler chickens were inoculated with turkey rotavirus strain Tu-2 or with chicken rotavirus Ch-2, and the development of rotavirus-induced lesions were evaluated macroscopically and microscopically (light microscopy and scanning electron microscopy). Morphometric evaluations were conducted to determine morphologic changes in the villi of infected turkeys. Macroscopic lesions that were found in turkeys, but not in chickens, consisted of pallor of the intestinal tract and distension of the cecum with frothy or nonfrothy fluid contents. Histologic lesions in turkeys consisted of basal vacuolation of enterocytes, separation of enterocytes from the lamina propria (with subsequent desquamation), villus atrophy accompanied by widening of the lamina propria, scalloping of the villus surface, fusion of the villi, and leukocytic infiltration of the lamina propria. Scanning electron microscopy indicated roughened villus surfaces, distortion of the normal morphologic features of the villi, and loss of microvilli in cells located on the tips of the villi. Most of the lesions disappeared by 8 days after inoculation. Results of the morphometric evaluations indicated that the crypt length had increased and the villus-to-crypt ratio had significantly decreased, compared with that of noninoculated control turkeys. Broilers greater than or equal to 21 days old and White Leghorn chickens greater than or equal to 35 days old had minimal leukocytic infiltration of the lamina propria and minimal loss of microvilli in cells located on the tips of the villi. The loss of microvilli was more extensive in chickens greater than or equal to 119 days old than in younger birds. Generally, turkeys 1 to 112 days old developed more severe lesions than did chickens, and lesions were more pronounced in turkeys at 112 days of age.     

Pathogenesis of rotavirus infection in various age groups of chickens and turkeys: clinical signs and virology

Age-related susceptibility patterns of turkeys, broilers, and specific pathogen-free (SPF) White Leghorn chickens to experimentally induced infection with turkey or chicken rotavirus isolates were compared. The following determinants were evaluated: clinical signs, onset and duration of virus production, viral titers, involvement of intestinal villi in the replication of the virus, and the development of antibodies against the virus. Older turkeys and chickens were more susceptible than were their younger counterparts, turkeys were more susceptible than were broiler and White Leghorn chickens (regardless of age), and broiler chickens were slightly more susceptible than were age-matched White Leghorn chickens. Turkeys developed diarrhea, accompanied by high viral titers within 1 day after inoculation with virus. Viral antigen was found in the epithelial cells of the intestinal villi throughout the intestinal tract and some cells of the cecal tonsils. Antibodies could be detected as early as 4 to 5 days after inoculation. These findings were more pronounced in turkeys inoculated at 112 days of age than in birds inoculated at a younger age. Age-related susceptibility patterns were similar in White Leghorn and broiler chickens. Infection was subclinical in birds less than 56 days old, whereas older birds developed soft feces. Egg production in the White Leghorn chickens decreased after being inoculated with virus at 350 days of age.     

A comparative analysis of the mitogenic response of intestinal intraepithelial lymphocytes in various age groups of turkeys.

Mitogenic responsiveness of intestinal intraepithelial lymphocytes (i-IEL) to concanavalin A (Con A), phytohemagglutinin P (PHA-P), and lipopolysaccharide (LPS) from Salmonella typhimurium were evaluated in various age groups of turkeys by a colorimetric blastogenic microassay. Comparisons were made between mitogenic responses of turkey i-IEL and peripheral blood lymphocytes (PBL). The results from this study demonstrated that i-IEL and PBL of turkeys responded to T-cell mitogens, Con A and PHA-P, in every age group examined. The LPS induced a significant mitogenic response in PBL but not in i-IEL of turkeys. The mitogenic responses of turkey i-IEL and PBL to the three mitogens examined were similar to mitogenic responses observed in an earlier study performed by using chicken i-IEL and PBL. The results indicated a difference in mitogenic response between different age groups. An increase was found in mitogenic response of i-IEL to both T-cell mitogens from 3 days of age to 1 wk of age, whereas mitogenic response of PBL to all three mitogens declined significantly from 1 day of age to 3 days of age. The highest mitogenic response of i-IEL to T-cell mitogens was observed at 1 wk of age. The highest mitogenic response of PBL to both T-cell mitogens was observed at 1 day of age and the highest PBL response to LPS was observed at 16 wk of age. The mitogenic response induced by PHA-P provided less variability between age groups than the mitogenic response induced by Con A.     

Different responses of protein synthesis to refeeding in various muscles of fasted chicks

1. The change in the rate of protein synthesis of different muscles, concentrations of plasma insulin, plasma insulin-like growth factor-I (IGF-I) and other plasma components were investigated after refeeding in fasted chicks. 5.2 g of the complete diet was refed. This was the maximum that could be force-fed with water. 2. The fractional synthesis rates (FSR) of breast (M. pectoralis major) and leg (M. gastrocnemius) muscles were measured after injection of L-[2, 6-(3)H]phenylalanine. Plasma insulin and IGF-I concentration were determined by radioimmunoassay. 3. In the breast muscle, FSR was significantly reduced by 2-d fasting. The FSR had recovered completely after 1 h of refeeding and was maintained until 6 h. The change in FSR after refeeding was associated with the change in ribosomal efficiency (K(RNA); absolute synthesis rate per unit RNA), while no change in ribosomal capacity (C(S); RNA: protein ratio) was observed. 4. In the leg muscle, FSR was decreased by 2-d fasting and increased gradually toward 6 h after refeeding but did not reach the level of the fed control. In contrast to the breast muscle, no significant changes in Cs and K(RNA) in the leg muscle were observed. 5. Plasma glucose concentration increased significantly at 1 h after refeeding but returned to the fasted level after 24 h. Plasma insulin concentration in chicks refed for 1 h was higher than in the fasted group. There was no significant change in plasma IGF-I concentration. 6. These results suggest that the FSR of breast muscle was more sensitive to refeeding than that of leg muscle which may be explained, in part, by differences in sensitivity to the change in circulating plasma insulin concentration after refeeding.     

Differential leukocyte counts determined in chicken blood using the Cell-Dyn 3500

Background: Automated hematology instruments commonly are used for mammalian blood analysis, but there is a lack of accurate automated methods available for avian leukocyte analysis. Objective: The aim of this study was to validate differential leukocyte counts in blood from chickens using the Cell-Dyn 3500 hematology system and avian-specific software.
Methods: Blood samples were collected in lithium-heparin tubes from 2 groups (n = 84 and n = 139) of laying hens. Manual 200-cell differential counts were done on routinely-stained blood smears, and manual total granulocyte counts (heterophils and eosinophils) were done using an eosinophil stain in a counting chamber. Automated differential counts were done using VET 2.3, a research and development version of avian-specific software for the Cell-Dyn 3500. Results were analyzed using Pearson's correlation and difference plots.
Results: Automated granulocyte counts from the Cell-Dyn were in good agreement with manual granulocyte counts ( r = 0.93 and 0.80 for the 2 study groups). No correlation was found between automated and manual lymphocyte counts. Correlation coefficients for monocyte counts were 0.70 and 0.43. Conclusion: Automated leukocyte results from the Cell-Dyn using VET 2.3 software were not fully accurate. Total granulocyte counts may be of clinical usefulness, but results obtained for other parameters were unreliable.     

Effect of high concentrations of dietary vitamin E during various age periods on performance, plasma vitamin E and meat stability of broiler chicks at 7 weeks of age.

1. The effect of high concentrations of vitamin E (alpha-tocopheryl acetate) fed during various age periods on the performance and the oxidative stability (thiobarbituric acid [TBA] values) of the drumstick meat of 7-week-old broiler chicks was determined. The basal diets (for the age periods 0 to 3, 3 to 6 and 6 to 7 weeks) contained 60 g soyabean oil and 24 mg vitamin E/kg. The following five treatments were evaluated: (1) the basal diets from 0 to 7 weeks of age (control); (2) vitamin E, 100 mg/kg diet from 0 to 7 weeks of age; (3) vitamin E, 150 mg/kg diet from 0 to 3 weeks of age; (4) vitamin E, 150 mg/kg diet from 0 to 3 weeks of age and 100 mg/kg diet from 6 to 7 weeks of age; (5) vitamin E, 100 mg/kg diet from 5 to 7 weeks of age. 2. Food intake, weight gain and food efficiency were not significantly (P greater than 0.05) affected by the vitamin E treatments. 3. Plasma alpha-tocopherol (AT) concentrations in treatments 2, 4 and 5 were similar, and markedly higher than those in treatments 1 and 3, while those of treatment 3 were significantly (P less than 0.001) higher than those of treatment 1. Plasma retinol concentrations were not significantly (P greater than 0.05) affected by the vitamin E treatments. 4. TBA values of the meat were very low and not significantly affected by the vitamin E treatments. However, after incubation the TBA values were highly significantly (P less than 0.01) negatively correlated with the amount of vitamin E consumed during the experiment. The stability of meat of birds fed the various combinations of vitamin E (treatments 3, 4 and 5) was significantly (P less than 0.05) higher than that of birds which did not receive additional vitamin E (treatment 1), but it was significantly (P less than 0.001) lower than that of birds which received vitamin E continuously (treatment 2). 5. It is concluded that a high concentration of vitamin E fed during 0 to 3 weeks of age may significantly improve AT status of the broiler chick up to 7 weeks of age.     

Detection of streptococci from various serological groups in animals

During the period from 1985 to 1988 we determined 228 strains of streptococci isolated from samples of various sorts of biomaterials, mainly animals. From this set of streptococci we classified 207 strains into serological groups according to the Lancefield classification and about 30% strains into species by means of serological and biochemical methods. Most of the strains were allocated to group C (37.28%) and group Q (17.39%). 89 streptococci strains originated from pigs, 40 strains from horses, 13 from cattle, 12 from dogs, 9 from poultry and 8 from coypu. The other streptococci strains originated from other animal species or from different material. Most serological groups of streptococci were determined in pigs, less in cattle (7), in poultry (6), in dogs (6), in horses (5) and in coypu (3). Streptococci of the serological group Q were determined in as many as 9 animal species, group C in 8 species and group G in 6 species.     

Zinc, copper and iron utilisation by chicks fed various concentrations of zinc

1. Zinc, iron and copper interactions were examined in chicks (New Hampshire X Single Comb White Leghorn) grown individually in stainless steel cages and fed on purified diets with three concentrations of zinc: control (37 mg Zn/kg), moderate (100 mg Zn/kg) and excess (2000 mg Zn/kg) in three studies. 2. Chicks given either moderate or excess zinc excreted more than twice as much 65Zn from a test diet as those fed on the control diet. Thus chicks given the moderate amount of zinc had concentrations of zinc in tissues similar to those of controls but chicks given excess zinc accumulated zinc in their tissues. 3. The specific activity of 65Zn in the tissues, especially in the bursa of Fabricius, of chicks given excess zinc was not reduced as much as would be predicted. Thus, ingestion of excess zinc appeared to reduce tissue turnover of 65Zn, especially in the bursa. However, humoral immune responses, as measured by antibody titres to sheep red blood cells, were not affected. 4. Chicks given excess zinc or pair-fed on the control diet retained less 59Fe from a test diet than chicks given control or moderate concentrations of zinc ad libitum. The iron concentrations in tibiae of chicks given excess zinc were depressed.     

Effects of age and diet on the viscosity of intestinal contents in broiler chicks.

1. A standard methodology was developed for the determination of the viscosity of digesta in broiler chickens. 2. The best variables considered for use (those which gave the most consistent results) were: digesta obtained from the foregut area (defined as the region from the pancreas to Meckel's diverticulum) using a minimum of 6 replicates and offering experimental diets for 5 d before slaughter at 25 d of age. 3. There was evidence that the viscosity of digesta obtained from the hindgut (defined as the region between Meckel's diverticulum and the ileo-caecal junction) was reduced the longer the birds were fed on one diet, suggesting possible dietary acclimatisation. Hindgut digesta viscosity from birds fed on a barley-based diet over a longer period was 10% to 30% less than that of birds fed for 5 d. 4. There was an apparent reduction in viscosity with age of bird up to 45 d of age, with hindgut digesta viscosity from birds fed on barley-based diets falling from 20.6 cps at 25 d to 9.8 cps at 45 d. 5. In an assessment of the procedure developed, the following digesta viscosities were obtained at 25 d: 3.1 cps (wheat-based diet, foregut), 19.8 cps (barley-based diet, foregut), 5.7 cps (wheat-based diet, hindgut), 22.8 cps (barley-based diet, hindgut).     

Differential expression of U2AF35 in the arthritic joint of avian reovirus-infected chicks

To identify cell types and genes that are differentially expressed during immunopathogenesis of avian reovirus (ARV)-induced viral arthritis (VA), we inoculated arthrotropic strain S1133 of ARV into 1-day-old broilers, and examined tissue histology as well as RNA expression at different days post-inoculation (PI). Using immunohistochemical staining, we detected many CD68 expressing macrophages in and around the blood vessels of the arthritic joints. By RT-PCR, we found that expression of matrix metalloproteinase-2 (MMP-2) and bone morphogenetic protein-2 (BMP-2) was induced earlier in footpads and hock joints of ARV-infected chickens. By employing suppression subtractive hybridization (SSH) technique and RT-PCR, we further identified that small subunit of U2 snRNP auxiliary factor (U2AF35 or U2AF1) mRNA was differentially induced in the joint of ARV-infected chickens. By in situ hybridization (ISH), mRNA signals of U2AF35 and BMP-2 were located in chondrocytes within/near the epiphyseal plate and secondary center of ossification, and in epidermal cells and dermal fibroblast-like cells of arthritic joints. In addition, U2AF35 mRNA was expressed in the inflammatory infiltrates of the bone marrow of ARV-infected arthritic joints, while MMP-2 was mainly detected in chondrocytes. Interestingly, among U2AF35, MMP-2, and BMP-2 that were differentially expressed in the joint of ARV-infected chickens, only U2AF35 induction correlated well with arthritic manifestation. Because U2AF35 may assist in mRNA splicing of proinflammatory chemokines and cytokines, our results indicated that U2AF35 induction might play an immunopathological role in ARV-induced arthritis. This study has first associated U2AF35 to viral arthritis.     

Growth response of chicks following addition to the diet of various sources of nitrogen

Two experiments involving a total of 320 day‐old Chunky P male chicks were conducted. In the first experiment chicks were divided into 6 groups and given one of the following diets ad libitum for 6 weeks: A, with determined essential amino acids at minimal required levels; B, with published values for essential amino acids at minimal required levels; C, conventional broiler diet; D, A+1.5 per cent diammonium phosphate (DAP); E, A+3.0 per cent DAP; and F, A+4/4 per cent DAP. Adding 1.5 per cent DAP gave a significant increase in live‐weight at 4 weeks, but adding 3.0 or 4.4 per cent DAP depressed weight significantly at 4 or 6 weeks. Weights of birds receiving diet B were significantly lower than those of birds receiving diets A or C.

In the second experiment chicks were divided into 5 groups and given one of the following diets ad libitum for 4 weeks: GA (similar to A) or GA supplemented with the equivalent of 2 per cent crude protein in several forms. In HM the form was herring meal and in GG, DS and DP it was glycine+glutamic acid, diammonium sulphate and DAP, respectively. Body weights of birds receiving HM were greater (though not significantly) than those receiving GA but were significantly poorer than those fed GG, DS or DP.     

Endoparasites in swine in different age groups and management systems

In different age groups endoparasites are of varying importance. Sows are predominantly infected with gastrointestinal strongyles (mainly Oesophagostomum spp.), Ascaris suum and Eimeriae, to a lesset extent with Trichuris suis, Hyostrongylus rubidus, Strongyloides ransomi or Isospora suis, while in suckling piglets I. suis and occasionally S. ransomi frequently occur. Weaners and fatteners are infected with coccidia and gastrointestinal strongyles, later with A. suum. Whipworms are also found occasionally. I suis causes diarrhoea in suckling piglets, while in older animals the infection is not correlated with disease. Damage induced by helminths is mainly due to reduced performance, in the case of ascarosis to reduced carcass value. Therefore planned antiparasitic measures should be taken at all stages of pig keeping. Hygienic measures can reduce infection pressure; however parasite elimination is difficult to obtain under conventional management conditions. Consequently the control of parasitic infection at the early stage of piglet production is desirable.     

Dimensional differences among the groups of retinal ganglion cells according to the retinal zones in chicks

The populations of retinal ganglion cell (RGC) groups (Groups I, II, III, IV) were similar each other between the central and intermediate zones, but the population in the peripheral zone were clearly different from those in the central and intermediate zones due to increase of Group III and IV cells and decrease of Group I cells. The dimensions of somal area and dendritic field of Group I cells increased very gradually toward the peripheral zone, but those of other three Groups grew steeply in the peripheral zone. The correlation index between somal area and dendritic field of RGCs showed high coefficient in the central (r=0.73) and intermediate (r=0.77) zones, but lowered clearly in the peripheral zone (r=0.64) due to increase of Group III cells, which showed nonlinear relation between somal area and dendritic field.     

Estimate of choline nutritional requirements for chicks from 1 to 21 days of age

Choline is an essential nutrient in poultry diets because it performs various important metabolic functions. The objective of this study was to re‐evaluate the choline requirements of male broiler chickens from 1 to 21 days of age at two levels of methionine. Two assays using 2,160 Cobb^® chickens (1,080 in each assay) were conducted. The study design was completely randomized and consisted of six treatments and six replicates, with 30 animals per experimental unit. The semipurified basal diet was formulated with corn, soya bean meal, soya protein concentrate, starch and sugar, providing 390 mg/kg choline and 0.593% digestible methionine (requirement level) in Assay 1 and a reduction of about one‐quarter in the requirement level of digestible methionine (0.440%) in Assay 2. Choline chloride (62.5%) was added by a supplementation technique to both basal diets to compose crescent levels of choline supplementation (715, 1,040, 1,365, 1,690 and 2,015 mg/kg). The weight gain responses were fitted using quadratic polynomial (QP) and broken‐line (BL) models. The ideal intake of choline (mg/bird.day) was estimated from the first intercept of the QP with the BL plateau (BL + QP). The results showed that the diet with the 25% reduction in digestible methionine limited the maximum weight gain by approximately 10%. The choline requirements of broilers from 1 to 7, 1 to 14 and 1 to 21 days of age were 27,013, 44,458 and 62,535 mg/bird.day, respectively, for the requirement level of digestible methionine and 26,796, 41,820 and 56,578 mg/bird.day for the broilers receiving the diet with the 25% reduction in digestible methionine.     

Persistence of Ehrlichia phagocytophila infection in two age groups of lambs

Tick-borne fever (TBF) is caused by the rickettsiae Ehrlichia phagocytophila and is a common disease in sheep in tick (Ixodes ricinus) infested areas in Norway. Earlier investigations have shown that some sheep could remain infected for several months after the primary infection. In this study, the persistence of E. phagocytophila after experimental infection was investigated in 2 age groups of lambs. Six lambs (1-2 weeks old) and 14 lambs (6-8 months old) were inoculated intravenously with an ovine strain of E. phagocytophila and thereafter examined clinically (including daily body temperature recording) and by haematological and serological (E. equi antibodies) methods for the next 4 months. At the end of this period, the lambs were examined for a TBF infection by blood smear investigation and blood inoculation studies. The infection was demonstrated in 19 (95%) of the 20 lambs.