Effects of zinc levels on activities of gastrointestinal enzymes in growing rats

The present study investigated the effect of different zinc (Zn) levels on activities of gastrointestinal digestive enzymes of growing rats. Four diets including Zn‐adequate (ZA; 46 mg/kg, control), Zn‐deficient (ZD; 3 mg/kg), high Zn supply (ZH; 234 mg/kg) and pair‐fed in which animals received the ZA diet at restricted amounts reflecting feed intake of the ZD group were fed to rats for 5 weeks. Dietary Zn was supplemented with ZnO. The results showed that Zn deficiency resulted in decreases in body weight, while ZH supply stimulated growth. The activities of sucrase, lactase and lipase were unaffected by dietary Zn levels. Maltase activity, however, was reduced in ZD group and elevated in ZH group. Amylase and protease activities were depressed by zinc deficiency. However, rats fed the Zn‐repletion diet displayed higher activity of pepsin, pancreatic amylase and protease. In particular, ZH supply did have no effect on intestinal hydrolases activities. The present study suggested that zinc deficiency impaired the activities of digestive enzymes and growth of animals. However, ZH supply might improve the digestion of nutrients via increasing activities of gastrointestinal hydrolase and probably enhanced animal health.     

Einfluß von alimentärem Zn-Mangel auf die Stickstoffelimination und Enzymaktivitäten des Harnstoffzyklus

Influence of alimentary zinc deficiency on nitrogen elimination and activities of urea cycle enzymes
This study was conducted to investigate whether the hyperammonaemia shown in earlier zinc-deficiency experiments was the result of disturbed enzyme activities of the urea cycle. For this study 36 male Sprague-Dawley rats with an average body weight of 85 g were divided into three experimental groups of 12 animals each. Group 1 received the semisynthetic zinc-deficient diet (AIN-93G; 1.2 mg Zn/kg DM) ad libitum over 33 experimental days. Group 2 received the zinc-sulphate-supplemented control diet (60 mg Zn/kg DM) ad libitum and group 3 received the same diet matched to the feed intake of the zinc-deficient rats. Alimentary zinc deficiency reduced the zinc concentration and the activity of the alkaline phosphatase in serum by 75 and 67%, respectively. The activity of the glutamate dehydrogenase and the concentrations of ammonia and urea in the serum of the zinc-deficient rats showed no significant differences compared with pair-fed control rats. On the other hand the hepatic activity of the mitochondrial localized glutamate dehydrogenase of the zinc-deficient rats was significantly increased and the carbamoylphosphate synthetase and ornithine carbamoyltransferase were reduced about half in comparison with both control groups. The activities of the cytosolic liver enzymes such as argininosuccinate synthetase, argininosuccinase and arginase were again significantly increased in zinc-deficient rats compared with both control groups. The increased hepatic activity of the glutamate dehydrogenase possibly led to an enhanced NH₃ elimination in addition to urea synthesis. The typical reduction of feed intake in consequence of zinc deficiency is therefore not the cause of hyperammonaemia due to disturbed urea synthesis, as has been hypothesized in earlier studies.     

Suppression of Babesia microti infection in mice concurrently infected with Fasciola hepatica

Blood cell parasitaemia of Babesia microti and the associated haematological changes were examined in mice harbouring patent Fasciola hepatica infections and in fluke-free control mice. B. microti parasitaemia was markedly suppressed in mice harbouring primary 7-week F. hepatica infections, as reflected in a reduction in the percentage of erythrocytes parasitised and in the incidence of multiple B. microti infections in the red cells. This suppression was accompanied by an annulment of B. microti induced reductions in haemoglobin and haematocrit levels in F. hepatica infected mice. In naive recipient mice, inoculated with blood from mice concurrently infected with F. hepatica and B. microti, the course of B. microti infection was characterised by a prolonged pre-parasitaemia period, a reduced peak parasitaemia and a delayed fall in haematocrit levels as compared to those inoculated with blood from mice infected with B. microti only. This feature may presumably be dose-related. The present study does not reveal the actual mechanism(s) involved in the suppression of the blood protozoan by F. hepatica. However, since B. microti has a preference for mature erythrocytes, the suppression may be a result of the altered erythrocyte kinetic state induced by the removal of erythrocytes by the blood-sucking fluke resulting in high levels of reticulocytes.     

Suppression of Babesia microti infection in mice concurrently infected with Schistosoma mansoni

Blood cell panasitaemias of Babesai microti and associated haematological changes were studied in mice concurrently infected with Schistosoma mansoni and in controls with no schistosome infections. In comparison to the controls B. microti parasit-aemias were suppressed markedly in mice harbouring 6 and 8 weeks old patent S. mansoni infections at the time of infection with B. microti. The suppression was accompanied by an alleviation/annulment of the B. microti induced reductions in haemoglobin and haematocrit levels and in its erythropoetic stimulation. The suppressive effect of patent S. mansoni infections on B. microti is suggested to be at least partly attributable to non-specific immunological factors although the altered erythrocyte kinetic state induced by the schistosoma infection in combination with the preference of B. microti for mature (old) erythrocytes might also play a role in the suppression. In mice harbouring 2 weeks old prepatent S. mansoni infections B. microti was not suppressed.     

Changes in food intake and circulating leptin due to gastrointestinal parasitism in lambs of two breeds

A reduction in food intake is a prominent feature of many infectious diseases. However, the underlying mechanisms of parasite-induced anorexia in sheep are poorly understood. Here, we tested the hypotheses (a) that the degree of parasite-induced anorexia in lambs is influenced by their growth potential and (b) that nematode infection results in elevated plasma leptin concentration in lambs. The hypotheses were tested with Suffolk x Greyface (S) and Scottish Black-face (B) lambs that are known to differ in their growth potential (S lambs are of greater growth potential than B lambs). During a primary parasite infection, 24 out of 48 lambs per breed were trickle-infected with 7,000 infective Teladorsagia circumcincta larvae per day, 3 d/wk, for a period of 12 wk (experiment I). The lambs were then dewormed, and after a 2-wk interval, half of the 24 lambs per breed that were previously infected were reinfected for another 12 wk with the same parasite and dose as used in the primary infection (experiment II). In both experiments, infected lambs were fed grass pellets for ad libitum intake, whereas noninfected lambs were fed grass pellets for either ad libitum or restricted intakes. The S lambs were more susceptible than B lambs to nematode infection, as judged from the differences in fecal egg counts (P = 0.007). Parasitized lambs of the more susceptible breed (S) showed anorexia [i.e., a decrease in intake of 13% compared with uninfected controls (P = 0.01)], whereas no significant reduction in food intake was observed in lambs of the more resistant breed (B). Reexposure to nematode infection of previously infected animals tended to result in renewed anorexia in S lambs but not in B lambs (P = 0.08) in a similar extent as during primary infection. Plasma leptin concentrations did not differ between ad libitum-fed infected and control lambs but were greater in infected than in noninfected lambs at a similar level of food intake during both the primary (P = 0.02) and the secondary parasitic infection (P = 0.004) in both breeds. The results show that leptin may be involved in the response of lambs to infection but that it is unlikely that leptin alone is responsible for the parasite-induced anorexia in lambs.     

The effect of T. vivax infection in west African dwarf goats on energy and nitrogen metabolism.

To investigate how T. vivax affects metabolism in dwarf goats, nine wethers (infection group) given alfalfa pellets ad libitum were infected intravenously and food intake was recorded up to 49 days after infection in the infection group and in the control group (n = 9). Controls received the same diet, ad libitum before infection and in restricted amounts after infection in order to obtain similar intakes in the two groups. Digestible organic matter intake (DOMI) and nitrogen balance (NB) were determined during four balance trials. All animals were bled regularly to measure parasitaemia, packed cell volume (PCV) and a number of serum metabolites. All infected animals showed symptoms typical for T. vivax infection as judged by parasitaemia, PCV and rectal temperature. Infection had a non-uniform negative effect on food intake. Compared with controls at equal DOMI, NB was lower in infected animals, the difference being significant 4 weeks after infection. This was caused by a gradual increase in NB at equal DOMI of the control group. The NB of the ad libitum fed infected animals 2 and 4 weeks after infection was comparable to values normally found in healthy ad libitum fed dwarf goats with an equal DOMI. NEFA values in serum were significantly elevated after infection. Except for two infected animals with an extremely low food intake towards the end of the experiment, no rise in serum ketone bodies was evident. After infection, serum protein increased, differences with controls being significant 4 and 7 weeks after infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of T. vivax infection in West African Dwarf goats on energy and nitrogen metabolism

Summary

To investigate how T. vivax affects metabolism in dwarf goats, nine wethers (infection group) given alfalfa pellets ad libitum were infected intravenously and food intake was recorded up to 49 days after infection in the infection group and in the control group (n=9). Controls received the same diet, ad libitum before infection and in restricted amounts after infection in order to obtain similar intakes in the two groups. Digestible organic matter intake (DOMI) and nitrogen balance (NB) were determined during four balance trials. All animals were bled regularly to measure parasitaemia, packed cell volume (PCV) and a number of serum metabolites.

All infected animals showed symptoms typical for T. vivax infection as judged by parasitaemia, PCV and rectal temperature. Infection had a non‐uniform negative effect on food intake. Compared with controls at equal DOMI, NB was lower in infected animals, the difference being significant 4 weeks after infection. This was caused by a gradual increase in NB at equal DOMI of the control group. The NB of the ad libitum fed infected animals 2 and 4 weeks after infection was comparable to values normally found in healthy ad libitum fed dwarf goats with an equal DOMI.

NEFA values in serum were significantly elevated after infection. Except for two infected animals with an extremely low food intake towards the end of the experiment, no rise in serum ketone bodies was evident. After infection, serum protein increased, differences with controls being significant 4 and 7 weeks after infection.

It is concluded that T. vivax infection results in a decrease in energy intake and a decrease in NB up to at least 4 weeks after infection. At equal DOMI, NB of infected animals was not lower than expected for ad libitum fed healthy animals but was lower than in healthy controls on a restricted diet, probably as a result of a decrease in maintenance requirements of the latter. The data on NB and serum NEFA concentrations suggest that non‐protein energy sources are used to supply the increased energy demand as a result of infection.     

Babesia microti-like rodent parasites isolated from Ixodes persulcatus (Acari: Ixodidae) in Heilongjiang Province, China

A Babesia microti-like rodent parasite was isolated from the tick, Ixodes persulcatus, collected from the northern forest area of Heilongjiang province, China. The collected I. persulcatus were allowed to feed on specific pathogen-free SCID mice and red blood cells from the mice were used to isolate Babesia spp. with the microareophilous stationary-phase culture technique. Paired and tetrad forms of merozoites were observed by light microscope in red blood cells of SCID mice. In vitro growth of the parasites was also achieved in mice erythrocytes, which indicated the presence of Babesia spp. in I. persulactus. To further identify the Babesia species, polymerase chain reaction screening and subsequent sequencing of nuclear small subunit ribosomal RNA (nss-rRNA) was employed. The results indicate that the observed parasites might be an isolate strain responsible for human babesiosis -B. microti - which has 99.3% identity with that of B. microti isolate RcM5201 (AB112050) from Mishan in Heilongjiang and Kobe isolates from Japan. In addition, the infection rate of B. microti in I. persulcatus ticks in the region was 3.6-4.0% in adult females and no infection in males. Though the infection rate is low, the high attack frequency of tick species on local residents indicates the risk of human babesiosis in the region and the necessity of precautionary measures.     

Response to elemental sulfur by calves and sheep fed purified diets

Free amino acid profiles in plasma and liver as well as body, organ and gastrointestinal growth were compared in 20 weanling bulls (four per treatment) fed diets deficient (.04%), excessive (.94 and 1.72%) or adequate (.34%) in S. Body, organ and gastrointestinal comparisons also were made with yearling rams fed .04 and .34% S diets. The .34% S diet was fed at two levels, one ad libitum, the other in amounts equal on a body weight.75 basis to that consumed by animals fed the .04% S diet ad libitum. Animals were allowed to consume other diets ad libitum. The calves fed the .04% S diet had negative S, but slightly positive N, balance and were unable to maintain body weight. As dietary S content was increased, plasma and liver methionine increased linearly. An increased histidine in plasma of calves fed the .04% S diet may be due to reduced intake because the calves restricted-fed the .34% S diet also had high plasma histidine. Plasma citrulline, cystine, serine and total nonessential amino acids decreased markedly as dietary S intake became adequate. Intermediate S diets resulted in reduced concentrations of plasma alanine, serine, proline and total nonessential amino acids. Calves restricted-fed the .34% S diet were the most efficient in retaining N with less urinary N. Excesses of S were not detrimental to growth, but plasma valine increased linearly as S intake increased. The S deficiency in calves reduced the ratio of the rumen-reticulum tissue to body weight, and in rams it reduced the ratio of gastrointestinal tissue and preintestinal tissue to body weight. Per kilogram of intestinal-free body weight, there was a linear decrease in liver and testes but an increase in adrenals as S was decreased for calves. The kidney, adrenals and pituitary were increased by S deficiency in rams. Of the amino acids assayed, only methionine from the plasma and liver in calves reflected both an excess and a deficiency of S independent of feed intake effects.     

Changes of splenic lymphocyte subpopulation in mice inoculated with Babesia microti and Babesia rodhaini.

Changes of splenic lymphocyte subpopulation after Babesia microti and Babesia rodhaini inoculation in mice were examined by flow cytometric analysis. The B. microti inoculated mice showed a longer period of time from inoculation to the onset of increase or decrease parasitaemia (%), packed cell volume, total spleen cell numbers and surface immunoglobulin positive splenic cell numbers than respective periods in B. rodhaini inoculated mice. The Thy-1 positive cell numbers in B. microti inoculated mice and B. rodhaini inoculated mice pre-immunized with homologous parasites were significantly higher than that of B. rodhaini inoculated mice. The ratio of L3T4 positive cell/Lyt-2 positive cell after inoculation with B. microti was quite similar to that in B. rodhaini mice pre-immunized. However, the ratio in B. rodhaini inoculated mice revealed a lack of an increasing phase. These results suggested that the T-cell dependent early immune response, especially suppressor activity, was closely related to the difference in the course of infection between the non-lethal B. microti and the lethal B. rodhaini infection in mice.     

High susceptibility of Djungarian hamsters (Phodopus sungorus) to the infection with Babesia microti supported by hemodynamics

As the comparative study was carried out on the susceptibility by the pursuit of parasitemia among the Djungarian, Syrian, and Chinese hamsters as well as BALB/c mice infected with the Syrian hamster-adapted Babesia microti strain, and Djungarian hamsters showed the highest parasitemia among them. Then, the other hematological parameters were pursued in the Djungarian hamsters infected with the hamster-adapted B. microti strain. Remarkable symptoms observed were hemoglobinuria clinically, anemia hematologically, and splenomegaly macroscopically during all over the observation period for 24 weeks post infection (PI). Parasitemia began to rise at 2 weeks and peaked at 4 weeks PI. After that, parasitemia decreased gradually but was maintained with a level of about 10% on average until 24 weeks PI at the end of the experiment. A decrease in the RBC count, Hb, and PCV, and an increase in the reticulocyte and WBC counts due to the development of immature neutrophils, lymphocytes and monocytes were recognized together with a rise of parasitemia. The hamsters had macrocytic hypochromic anemia due to the increase of MCV and the decrease of MCHC in the growth phase of the parasite. It was considered that the Djungarian hamsters will be useful for the infection examination, isolation, maintenance, and passage of B. microti in laboratory.     

锌对雏鸭外周血T-淋巴细胞的影响

15 0只 1日龄天府肉鸭健雏随机分为 3组 ,分别喂给缺锌 (每千克日粮含 Zn 2 2 .9mg)、对照 (每千克日粮含 Zn10 0 mg)和锌中毒 (每 kg日粮含 Zn130 0 mg)日粮 7周或 4周 ,以酸性 - α-醋酸萘酯酶 (ANAE)染色法观测外周血 T-淋巴细胞的动态变化。结果锌缺乏组和锌中毒组雏鸭外周血 T-淋巴细胞的 ANAE阳性率显著低于对照组 (P<0 .0 1) ,表明锌缺乏或锌中毒可抑制 T-淋巴细胞的生成 ,降低其在外周血中的数量。本试验还对锌缺乏和锌中毒引起的外周血 T-淋巴细胞减少的机理进行了探讨     

Reproductive performance of first and second parity sows fed daily or every third day

Crossbred gilts were used in a two-parity experiment to measure the effect on reproductive performance of feeding every third day during gestation.Diets were formulated with maize and soybean meal to 12% and 16% crude protein for gestation and lactation, respectively. Experimental feeding regimens were imposed from an average day 30 to an average day 109 of gestation. During this period, the gravid gilts or sows housed in confinement were fed either 1.9 kg of the gestation diet daily or permitted ad libitum access to the diet for 1 day in each 3-day period. The lactation diet was provided ad libitum from farrowing until weaning at 28 days post partum. From weaning until the dietary treatments were reimposed about 30 days post-coitus, the females were fed 1.9 kg of the gestation diet per day.First-parity females fed ad libitum every third day consumed an average of 0.4 kg more feed per day than did those restricted to 1.9 kg of diet per day. There was no effect of feeding regimen on gestation weight gain or any criteria of reproductive performance, e.g. litter size or weaning weights of piglets. During the second parity, sows allowed to eat ad libitum every third day gained significantly more weight during gestation than those fed daily, reflecting an average daily feed intake that was 1.2 kg greater than that of the control animals fed 1.9 kg day^?1. Second parity reproductive performance was not affected by treatment. Backfat thickness measured at the point of the shoulder and at the last rib on day 30 and day 109 of gestation and at weaning increased during gestation and decreased during lactation regardless of feeding regimen or parity.Feeding gravid pigs every third day did not adversely affect reproductive performance; however, average daily feed intake was increased. Although the sows seemed to adapt quickly to a three-day feeding schedule, welfare aspects need to be investigated further.     

Growth performance, diet apparent digestibility, and plasma metabolite concentrations of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding level

Two experiments, each with 36 barrows with high-lean-gain potential, were conducted to evaluate apparent nutrient digestibilities and performance and plasma metabolites of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets. The low-protein diets were supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis or by feeding 90 or 80% of ad libitum intake. Pigs were fed for 55 d. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis or by feeding 80% of the ad libitum intake. Pigs were fed for 27 d. Pigs fed the CONTROL diet had greater (P < 0.05) ADG and feed efficiency (G/F) than pigs fed the IDEAL (Exp. 1 and 2) and AACON diets (Exp. 2). As the level of feed intake decreased, ADG decreased (P < 0.05), but G/F tended to improve (P < 0.10) for pigs fed 90% of ad libitum in Exp. 1 and for pigs fed 80% of ad libitum in Exp. 2. In Exp. 1, the apparent total tract digestibilities of DM and energy were greater (P < 0.01) for pigs fed the IDEAL diet than for pigs fed the CONTROL diet. In Exp. 2, the apparent total tract digestibility of protein was greatest in pigs fed the CONTROL diet (P < 0.05) and was greater (P < 0.05) in pigs fed the AACON diet than in pigs fed the IDEAL diet. Plasma urea concentrations were lower in pigs fed the IDEAL diet than in pigs fed the CONTROL diet, regardless of feeding level. For pigs fed the CONTROL diet, plasma urea concentrations were lower when feed intake was 80% of ad libitum (diet level, P < 0.01). In summary, pigs fed the IDEAL and the AACON diets gained less and had lower plasma urea concentrations than pigs fed the CONTROL diet. Based on these data, it seems that the growth potential of pigs fed the IDEAL and AACON diets may have been limited by a deficiency of lysine, threonine, and(or) tryptophan and that the amino acid pattern(s) used was not ideal for these pigs.     

Antibody responses in New World camelids with tuberculosis caused by Mycobacterium microti

Antibody responses in New World camelids (NWC) infected with Mycobacterium microti were studied by two serological methods, multiantigen print immunoassay (MAPIA) and lateral-flow-based rapid test (RT). Serum samples were collected during 2004-2006 from 87 animals including 1 alpaca and 7 llamas with confirmed or suspected M. microti infection, 33 potentially exposed but clinically healthy animals from known infected herds, and 46 control NWC from herds where infection had not been previously diagnosed. The serological assays correctly identified infection status in 97% (MAPIA) or 87% (RT) cases. In three llamas with confirmed M. microti infection and one llama with gross pathology suggestive of disease, for which multiple serum samples collected over time were available, the antibody-based tests showed positive results 1-2 years prior to the onset of clinical signs or being found dead. In MAPIA, MPB83 protein was identified to be an immunodominant serological target antigen recognized in NWC infected with M. microti. With the limited number of animals tested in this study, the serological assays demonstrated the potential for convenient, rapid, and accurate diagnosis of M. microti infection in live llamas and alpacas.     

Effects of Different Forced Molting Methods on Postmolt Production,Corticosterone Level,and Immune Response to Sheep Red Blood Cells in Laying Hens

The objective of this study was to evaluate the effects of different molting methods on postmolt production, plasma corticosterone levels, and antibody production to SRBC for the welfare of laying hens. This experiment was conducted with 120 IGH-type Brown laying hens (70 wk of age), randomly divided into 3 experimental groups. The hens in one group were fed a whole-grain barley diet during the first 10 d (WB diet). On d 11, hens consumed 100 g of layer diet/d until d 28. In the second group, hens were fed a Zn diet containing 10,000 mg/kg of Zn as ZnO for 10 d (Zn diet). Hens were then provided 100 g of a layer diet from d 11 to 28. In the third group, feed was withdrawn for 10 d, and on d 11 hens were fed a cracked corn diet ad libitum until d 28 (California method; CAL diet). Hens in all groups were returned to the layer diet ad libitum on d 29. Egg weight was lower in the Zn treatment than in the other treatments. Feed intake and plasma corticosterone levels were higher and antibody production was lower in the CAL treatment than in the WB and Zn groups. The FCR was better in the WB than in the Zn group. Mortality, egg production, and egg quality were not significantly different among the molting methods. As a result, the WB molting program was the best method for postmolt production among the programs examined.     

Body composition and tissue accretion rates of barrows fed corn-soybean meal diets or low-protein, amino acid-supplemented diets at different feeding levels

Two experiments, each with 39 high-lean-gain potential barrows, were conducted to evaluate the organ weights, body chemical composition, and tissue accretion rates of pigs fed corn-soybean meal diets (CONTROL) and low-protein diets supplemented with crystalline lysine, threonine, tryptophan, and methionine either on an ideal protein basis (IDEAL) or in a pattern similar to that of the control diet (AACON). Amino acids were added on a true ileally digestible basis. The initial and final BW were, respectively, 31.5 and 82.3 kg in Exp. 1 and 32.7 and 57.1 kg in Exp. 2, and pigs were fed for 55 and 27 d in Exp. 1 and 2, respectively. In Exp. 1, the CONTROL and IDEAL diets were offered on an ad libitum basis, or by feeding 90 or 80% of ad libitum intake. In Exp. 2, the CONTROL, IDEAL, and AACON diets were offered on an ad libitum basis, or by feeding 80% of the ad libitum intake. Three pigs were killed at the start of the experiments and three from each treatment were killed at the end of each experiment to determine body chemical composition. In both trials, the whole-body protein concentration (g/kg) and the accretion rates of protein (g/d) were greater (P < 0.05) for pigs fed the CONTROL than for pigs fed the IDEAL and AACON diets. In Exp. 1, pigs fed the CONTROL diet had a trend (P < 0.10) for greater water and lower lipid concentration and had greater (P < 0.05) water and ash accretion rates. Whole-body protein concentration was greatest (P < 0.05) in pigs fed at 80% of ad libitum, but protein, water, and ash accretion rates were greatest (P < 0.05) in pigs allowed ad libitum access to feed. In summary, pigs fed the IDEAL and the AACON diets had less protein in the body and lower protein accretion rates than pigs fed the CONTROL diet. It seems that reductions in protein deposition in pigs fed the IDEAL and AACON diets may have been due to a deficiency of one or more essential amino acids or possibly to increases in the NE for metabolic processes leading to increases in adipose tissue deposition.     

Energy and nitrogen metabolism of chickens infected with either Eimeria acervulina or Eimeria tenella.

1. The effects of sublethal infections of E. acervulina and E. tenella on the energy and nitrogen metabolism of groups of five broilers aged 16 d were studied for 16 d in respiration chambers. 2. The metabolisable energy content of the diet for chickens infected with E. acervulina was 0.689 of its gross energy content and N retention was 42.5 g/100 g N intake compared with 0.738 and 47.1 g respectively, in uninfected pair-fed controls. Chickens infected with E. tenella were similarly affected. 3. Efficiency of utilisation of ME by chickens infected with E. acervulina was 0.43 during the first 8 d after infection, and 0.52 during the second 8 d compared with an overall efficiency by non-infected chickens fed ad libitum of 0.73. Maintenance energy requirement of infected chickens was higher during the first 8 d after infection than during the second 8-d period. 4. Body composition measurements showed that of the total gain in weight of chickens infected with E. acervulina, only 7.5 g/kg gain was fat and 213 g/kg was protein compared with 45 g and 210 g respectively for non infected chickens fed ad libitum. 5. E. acervulina and E. tenella infections reduced the apparent digestibility of total mineral, calcium and phosphorus.     

Vitamin A deficiency impairs cytotoxic T lymphocyte activity in Newcastle disease virus-infected chickens

The effect of vitamin A deficiency on cytotoxic T lymphocyte (CTL) activity was investigated during the acute phase of disease 7 days after primary inoculation and 1 day after secondary inoculation in chickens with or without Newcastle disease virus (NDV, La Sota strain) infection. Day-old chickens with limited vitamin A reserves were fed purified diets containing either marginal (ad libitum) or adequate (pair-fed) levels of vitamin A, and at 3 weeks of age half of the chickens in each group were infected with NDV. Cytotoxic activity was investigated during the acute phase of disease (7 days after primary inoculation) and 1 day after secondary inoculation, in an assay system with either peripheral blood lymphocytes (PBL) or nonadherent splenocytes as effector cells and adherent splenocytes from the same animal as target cells. After primary inoculation, cytotoxic activity could only be demonstrated in nonadherent splenocytes. Vitamin A deficiency resulted in significantly reduced CTL activity at all effector/target cell ratios tested. After reinfection CTL activity could also be demonstrated in PBL, but only from chickens fed the control diet, suggesting a diminished pool of CTL in vitamin A deficiency. The results of this study indicate that vitamin A deficiency impairs CTL activity - a part of the cell-mediated defense system - and this may have important implications for recovery from viral infection.