Hepatic iron accumulation over time in European starlings (Sturnus vulgaris) fed two levels of iron.

European starlings (Sturnus vulgaris) were used as a passerine bird model to examine the effect of dietary iron on the level of hepatic iron in birds. Nestling and fledgling starlings (n = 56) were raised on a controlled-iron diet. When birds maintained constant body weight, they were assigned in pairs to cages, and baseline sampling was performed. Pairs were then assigned to one of two diets: the controlled-iron diet (168 ppm, dry basis) or a high-iron diet (3,035 ppm, dry basis). Dry-matter intake and iron consumption were recorded. Dry-matter intake did not differ between the dietary treatment groups and was stable during treatment periods. Iron intake was higher in the high-iron group (P < 0.05). Birds were euthanized at baseline, 8 wk, and 16 wk. Body, liver, and spleen weights were measured. Hepatic iron and copper concentrations were determined. Body weight did not differ between the two treatment groups or among individuals for the study duration. Liver iron concentration differed over time and between treatment groups. Birds receiving both treatments had similar liver iron content at week 8 (3,107 +/- 228.6 ppm and 3,122 +/- 306.2 ppm high and controlled iron, respectively; P > 0.05), but by week 16, birds consuming the high-iron diet had greater hepatic iron levels than those consuming the controlled-iron diet (5,929 +/- 937.2 ppm and 3,683 +/- 229.5 ppm high and controlled iron, respectively; P < 0.05). Birds on the controlled-iron diet also had higher hepatic iron at 16 wk than at 8 wk. Liver copper decreased over time in all birds regardless of treatment. Results show that both dietary iron level and duration of time influenced hepatic iron storage. The controlled-iron diets still allowed accumulation of hepatic iron in an 8-wk period.     

Subacute toxicity of Dietary T-2 toxin in mice: influence of protein nutrition.

The subacute toxic effects of dietary T-2 toxin (20 ppm) incorporated in semipurified diets of 8%, 12% or 16% protein, were examined in young Swiss mice after one, two, three and four weeks. Dietary T-2 toxin caused substantial reductions in growth and food consumptaion, the degrees of which were greatest in mice fed the diets of reduced protein content. T-2 toxin consistently caused similar degrees of nonregenerative anemia, lymphopenia, thymic atrophy and gastric hyperkeratosis irrespective of the dietary protein level. However, erythroid hypoplasia was temporary in mice fed T-2 toxin in the 16%-protein diet such that erythroid precursors regenerated in splenic and bone marrow and were hyperplastic after four weeks. Liver to body weight ratios of mice fed T-2 toxin in the 16%-and 12%-protein diets increased during the four week trial in comparison to control mice fed at a similar rate. These observations indicated that suppression of erythropoiesis in mice by dietary T-2 toxin was temporarty and that the interval before regeneration was prolonged by diets of reduced protein content.     

Effect of dietary iron and copper on performance and oxidative stability in broiler leg meat

1. An experiment was carried out to determine the effect of removal of supplemental iron and copper from broiler diets during the last 3 weeks before slaughter on broiler performance, tissue vitamin E concentrations and oxidation values in raw; cooked and stored broiler leg meat. 2. Removal of supplemental iron and copper from the diet slightly decreased food efficiency; the differences were significant only when both minerals were removed simultaneously 3. Effect of iron withdrawal on iron concentration in tissue was low. However, total copper concentration in tissue was reduced in animals deprived of iron or both minerals simultaneously. 4. Removal of dietary iron and copper did not affect vitamin E concentration in raw and cooked meat, while stored meat showed lower concentrations in animals deprived of iron and copper simultaneously. 5. The removal of iron and copper from the diet reduced oxidation values in cooked broiler leg meat as measured by the thiobarbituric acid-reacting substances method (TBARS).     

Iron storage disease in captive Egyptian fruit bats (Rousettus aegyptiacus): relationship of blood iron parameters to hepatic iron concentrations and hepatic histopathology.

This study evaluated the relationship between blood iron parameters and hepatic iron concentrations, and correlation of histologic findings with hepatic iron concentrations in a captive population of Egyptian fruit bats (Rousettus aegyptiacus) and island flying foxes (Pteropus hypomelanus). Blood samples were collected for complete blood counts, plasma biochemical profiles, serum iron concentrations, total iron-binding capacity, whole-blood lead concentrations, and plasma ferritin assays. Liver samples obtained by laparotomy were divided, with one half processed for histologic examination and the other half frozen and submitted for tissue mineral analysis. The histologic sections were scored by two blinded observers for iron deposition, necrosis, and fibrosis. The Egyptian fruit bats had significantly higher liver iron (mean = 3,669 +/- 1,823 ppm) and lead (mean = 8.9 +/- 5.8 ppm) concentrations than the island flying foxes (mean [Fe] = 174 +/- 173 ppm, mean [Pb] = 1.9 +/- 0.5 ppm). Hepatic iron concentrations significantly correlated with tissue lead concentrations, histologic grading for iron and necrosis, serum iron, transferrin saturation, and plasma ferritin (P < 0.001). Blood lead concentrations negatively correlated with tissue lead concentrations (P < 0.001). When the product of transferrin saturation and serum iron was greater than 51, an individual animal had a high probability of having iron overload. When the product of these two variables was greater than 90, there was a high probability that the animal had hemochromatosis. On the basis of this study, it appears that evaluation of serum iron, transferrin saturation, and plasma ferritin are useful and noninvasive methods for diagnosis of hemochromatosis in Egyptian fruit bats.     

Some aspects of extra iron supply in veal calf fattening

Extra iron (5 ppm) in a normal commercial milk replacer given from the end of the sixth week until the end of the sixteenth week of the fattening period influenced food conversion positively without a loss in meat quality. Even when the extra iron was given to the end of the fattening period there was no perceptible improvement of the haematological status of the calf, though liver iron concentration was increased. During all the experiments no stainable iron could be found in bone marrow smears. Iron and copper concentration measured in liver biopsies appeared to give reliable information about, respectively, iron and copper status of the veal calf. In relation to the colour of the meat at slaughter the blood haemoglobin concentration during the fattening period was found to be the most reliable parameter.     

Some aspects of extra iron supply in veal calf fattening

Extra iron (5 ppm) in a normal commercial milk replacer given from the end of the sixth week until the end of the sixteenth week of the fatting period influenced food conversion positively without a loss in meat quality. Even when the extra iron was given to the end of the fattening period there was no perceptible improvement of the haematological status of the calf, though liver iron concentration was increased. During all the experiments no stainable iron could be found in bone marrow smears. Iron and copper concentration measured in liver biopsies appeared to give reliable information about, respectively, iron and copper status of the veal calf. In relation to the colour of the meat at slaughter the blood haemoglobin concentration during the fattening period was found to be the most reliable parameter.     

Investigations on iron bioavailability of different sources and supply levels in piglets

Two experiments were conducted to investigate the iron bioavailability of different sources and supply levels in piglets. In experiment 1, the influence of feeding an iron deficient basal diet or the basal diet supplemented with 28 ppm Fe either in form of Fe-chelate, crystalline Fe-glycinate, or Fe-sulphate on apparent iron digestibility and on blood parameters was determined. In experiment 2, a dose-response approach was used to determine the effects of supplementing an iron-deficient basal diet with 30, 60, or 90 ppm of Fe either in form of crystalline Fe-glycinate or Fe-sulphate on digestibility of Fe, growth and blood parameters. In experiment 1, comparison of iron sources revealed a tendency (0.05 < p < 0.1) for a higher Fe digestibility from Fe-glycinate (40.9%) compared with Fe-chelate (30.8%) or Fe-sulphate (30.7%). Fe-balance was higher (p < 0.05) for Fe-glycinate compared with Fe-sulphate but iron balance was similar for iron sulphate and iron chelate. Those results, however, were not reflected in data of blood parameters. In experiment 2, iron digestibility, blood parameters and performance were significantly (p < 0.05) influenced by iron supply. Effects of iron source on digestibility of iron were lower than observed in the first experiment.     

The role of experience in the development of selective zinc intake in pullets

Selective food intake behaviour was studied in pullets that were subjected to different zinc supply in early life. During the first four weeks post-hatching three groups, totaling 72 birds, were fed either a low zinc diet (25 ppm), a complete diet (50 ppm) or both diets in a choice situation. The prior feeding experience was investigated during the subsequent ontogenetic development in two-choice dietary tests. Chicks first exhibited a preference for the high zinc diet as deficiency symptoms can be seen in depleted birds. Juvenile pullets did not prefer any diet for the duration of experimental period. Layers were initially indifferent to the supplemented zinc diet, but after reaching high laying capacity they began preferentially to select the complete diet. The results indicate that early experience with diets different in zinc content have no influence on subsequent diet preferences at choice. The ability to select is based on association learning following ingestion. A conditioned diet aversion first developed in phases of high zinc requirement as a result of negative feedback mechanisms produced by the deficient diet.     

Serum iron, total iron binding capacity, plasma copper and hemoglobin types in anemic and poikilocytic calves.

Ninety-eight calves were studied to determine if anemia and poikilocytosis were related to iron or copper status or hemoglobin type. No significant differences were found in serum iron, total iron binding capacity, marrow iron, plasma copper or hemoglobin type between affected and normal calves. Poikilocytes were strongly inversely correlated (-0.9177) with age. Calves less than six weeks of age had more poikilocytes, lower serum iron, higher total iron binding capacity, less adult hemoglobin and more neonatal and fetal hemoglobin than calves greater than six weeks of age.     

The effects of dietary T-2 toxin on acute herpes simplex virus type 1 infection in mice

Young male white Swiss mice were fed control diet or diet supplemented with 20 or 10 parts per million (ppm) of T-2 toxin for two or three weeks. These mice then were inoculated with herpes simplex virus type 1 (HSV-1) (9.6 x 10(6) plaque forming units) intraperitoneally. To compare the effects of T-2 toxin against a known immunosuppressive drug, cyclophosphamide was injected intraperitoneally at 150 mg/kg, 24 hours after treatment with HSV-1, into mice fed the control diet. Mice were necropsied and tissues were collected for microscopic and virologic examination. White Swiss mice which consumed a daily diet containing 20 ppm of T-2 toxin for two or three weeks were highly susceptible to HSV-1 infection and 27 of 36 (75%) died as a result of extensive hepatic and adrenal necrosis. Although HSV-1 was isolated from livers and brains of mice fed 20 ppm of T-2 toxin for two or three weeks, there was little or no inflammatory response found in the adrenals, livers, spinal cords, brains, or ganglia. The necrotizing encephalomyelitis observed in control mice was absent. High levels of dietary T-2 toxin appeared to be more immunosuppressive than cyclophosphamide because only one mouse died after treatment with HSV-1 and cyclophosphamide. Mice treated with cyclophosphamide had changes in brain, spinal cord, spleens, thymus, and bone marrow which were similar to those fed 20 ppm of T-2 toxin and infected with HSV-1, however, liver lesions were much less severe. HSV-1-infected mice on a diet with 10 ppm T-2 toxin had lesions of intermediate severity when compared with HSV-1-infected mice fed a diet with 20 ppm T-2 toxin and HSV-1-infected mice on control diets. Necrosis was less extensive in the livers and adrenals. The infrequent isolation of virus from liver and brain was consistent with the lack of intranuclear inclusion bodies and a more marked inflammatory response. Ten ppm of dietary T-2 toxin only depressed bone marrow and splenic red pulp to a mild or moderate degree. This may have enhanced the necrotizing encephalomyelitis observed in mice killed on days 6 and 8 after HSV-1 infection. Liver lesions were mild and those of the adrenals were moderate in mice fed control diet. The rare isolation of HSV-1 from the liver and brain and the findings of a moderate to severe necrotizing encephalomyelitis in these mice was consistent with an essentially functional immune system.     

Effect of dietary copper source (cupric citrate and cupric sulfate) and concentration on growth performance and fecal copper excretion in weanling pigs

In each of two experiments, 924 pigs (4.99 kg BW; 16 to 18 d of age) were assigned to 1 of 42 pens based on BW and gender. Pens were allotted randomly to dietary copper (Cu) treatments that consisted of control (10 ppm Cu as cupric sulfate, CuSO4 x 5H2O) and supplemental dietary Cu concentrations of 15, 31, 62, or 125 ppm as cupric citrate (CuCit), or 62 (Exp. 2 only), 125 (Exp. 1 only), or 250 ppm as CuSO4. Live animal performance was determined at the end of the 45-d nursery phase in each experiment. On d 40 of Exp. 2, blood and fecal samples were collected from two randomly selected pigs per pen for evaluation of plasma and fecal Cu concentrations and fecal odor characteristics. In Exp. 1, ADG, ADFI, and G:F were increased (P < 0.05), relative to controls, when pigs were fed diets containing 250 ppm Cu as CuSO4. Pigs fed diets containing 125 ppm Cu as CuCit had increased (P < 0.05) ADG compared with pigs fed diets supplemented with 15 or 62 ppm Cu as CuCit. The ADG, ADFI, and G:F did not differ among pigs fed diets containing 125 and 250 ppm Cu as CuSO4 or 125 ppm Cu as CuCit. In Exp. 2, pigs fed diets containing 250 ppm Cu as CuSO4 had improved (P < 0.05) ADG, ADFI, and G:F compared with controls. In addition, ADG, ADFI, and G:F were similar when pigs were fed diets containing either 250 ppm Cu as CuSO4 or 125 ppm Cu as CuCit. Pigs fed diets containing 62 ppm Cu as CuSO4 or CuCit had similar ADG, ADFI, and G:F. Plasma Cu concentrations were not affected by dietary Cu source or concentration, but fecal Cu concentrations were increased (P < 0.05) as the dietary concentration of Cu increased. Pigs consuming diets supplemented with 125 ppm Cu as CuCit had fecal Cu concentrations that were lower (P < 0.05) than pigs consuming diets supplemented with 250 ppm Cu as CuSO4. Fecal Cu did not differ in pigs receiving diets supplemented with 62 ppm Cu as CuSO4 or CuCit. Odor characteristics of feces were not affected by Cu supplementation or source. These data indicate that 125 and 250 ppm Cu gave similar responses in growth, and that CuCit and CuSO4 were equally effective at stimulating growth and improving G:F in weanling pigs. Fecal Cu excretion was decreased when 125 ppm Cu as CuCit was fed compared with 250 ppm Cu as CuSO4. Therefore, 125 ppm of dietary Cu, regardless of source, may provide an effective environmental alternative to 250 ppm Cu as CuSO4 in weanling pigs.     

Importance of diet of dam and colostrum to the biological antioxidant status and parenteral iron tolerance of the pig

Fifteen second-parity sows were used to determine the importance of vitamin E (E) and selenium (Se) supplementation of the sow's diet and colostrum consumption by the neonatal pig on tolerance to parenteral iron. Selenium (.1 ppm) and E (50 IU/kg) supplementation of the diet of the sow increased plasma tocopherol and Se concentrations, but did not increase plasma glutathione peroxidase (GSH-Px) activity. Colostrum had greater concentrations of E (primarily alpha-tocopherol) and Se than milk. Plasma biological antioxidant status (tocopherol level and GSH-Px activity) of pigs at birth was very low, but by 2 d of age had increased, especially in alpha-tocopherol (nearly a 20-fold increase). Liveability and body weight gain of pigs were not affected by the pre-colostrum iron injection (200 mg Fe as gleptoferron); however, plasma tocopherol concentrations of Fe-injected pigs were lower and plasma Se concentration and GSH-Px activities were higher at 2 d of age than values of pigs not receiving parenteral Fe. Supplementation of the dam's diet with E and Se maintained high tocopherol and Se levels in her colostrum and milk and a high biological antioxidant status in her pigs throughout the nursing period.     

Effect of dietary iron content on hematologic and other measures of iron adequacy in dogs

Eighteen 9- to 10-week old Beagles were fed casein-based diets (4,710 kcal of metabolizable energy/kg of body weight) containing either 12, 80, or 160 mg of iron/kg of diet. Growth and feed consumption were monitored throughout the 47-day study. Hematocrit (Hct), hemoglobin (Hb) concentration, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), RBC numbers, erythrocyte protoporphyrin (EP) concentration, serum iron concentration, serum total iron-binding capacity (TIBC), and serum ferritin concentration were determined weekly. Growth rate and feed efficiency were not significantly influenced by dietary iron content. At 14 days, Hb concentration, Hct, MCV, MCH, RBC numbers, and serum iron concentration were significantly (P less than 0.05) lower in dogs fed the 12 mg/kg diet, and remained significantly low for the remainder of the study. Erythrocyte protoporphyrin concentration increased significantly (P less than 0.05) by 14 days in dogs fed the basal diet, and remained significantly high relative to that in dogs of the other dietary groups for the remainder of the study. Serum ferritin concentration decreased in dogs of the group fed the basal diet, with a significant (P less than 0.05) difference beyond day 42. Differences in Hct, MCH, MCV, or hemoglobin, serum iron, serum ferritin, or EP concentration were not found between groups fed 80 and 160 mg of iron/kg of diet. Liver nonheme iron content was significantly (P less than 0.05) affected by dietary iron content.     

Effect of supplemental iron on finishing swine performance, carcass characteristics, and pork quality during retail display

Crossbred pigs (n = 185) were used to test the effects of dietary Fe supplementation on performance and carcass characteristics of growing-finishing swine. Pigs were blocked by BW, allotted to pens (5 to 6 pigs/pen), and pens (5 pens/block) were allotted randomly to either negative control (NC) corn-soybean meal grower and finisher diets devoid of Fe in the mineral premix, positive control (PC) corn-soybean meal grower and finisher diets with Fe included in the mineral premix, or the PC diets supplemented with 50, 100, or 150 ppm Fe from Availa-Fe (an Fe-AA complex). When the lightest block averaged 118.2 kg, the pigs were slaughtered, and bone-in pork loins were collected during fabrication for pork quality data. During the grower-I phase, there was a tendency for supplemental Fe to reduce ADG linearly (P = 0.10), whereas in the grower-II phase, supplemental Fe tended to increase ADG linearly (P = 0.10). Even though pigs fed NC had greater G:F during the finisher-I phase (P < 0.05) and across the entire trial (P = 0.07), live performance did not (P > or = 0.13) differ among dietary treatments. There were linear increases in 10th-rib fat depth (P = 0.08) and calculated fat-free lean yield (P = 0.06); otherwise, dietary Fe did not (P > 0.19) affect pork carcass muscling or fatness. Moreover, LM concentrations of total, heme, and nonheme Fe were similar (P > 0.23) among treatments. A randomly selected subset of loins from each treatment was further fabricated into 2.5-cm-thick LM chops, placed on styrofoam trays, overwrapped with polyvinyl chloride film, and placed in coffin-chest display cases (2.6 degrees C) under continuous fluorescent lighting (1,600 lx) for 7 d. During display, chops from NC-fed pigs and pigs fed the diets supplemented with 100 ppm Fe tended to have a more vivid (higher chroma value; P = 0.07), redder (higher a* value; P = 0.09) color than LM chops of pigs fed 50 ppm of supplemental Fe. Moreover, greater (P < 0.01) redness:yellowness ratios in chops from pigs supplemented with 100 ppm Fe indicated a more red color than chops from PC-fed pigs or pigs fed diets supplemented with 50 ppm Fe. In conclusion, however, increasing dietary Fe had no appreciable effects on performance, carcass, or LM characteristics, suggesting that current dietary Fe recommendations are sufficient for optimal growth performance, pork carcass composition, and pork quality.     

Effects of molybdenum or iron induced copper deficiency on the viability and function of neutrophils from cattle

Neutrophils from cattle with copper deficiency induced by molybdenum (0.052 mmol molybdenum kg-1 diet) or iron (8.95 mmol iron kg-1 diet) had an impaired ability to kill ingested Candida albicans and were less viable than those from copper-supplemented cattle in in vitro tests of function. Restricted intake (80 per cent of ad libitum) of a copper-adequate diet by cattle also decreased neutrophil candidacidal activity and viability. Additionally, the ingestion of C albicans by neutrophils was impaired by the molybdenum or iron treatments but not by restricted food intake. The changes in neutrophil function and the severity of copper deficiency, in biochemical terms, induced by the molybdenum or iron treatments were greater than those induced by diets of low copper content.     

The Kidneys of Infant Mice are not Sensitive to the Food Mycotoxin Contaminant Nivalenol

Nivalenol (NIV) is a trichothecene mycotoxin produced by Fusarium fungi that frequently contaminates agricultural commodities. Dietary administration of NIV to adult mice affects the renal glomeruli, but data about NIV toxicity in human infants are limited. To evaluate the effects of NIV on infant kidneys, 3-week-old male ICR-derived glomerulonephritis (ICGN) and ICR mice were administered 0, 4, 8 or 16 ppm NIV in diet for 4 weeks, and their renal status was compared with age-matched or adult ICR mice. In ICGN mice, the number of glomeruli showing mesangial expansion and α-smooth muscle actin (SMA)-positive mesangial cells was higher with 16 ppm NIV compared with controls. No other significant differences were observed in ICGN mice. In infant ICR mice, the IgA serum concentrations were significantly elevated without glomerular morphological changes in the 16 ppm NIV group. There was no difference in NIV sensitivity in the kidneys of infant ICGN and ICR mice. These data suggest that the kidneys in infant mice are not sensitive to nivalenol under the present conditions.     

Effects of dietary iron level on growth performance,hematological status,and intestinal function in growing-finishing pigs

This study investigated the different addition levels of iron (Fe) in growing-finishing pigs and the effect of different Fe levels on growth performance, hematological status, intestinal barrier function, and intestinal digestion. A total of 1,200 barrows and gilts ([Large White × Landrace] × Duroc) with average initial body weight (BW; 27.74 ± 0.28 kg) were housed in 40 pens of 30 pigs per pen (gilts and barrows in half), blocked by BW and gender, and fed five experimental diets (eight replicate pens per diet). The five experimental diets were control diet (basal diet with no FeSO₄ supplementation), and the basal diet being supplemented with 150, 300, 450, or 600 mg/kg Fe as FeSO₄ diets. The trial lasted for 100 d and was divided into the growing phase (27 to 60 kg of BW) for the first 50 d and the finishing phase (61 to 100 kg of BW) for the last 50 d. The basal diet was formulated with an Fe-free trace mineral premix and contained 203.36 mg/kg total dietary Fe in the growing phase and 216.71 mg/kg in the finishing phase based on ingredient contributions. And at the end of the experiment, eight pigs (four barrows and four gilts) were randomly selected from each treatment (selected one pig per pen) for digesta, blood, and intestinal samples collection. The results showed that the average daily feed intake (P = 0.025), average daily gain (P = 0.020), and BW (P = 0.019) increased linearly in the finishing phase of pigs fed with the diets containing Fe. On the other hand, supplementation with different Fe levels in the diet significantly increased serum iron and transferrin saturation concentrations (P < 0.05), goblet cell numbers of duodenal villous (P < 0.001), and MUC4 mRNA expression (P < 0.05). The apparent ileal digestibility (AID) of amino acids (AA) for pigs in the 450 and 600 mg/kg Fe groups was greater (P < 0.05) than for pigs in the control group. In conclusion, dietary supplementation with 450 to 600 mg/kg Fe improved the growth performance of pigs by changing hematological status and by enhancing intestinal goblet cell differentiation and AID of AA.     

Sleep time following anesthesia in mouse lines selected for resistance or susceptibility to fescue toxicosis

In previous work, a mouse line selected for resistance (R) to fescue toxicosis had higher activities of two hepatic Phase II detoxification enzymes than a mouse line selected for fescue toxicosis susceptibility (S). The primary objective of the present study was to determine whether those same lines also differed in hepatic Phase I enzyme activity, estimated from sleep time (ST) following sodium pentobarbital anesthesia. Additional objectives were to determine whether ST differences between lines were modulated by endophyte-infected fescue in the diet (with or without an enzyme inducer) and whether ST of individual mice was correlated with the effect of a toxin-containing diet on the postweaning growth of those mice. In Exp. I, 24 males from each line were randomly assigned to each of five diets: control (commercial rodent food meal); E+ (50% endophyte-infected fescue seed, 50% control); E+P (the E+ diet supplemented with 1,000 ppm phenobarbital); E- (50% endophyte-free fescue seed, 50% control); and E-P (the E- diet supplemented with 1,000 ppm phenobarbital). After 4 wk on these diets, ST was measured on all the mice. A second ST was recorded on each mouse by randomly sampling one-fourth of the population after 1, 2, 3, or 4 wk on a pelleted rodent food diet. Regardless of diet, R mice had shorter first and second ST than S mice (P < 0.01), suggesting higher hepatic Phase I microsomal enzyme activity. Mice on both phenobarbital-supplemented diets had shorter first ST than mice whose diets did not include that microsomal enzyme inducer (P < 0.01). In Exp. II, ST was measured on male and female R and S mice (n = 280) after they had been fed the E- diet for 2 wk, then the E+ diet for 2 wk, and then a pelleted rodent food diet for 2 wk. Growth response to the E+ diet was the percentage of reduction in gain on the E+ diet compared to gain on the E- diet the previous 2 wk. As in Exp. I, S mice slept longer than R mice (P < 0.01). The residual correlation between ST and gain reduction associated with the E+ diet equaled 0.04. Thus, an animal's apparent Phase I enzyme activity did not predict its growth rate depression on the toxin-containing diet. Based on these and previous studies, divergent selection for toxicosis response in mice was successful partially by causing divergence in activities of hepatic Phase I and II detoxification enzymes.     

The effect of copper addition to diets with various iron levels on the performance and hematology of weanling swine

A 2 x 6 factorial experiment with Cu added at 5 or 250 ppm and Fe added at 50, 100, 150, 200, 250, or 300 ppm was conducted using 480 crossbred weanling pigs with an average initial weight of 7.0 kg. The basal corn-soybean meal-whey diet contained 4 ppm Cu, 169 ppm Fe, and 199 ppm Zn. Pigs were allotted by weight, sex, and litter outcome group and had ad libitum access to feed and water during the 28-d trials. Animals were weighed and pen feed intake was recorded weekly. Blood samples were collected on d 1, 14, and 28 of the experiment. The addition of 250 ppm Cu increased ADG (P less than .001) and average daily feed intake (ADFI, P less than .01) during the 28-d trials. The addition of Fe had no effect on ADG and ADFI (P greater than .10). A Cu x Fe interaction (P less than .01) was observed for feed/gain. Increasing Fe levels linearly improved hematocrit status (P less than .05) on d 28 of the trial. A Cu x Fe interaction (P less than .08) was observed for hemoglobin at the end of the trial; hemoglobin levels were increased by the addition of Fe to the diet containing 250 ppm of Cu. Plasma Cu was increased (P less than .001) by the addition of 250 ppm of Cu. Plasma Fe was low when either 50 or 100 ppm of Fe was added in the presence of 250 ppm of Cu, but it was not affected at other levels, resulting in a Cu x Fe interaction (P less than .05). These data indicate that levels of added Fe up to 300 ppm may help to improve the hematological status of weanling pigs fed growth-promoting levels of Cu but that it has little effect on performance.