Effect of feeding corn naturally contaminated with aflatoxin on feed efficiency, on physiologic, immunologic, and pathologic changes, and on tissue residues in steers

Two of 3 groups of Holstein-Friesian steers (groups II and III; n = 5 each) were fed a ration containing corn naturally contaminated with 800 ng of aflatoxin/g. The other group of steers (group I; n = 5) was fed a ration containing noncontaminated corn. The respective rations were fed for 17.5 weeks, except the ration given to group III; the latter's first diet (contaminated with aflatoxin) was changed to a noncontaminated diet after 15 weeks, continuing for the remaining 2.5 weeks. All steers were killed and tissues and fluids were obtained for aflatoxin analysis. Although aflatoxin B1 and M1 could be detected in blood and urine at several sampling times during the experimental period in groups II and III steers (given the diets containing aflatoxin), there appeared to be no effects on body weight gains and immune phenomena, such as lymphoblastogenesis and antibody production, but there was a waning of the delayed cutaneous hypersensitivity in steers given aflatoxin-contaminated diets. In group III animals (diet was changed to noncontaminated ration at 15 weeks), aflatoxin B1 and M1 disappeared from urine before they were slaughtered. All tissues and fluids, except the rumen contents from these group III steers, were void of detectable aflatoxins B1 and M1 at necropsy. The concentrations of aflatoxin B1 in the rumen content of the latter steers were low. All tissues collected at necropsy from the group II steers fed the aflatoxin diet throughout the 17.5 weeks had detectable aflatoxins B1 or M1 present.     

Influence of selenium on aflatoxin B1 or crotalaria toxicity in turkey poults

This research compared the toxic effects of aflatoxin B1 and monocrotaline, the active principle of Crotalaria spectabilis, and the additive effect between aflatoxin B1 and monocrotaline in turkey poults. It was of interest whether selenium fed at dosage levels of 0.1, 5, or 10 micrograms/g of feed would protect against the toxic effect of aflatoxin and/or monocrotaline, and whether the toxicants would result in detectable residues in poult tissues. A total of 180 healthy 1-day-old male turkey poults was assigned at random to 12 treatment groups (15 birds/group). Body and liver weight losses, and low serum concentrations in total protein (TP), albumin (A), alpha-globulin (alpha G), and beta-globulin (beta G), as well as high values in gamma-globulin (gamma G), were produced in the groups fed crotalaria. Pathologic changes were induced by monocrotaline with no protection afforded by the added selenium. Low values in TP, A, alpha G, and beta G and in body and liver weights were observed in groups given the combination of aflatoxin plus crotalaria. Gross lesions were associated with an additive toxic effect and a lack of protective effect of selenium against this combination. However, higher values in TP, A, alpha G, and beta G, and liver weights in groups fed aflatoxin B1 plus selenium indicated that selenium had a protective effect against aflatoxin toxicity. Residues of aflatoxin B1 and aflatoxin M1 were found in the kidneys of poults fed aflatoxin B1; also, dehydroretronecine (the metabolite of monocrotaline) was detected in livers of poults fed Crotalaria spectabilis seeds.     

Energy and nitrogen metabolism of diseased chickens: aflatoxicosis.

1. New Hampshire chicks were fed on diets containing 0 (control), 0-7 (A), or 1-1 (B) ppm of aflatoxin B1. In two trials 1-d-old chicks were offered ad libitum the three diets for 14 d. The gaseous exchange of five chickens from each group was measured for 3 or 4 d, the same diets being fed, at 2, 3, 4 and 5 weeks of age in two series of experiments. The controls were fed at the lower intake of the two other groups. Following each series of experiments at the various ages, birds were starved for 24 h and their heat production was re-measured over the next 24 h. 2. Mortality was highest and growth and food conversion poorest where the diet with the highest aflatoxin concentration was fed. Mortality was confined to the first 2 weeks. 3. Performance of birds in the chambers was improved in the second series due to differences in food intake. It also improved with age suggesting some resistance to the toxin. 4. Mean respiratory quotient was 0-97 for fed chickens on diet B. This was significantly different from 0-92 for the two other groups. Similarly, during starvation the RQ was 0-76 compared with 0-73. 5. birds fed on diet B generally grew better, retained more nitrogen and had a better energy balance in the respiration chambers than the other two groups. Metabolisability of dietary energy was less (68.5%) for all groups at 2 to 3 weeks than when older (70%) but availability of ME was the same (71%) for all groups. 6. Heat production (kJ/kg0-75) of starved birds on diet B was significantly lower than the other two groups, while endogenous nitrogen excretion was higher. 7. Water consumption (ml/g food and g/100 g body weight) was greatest for birds on diet B. 8. Although aflatoxin in the diet substantially reduced intake there was no indication that at these reduced levels of intake, nitrogen or energy metabolism were measurably impaired.     

Effect of field beans and supplemental methionine on growth of turkey poults

Male poults housed at 10 and 15 birds/pen and female poults housed at 15 birds/ pen were fed, from 6 to 10 weeks, on diets containing o, 15, 30 and 30% field beans (Vicia faba L.). The difference between the last two diets was in the level of methio‐nine; one contained 1.6 and the other 1.9%. From 10 to 16 weeks of age birds were fed on diets containing 0 or 20% field beans. At 10 weeks birds given diets with 30% beans were significantly lighter than other poults. At 16 weeks only the poults previously given a diet with 1.9% methionine were significantly lighter than control birds. Males given 0.37 m² of floor space were significantly heavier at 16 weeks than those given 0.25 m².     

Tolerance of young turkey poults to various combinations of dietary furazolidone and salt.

Three feeding trials were conducted to study the tolerance of young turkey poults to furazolidone and to various combinations of salt and furazolidone in the diet. Poults of mixed sexes tolerated up to 0.03% dietary furazolidone from hatch to six weeks of age without harmful effects as judged from the data on mortality rate, feed intake, body weight and plasma composition. High mortality with cardiac dilation and ascites occurred in poults fed the same basal diet containing 0.05 or 0.07% furazolidone. Mortality was positively related to levels of dietary furazolidone, and occurred mainly between two and four weeks of age. The cumulative feed intake and body weight of these poults were significantly lower than those of the control poults at six weeks of age. There was indication of decreased renal function in poults on high furazolidone intake and the mechanism of furazolidone-induced cardiac dilation is discussed. Mortality rate, incidence of cardiac dilation with ascites and heart, liver and body weights and feed efficiency were similar in poults fed diets containing 0.022% furazolidone and varying levels of salts (0.5, 1.0 or 1.5%) compared with the control fed the same basal diet containing 0.5% salt from hatch to eight weeks of age. It is concluded that a starter diet containing 0.022% furazolidone and up to 1.5% salt does not affect the performance of poults from hatch to eight weeks of age.     

Chick Edema Disease Syndrome in Young Turkey Poults

Two feeding bioassays were conducted to study the mortality pattern, incidence of edema and ascites formation and plasma composition of turkey poults fed diets containing varying levels of toxic fat (fat contaminated with polychlorinated dibenzo-p-dioxins) and/or salt. No significant changes in plasma concentrations of electrolyte and total protein and packed cell volume were observed in slaughtered poults fed diets containing toxic fat compared with poults fed a normal diet. However, a positive dose-response relationship between levels of dietary toxic fat (0,2 and 5%) and incidence of mortality with edema, ascites and hydropericardium was observed in poults fed diets containing 1% salt. The toxic effects of polychlorinated dibenzo-p-dioxins were accentuated by increasing the level of salt (0.5, 1 and 3%) in the diet. Mortality started at nine days of age and increased on days 10 and 11. The present experiments demonstrated that gross pathological changes similar to those reported for “chick edema disease” caused by feeding polychlorinated dibenzo-p-dioxins, could also be produced in young turkey poults. The etiology of the toxic effects of these organic compounds in edema formation is discussed.     

Effects of exchange of dietary medium chain triglycerides for long-chain triglycerides on serum biochemical variables and subjectively assessed well-being of dogs with exocrine pancreatic insufficiency

OBJECTIVE: To test the hypothesis that exchange of medium-chain triglycerides (MCTs) for long-chain triglycerides (LCTs) in the diet of dogs with well-managed exocrine pancreatic insufficiency (EPI) changes serum biochemical variables and to subjectively assess the well-being of dogs with EPI in response to experimental diets. ANIMALS: 21 dogs with EPI and 6 healthy control dogs. PROCEDURE: The effects of 3 diets containing 0%, 16%, or 35% of the total fat content as MCTs were examined in a randomized controlled double-blind crossover trial. The 3 diets were fed for 12 weeks each. Dietary effects were evaluated by both subjective and objective variables. RESULTS: Analysis of subjective data revealed no significant difference in appetite, attitude, drinking behavior, volume of feces, defecation frequency, color of feces, consistency of feces, flatulence, or borborygmus among dogs fed the 3 experimental diets. A high MCT content in the diet was associated with significantly higher serum vitamin E, cholesterol, triglyceride, retinyl stearate, retinyl palmitate, and total vitamin A concentrations in dogs with EPI and significantly higher serum vitamin E concentrations in control dogs, compared with low MCT content. High MCT content in the diet was also associated with significantly lower concentrations of serum linoleic acid (C18:2[n-6]) in dogs with EPI and in control dogs, compared with low MCT content. CONCLUSIONS AND CLINICAL RELEVANCE: A high MCT content in the diet leads to increases in serum concentrations of cholesterol and certain fat-soluble vitamins. However, no effect was found on the subjective well-being of the dogs as evaluated by their owners.     

Compensatory growth after under-nutrition in market turkeys: effect of low protein feeding and realimentation on body composition

Turkey poults were fed starter diets containing either 29 or 20 per cent crude protein. Live‐weight at 6 weeks was depressed by about 30 per cent in poults fed the low protein diet. From 6 to 10 weeks of age four protein levels were fed but carcass studies were restricted to the groups which received adequate amounts of protein at this stage. Sixty poults from each treatment were slaughtered for carcass studies at 6 weeks of age, and also at 7 weeks when the undernourished poults had reached the body weight attained by fully fed groups at 6 weeks. Further samples were taken for carcass analysis at 20 weeks of age.

Percentage body fat was increased and percentage protein in the fat‐free dry matter was decreased by feeding a low protein starter diet from o to 6 weeks. Poults fed the low protein starter diet retained nitrogen more efficiently during the period of undernutrition and in the first stages of recuperation. Following a return to full feeding at six weeks, body protein content was quickly restored, but a longer period was required before their body fat percentage was reduced to the level of fully fed controls.

The organs which were weighed were little affected, except in the case of the gizzard and liver which became proportionately heavier in retarded turkeys at 6 weeks of age. Only spleen weight appeared to have been reduced in relation to total body weight but it occupied a similar proportion in high and low groups when compared on a fat‐free basis. Some, but not all, of the organs weighed were restored to normal proportions by 20 weeks of age. However, dressing percentage and economic value of carcasses at market weight were not materially affected by early nutritional treatment.     

Role of Insoluble Fiber on Gizzard Activity in Layers

Effect of access to wood shavings on gizzard activity was examined for birds fed pelleted wheat and oat diets with or without whole cereal inclusion. Layers on litter floor fed wheat diets with access to coarse wood shavings showed up to 60% higher weight of the gizzard and its content than caged layers fed the same diets without access to wood shavings. No such effect was found by feeding oat diets. Thus, a significant interaction was found, indicating that the appetite for wood shavings may be dependent of fiber level of the diet. Appetite for wood shavings and paper was examined for birds fed wheat and oat diets in 2 other experiments. The intake of wood shavings and paper by birds fed a wheat-based diet was numerically twice as high as in birds fed an oat-based diet. However, the individual variation was remarkably high. Neutral detergent fiber (NDF) concentration in the gizzard of birds fed the oat diet was up to twice (P < 0.05) the fiber concentration in the gizzard of birds fed the wheat diet. Passage of structural fibers through the gizzard and the appetite for feathers in the absence of structural fibers were also studied in an experiment using diets based on rice and casein. Coarse fiber structures were observed to accumulate in the gizzard. In the absence of fiber, birds ate feathers, indicating that birds may eat feathers to compensate for the lack of structural components in the feed.     

葡甘露聚糖对饲喂黄曲霉毒素B1日粮肉仔鸡生长性能、血清指标及器官指数的影响

本文通过测定肉仔鸡生长性能、血清指标及器官指数,探讨葡甘露聚糖对黄曲霉毒素B1(AFB1)的吸附作用。选用180只体重接近的8日龄肉仔鸡随机分成3组,分别为基础日粮组、基础日粮 0.1mg/kgAFB1组、基础日粮 0.1mg/kgAFB1 0.1%葡甘露聚糖组,试验期21d。试验结果表明:(1)基础日粮中加入0.1mg/kgAFB1,肉仔鸡的体重、日增重、日采食量显著下降,料重比升高。血清中总蛋白、白蛋白含量显著下降,谷草转氨酶、谷丙转氨酶活性显著升高。肝脏、肾脏、心脏和脾脏肿胀,胸腺、法氏囊萎缩;(2)0.1mg/kgAFB1日粮中加入0.1%葡甘露聚糖,明显改善肉仔鸡的生长性能,以上相关指标基本恢复到正常水平。由此可知,葡甘露聚糖减轻或基本消除了AFB对肉仔鸡生长性能、组织器官的不良影响。     

Experimental combined aflatoxin B1 and ochratoxin A intoxication in pigs

Twenty-one pigs weighing approximately 18 kg were placed in 7 groups of 3 and given diets containing respectively aflatoxin B1 alone at 0.375 and 0.0750 mg/kg, ochratoxin A alone at 1 and 2 mg/kg, 0.375 mg/kg of aflatoxin B1 plus 1 mg/kg of ochratoxin A and 0.750 mg/kg aflatoxin B1 and 2 mg/kg of ochratoxin A. The remaining group served as untreated control. At the respective dose levels, pigs receiving similar doses of ochratoxin A alone or in combination with aflatoxin B1, were similarly affected, the clinical effects of aflatoxin having been mostly obscured by those due to ochratoxin A. Mild degenerative hepatic changes typical of aflatoxicosis were observed in pigs fed this toxin alone or in combination with ochratoxin A. In kidneys of pigs fed diet containing 1 and 2 mg of ochratoxin A alone changes included interstitial fibrosis of the vortex and dystrophy and degeneration of the tubular epithelium. Similar lesions but less pronounced fibrosis were found in kidneys of pigs receiving both toxins. The respective lower dose levels of mycotoxins selected were judged to be about the no-effect levels for each dosed separately under the conditions of the trial. Such levels have been found not infrequently on mould affected grain and stock foods. The result highlights the difficulties that may be experienced in the recognition of such multimycotoxicoses as they are likely to occur in the field and indicate the need for toxicological analysis as well as pathological investigation in establishing a diagnosis.     

Nutritional Management of Idiopathic Chronic Colitis in the Dog

Idiopathic chronic colitis was diagnosed in 13 dogs. Owners sought veterinary care because of semiformed to liquid feces, fresh blood and/or mucus in the feces, tenesmus, increased frequency of defecation, vomiting, weight loss, and flatulence in their dogs. A lymphocytic, plasmacytic infiltration in the colonic lamina propria was found on colonic biopsy specimens. Signs resolved in all 13 dogs after they were fed a low residue, easily assimilated, relatively hypoallergenic diet. In 11 dogs, two commercial diets not previously fed to these dogs were successfully substituted for the initial test diet, without causing recurrence of signs. Only two of these 11 dogs subsequently tolerated a switch to diets that had been fed at the time of onset of signs of colitis. All 13 dogs have been successfully managed from 2 months to 28 months following the initiation of dietary therapy. The results of these dietary challenges strongly suggest a dietary role in the pathogenesis of this disorder, and also illustrate the importance of dietary therapy in the management of idiopathic chronic colitis.     

Withdrawal of zinc oxide-containing diets from mature, female domestic fowl: effects on selected tissue mineral contents

1. Two hundred and sixteen laying hens of two strains were given diets containing ZnO to provide 0, 0.5, 0.75, 1.00, 1.25, 1.50, 2.00, 3.00 or 4.00 g added Zn/kg. These diets were offered ad libitum for 5 consecutive 28-d periods. All hens were subsequently offered the control diet with no added ZnO for 5 weeks. 2. Four hens from each treatment were killed 0, 1 and 5 weeks after substitution of the ZnO-supplemented diets by the control diet. 3. Dietary addition of ZnO significantly increased liver, kidneys, pancreas and gizzard Zn contents but this effect was rapidly reversed on removal of the ZnO-containing diets. 4. Hepatic and renal Fe contents were significantly depressed by dietary ZnO but after substitution of these diets by the control diet the values were comparable to that of the controls. 5. Liver Cu content declined significantly as dietary ZnO concentration increased but there was a return towards normal after ZnO withdrawal. Renal, pancreatic and gizzard Cu contents showed quadratic responses to added ZnO. 6. After ZnO withdrawal for 5 weeks, pancreas Cu contents declined linearly, whereas renal and gizzard Cu values were similar for all treatments. 7. Overall the long-term feeding of ZnO-supplemented diets followed by a period of withdrawal of the ZnO supplement had no detrimental effects on tissue mineral contents.     

Performance of Broilers Fed on Diets Containing Different Amounts of Chaya (Cnidoscolus aconitifolius) Leaf Meal

The performance and gut measurements of broilers fed on diets containing different amounts of chaya (Cnidoscolus aconitifolius) leaf meal (CLM) were examined in two experiments. In the first experiment, 60 Hubbard chickens (30 males and 30 females; 2 weeks old) were fed on five maize diets; these were formulated using 0, 150 (CLM150), 250 (CLM250) or 350 (CLM350) g CLM/kg, and the fifth diet contained soyabean. In the second experiment, 148 Ross male chicks, 1 day old, were fed on three isonitrogenous and isoenergetic maize–soyabean-based diets, which included 0 (control), 150 (C150) or 250 (C250) g CLM/kg. The diets were offered ad libitum for 2 or 3 weeks in the first and second experiments, respectively. Food intake, weight gain and the food:weight gain ratio were recorded. The weight of the gizzard and intestine and the weight and length of the caeca were also determined in the second experiment. In experiment 1, the birds fed on the maize–soyabean diet had a higher (p<0.05) weight gain and final weight than birds fed on maize only or on the CLM150 diets. There were no differences for any of the variables studied between the birds fed on the maize–soyabean diet and those fed on the CLM250, nor between males and females. In the second experiment, weight gain, food intake and the food:weight gain ratio for birds fed on C250 were lower (p<0.05) than those in birds fed on either the control or C150 diets. The weights of the gizzard and intestine were the lowest and the highest, respectively, in birds fed on C250 (p<0.05). The length and weight of the caecum from birds fed on the control diet were lower (p<0.05) than those of birds fed on either the C150 or C250 diets. The results from this study suggest that CLM may be included up to 150 g/kg in commercial diets without having an adverse effect on poultry performance, and may also be mixed with maize up to 250 g/kg to improve the performance of chickens fed on low-protein diets.     

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.     

Effect of dietary supplementation with clay‐based binders on biochemical and histopathological changes in organs of turkey fed with aflatoxin‐contaminated diets

This study was carried out to investigate the effect of dietary supplementation with molecular or nano‐clay binders on biochemical and histopathological examination of organs of turkeys fed diets contaminated with aflatoxin B_1. Two hundred and sixteen unsexed 1‐day‐old British United Turkeys were randomly allotted to nine diets in a 3 × 3 factorial arrangement of diets supplemented with no toxin binder, molecular toxin binder (MTB) and nano‐clay toxin binder, each contaminated with 0, 60 and 110 ppb aflatoxin B₁ respectively. There were three replicates per treatment with eight turkeys per replicate. Biochemical analyses, organ weights and histopathological changes of some organs were examined at the end of the study which lasted for 84 days. Turkeys fed diets supplemented with molecular and nano‐binders showed higher (p < 0.001) total serum protein, reduced (p < 0.001) serum uric acid and GGT concentration values when compared with those fed aflatoxin‐contaminated diets supplemented with no binder. Turkeys fed aflatoxin‐contaminated diets supplemented with no binder had increased (p < 0.001) AST and ALT concentration when compared with other treatments. The heaviest (p < 0.001) liver and intestinal weight was noticed with turkeys fed diets supplemented with no binder and contaminated with 110 ppb aflatoxin B₁. Pathologically, there was no visible morphological alteration noticed in all turkeys fed uncontaminated diets and nano‐clay‐supplemented group. Hepatic paleness, hepatomegaly and yellowish discolouration of the liver were observed with turkeys fed diets containing no binder but contaminated with 60 and 110 ppb aflatoxin B1. Intestinal histopathological changes such as goblet cell hyperplasia, villous atrophy and diffuse lymphocytic enteritis were more prominent in turkeys fed diets containing no toxin binder and MTB. In conclusion, there were improved biochemical parameters and reduced deleterious effects of aflatoxin B₁ in turkeys fed diet supplemented with clay binders. However, the improvement was more conspicuous in the nano‐clay‐supplemented group than molecular clay group.     

Effects of diet form on the performance of table ducklings

Two hundred Pekin ducklings were fed to 3 weeks of age on a pelleted starter diet and in the subsequent 4 weeks the effects of feeding grower diets in mash, crumb or pellet forms were examined. Diet form did not cause significant differences in live‐weight at 7 weeks. The mash form caused significant increases in food consumption, giblet weight and gizzard weight and a significant decrease in weight gain. There were no significant interactions between diet composition and diet form.     

Feeding diets supplemented with zinc and vitamin A in laying hens: effects on histopathological findings and tissue mineral contents

The effects of different dietary levels of zinc and vitamin A on tissue mineral accumulation and histopathological alterations were examined in laying hens. For this purpose, 130 Hisex brown laying hens aged 56 weeks were divided into two main groups. Each group of hens were fed on diets supplemented with two different levels of vitamin A (0-10,000 IU kg(-1)). Then, laying hens in both of the main groups were subdivided into five treatment groups given different levels of zinc (0, 25, 50, 100, and 200 mg kg(-1)) for 12 weeks. Dietary additions of zinc and/or vitamin A did not significantly affect the zinc concentrations of the pancreas, liver, gizzard, thyroid, and copper concentrations of the pancreas, gizzard, and thyroid. The group fed the highest zinc (200 mg kg(-1)) in the diet had twofold iron concentration in their thyroid tissue compared to the concentration of the control group receiving no extra zinc. Histopathologically, there was slight oedema, degranulation, and vacuolation in exocrine cells and some fibrotic areas in the pancreas and reduced follicular size. Follicular cell hypertrophy and hyperplasia occurred in the thyroids, and gizzard erosions were seen in some cases.     

Withdrawal of zinc oxide-containing diets from mature, female domestic fowl: effects on laying performance and the weights of selected tissues

1. Two hundred and sixteen laying hens of two strains were given diets containing ZnO to provide 0, 0.5, 0.75, 1.00, 1.25, 1.50, 2.00, 3.00 or 4.00 g added Zn/kg. These diets were given ad libitum for 5 consecutive 28-d periods. All hens subsequently received the control diet with no added ZnO for 5 weeks. 2. Four hens from each treatment were killed 0, 1 and 5 weeks after substitution of the ZnO-supplemented diets by the control diet. 3. The adverse effects of the ZnO-containing diets on body weight, food intake, egg production, pancreas, gizzard, oviduct and ovary weights/kg body weight were reversed by removal of the ZnO from the diets. 4. Five weeks after withdrawal egg production of the group which had received the diet with the highest concentration of added ZnO was only 50% of that of the control birds. 5. The beneficial effect of the added ZnO on internal egg quality was not maintained after withdrawal of the ZnO-containing diets.     

Relationships between body weight and bone length at one day and at six weeks of age in male turkeys fed on adequate and low protein starter diets

Male turkey poults were fed on diets containing either adequate (29%) or inadequate (20%) amounts of crude protein from 1 d to 6 weeks of age. Each bird was weighed and the length of its lower‐leg measured at 1 d and at 6 weeks of age.

The initial body weight of adequately‐fed turkeys bore little or no relationship to 6‐week body weight. Length of lower‐leg at 1 d gave a more reliable prediction of body weight ranking at 6 weeks. In contrast initial body weight was more reliable than initial bone length in predicting body weight ranking at 6 weeks when the low‐protein diet was fed.