Lipid oxidation products and chick nutritional encephalopathy.

Safflower oil and its distilled methyl esters were thermally oxidized and fed to young chicks in a vitamin E deficient diet. At a dietary level of 10%, the oxidized lipids caused more severe nutritional encephalopathy (NE) than the unoxidized methyl esters, indicating that factors other than dietary linoleic acid and vitamin E affect the development of NE. A polar lipid extract from oxidized methyl esters accelerated the induction of NE, as did the synthetic methyl esters of keto-octadecenoic and keto-octadecadienoic acids. Dicumarol exerted a protective action against NE. The possibility is discussed that conjugated keto-polyenoic fatty acids, provided by oxidized oils or formed endogenously in vitamin E deficiency, may play a role in causing NE.

Effect of dietary fat and protein levels on monensin toxicity in broiler chicks.

The effects of dietary fat level, fat source, and protein level on the growth response of broiler chicks were evaluated in two experiments with a factorial design. A higher level of soybean oil (SO) (3.5 vs. .5%) in diets containing either 18.2 or 20.4% protein significantly (P less than .05) counteracted the depressing effect of monensin on feed intake and weight gain in male chicks in the first experiment. Dietary protein level did not significantly (P greater than .05) affect the response to monensin, nor did monensin affect feed to gain ratio. The higher SO level of 3.5% in diets containing 18.2% protein reduced, at times significantly (P less than .05), the depressing effect of monensin on feed and water intake, water to feed ratio, weight gain, and the retention of dry matter and nitrogen in female chicks in the second experiment. A similar higher level of tallow resulted in less pronounced effects on most of the parameters. Monensin supplementation did not affect dietary metabolizable energy content, but significantly (P less than .01) increased feed to gain ratio and the percent of fecal dry matter. It was concluded that the toxicity of monensin to chicks might be alleviated by increasing dietary unsaturated fat and protein levels.

Lack of interactive effect of nicarbazin and dietary energy-to-protein ratio on performance and abdominal fat pad weight of broiler chicks.

An experiment was carried out, in a factorial arrangement, with female broiler chicks during the period from 8 to 49 days of age. Combined effects were evaluated of dietary energy-to-protein ratio (E:P; 130 vs. 170 from 8 to 28 days of age and 140 vs. 190 from 28 to 49 days of age) and nicarbazin supplementation (0 vs. 125 mg/kg) on performance and fattening. At 49 days of age, feed intake was not affected either by dietary E:P or by nicarbazin supplementation. The latter significantly depressed weight gain (P less than .01) and feed efficiency (P less than .001), but did not affect abdominal fat pad weight. The wide E:P significantly decreased feed efficiency (P less than .01) and increased abdominal fat pad weight (P less than .001). Neither of the parameters was affected by the interaction between nicarbazin and dietary E:P. It was suggested that the growth-depressing effect of nicarbazin was due to its effect on increasing the metabolic rate, an increase which did not affect fattening as measured by abdominal fat pad weight.

The use of diets containing high levels of zinc for controlling early growth in female broiler chicks.

A study was carried out with White Rock female chicks to evaluate the possibility of using dietary Zn supplied as ZnO, to control feed intake and weight gain during the period of 1 to 3 wk of age. The levels of supplemental Zn tested were 0, 0.25, 0.50, and 1.0% (Experiment 1); 0, 0.65, 0.75, and 0.85% (Experiment 2); 0.7 and 0.8% (Experiment 3). The effect of Zn supplementation was compared with that of a low sodium chloride diet (L-NaCl-D) and of severe feed restriction (SFR), which was calculated to supply energy only for maintenance (Experiments 1 and 3, respectively). The compensatory growth of the chicks from 3 to 4 wk of age was also evaluated. Feed intake and weight gain were negatively proportional to the levels of dietary Zn supplementation and there were significant (P < 0.02 and P < 0.01, in Experiments 1 and 2, respectively) negative correlations between supplemental dietary Zn levels and relative weight gains (values observed in the unsupplemented diet = 100%). The effects of L-NaCl-D and SFR on decreasing weight gain were calculated, according to the equations obtained in Experiments 1 and 2 to be equivalent to these of 0.58 to 0.65% and 0.78 to 0.87% Zn supplementation, respectively. Relative weight gain and feed efficiency of the chicks from 3 to 4 wk of age, after withdrawal of the growth-depressing factors, were positively related to the degree of growth depression during 1 to 3 wk of age; however, the intensity of recovery from a similar degree of growth depression induced by L-NaCl-D, SFR, or dietary Zn was least in the last mentioned treatment. It is concluded that dietary Zn supplementation can be used as an efficient tool for controlling early growth of young broiler breeder chicks.

Effect of storage duration on the nutritional value of corn kernels for broiler chicks.

A study was carried out to evaluate the effect of storage duration of corn on its chemical composition (DM, protein, fat, amino acid, and fatty acids) and nutritional value for chicks, with an emphasis on AMEn. Freshly harvested whole grains were stored for 110 mo in covered galvanized iron cans, kept inside a storehouse. The AMEn content of the grains was determined in 10 experiments in which the corn was incorporated in a diet designated for the evaluation of AMEn by the substitution method. These determinations were carried out with male broiler chicks at 15 to 17 d of age. The chemical composition of the grains did not change during storage, except for a significant (P < 0.02) increase in lysine and a decrease in valine levels. Moreover, the AMEn content was not affected significantly (P > 0.05) by storage duration. It is concluded, therefore, that storing corn grains for 110 mo, under proper conditions, does not adversely affect their nutritional value.

Effect of various dietary factors and age on plasma alpha-tocopherol concentration of turkeys.

Plasma alpha-tocopherol concentration of 15- to 22-week-old turkeys was found to be linearly related to dietary all-rac-alpha-tocopheryl acetate at levels ranging from 10 to 100 mg/kg. However, in 4-week-old poults a plateau was observed at a level of 30 mg alpha-tocopheryl acetate/kg diet. Increasing soybean oil level in diets containing 10, 50, and 100 mg alpha-tocopheryl acetate/kg from .5 to 3.0% significantly (P less than .05) elevated plasma alpha-tocopherol. The latter was not affected by the type of dietary fat (soybean vs. tallow). Supplementary cholic acid (.075 - .1%) in diets containing 20 mg alpha-tocopheryl acetate/kg elevated plasma alpha-tocopherol slightly but significantly (P less than .05); however, higher levels of this bile acid had no effect. Increasing dietary selenium supplementation from .1 to 1.1 ppm did not affect this parameter either. alpha-Tocopherol and alpha-tocopheryl acetate, when dissolved in soybean oil or in ethoxyquin at levels equivalent to 40 mg/kg diet, had a similar effect on plasma alpha-tocopherol concentration.

Effects of propionic acid and of copper sulfate on the nutritional value of diets containing moldy corn for broiler chicks.

Diets containing moldy corn (in which fat levels were restored or not restored by soybean oil) were supplemented with either propionic acid (PA) or copper sulfate (CS), and their nutritional value for young broiler chicks was evaluated. The fat content of a diet containing good quality grains decreased slightly, whereas that of diets containing moldy grains decreased markedly, during the 30 days of the experiment. The PA (.3%), but not CS (600 ppm), almost completely prevented this decrease. Dietary metabolizable energy (ME), retention of dry matter and protein, and the performance of the chicks fed the diet containing the moldy corn were markedly depressed. Neither CS, nor soybean oil supplementation, nor a combination of the two, counteracted these effects. Supplementation with PA however, significantly (P less than .05) increased dietary ME, increased retention of dry matter and protein, and improved performance of chicks fed the moldy grains. The combination of PA and soybean oil supplementation yielded essentially the same results as the diet containing the good corn. It is concluded, therefore, that the nutritional value of diets containing moldy grains can be completely restored if their fat content is increased in proportion to the amount lost in the moldy grains and an efficient fungistat is used.

Interrelationship between the effects of dietary factors and feed withdrawal on the content and composition of liver fat in broiler chicks.

Four experiments were carried out to evaluate the effects of the composition and pelleting of diets fed to broiler chicks up to marketing age on changes in their liver size and the content and composition of liver fat due to feed withdrawal (FW) during 0, 10, and 24 h. Birds not exposed to FW that were fed diets with high energy to protein ratio (E:P) and diets in pelleted from-diets that increase fattening-had significantly (P < 0.05) higher liver fat content than those fed diets with the recommended E:P and in mash form, respectively. Those fed pellets also had higher liver weight. Dietary energy level did not affect these variables. Feed withdrawal for 10 or 24 h decreased, at times significantly, liver weight and its fat content, irrespective of the diets fed previously. The values observed after FW were not affected by the dietary factors evaluated. The composition of liver fatty acid in chicks not exposed to FW was markedly affected by increases in dietary energy (soybean oil) level and E:P. The main effects of the former were increased levels of stearic, linoleic, and arachidonic acids and a decreased level of oleic acid; those of the latter were an increased level of oleic and decreased levels of stearic, linoleic, and arachidonic acids. Irrespective of the diets used, FW increased the concentrations of stearic, linoleic, and arachidonic acids, and decreased those of palmitic and oleic acids. This effect on arachidonic acid was consistently significant, whereas the effects on the other fatty acids were significant in two out of three experiments. Due to these effects of FW, part of the differences in the composition of liver fatty acids caused by dietary factors observed in fed chicks, completely disappeared after FW. The length of FW (10 vs 24 h) did not affect liver size or fat content, but the concentrations of oleic and arachidonic acids in liver fat were significantly higher in birds exposed to 24 h of FW. It was concluded that the composition and form of the diets markedly affect liver weight and the content and composition of its fat in birds not exposed to FW. The effects of the dietary factors on liver size and its fat content completely disappear after 24 h of FW.

Lack of effect of dietary factors on nicarbazin toxicity in broiler chicks.

Effects of dietary fat, protein, and methionine levels and the type of dietary grain in nicarbazin-containing diets on the growth response of broiler chicks were evaluated in five experiments in a factorial design. Nicarbazin at levels ranging from 100 to 200 mg/kg significantly (P less than .05) depressed weight gain and feed efficiency. Feed intake was significantly reduced only when nicarbazin was used at levels of 150 and 200 mg/kg. The latter concentration also significantly decreased water intake and water:feed ratio. Nicarbazin, at a level of 150 mg/kg, did not affect dietary metabolizable energy content or the retention of nitrogen and dry matter. A higher level of soybean oil (3.5 vs. .5 or 1.0%) did not counteract the growth-depressing effects of 100, 150, and 200 mg nicarbazin/kg. The growth-depressing effect of the highest dose also was not affected by increasing the protein level from 18.2 to 20.4%. Neither type of dietary grains (corn vs. sorghum) nor supplemental methionine level affected the toxicity of 125 mg nicarbazin/kg. Water intake and water:feed ratio were significantly increased due to elevation of dietary protein and fat levels. It was concluded that the severity of the growth-depressing effect of nicarbazin on chicks was not dependent on the levels of dietary unsaturated fat, protein, and methionine.

Comparative effects of antifungal compounds on the nutritional value of diets containing moldy corn for broiler chicks.

Propionic acid (.3%), sorbic acid (.3%), and Agrosil (.6%) were equally effective in preventing the decrease in fat in diets containing moldy corn (the fat content of which was restored by soybean oil) during 25 days of storage and in completely maintaining the nutritional value of the diets as evaluated by chick performance. Lower levels of either sorbic acid (.05%) or Agrosil (.1 and .3%) were not effective. None of the fungistats were able to prevent the decrease in dietary fat after storage periods longer than 50 days, but this decrease was consistently and significantly (P less than .05) slower in the propionic acid-supplemented diet.

Effect of high levels of dietary iron, iron injection, and dietary vitamin E on the oxidative stability of turkey meat during storage.

A study was carried out to evaluate the combined effect of excess Fe, supplied either in the diets (Experiments 1, 2, and 3) or by injection (Experiment 4), and various levels of dietary vitamin E on the oxidative stability of the thigh muscle of turkeys stored at -18 C for various periods. Iron was added to a commercial diet that already contained 20 mg/kg supplemental Fe, at concentrations of 0, 100, 250, and 500 mg/kg as ferrous sulfate or injected as Fe-dextran to the left drumstick muscle (total amount of 1.2 g per turkey). Vitamin E was added to the experimental diets not already supplemented with this vitamin, at levels of 0, 28, and 150 mg/kg. Thiobarbituric acid reactive substances (TBARS) values of the meat gradually increased as its storage duration increased from about 15 to 120 d. Increasing dietary Fe supplementation from 0 to 500 mg/kg tended to decrease TBARS values in one experiment only; otherwise, this variable was not affected by dietary Fe level. Injection of Fe significantly (P < 0.05) increased TBARS values, only in meat from the injected side. The TBARS values of the meat up to about 30 d of storage were significantly lower due to the supplementation of the diet with vitamin E at a level of 28 mg/kg in one out of three experiments and at a level of 150 mg/kg in two out of two experiments. The protective effect of the higher level of vitamin E remained evident after about 108 d of storage. No interaction was observed between Fe and vitamin E treatments in their effect on TBARS values. Blood hemoglobin concentrations were significantly increased by the supplementation of the diet with the high levels of Fe, in one experiment only. This variable was consistently and significantly increased from about 10 to 23 wk of age. The results show that high levels of dietary Fe do not adversely affect the oxidative stability of thigh meat of turkey; however, stability might be reduced by injected Fe. Dietary vitamin E, at a level of 150 mg/kg, consistently increased this stability.

Susceptibility of chicks to nutritional encephalopathy: effect of fat and alpha-tocopherol content of the breeder diet.

Chicks hatched from eggs containing 16.5% linoleic acid of total yolk fatty acids (eggs laid by hens fed soybean oil in their diet) were more susceptible to nutritional encephalopathy induced by alpha-tocopherol-deficient diet containing thermally oxidized safflower oil than chicks hatched from eggs containing 7.5% linoleic acid (eggs laid by hen fed tallow). Supplementation of the diets of breeders hens with alpha-tocopheryl acetate significantly increased yolk alpha-tocopherol levels with both types of fat sources. However, the elevated egg alpha-tocopherol content decreased the rate of encephalopathy only in those chicks hatched from eggs containing also the higher linoleic acid level. The effect of the breeder diet on the severity of encephalopathy was observed in 4-week-old chicks.

Protective effect of nicarbazin on nutritional encephalopathy in chicks.

Nutritional encephalopathy was induced in young chicks by vitamin E-deficient diets containing either 4% methyl esters of safflower oil or 10% thermally oxidized safflower oil. The coccidiostat nicarbazin (an equimolecular complex of 4,4'-dinitrocarbanilide and 2-hydroxy 4,6-dimethylpyrimidine) reduced the incidence of encephalopathy, but zoalene (3,5-dinitro-o-toluamide) and amprolium [1-(4-amino-2-n-propyl-5-pyrimidinylmethyl)-2-picolinium chloride hydrochloride] did not. Neither of the two components of nicarbazin affected the rate of development of encephalopathy when fed separately, but when included together in the diet, they reduced the incidence of the disease.

Dietary factors affecting experimental models of nutritional encephalomalacia.

Various factors affecting the experimental development of nutritional encephalomalacia (NE) were studied in young chicks. The effects of these factors were evaluated by calculation of the age at which one-half were affected (T1/2). The incidence of ataxia and mortality and statistical analysis of the intensity of the disease were also calculated. No differences were found among the safflower oil samples oxidized for periods ranging from 12 to 48 hr in their potency to induce NE, while oil oxidized for 72 hr was less effective. No difference was observed between the effects of oxidized safflower oil and freshly distilled methyl esters of safflower oil on the development of NE. This disorder was more severe in chicks fed a fat-free diet deficient in vitamin E for the first week and then the NE-inducing diet than in chicks fed the NE-inducing diet from hatching. Feeding chicks vitamin E for the first week delayed the development of encephalomalacia but did not prevent it. In order to prevent NE in young chicks fed oxidized safflower oil, a ratio of .3 mg alpha-tocopherol per gram oil was required.

Moderate excess of dietary protein increases breast meat yield of broiler chicks.

Two factorial experiments were carried out to evaluate the effects of dietary protein level, expressed as energy to protein (E:P) ratio, on yields of carcass and breast and on abdominal fat pad weight of male broiler chicks at 43 and 57 d of age. Two diets similar in their energy content and differing markedly in their protein content, in which the E:P ratios were lower and identical to the NRC (1994) recommendations, were used in Experiment 1. Four diets, the combination of two energy and two protein levels, in which the E:P ratios were lower and identical to the recommendations, were used in Experiment 2. There were no differences in feed intake or weight gain until 42 d of age between broilers fed the diets with the low and those fed the recommended E:P ratio. However, feed efficiency of the former was consistently and significantly (P < 0.05) higher. The high-energy diets did not affect feed intake but significantly improved weight gain between 7 and 28 d of age and feed efficiency until 42 d of age. In both experiments, carcass yield was not affected by dietary E:P ratio at 43 d of age; however, at 57 d of age it was increased significantly by the low E:P ratio in Experiment 1 and in birds fed the high energy diet in Experiment 2. On a factorial basis, the effect of the low E:P ratio on increasing yield was significant only in Experiment 1. The high dietary energy level increased carcass yield only at 43 d of age, but on a factorial basis its effect was significant. Carcass yield was significantly (P < 0.001) higher at 57 than at 43 d of age. In both experiments, breast meat yield was negatively correlated with dietary E:P ratio, a significant factorial effect. The difference in this variable between broilers fed the diets containing the low and the recommended E:P ratio was significant, at both ages in Experiment 1, and only at 57 d of age in Experiment 2. Breast meat yield was not affected by dietary energy level, and it was significantly (P < 0.001) higher at 57 than at 43 d of age. Relative abdominal fat pad weight was increased significantly by increasing dietary E:P ratio. Dietary energy level and age did not affect this variable. The relationship between abdominal fat pad weight and breast meat yield within the treatments tended (in most of the cases not significantly) to be negative. However, this negative relationship was significant, at both ages, when the analysis was carried out with the pooled data at each age. It is concluded that the optimal E:P ratio for maximal breast meat yield for broiler chicks, particularly at 57 d of age, may be below the NRC (1994) recommendations.

The nutritional value of high-oil corn for broiler chicks.

A variety of corn (Natan) with high fat and protein contents (6.7 and 9.8%, respectively) was developed at Newe Ya'ar, Israel. The nutritive value of this corn for broiler chicks from 7 to 28 d of age was evaluated in two experiments. In the first experiment, Natan and a local conventional corn variety (LCC-2.9% fat and 7.2% protein) were incorporated in a relatively low-protein diet designated for the determination of AMEn by the substitution method. The AMEn content of Natan was found to be 3,658 kcal/kg, whereas that of LCC was 3,437 kcal/kg. There were no differences in feed intake or weight gain between chicks fed the two corn varieties, but feed efficiency of those fed the diet containing Natan was improved (P < .05). In the second experiment, the effects on the performance of chicks of diets adequate in protein and containing either imported conventional corn (ICC), or Natan, or ICC-enriched with corn oil and soybean meal (to equalize its fat and protein content to that of the diet containing Natan), were compared. There were no differences in feed intake or weight gain among chicks fed the three diets and in feed efficiency among chicks fed the diet containing Natan and those fed the other two diets, whereas, the enrichment of the ICC-containing diet significantly improved feed efficiency. It was concluded, therefore, that in spite of the high nutritional value of the high-oil corn, its effect on improving the performance of chicks, when replacing a conventional corn in a well-balanced diet, was not pronounced.

The nutritional value of moldy grains for broiler chicks.

The effect was determined of mold development in corn and sorghum grains on their lipid content and nutritional value for broiler chicks. The grains, whole or ground, with their original moisture content (12.1 to 13.0%) or increased moisture content (15.0% moisture), were stored for 63 to 96 days prior to their incorporation into the diets fed to the chicks. Increasing the moisture content caused the development of the naturally occurring fungi (mainly Penicillium and Aspergillus spp.). The moldy grains did not contain aflatoxin B1, ochratoxin A, patulin, sterigmatocystin or zearalenone. Storage of whole or ground grains or of moistened whole corn did not result in differences in their fat content, in the metabolizable energy (ME) of the diets containing these grains, or in the performance of chicks fed these diets, but moistened whole sorghum affected performance adversely. Fat content in moistened ground grains decreased markedly during storage, but fatty acid ratios, vitamin E, carotene, xanthophyll, and protein levels were not markedly affected. These ground moldy grains reduced the dietary fat level during the 3 weeks of the feeding period in two out of three experiments and significantly (P less than .05) lowered ME values and depressed performance. Soybean oil supplementations to diets containing these grains increased dietary ME values and partially or completely restored performance. It is concluded, therefore, that the decreased energy level in diets containing ground moldy grains (not containing mycotoxins) is an important factor for their reduced nutritional value.

New formal approaches to the determination of energy and amino acid requirements of chicks.

Body weight and the intake of metabolizable energy of chicks as function of age, were resolved into a linear equation from which the energy requirements for maintenance and growth were extracted. The metabolizable energy requirement for maintenance was calculated to be 1.91 and 1.62 Cal./g. 2/3, and that for weight gain was 2.05 and 2.19 Cal./g. for male White Rock and female 2--8-week old Leghorn chicks, respectively. The amino acid requirements of growing broiler chicks were calculated from the maintenance requirements, body weight gain and body weight, the proportions of feather protein in total body protein, and the amino acid composition of carcass and feathers. The requirements thus calculated, correlated well with various values in the literature. Diets formulated on the basis of the present model, were lower in protein and amino acid contents than those formulated on the basis of NRC allowances. These differences were pronounced in diets designed for 6--8 week old chicks. The weight gains obtained were similar for both types of diets. Feed conversion were slightly poorer and abdominal fat higher in chicks fed the model diets. It is concluded that the present model can serve, at least as an initial approach, to calculate the protein and amino acid requirements.

Effect of dietary ingredients on monensin toxicity in chicks.

A corn-soybean (CS) diet and diets containing medium or high levels of animal protein (AP) calculated to contain the same concentrations of the main nutrients promoted essentially the same growth rate and feed utilization in 20-day-old chicks. Supplementation with monensin sodium (100 or 120 mg/kg) depressed growth rate of the chicks fed all three diets. However, effect of the drug was much more severe in chicks fed the diets containing AP. This interaction resulted in significant (P < .05) differences in body weights between chicks fed the CS diet and PA diets. Moreover, feed-to-gain ratio was significantly (P < .05) adversely affected by monensin only in chicks fed the AP diets. Supplementation of the high AP diet with extra vitamin E, a mixture of arginine and tryptophan, or a mixture of silicon, chromium, and molybdenum failed to prevent the growth depression caused by monensin. These studies demonstrate that ingredient composition of diets for broiler chicks affects the magnitude of growth depression caused by monensin supplementation.

Humoral immune response impairment following excess vitamin E nutrition in the chick and turkey.

The effect of high dietary intakes of vitamin E on antibody production was investigated in chicks and turkeys. Chicks were fed four diets with 0, 10, 30, and 150 mg/kg added vitamin E and turkeys were fed three diets with 0, 50, and 150 mg/kg added vitamin E. Antibodies produced in response to naturally occurring Escherichia coli and to Newcastle disease virus and turkey pox vaccines were determined. In chicks, antibody production in response to E. coli and Newcastle disease was affected by vitamin E nutrition: significantly higher responses were measured in chicks that received 0 and 10 mg/kg added vitamin E, whereas in chicks receiving 30 and 150 mg/kg, antibody production was significantly lower. In turkeys, concentrations of circulating antibodies to Newcastle disease virus and to turkey pox were also influenced by dietary vitamin E: antibody titers to Newcastle disease and turkey pox vaccines were highest in groups receiving 0 mg/kg added vitamin E, whereas titer in groups receiving 150 mg/kg were significantly lower. Responses of groups receiving 50 mg/kg added vitamin E were slightly lower than groups receiving 0 mg/kg, though not significantly so in most cases. These results indicate that humoral immune responses are directly effected by vitamin E, and that excessive vitamin E intake has a detrimental effect on antibody production in chickens and turkeys.