Responses of broilers to dietary zinc concentrations and sources in relation to environmental implications

1. Since high concentrations of zinc are associated with reduced crop yields, environmental concerns are emerging regarding zinc accumulation in areas where poultry production is prevalent. This study investigates growth performance and zinc utilisation during the life cycle of broilers when diets were supplemented with various concentrations of zinc from two different sources. 2. A total of 740 Cobb 500 1-d-old male broiler chicks was randomly distributed into 88 battery cages. Excreta were collected over a 48-h period on d 10, 17, 24, 31, 38, and 45 to measure zinc excretion on a dry matter basis. 3. During the 45-d experimental period, broilers were given a maize-soybean meal basal diet (30 mg/kg zinc) supplemented with 0, 20, 40, and 80 mg/kg of zinc from zinc sulphate, Availa Zn amino acid complex, or an equal combination of zinc sulphate and Availa Zn amino acid complex. 4. Progressive additions of zinc to the basal diet significantly increased body weight gain of broilers, but did not affect feed conversion or mortality. Optimum body weight gain was achieved at 80 mg/kg supplemental zinc, which exceeds the NRC recommendations of 40 mg/kg. 5. During each excreta collection period, increased supplemental zinc concentrations significantly increased zinc excretion. However, the zinc source did not influence zinc utilisation. 6. As compared with zinc sulphate supplementation, the cumulative zinc excretion data indicate that adding zinc to the basal diet in the form of Availa Zn amino acid complex decreased zinc excretion.     

Superior growth performance in broiler chicks fed chelated compared to inorganic zinc in presence of elevated dietary copper

Background: The goal of this study was to compare the antagonism of elevated dietary Cu(250 mg/kg) from Cu SO4 on three different Zn sources(Zn SO4· H2O; [Zn bis(-2-hydroxy-4-(methylthio)butanoic acid)], Zn(HMTBa)2,a chelated Zn methionine hydroxy analogue; and Zn-Methionine), as measured using multiple indices of animal performance in ROSS 308 broilers.Methods: Three experiments were conducted in broiler chicks fed a semi-purified diet. Al birds were fed a Zn-deficient diet(8.5 mg/kg diet) for 1 wk, and then provided with the experimental diets for 2 wks.Results: Experiment 1 was a 2 × 2 factorial design with two levels of Cu(8 vs. 250 mg/kg diet from Cu SO4) and two Zn sources at 30 mg/kg [Zn SO4· H2 O vs. Zn(HMTBa)2]. Elevated Cu impaired growth performance only in birds fed Zn SO4.Compared to Zn SO4· H2 O, Zn(HMTBa)2improved feed intake(12 %; P 0.001) and weight gain(12 %, P 0.001) and the benefits were more pronounced in the presence of 250 mg/kg diet Cu. Experiment 2 was a dose titration of Zn SO4· H2 O and Zn(HMTBa)2at 30, 45, 60, and 75 mg/kg diet in the presence of 250 mg/kg Cu SO4. Feed:gain was decreased and tibia Zn was increased with increasing Zn levels from 30 to 75 mg/kg. Birds fed Zn(HMTBa)2consumed more food and gained more weight compared to birds fed Zn SO4, especially at lower supplementation levels(30 and45 mg/kg; interaction P 0,05). Experiment 3 compared two organic Zn sources(Zn(HMTBa)2vs. Zn-Methionine)at 30 mg/kg with or without 250 mg/kg Cu SO4. No interactions were observed between Zn sources and Cu levels on performance or tissue mineral concentrations. High dietary Cu decreased weight gain(P 0.01). Tibia Cu and liver Cu were significantly increased with 250 mg/kg dietary Cu supplementation(P 0.01). No difference was observed between the two Zn sources.Conclusions: Dietary 250 mg/kg Cu significantly impaired feed intake and weight gain in birds fed Zn SO4· H2 O,but had less impact in birds fed Zn(HMTBa)2. No difference was observed between the two organic zinc sources.These results are consistent with the hypothesis that chelated organic Zn is better utilized than inorganic zinc in the presence of elevated Cu.     

Effects of dietary substitution of zinc‐methionine for inorganic zinc sources on growth performance,tissue zinc accumulation and some blood parameters in broiler chicks

This study was designed to evaluate the effects of dietary inclusion of zinc‐methionine (ZnMet) as a replacement for conventional inorganic zinc sources on performance, tissue zinc accumulation and some plasma indices in broiler chicks. A total of 450‐day‐old Ross male broiler chicks were randomly assigned to five pen replicates of nine experimental diets. Dietary treatments consisted of two basal diets supplemented with 40 mg/kg added Zn as feed‐grade Zn sulphate or Zn oxide in which, Zn was replaced with that supplied from ZnMet complex by 25, 50, 75 or 100%. At 42 days of age, three randomly selected birds from each pen were bled to measure plasma metabolites; then, the chicks were slaughtered to evaluate carcass characteristics. Results showed that dietary treatments affected (p < 0.05) feed intake during the starter period, and chicks on Zn oxide diets consumed more feed than sulphate counterparts. Furthermore, dietary substitution of inorganic Zn sources by ZnMet caused improvements (p < 0.01) in body weight gain during all experimental periods. Dietary supplementation of ZnMet improved feed conversion efficiency during 1–21 and 1–42, but not in 21–42 days of age. Complete replacement of inorganic Zn by that supplied from ZnMet caused an increase (p < 0.05) in relative liver weight. Similarly, dietary inclusion of ZnMet increased breast meat and carcass yields and reduced abdominal fat percentage (p < 0.05). Incremental levels of ZnMet increased (p < 0.05) zinc concentrations in liver and thymus, and the highest zinc accumulations were seen in 100% ZnMet‐supplemented birds. Interestingly, introduction of ZnMet into the diets partially in place of inorganic sources resulted in decreases (p < 0.01) in plasma uric acid and triglycerides concentrations. The present findings indicated that dietary ZnMet inclusion in replacement of inorganic sources in addition to improving growth performance, reduced plasma uric acid and triglycerides concentrations, consequently decreased abdominal fat pad and increased carcass meat yield.     

Effects of different sources and levels of dietary chromium supplementation on performance of broiler chicks

The current experiment was carried out to evaluate the effect of different dietary chromium supplementation sources, chromium oxide (Cr₂O₃), chromium methionine (Cr‐Met), or chromium yeast (Cr‐yeast), at different levels each (500 or 1,000 ppb) on growth performance, physiological traits, and carcass characteristics of broiler chicks. A total of 490 seven‐day‐old Arbor Acres chicks were randomly distributed into 7 experimental groups each in 10 replicates of 7 birds each. The groups were control, 500 ppb Cr₂O₃, 1,000 ppb Cr₂O₃, 500 ppb Cr‐Met, 1,000 ppb Cr‐Met, 500 ppb Cr‐yeast, and 1,000 ppb Cr‐yeast. The results showed significant superiority of the organic chromium sources (Cr‐Met or Cr‐yeast) concerning body weight and weight gain, the group supplemented with 1,000 ppb Cr‐yeast consumed the lowest feed (3,185 g) and had the best feed conversion ratio (1.60) compared to the control (1.73). The chromium treatments recorded significantly better protein and lipid profile, antioxidant status, and immunological parameters than the control group. Similarly, dietary chromium supplementation increased carcass yield and decreased intestinal pathogenic bacteria. In conclusion, supplementing broiler diets with organic chromium sources at 1,000 ppb promotes growth performance, physiological traits, and carcass characteristics; such chromium treatments enhanced the antioxidant status and immunity levels of broilers.     

Effect of dietary zinc proteinate supplementation on growth performance, and skin and meat quality of male and female broiler chicks

1. An experiment was conducted to evaluate the effect of dietary zinc proteinate (ZP) supplementation on growth performance and on skin and meat quality of male and female broiler chicks.

2. A total of 240 1-d-old male and 240 1-d-old female broiler chicks were randomly distributed into 24 floor pens (12 replicate pens/sex; 20 birds/pen) and were given either 0 (Control diet) or 40?mg/kg ZP (ZP 40), resulting in a 2?×?2 factorial arrangement of treatments.

3. The growth performance of male and female broiler chicks was not affected by the ZP supplementation, but the males showed significantly higher growth performance than did females.

4. ZP supplementation increased the total thickness of skin in both sexes, and males had thicker skin than females. It also increased the collagen content of skin, but not that of meat. Males had higher skin collagen contents than did females, but no sex difference was found in the meat collagen contents.

5. ZP supplementation did not affect the shear force values of skin and meat; however, males had higher shear force values of back skin than females. ZP supplementation increased the zinc contents of thigh meat and plasma in both sexes. Males had higher zinc contents in back skin than females.

6. It is concluded that dietary ZP supplementation could increase the skin quality of broiler chicks in both sexes, particularly in female broilers, without any effect on growth performance. Male broilers have better growth performance and skin quality than females.     

日粮中锌水平对肉仔鸡体组织中铁和铜的影响

试验选择180只1日龄艾维茵肉仔鸡,随机分为6组,每组30只,公母各半。对照组饲喂锌水平为22.61mg/kg的基础日粮,5个处理组分别在基础日粮中添加25、65、145、305和625mg/kg的锌,锌源为硫酸锌,旨在研究日粮中锌水平对鸡组织铁和铜浓度的影响。试验结果表明,日粮中锌水平较低时,肉仔鸡肝脏、胫骨、肾脏、胸肌和羽毛各组织铁浓度呈不同程度的增加;而锌水平较高时,各组织铁浓度均呈不同程度的降低。由此可见,锌和铁之间存在颉颃作用。此外,随日粮中锌水平的升高,胸肌和肾脏中铜的浓度均有升高的趋势,而胰腺中铜的浓度显著降低。     

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

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

Effect of dietary palmitic acid on broiler chicks fed on various concentrations of calcium.

1. The effect of dietary palmitic acid on body weight and bone-ash of chicks fed three concentrations of calcium was studied in a 2 X 3 factorial design (0 and 10% palmitic acid, 0.4, 0.7 and 1.0% calcium). 2. Body weight of chick not influenced by the calcium concentration when palmitic acid was not included in the diet. 3. When 10% palmitic acid was included the body weight of chicks fed 0.4 and 0.7% calcium was lower (P less than 0.01) than for the other groups. 4. Bone-ash was lower (P less than 0.01) for chicks fed 0.4% calcium than for the other two calcium concentrations when palmitic acid was not added and palmitic acid at 10% of the diet reduced bone-ash of the chicks fed 0.4 and 0.7% calcium (P less than 0.01).     

Effects of dietary sorghum of different tannin concentrations and tallow supplementation on the performance of broiler chicks

1. The chemical compositions and tannin contents of 17 varieties of grain sorghum were determined.

2. Commercial broiler chicks were fed from 7 to 49 d of age on 15 experimental diets which varied in their concentrations of tannins and animal fat (tallow), by the inclusion of different amounts of high and a low protein varieties of sorghum.

3. Substitution of a low tannin sorghum completely for maize did not have any significantly adverse effect on performance. Broiler chicks could tolerate up to 2.6 g tannin/kg above which their performance was reduced. Addition of tallow did not significantly affect broiler performance except at the highest tannin content and added fat intake, where weight gain and efficiency appeared to improve significantly.     

Pathology and histology of dietary tryptophan deficiency in broiler chicks

The purpose of this experiment was to characterize a lesion of the rhamphotheca associated with tryptophan (TIRP) deficiency, search for other histological abnormalities,and determine whether bird size and housing conditions are contributing factors to these lesions. Day-old broiler chicks (Ross X Ross 308) were placed in either floor pens with fresh pine shavings or Petersime battery brooders with two pens of 10 chicks each per treatment. Broiler chicks from 0 to 21 days of age were fed adequate (0.24%) and deficient (0.09%) levels of TRP in diets based on corn, corn gluten meal, and gelatin. Separate groups of control chicks were pair fed daily with the deficient chicks. Deficient chicks grew less efficiently than did the pair-fed controls. Upon gross examination, a lesion of the maxillary rhamphotheca in the vicinity of the nares was observed in 61% of TRP-deficient birds housed in the battery and 13% of the birds housed in floor pens. A similar gross lesion was only observed in one control bird. These lesions were located along the upper portion of the beak between the nares and appeared as a crusty or scab-like area on gross examination, composed of detritus, heterophils, and plasma protein. Inflammation occasionally was observed at the dermoepidermal junction. The incidence of lesions was reduced in floor pens compared to battery brooders, but similarly sized birds did not exhibit the lesion. The number of lesions seen grossly and histologically in TRP-deficient birds, as compared to control birds, supports the hypothesis that TRP deficiency is the primary cause of these lesions around the nares of broilers. Secondary environmental factors, perhaps coprophagy, also influence the incidence of the lesion.     

Different concentrations and sources of dietary fibre may improve the welfare of female broiler breeders

1. Broiler breeder females were fed restricted allocations of food to meet target body weights. They were fed on a standard wheat-soy ration or on one of three series of rations containing 50, 100 or 200 g/kg of ground oat hulls, ground unmolassed sugar beet pulp or sunflower meal. Changes in behaviour and heterophil-lymphocyte ratio (HLR) were measured at 5, 10 and 15 weeks of age. 2. Body weight at 15 weeks of age decreased in a linear manner with increasing concentrations of the experimental ingredients. 3. Decreased spot pecking was observed in birds fed on the rations containing 50 g/kg of sugar beet pulp and 200 g/kg of oat hulls. 4. The HLR was higher in birds fed on the control diet and diets containing 50 g/kg of the high fibre ingredients. 5. Rations containing sugar beet pulp were associated with higher water contents in the gastrointestinal tract and it is proposed that this improved satiety and welfare.     

Estimation of the relative bioavailability of copper sources in chicks fed on conventional dietary amounts

1. Tissue accumulation of Cu from dietary additions of 0, 5, 10, or 20 mg/kg Cu as reagent grade Cu acetate and feed grade Cu carbonate was determined in day‐old chicks fed on conventional maize‐soyabean meal starter diets (5.41 mg/kg Cu as‐fed basis) for 3 weeks.

2. Average daily food intake, daily weight gain and food conversion were similar among treatments.

3. There were linear increases in plasma and liver Cu concentrations (P< 0.01) as dietary Cu increased.

4. Bioavailability of Cu as carbonate was 0.66 that of Cu in the acetate based on the multiple regression slope ratio of liver Cu concentration on added dietary Cu. Although responses for the two Cu sources did not differ significantly, the relative bioavailability of the Cu carbonate was similar (0.66 vs 0.68) to that obtained in an earlier study (Ledoux et al., 1991) with greater dietary Cu contents (150, 300 and 450 mg/kg) in which the slopes of the equations representing the two sources differed (P<0.05).     

Response of broiler chicks to dietary Rhazya stricta and Nigella sativa

1. Rhazya stricta leaves and Nigella sativa seeds were fed to 7-d-old Hibro broiler chicks at 20 and 100 g/kg of the diet for 7 weeks. Although 20 and 100 g/kg N. sativa seed diets did not adversely affect growth, a decrease in body weight and feed efficiency and hepatonephropathy were observed in the chicks fed on the 100 g/kg R. stricta diet. 2. These changes, associated with macrocytic hypochromic anaemia, were correlated with alterations in serum aspartate transaminase' (AST) and alanine transaminase (ALT) activities and concentrations of total protein, albumin, globulin, cholesterol, calcium and other serum constituents. 3. The effect of 20 g/kg R. stricta diet on chicks was not associated with development of biliary hyperplasia or catarrhal enteritis after 7 weeks of treatment.     

Effects of supplemental dietary phytase and pharmacological concentrations of zinc on growth performance and tissue zinc concentrations of weanling pigs

Three experiments were conducted to determine the effects of phytase, excess Zn, or their combination in diets for nursery pigs. In all experiments, treatments were replicated with five to seven pens of six to seven pigs per pen, dietary Ca and available P (aP) levels were decreased by 0.1% when phytase was added to the diets, excess Zn was added as ZnO, a basal level of 127 mg/kg of Zn (Zn sulfate) was present in all diets, and the experimental periods were 19 to 21 d. In Exp. 1, pigs (5.7 kg and 18 d of age) were fed two levels of phytase (0 or 500 phytase units/kg) and three levels of excess Zn (0, 1,000, or 2,000 ppm) in a 2 x 3 factorial arrangement. Added Zn linearly increased ADG and ADFI during Phase 1 (P = 0.01 to 0.06), Phase 2 (P = 0.02 to 0.09), and overall (P = 0.01 to 0.02). Gain:feed was linearly increased by Zn during Phase 1 (P = 0.01) but not at other times. Dietary phytase decreased ADG in pigs fed 1,000 or 2,000 ppm Zn during Phase 2 (Zn linear x phytase interaction; P = 0.10), did not affect (P = 0.27 to 0.62) ADFI during any period, and decreased G:F during Phase 2 (P = 0.01) and for the overall (P = 0.07) period. Plasma Zn was increased by supplemental Zn (Zn quadratic, P = 0.01) but not affected (P = 0.70) by phytase addition. In Exp. 2, pigs (5.2 kg and 18 d of age) were fed two levels of phytase (0 or 500 phytase units/kg) and two levels of Zn (0 or 2,000 ppm) in a 2 x 2 factorial arrangement. Supplemental Zn increased ADG and G:F during Phase 2 (P = 0.02 to 0.09) and overall (P = 0.07 to 0.08), but it had no effect (P = 0.11 to 0.89) on ADG during Phase 1 or ADFI during any period. Phytase supplementation increased ADG (P = 0.06) and G:F (P = 0.01) during Phase 2. Gain:feed was greatest for pigs fed 2,000 ppm Zn and phytase (Zn x phytase interaction; P = 0.01). Bone (d 20) and plasma Zn (d 7 and 20) were increased (P = 0.01) by added Zn but not affected (P = 0.51 to 0.90) by phytase. In Exp. 3, pigs (5.7 kg and 19 d of age) were fed a basal diet or the basal diet with Ca and aP levels decreased by 0.10% and these two diets with or without 500 phytase units/kg. Supplemental phytase had no effect (P = 0.21 to 0.81) on growth performance. Reduction of dietary Ca and aP decreased (P = 0.02 to 0.08) ADG, ADFI, and G:F for the overall data. These results indicate that excess dietary supplemental Zn increases ADG and plasma and bone Zn concentrations. Dietary phytase did not affect plasma or bone Zn concentrations.     

Toxicosis in broiler chicks due to excess dietary ethoxyquin.

A commercial broiler company experienced a sudden increase of mortality in four flocks at two separate locations. Affected houses had red dust on inside walls and on the equipment. Affected chickens were 10 to 18 days old. Grossly, chickens had pale, swollen kidneys, dark-brown enlarged livers, and urates in joint spaces. Histologically, the kidneys had multifocal proximal tubular necrosis, the livers had dilated sinusoids, biliary hyperplasia, and accumulation of brown pigment in hepatocytes and bile ducts. One starter ration was analyzed, and it contained 6500 mg ethoxyquin/kg. The red dust in the houses and the brown pigment in livers were interpreted to be ethoxyquin. Clinical signs and histologic lesions were reproduced experimentally with 12,500 mg ethoxyquin/kg feed.     

维生素C、E及其交互作用对肉仔鸡生长性能及鸡肉品质的影响

本试验旨在研究维生素C、E(VC、VE)及其交互作用对肉仔鸡生长及其鸡肉品质的影响。试验采用4×4完全随机试验设计将800只1日龄健康的艾维茵肉仔鸡随机分成16个处理,每个处理5个重复,每个重复10只。其中,VE设4个添加水平,分别为50、100、200、400 mg/kg日粮,VC的添加水平为50、100、200、400 mg/kg日粮。结果表明:在生长前期(0～21 d),日粮VE、VC的添加量对肉仔鸡日增重均无显著影响(P>0.05),VE、VC的互作效应在生长前期对肉仔鸡日增重和料重比的影响均不显著(P>0.05),前期VE(200 mg/kg)×VC(50 mg/kg)组料重比最低;在生长后期(4～6周龄),日粮VE、VC的添加量对肉仔鸡日增重、料重比的影响均显著(P<0.05),VE、VC的互作效应对肉仔鸡生长后期日增重和料重比的影响均显著(P<0.05);不同的VE、VC处理组之间pH 45 min、pH 12h、pH 24 h值、肉色、肌间脂肪、最大剪切力的差异均不显著(P>0.05),且VE、VC之间无显著的互作效应(P>0.05);不同维生素E组之间的滴水损失率差异极显著(P<0.01),...     

Effect of dietary zinc source and method of oral administration on performance and tissue trace mineral concentration of broiler chicks.

Two experiments were conducted with chicks to examine the effect of high dietary levels of soluble sources of Zn on tissue Zn, Cu, and Fe concentrations as influenced by two methods of oral Zn administration from 14 to 21 d of age. Treatments included the basal diet (62 ppm Zn), basal diet supplemented with 1,000 ppm Zn from Zn sulfate, acetate, or chloride fed continuously, or basal diet plus crop intubation with a single oral dose of water (control) or 1,000 ppm Zn dietary equivalent from the sources based on feed intake from the previous day. In Exp. 2, crop-intubated doses were administered daily from 14 to 21 d of age. In Exp. 1, chicks given Zn by gavage decreased (P < .0001) feed intake at 24 h after oral dose compared with chicks fed either the control or high-Zn diets. After the gavage dosing stopped, feed intake was similar among treatments. Bone Zn was increased (P < .0001) by Zn source and was greater at 24 than at 168 h after dosing by gavage. In chicks given a single gavage dose of Zn, liver and kidney Zn measured at 24 h after oral dosing was greater (P < .0001) than at 168 h. In birds given a single oral dose of Zn, time x Zn source interactions were observed in pancreas (P < .0001), mucosal cells (P < .01), and remaining intestinal tract segments (P < .001). In Exp. 2, greater bone, pancreas, kidney (P < .0001), and liver (P < .001) Zn accumulations were observed in chicks given daily gavage doses of Zn compared with those fed Zn in diets. Zinc from the four sources was absorbed and stored in tissues to a similar extent.