Avian tibial dyschondroplasia: a comparison of the incidence and severity as assessed by gross examination and histopathology.

The assessment of avian tibial dyschondroplasia (TD) in many recent studies is based on examination of slices of the proximal tibiotarsus with the naked eye. This study examines the incidence and severity of TD in broilers under four different dietary regimes and compares the efficacy of naked eye assessment with histopathological examination. The diets contained reduced levels of calcium relative to phosphorus with adequate (diet 1) and high (diet 2) levels of vitamin D3 supplementation; a very low calcium diet (diet 3) and a standard diet (diet 4) were also included. Gross examination suggested that TD was present in 80 per cent, 79 per cent and 27 per cent of tibiotarsi from birds on diets 1, 2 and 4, respectively. However, histological examination indicated TD, correspondingly, to be present in 18 per cent, 39 per cent and 6 per cent of tibiotarsi. Some birds on diet 1 exhibited physeal changes consistent with mild hypocalcaemic rickets. Many of the bone extremities which, grossly, were considered dyschondroplastic (diets 1, 2 and 4), histologically were shown to have an extensive hypertrophied zone with poor metaphyseal vessel penetration, but no cellular or matrix changes consistent with TD. This cast doubt on the validity of earlier studies of TD which relied solely on naked eye examination. The birds on diet 3 all demonstrated histopathology considered consistent with severe hypocalcaemic rickets and the present study suggests that in three-week-old broilers a moderately hypocalcaemic diet with a high level of vitamin D3 will not cause rickets but will increase the incidence and severity of TD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fowl typhoid: assessment of a disinfectant oral dose to reduce horizontal spread and mortality

To determine the most appropriate dose in drinking water of the disinfectant N-alkyl dimethyl benzyl ammonium chloride (TIMSEN), a fowl typhoid challenge trial was carried out using 21-day-old Salmonella-free chickens. In a pretrial, performed with six groups of 10 chickens each, it was shown that the disinfectant was atoxic and safe when administered during 15 days at doses of 0 ppm, 200 ppm, 400 ppm, 800 ppm, 1600 ppm, or 3200 ppm. Thereafter, a challenge trial was performed with 390 chickens divided into six groups of 65 birds each. Chickens were treated during 9 days with oral doses of 0 ppm, 25 ppm, 50 ppm, 100 ppm, 250 ppm, and 500 ppm (groups identified as A, B, C, D, E, and F, respectively). Twenty-four hours after the beginning of the treatment, 30 chickens of each group were orally inoculated with 10(9) colony-forming units of Salmonella Gallinarum strain INTA 91 per bird. The remaining 35 unchallenged chickens from each group were left in the same cage in close contact with the other challenged birds of their group. All surviving chickens were sacrificed 8 days after challenge. Livers from all birds were examined for the presence of Salmonella Gallinarum. Salmonella Gallinarum was isolated from all challenged chickens and from some unchallenged chickens of groups A (4/35), E (3/35), and F (6/35), but not from any unchallenged chicken from groups B, C, and D. Doses of 50 ppm (group C) significantly reduced mortality (30%) in comparison with the untreated control group A (65%). Mortality in group B (45%) was not significantly different from group C. Administration of higher doses of the disinfectant resulted in significantly higher mortality rates, 70% in group E and 85% in groups D and F. Increased infection and mortality rates of groups D, E, and F might have been caused by inhibition of the protective action of the normal gut flora. To reduce horizontal infection and mortality, the manufacturer's prescribed oral dose of 25 ppm may be increased up to 50 ppm. Nevertheless, higher doses should be avoided because they may cause horizontal increased spread of the disease and mortality.     

ORIGINAL ARTICLE: Effect of the level of cholecalciferol supplementation of broiler diets on the performance and tibial dyschondroplasia

A study was conducted to evaluate four different cholecalciferol levels (NRC; modified), using diets supplemented with 200 (control), 1500, 2500 or 3500 IU/kg of cholecalciferol (VIT‐D3). Each treatment was assigned to 3 pens of 17 broiler chicks of a commercial strain grown in an open‐sided house with sidewall curtains. At 21and 42 days, BW and feed conversion (FCR) were determined. At 42 days, five birds per pen were slaughtered to evaluate tibia and toe ash of the right leg, and incidence and severity of tibial dyschondroplasia (TD) of the left tibia and also measured dressing percentage and breast meat yield. Serum calcium and phosphorus concentrations were also determined. Haemagglutination inhibition antibody titre against Newcastle disease virus and lymphoid organs weight/body weight ratio were also determined. At both 21 and 42 days, the BW of birds fed 1500 IU/kg to 3500 IU/kg of VIT‐D3 was significantly greater than birds fed 200 IU/kg. Similarly, better FCR was observed in birds those fed diets of high level of VIT‐D3. No significant difference was observed for mortality at any age. Better dressing percentage and breast meat yield were noted in birds fed diets containing 2500 or 3500 IU/kg VIT‐D3. Both tibia and toe ash contents were increased (p < 0.05) progressively with increased concentrations of cholecalciferol in feed. The incidence of TD (percentage of birds having TD scores greater than zero) was significantly (p < 0.05) influenced by level of 3500 IU VIT‐D3/kg at 42 days. The severity of TD in birds fed diets containing 200 IU/kg VIT‐D3 was apparently higher than birds fed diets with higher levels of VIT‐D3. Concentrations of calcium and phosphorus minerals in the serum increased progressively with the high level of VIT‐D3 supplementation to birds at both 21 and 42 days of age. Feeding levels of 1500 or 3500 IU of vitamin D3 did positively affect the immune system within the parameters measured. It may be concluded that performance, bone mineralization, blood chemistry and immunity against disease in broilers could be maintained when supplementing high level of VIT‐D3 incorporated in broiler diets.     

Vitamin C Overcomes the Detrimental Effect of Vanadium on Brown Eggshell Pigmentation

Phosphorus supplementation from poor quality feed-grade sources may introduce excessive levels of vanadium (V) into the diets of laying hens. Vanadium in the diet of chickens has been shown to be detrimental to egg production, albumen height, BW, and feed consumption. This study showed that dietary V also has a negative effect on the color of brown eggshells from commercial-type layers. Commercial-type brown egg layers were fed a cornsoybean meal basal diet supplemented with 0, 50, or 100 ppm of V as NH₄ VO₃ to determine the effect on shell pigmentation. Hens fed V at both dietary concentrations laid lighter colored eggs (less redness) after only 2 d. Another experimental group of the same type of hens that were fed lower V concentrations (0, 15, or 30 ppm) also had less shell pigmentation. After the detrimental “bleaching” effect on shell color was observed, these diets were supplemented with 1 of the following: no supplement, 100 ppm of vitamin C, 100 IU of vitamin E, or 100 ppm of β-carotene. Only vitamin C restored the eggshell color of eggs from hens fed both levels of V. When these same antioxidants were added as preventive agents to diets supplemented with 15 ppm of V before the effects of V were established, brown layers benefited again from 100 ppm of vitamin C but not from vitamin E or β-carotene.     

High vitamin D3 requirements in broilers for bone quality and prevention of tibial dyschondroplasia and interactions with dietary calcium, available phosphorus and vitamin A

1. Two experiments were carried out to investigate responses in performance and bone compositional and structural characteristics in broilers fed diets containing 4 concentrations of vitamin D3 (5, 20, 125 and 250 microg cholecalciferol/kg) at different concentrations of calcium, available phosphorus and vitamin A. 2. In experiment 1, body weight and tibia breaking strength were maximised at 14d with 250 microg vitamin D3/kg, tibia ash was maximised with 125 microg vitamin D3/kg. A high incidence of tibial dyschondroplasia (TD) was decreased to very low levels with 125 microg vitamin D/kg. 3. At 42d, performance and bone characteristics showed no response to vitamin D3 concentrations above 20 microg/kg. 4. Dietary vitamin A within the range 2-4 to 4.5 mg retinol/kg did not show any interaction with vitamin D3 status at either age. 5. In experiment 2, responses to vitamin D3 were strongly influenced by dietary calcium/available phosphorus. With 13 g calcium and 5 g available phosphorus/kg, performance and bone characteristics responded to vitamin D3 concentrations up to 125 microg/kg but more was needed at less optimal concentrations of calcium and available phosphorus. TD incidence was minimised with 250 microg/kg. 6. This study shows that high dietary concentrations of vitamin D3 can prevent TD. It is concluded that the vitamin D3 requirement of broilers up to 14 d of age at optimal dietary calcium and available phosphorus concentrations may be in the range 35 to 50 microg/kg for cortical bone quality and up to 250 microg/kg for prevention of TD. The vitamin D3 requirement for cortical bone quality after 14 d is not higher than 20 microg/kg. These requirements are much higher than earlier estimates and may be related to higher calcium requirements of modern broiler genotypes. Current regulations limiting maximum vitamin D3 concentrations in broiler starter diets may need to be reviewed.     

Induction of tibial dyschondroplasia by carbamate and thiocarbamate pesticides

Tibial dyschondroplasia (TD) is a major poultry leg problem, the natural etiology of which is unknown. Certain dithiocarbamate pesticides such as tetramethyl thiuram disulfide (thiram) have been shown to induce the disease in chickens. Because many different carbamate and thiocarbamate chemicals are used in a number of agricultural, industrial, and household applications, the objective of this study was to determine whether all chemicals of these categories induce TD and whether there is a concentration-dependent relationship between the ingestion of these chemicals and the incidences and the severity of the disease. Week-old broiler chicks were fed diets containing thiram or other assorted carbamate and thiocarbamate pesticides mixed in feed for 24-48 hr between ages 8 and 10 days. The birds were killed on day 15 and the proximal tibial and tarsometatarsal growth plates were evaluated for the presence and severity of TD lesions. TD was distinguished by broadening of growth plates; upon histologic exam chondrocytes appeared to be shrunken and dead. When compared by including equimolar concentrations of these chemicals in the feed, the dithiocarbamates with more than two sulfide groups, such as disulfiram, ferbam, thiram, and ziram were potent inducers of TD, whereas those with two sulfides to no sulfide group appeared ineffective at inducing TD. Both thiram and ferbam also reduced the bird's body weights. Thiram increased the incidence and the severity of the disease, denoted by TD index, in a dose-dependent manner. These results suggest that inadvertent contamination of feed or litter with some of these or similar chemicals may cause leg problems in poultry.     

Performance and bone development in broiler chickens given 25-hydroxycholecalciferol

1. A series of 5 trials was conducted with Cobb chickens in order to determine the effect of 25-hydroxycholecalciferol (25OHD3) on their performance and bone development under adequate Calcium (Ca) and Phosphorus (P) supplementation, and under moderate dietary restriction of Ca and P. Formulated beadlets of 25OHD3, trade name HY-D (IsoGen, Naperville, IL, USA) were used as the 25OHD3 source. 2. Five to 10 microg of cholecalciferol (vitamin D3) or 25OHD3/kg diet were sufficient to ensure normal body weight (BW) and bone ash in chickens under continuous lighting. The two materials had similar effects on BW and bone ash. 3. In one out of the three experiments, 25OHD3 increased BW and BW gain, while in the others it had a similar effect to that of vitamin D3, or even a slight negative effect in a trial conducted on the floor, in which the diets were supplemented with the D sources at 75 microg/kg. The effects of both D sources on bone ash and on the severity or frequency of tibial dischondroplasia were similar. 4. 25OHD3 restrained the effect of moderate dietary P restriction, but not of Ca restriction, on BW gain and bone ash in 22-d-old chickens. This effect could not be explained by an higher P bioavailability in the 25OHD3-fed chickens.     

Effects of vitamin or mineral deficiency on the morphology of medullary bone in laying hens.

Adult laying hens were fed diets deficient in phosphorus, calcium, calcium and phosphorus, and vitamin D3 to determine their effects on bone histology and parathyroid gland size. The phosphorus deficient diet caused an insignificant decrease in parathyroid size while the other diets caused significant increases. A considerable amount of individual variation in medullary bone volume and osteoid seam width was observed in all groups but, despite this, the calcium, calcium and phosphorus and vitamin D3 deficient diets clearly resulted in increased osteoid. Birds receiving diets deficient in calcium and phosphorus, and in vitamin D3 for longer periods were observed to have partially or completely resorbed medullary bone. Osteodystrophia fibrosa was noted in vitamin D3 deficient birds which had no follicular activity.     

日粮代谢能水平对北京油鸡脂肪沉积和LPL基因表达的影响

试验旨在研究不同日粮代谢能水平对北京油鸡脂肪沉积及脂蛋白酯酶（LPL）基因mRNA表达影响。试验以3周龄北京油鸡公鸡为研究对象,将480只公鸡随机分为4组,分别饲喂4个代谢能水平的日粮（12.122、12.540、12.958和13.376 MJ/kg）,每个处理组5个重复,每个重复24只鸡。试验期为10周。采用荧光定量PCR方法检测LPL基因mRNA表达水平。结果表明,日粮代谢能水平对鸡体脂沉积各项指标和LPL基因mRNA表达水平影响极显著,随日粮代谢能水平提高,各项体脂沉积指标极显著上升,胸肌和腿肌IMF、皮脂重和皮脂率在ME3达到峰值,LPL基因mRNA表达水平在ME2组达到峰值（P＜0.01）。LPL基因mRNA表达水平与腹脂率、皮脂重和皮脂率呈显著正相关（P＜0.05）。研究结果提示,日粮代谢能水平显著影响北京油鸡体脂沉积和LPL基因mRNA表达;LPL基因表达影响北京油鸡体脂沉积状况。     

Efficacy evaluation of lasalocid plus roxarsone combination medication with different geographic field strains of Eimeria acervulina

Performance of broiler chickens medicated with lasalocid alone (at 125 ppm) or in combination with roxarsone (at 50 ppm) was evaluated in battery and floorpen trials after challenge with geographically different field strains of coccidia containing predominately the upper intestinal species Eimeria acervulina. No significant difference in bird performance measured at 6 days postinfection (PI) was observed between lasalocid plus roxarsone-medicated (L+RM) or lasalocid-medicated (LM) birds challenged in separate battery trials with mixed-species inocula from Alabama or Georgia containing 92% or 88% E. acervulina, respectively. In contrast, L+RM birds challenged in another battery trial with a Louisiana mixed-species inoculum containing 92% E. acervulina showed significant reduction in average weight gain at 6 days PI compared with LM-challenged birds. A floorpen trial done with the same Louisiana inoculum showed significant reduction in average bird weight gain at 27 and 35 days of age (6 and 14 days PI) for L+RM-challenged birds compared with both unmedicated-nonchallenged (UMNC) control and LM-challenged birds. The LM+R groups were significantly lower in average bird weight at 27 days of age than the unmedicated-challenged controls. Feed conversions (FCs) for L+RM birds were significantly higher than those for the UMNC control birds during time of challenge (21-27 days of age) and for the 1-to-27-day-of-age time period. No significant difference in FC was seen between the UMNC and LM groups. Results of this study showed that performance of broiler birds medicated with lasalocid plus roxarsone could vary for geographically different mixed-species challenge inocula that contained predominately E. acervulina.     

Ultrastructure of parathyroid glands of growing chickens with vitamin D deficiency rickets

Ultrastructural studies were conducted on the parathyroid glands (PTG) of 2- to 7-week-old nontreated control growing broiler chickens (group A, 6 chickens); the same aged chickens with experimentally induced vitamin D deficiency rickets (18 morbid chickens each from groups B, C, and D); and in 4- to 9-week-old chickens naturally affected with rickets (group E, 8 chickens). Four types of principal cells were classified in the PTG of clinically normal birds and in PTG of birds with secondary hyperparathyroidism as follows: Type I cell (small cell in the resting phase); type II cell (medium-sized cell with well-developed rough-surfaced endoplasmic reticulum in the synthesizing phase); type III cell (large cell with well-developed Golgi apparatus and cytoplasmic organelles in the packaging and secretory phase); and type IV cell (medium-sized cell with poor cytoplasmic organelles in the involuting phase). Many coated vesicles were observed in type II and type III cells. In young control chickens, principal cells of the PTG were considered in the resting phase; in older control chickens, there were increased numbers of cells in the synthesizing phase. In the vitamin D deficiency groups, principal cells were in the synthesizing and packaging and secretory phases. In birds with naturally occurring rickets, principal cells were in packaging and secretory phases, with a small number of cells in the involuting phase. The ultrastructural changes of the PTG from the initial to final phases in growing chickens with secondary hyperparathyroidism were demonstrated.     

两种锗化合物对肉鸡的促生长作用及其毒性

就使用两种不同锗化合物——二氧化锗(GeO_2)和四氯化锗(GeCl_4)对肉用仔鸡的促生长作用及其毒性进行了研究。每次试验使用144只不同处理组。喂饲基础日粮组为对照组。在各试验组中分别加入1,10,100,1000mg/kg 锗(GeO_2)和1,10,100,1000mg/kg 锗(GeCl_4)。加二氧化锗的试验组中,当加入锗10mg/kg 时,鸡增重提高12%(P<0.05),饲料转化率提高7.5%(P<0.05)。相反,四氯化锗不能促进鸡的生长,当锗为100mg/kg 时,鸡的各项生产性能指标均有所下降。当饲料中锗浓度为1000mg/kg,不论它来自二氧化锗还是四氯化锗均对鸡有很大毒性,所有鸡分别于17天和28天后死亡。在试验2中,将鸡分为8个不同处理组,喂以基础日粮(对照组)和2,5,10,20,50,100和200mg/kg。锗(二氧化锗)。当锗浓度为5mg/kg时。对鸡的生长有轻微促进作用,与对照组相比提高3.3%,各处理组均未发现中毒症状。根据试验结果可推断,锗对鸡的半致死量(LD_(50))略低于大鼠,约为500～600mg/kg 体重。每日每只鸡摄入18mg 锗,是安全的。     

Dose-titration of fenbendazole in the treatment of poultry nematodiasis

Broiler chickens were fed ad libitum diets containing fenbendazole at various concentrations and durations for the removal of adult Ascaridia galli, Heterakis gallinarum, and Capillaria obsignata. All regimens were 100% effective against A. galli. Fenbendazole at doses of 80 ppm for 3 days and 48 or 30 ppm for 5 days was 100% effective against H. gallinarum. C. obsignata was not removed completely by any regimen, but greater than or equal to 95% effectiveness was seen in birds given fenbendazole at doses of 80 ppm for 3 days and 48 ppm for 5 days. All medicated rations were readily consumed, and the treated birds exhibited no adverse reactions.     

Effect of casein phosphopeptide and 25-hydroxycholecalciferol on tibial dyschondroplasia in growing broiler chickens

1. An experiment was conducted to investigate the influence of dietary casein phosphopeptides and 25-hydroxycholecalciferol on the incidence of tibial dyschondroplasia (TD) in 14-d-old commercial broiler chickens. 2. Three hundred and twenty broiler chicks (one day old) were randomly allocated to one of 4 dietary treatments. A standard broiler diet was used as the control with the three experimental treatments receiving the control diet supplemented with 10 g casein phosphopeptide/kg, 14 g casein phosphopeptide/kg or 69 microg 25-hydroxycholecalciferol/kg. 3. Those birds fed the diets supplemented with 14g casein phosphopeptide/kg or 25-hydroxycholecalciferol had a lower incidence of TD than both the control and 10g casein phosphopeptide/kg treatments when assessed grossly. 4. The body weight of birds fed the 10 g casein phosphopeptide/kg diet or the 25-hydroxycholecalciferol diet was higher than birds fed the control diet. Although not significant, the body weight of birds fed the 14 g casein phosphopeptide/kg diet was also greater than the control birds. 5. The current experiment demonstrated that both casein phosphopeptide and 25-hydroxycholecalciferol can reduce the incidence of TD in the young broiler chicken. More research is required to explain the unexpected increase in body weight described above.     

Effects of high dietary vitamin A supplementation on tibial dyschondroplasia, skin pigmentation and growth performance in avian broilers

An experiment was conducted to study high dietary vitamin A on tibial dyschondroplasia, growth performance and skin pigmentation in broilers. One hundred and twenty Avian commercial broilers were randomly allotted to three treatments: group C (control group), in which broilers were fed basic diet containing vitamin A 5512IU/kg diet; group A, in which broilers were fed basic diet with addition vitamin A 35512IU/kg; group B, broilers were fed basic diet with supplement vitamin A 65512IU/kg. The experiment lasted 35d and at the end of the trial, broilers were killed and the right proximal tibiotarsi were dissected in longitudinal section for the assessment of TD incidence and TD index, skin from the same area of breast and tibia in broilers were collected to determine pigmentation. The results showed that a high level vitamin A significantly increased the rate of TD incidence and TD index, but middle level vitamin A did not have a significant effect on that. Both low and high retinoic acid decreased growth performance and skin pigmentation in broilers. It suggests that a high dietary vitamin A cause tibial dyschondroplasia in broilers, decreased growth performance and skin pigmentation. It is likely that the effect of vitamin A on TD is mediated through a depression of vitamin D status.     

Effect of lemon verbena powder and vitamin C on performance and immunity of heat‐stressed broilers

An experiment was conducted to investigate the effect of lemon verbena powder and vitamin C on performance and immunity of broilers under heat stress. The experiment was carried out with a total of 160‐day‐old male Ross 308 broiler chickens in a completely randomized design. From 25 days of age, the birds were assigned to four diets including control diet and treatment diets which were supplemented with 2 levels of lemon verbena (0.5% and 1.0%) and one level of vitamin C (250 mg/kg) in 16‐floor pens with 10 chickens each and reared to 42 days of age. To induce chronic heat stress, birds were exposed to an ambient temperature of 35 ± 2 °C for 8 h daily (from 09:00 AM until 17:00 PM) between 25 and 42 days of age. At the end of experiment, one chick/pen was randomly selected, and the performance and blood parameters were evaluated. Dietary supplementation of 1.0% lemon verbena increased (p < 0.05) average weight gain and feed intake by 5.81% and 3.29%, and reduced feed conversion ratio by 2.59% respectively compared to control group. Birds fed diets containing 1.0% lemon verbena had significantly higher relative weight of bursa of fabricius and breast (p < 0.05). LDL decreased by 15.85% and 17.57%, for birds fed 0.5% and 1.0% lemon verbena respectively. The ratio of heterophyl to lymphocyte was reduced (p < 0.05) by 20.68% via significant decrease in heterophyl by 15.55% and significant increase in lymphocyte by 4.51% in birds fed lemon verbena at the rate of 1.0% compared to those fed the control diet. 1.0% lemon verbena and vitamin C elevated (p = 0.0005) the level of glutathione peroxidase by 51.81% and 27.90%, respectively. In conclusion, lemon verbena and vitamin C improved some performance data and blood metabolites which somehow suppressed the negative effects of heat stress.     

Dietary supplementation of phenyllactic acid on growth performance,immune response,cecal microbial population,and meat quality attributes of broiler chickens

A total of 750 one-day-old male broiler chicks were randomly fed 5 dietary treatments with 5 replicate pens per treatment. The 5 dietary treatments fed for 42 d were a corn-soybean meal basal diet without antibiotic (control); a mixture of 10 ppm of avilamycin + 60 ppm of salinomycin as antibiotic growth promoters (AGP); 0.1% phenyllactic acid (PLA); 0.2% PLA; and 0.4% PLA. The BW gain and FE were significantly improved in AGP and PLA groups compared with control group. The white blood cells and heterophil counts were significantly higher in the PLA-supplemented groups compared with AGP and control groups, but the heterophil-to-lymphocyte ratio was lower in the control group than other groups. The plasma IgY concentration was significantly increased in birds fed PLA-supplemented diets, but the plasma IgA and IgM concentrations were not different among the treatment groups. In addition, the antibody titer against Newcastle disease virus was significantly higher in PLA-treated compared with control and AGP-treated groups. Neither PLA nor AGP treatments affected the cecal aerobes andSalmonella content; however, cecalLactobacillus population increased in chickens fed 0.1% PLA, and total coliform bacteria population significantly decreased in chickens fed various levels of PLA and AGP. Dietary supplementation of PLA did not affect the pH, lightness, and redness of breast meat, but the water-holding capacity and shear force value increased and the yellowness decreased significantly when birds were fed PLA. It was concluded that dietary supplementation of 0.1 and 0.2% PLA improves BW gain and FE of broiler chickens. In addition, PLA supplementation increases the immune characteristics and the number of lactic acid bacteria, decreases the number of coliform bacteria, and improves the meat quality attributes of broiler chickens. Thus, dietary PLA could be a viable alternative to antibiotics in broiler diets.     

The effect of dietary lysozyme with EDTA on growth performance and intestinal microbiota of broiler chickens in each period of the growth cycle

Lysozyme is a potential replacement for antibiotics in the poultry industry. Two trials were conducted using new or used litter to determine the effect of 100 ppm lysozyme in feed on growth performance and intestinal microbiota of broiler chickens in each period of the growth cycle. The new litter trial and used litter trial were each analyzed as a one-way analysis of variance with length of time in which 100 ppm lysozyme was fed to the birds as the main factor (no lysozyme d zero to 35; positive lysozyme d zero to 4; positive lysozyme d 5 to 14; positive lysozyme d 15 to 24; positive lysozyme d 25 to 35; positive lysozyme d zero to 35; positive virginiamycin d zero to 35). Effects of lysozyme were not detected under clean conditions (P > 0.05). When used litter was provided, growth performance was not improved by lysozyme (P > 0.05). However, feeding lysozyme to birds from d 5 to 14 and throughout the trial reduced the number of E. coli in the ileum compared with feeding virginiamycin (positive lysozyme d 5 to 14 and zero to 35, and virginiamycin d zero to 35: 1.7 × 10⁴ cfu g⁻¹, 1.9 × 10⁴ cfu g⁻¹ and 9.3 × 10⁴ cfu g⁻¹, respectively) to birds (P < 0.05). Dietary lysozyme at 100 ppm can change intestinal microbiota of broiler chickens.     

Absence of a role for selenium deficiency in the runting syndrome of broiler chickens in Australia

The role of selenium deficiency in the etiology of the runting-stunting syndrome (RSS) of broiler chickens in Australia was investigated. Commercial broiler chickens maintained on selenium-deficient developed signs consistent with selenium deficiency of exudative diathesis and markedly reduced plasma glutathione peroxidase activity, but they did not develop pancreatic atrophy and fibrosis or elevated plasma amylase activity, which are the other lesions associated with RSS. Supplementation of the diets of birds from a RSS-susceptible flock with a mixture of selenium, vitamin E, cysteine, and sulfate had no effect on the incidence of runting in the treated birds. In field outbreaks of RSS there were no observable differences between affected and unaffected birds in the concentration of selenium in tissue samples. Furthermore, evidence is presented which suggests that in cases of RSS, pancreatic atrophy and elevations in plasma amylase precede reductions in plasma glutathione peroxidase activity.     

Flubendazole: safety regarding egg production and reproductive performance of breeder chickens

In a comparative field trial, 5,950 meat breeder chickens were medicated via feed for 7 consecutive days with 60 ppm of the anthelmintic flubendazole. This treatment cured the birds of an infection with Ascaridia galli and Capillaria obsignata. A slight but transitory diarrhea was observed in treated chickens. The applied medication did not unfavorably affect egg production, fertility, or hatchability.