Hybrid Broiler Research Articles

Lymphocyte subpopulations in blood and duodenal epithelium of broilers fed diets contaminated with deoxynivalenol and zearalenone

The effects of two dietary levels of Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEA) on subpopulations of peripheral blood and duodenal intraepithelial lymphocytes in Ross 308 hybrid broiler chickens of both sexes were examined. From the day of hatching to the age of two weeks three groups of chickens were fed the same uncontaminated control diet. After 14 days, broilers in two of the groups were switched to otherwise identical experimental diets containing DON and ZEA. The diet of Group 2 contained DON and ZEA, each at a level of 3.4 mg/kg and the Group 3 diet contained DON and ZEA at 8.2 and 8.3 mg/kg, respectively. Contaminated diets were prepared in the laboratory using maize cultivated with Fusarium graminearum. Group 1 (control) continued with intake of uncontaminated diet for entire experiment. At the age of four weeks samples of blood and duodenal tissue were collected. Intake of both contaminated diets reduced blood phagocytic activity (P<0.001) whereas numbers of various types of peripheral white blood cells were not affected. Among different blood lymphocyte populations investigated, only the counts of CD3 + cells were lowered by diet with higher mycotoxin levels (P=0.021). In duodenal epithelium, the large increase in cells expressing MHC II was observed due to intake of both diets contaminated with lower and higher mycotoxins contents (P<0.001) while the IgA + cell subpopulation was decreased (P=0.018). The other intraepithelial lymphocyte subpopulations in duodenum examined (CD3 +, CD4 +, CD8 + and CD44 +) were not influenced by intake of contaminated diets (P>0.05). Results suggest that intake of diets contaminated with DON and ZEA at medium levels may affect some blood and intraepithelial duodenal lymphocyte subpopulations and compromise blood phagocytic activity in broilers.

Allometric growth of protein, amino acids, fat and minerals in slow- and fast-growing young chickens

Allometric growth of body constituents and apparent efficiency of amino acid and nitrogen retention were examined in slow-growing laying-type cockerels (SG) and in fast-growing male broiler hybrids (FG) during the growth period from hatch to Day 22. The respective allometric coefficients for water, protein, (N &amp;times; 6.25)ash and fat in relation to body weight were 0.971, 1.080, 1.096 and 1.284 for SG chickens and 0.977, 1.099, 0.993, and 1.198 for FG chickens. The respective allometric coefficients describing the relationships of water, fat and ash weight with protein weight were 0.894, 1.014, and 1.186 for SG chickens and 0.893, 0.910, and 1.097 for FG chickens. High allometric coefficients for ash in both genotypes likely indicate the rapid growth of skeletal tissues which requires adequate mineral nutrition during this period of growth. The deposition of ash relative to protein was significantly higher (P &amp;lt; 0.05) in SG chickens thus suggesting that the relative growth of ash may be affected by genotype. Allometric coefficients relating amino acids to body protein were less than unity in most cases which indicates that an increasing amount of non-protein N is deposited in the body with advancing age. Except for cysteine, the apparent efficiency of amino acid retention was lower in SG as compared to FG chickens. The high retention efficiency of cysteine in SG genotype was likely associated with the conversion of surplus methionine to cysteine, required for feather protein synthesis in laying-type birds at an early age.

Influence of oregano extract on the intestine, some plasma parameters and growth performance in chickens

The effect of oregano essential oil on growth performance, intestinal alkaline phosphatase (IAP) level, enterocyte proliferative ability, plasma proteins, and plasma minerals (calcium and magnesium) were studied in 1 day-old Ross 308 hybrid broiler chickens under commercial conditions during 42 experiment. Chickens fed oregano oil supplemented diet (0.707 g.kg-1) had significantly higher body weight gain (BWG) in the grower (19-29 d) and finisher (30-42 d) periods. Total plasma immunoglobulin levels were lower while mineral levels were higher during the finisher period. Significant decrease of IAP activity was demonstrated in animals fed oregano oil supplemented diet on 29, and 42 days of the experiment. Proliferative activity of enterocytes significantly increased in the finisher period along duodenal villi in animals treated with essential oil extracted from oregano. We suppose that higher body performance was probably the result of higher digestibility in the digestive tract. It is suggested that the antibacterial effect of carvacrol caused a lower number of intestinal bacteria, decrease of immunoglobulins and increase of investigated plasma proteins.

Intestinal mucin dynamic and leukocytic responses of chickens infected with Eimeria acervulina and fed oregano supplemented diet

We studied the effect of oregano supplemented diet on mucin dynamics in small intestine, peripheral blood leukocytes, and jejunal immunocompetent cells in ROSS 308 hybrid broilers infected withEimeria acervulinachickens’ oocyst. From the day of hatching chicks of groups 1 and 2 were fed a commercial diet without anticoccidial drug, the diet of group 3 was supplemented with oregano (0.707g·kg-1), and that of group 4 with anticoccidial drug (Robenidin hydrochloride – 33 mg·kg-1). Chickens of groups 2, 3, and 4 were inoculated withE. acervulinaoocysts (25.103) on day 12. The samples were collected on 3, 10, 17 days post infection (dpi). In blood on 3 dpi significant increase of leukocytes was found in group 3 compared to groups 1, 2, and 4, higher density of IgM+ cells in group 3 than group 2, and on 10 dpi phagocytic activity of group 3 was higher than group 1. Number of jejunal CD4+ and CD8+ cells in group 3 was consistent with values in group 4, despite higher density ofE. acervulinameronts on 10 dpi. The quantity of jejunal mucin adherent layer of group 3 was similar to that in group 4. Counts of oocysts in faeces were lower in group 3 than group 2. Results suggest that dietary supplementation of oregano to chickens infected withE. acervulinahas a modulating effect on some blood indicators and functions of phagocytes. The beneficial effect of oregano components on jejunal mucin quantity and its turnover is the first finding published in relation to oregano and coccidia.

The influence of dietary zinc content on mechanical properties of chicken tibiotarsal bone

The authors evaluated the effect of diets with different Zn levels on mechanical properties of bones in 60 Ross 308 hybrid broilers, from 2 to 35 days of age, which were randomly divided in 2 groups, with 30 chickens each. The first group (Zn50) was fed a commercial basal diet with no Zn additives (zinc content - 50 mg/kg feed). The second group (Zn100) was fed the basal diet + 50 mg of Zn/kg feed. In this group the dietary Zn level was increased by adding 62.23 mg of zinc oxide (ZnO)/kg feed to starter and grower feeds. In group Zn100 compared to Zn50 the values of blood zinc level were significantly higher on days 7 and 35 (p<0.01 and p<0.05). Significant differences in bone zinc content were not detected. On days 7, 21, and 35 the selected mechanical properties of the tibiotarsus were evaluated. The results obtained in the experiment showed differences in biomechanical competence of broiler bones from group Zn50 compared to Zn100. In broilers from group Zn100, there were significantly higher values in the limit of elasticity (Re), bending strength (Rm) and fracture stress (Rl) (p<0.05 to p<0.01) of chicken bones on day 35. The mean levels (117.80 ± 19.66, 126.70 ± 32.56, 114.10 ± 19.92, respectively) were determined in broiler bones from group Zn100 compared to Zn50 (95.27 ±18.71, 100.2 ± 20.56, 80.93 ± 35.22, respectively). In group Zn100 were observed significantly increased values of the bone crosssection area (Ar) on day 35 and moment of inertia (I) on days 21 and 35 (p<0.05). The clinical examination of the locomotory system showed bone deformities of the intertarsal joint in 10% of broilers from group Zn50. Present results suggest that the determination of the weight bearing of the tibial bone evaluated by assessing of mechanical properties of bones is an indicator of the locomotory system disorders and the Zn content in feed has a direct and statistically significant effect on bone strength in broiler chickens.

Morphodynamics of Embryonic Development of Skeletal Musculature of Broiler and Layer Chickens

Eggs of broiler (Ross 308) and layer (Hy-Line Brown) chicken hybrids were incubated and tissue samples from the leg muscle (m. biceps femoris) and breast muscle (m. pectoralis profundus) were taken on embryonic days 9, 12, 15, 18 and 20, as well as on the first day post hatching. Histological preparations were made from the samples and the diameter of muscle cells, the volume density of connective tissue of muscles, and the nucleocytoplasmic ratio of muscle cells were recorded. Comparison of the diameter of muscle cells of leg muscle and the breast muscle between broiler and layer chicken during the period of late incubation and day 1 post hatching showed the diameter of the examined muscle cells was greater in layers, while the nucleocytoplasmic ratio of muscle cells was higher in broilers. No differences were established between these two strains in the volume density of connective tissue in both muscles examined. Such results are explained by the prolonged proliferation of myoblasts and delayed differentiation of muscle cells in broilers, which leads to a greater development of the skeletal musculature during the postnatal period. These processes in the embryonic period of development are the cause of differences in the morphodynamics of embryonic development of the skeletal musculature between broilers and layers presented in this paper.

Effect of different salinity levels in drinking water on growth of broiler chickens

During breaks in supply of treated water, farmers turn to surface and underground sources, such as wells and boreholes. Though seemingly wholesome, such water usually contains dissolved salts of various kinds that may affect productivity in poultry and other farm livestock. Fifteen 2-week-old, imported broiler hybrid chicks were fed a common ration, but offered drinking water from one of three sources, for 21 days, to investigate any effects of water quality on productivity. Three treatments (water source), each with five replicates (individually penned birds) were tested, in a completely randomised designed experiment. The treatments were (i) water from the tap (TAP), (ii) water from a borehole (BH1), and (iii) water from a second borehole (BH2). Birds were raised in battery cages, given water and fed ad libitum and weighed weekly. Water samples from the three sources were analyzed weekly for quality (i.e. conductivity, salinity, dissolved oxygen, pH, and total dissolved solids). Mean water salinity level were 0.00, 0.07 and 3.80 per cent for TAP, BH1, and BH2, respectively. Water treatment had no significant effects (P>0.05) on feed intake (110.8, 95.3 and 106.1 g per bird per day), weight gain (45.0, 43.6 and 43.0 g per bird per day), feed conversion ratio (46.8, 50.0 and 47.2%), and final weight of birds after 21 days (1.33, 1.30 and 1.32 kg), for TAP, BH1, and BH2, respectively. However, water intake by birds was significantly (P

Effects of feeding diets contaminated with Fusarium mycotoxins on blood biochemical parameters of broiler chickens

This study was conducted to investigate the effects of deoxynivalenol (DON) and zearalenone (ZEA) on some biochemical indices of broiler chickens. Twenty-four Ross 308 hybrid broiler chickens of both sexes were fed diets containing maize contaminated with Fusarium mycotoxins. The diets included a control diet (DON 0.60 mg/kg feed; ZEA 0.07 mg/kg feed), an experimental 1 diet (DON 3.4 mg kg⁻¹ feed; ZEA 3.4 mg kg⁻¹ feed), and an experimental 2 diet (DON 8.2 mg kg⁻¹ feed; ZEA 8.3 mg kg⁻¹ feed). Contaminated diets were fed from 14 days of age for 14 days. Blood samples were collected from 4-week-old birds. Chicks fed a diet containing a low level of contaminated maize (experimental 1) had decreased plasma potassium, magnesium, phosphorus, total protein, albumin, triglycerides, free glycerol concentrations and increased cholesterol and calcium levels as well as alkaline phosphatase (ALP) and aspartate aminotransferase (AST) enzyme activities as compared to the control. Feeding a diet contaminated with high levels of mycotoxins (experimental 2) resulted in decreased plasma potassium, magnesium, total protein, albumin, triglycerides, free glycerol concentrations and increased plasma ALP, alanine aminotransferase (ALT) and AST enzyme activities. The effect of mycotoxin-contaminated diets on ALP activity was dose dependent. Chloride concentration was not affected by the diets. It can be concluded that feeding diets contaminated with both levels of Fusarium mycotoxins significantly affected protein, lipid and mineral metabolism as well as AST and ALP enzyme activities in broiler chickens.

The effect of breed and feed-type on the sensory profile of breast meat in male broilers reared in an organic free-range system

1. Studies on the sensory profiling of male broiler breast meat were carried out to evaluate the effect of two very different broiler breeds (JA757 and New Hampshire), two different feed types (broiler and grower feed) and age at slaughter (82 and 110 d). 2. The sensory profiling consisted of a pilot study, 4 training sessions, and finally the assessment. During the training session a panel of 9 assessors defined 17 attributes, which were used to describe the smell, texture and flavour of the breast fillets. Each attribute was evaluated on a 15-cm unstructured line scale. 3. The breast meat became significantly less hard, and more juicy and tender in the New Hampshire at 110 d of age, whereas the opposite was found in JA757, which also acquired a more “sourish” flavour with age. The smell of “sweet/maize” and “bouillon” became weaker with age in JA757, but not in New Hampshire. 4. Several significant differences in relation to the main factors of breed and age were found. The traditional broiler hybrid JA757 did best for most smell and flavour attributes, whereas New Hampshire did best for the texture attributes. Age had a negative effect on the flavours and smell attributes “fresh chicken”, “neck of pork” and “sweet maize”, but a positive effect on the texture attribute “crumbly”. In addition meat was more “stringy” at 110 d of age. 5. The flavours “neck of pork” and “umami” were significantly improved when JA757 was fed on the broiler feed and when New Hampshire was given the grower feed. The meat smelt more “sourish” at 82 d of age and less “sourish” at 110 d of age when the grower feed was consumed. Meat was significantly harder and stringier when JA757 was fed on the grower feed. This was not the case for New Hampshire. In general, the meat was significantly less crumbly and stringier with the grower feed. 6. Overall a very distinct difference in sensory profile was found between the two breeds. In addition different slaughter ages and feeding strategies should be taken into consideration in a niche production based on alternative genotypes.

Effects of genotype and population density on growth performance, carcass characteristics, and cost-benefits of broiler chickens in north central Nigeria

The influence of genotype and stocking densities on growth performance, carcass qualities, and cost-benefits of broilers were examined in a 28-day trial. Two hundred and seven 4-week-old birds each of Anak Titan and Arbor Acre hybrid broiler types were randomly assigned to three stocking density treatments of 8.3, 11.1, and 14.3 birds/m(2) in a 2 x 3 factorial arrangement. Final body weight, average weekly body weight and average weekly feed intake were affected (P < 0.05) by strain, with higher means recorded for Arbor Acres. However, average weekly body weight gain and feed conversion ratio were similar (P > 0.05) in both genetic groups. The effect of placement density on some growth parameters did not follow a linear trend. Arbor Acres had significantly (P < 0.05) higher relative (%) fasted body, carcass, back, neck, and wing weights compared to Anak Titans. Housing density effect (P < 0.05) was observed for relative (%) fasted body, shank, and wing weights of birds. However, the relative weights of visceral organs of birds were not significantly (P > 0.05) influenced by genotype and housing density. The economic analysis revealed that higher gross margin was recorded for Arbor Acres compared to Anak Titans (euro 2.76 versus euro 2.19; P < 0.05, respectively). Conversely, stocking rate did not exert any influence (P > 0.05) on profit margin. Genotype x stocking density interaction effect was significant for some of the carcass indices investigated. It is concluded that under sub-humid conditions of a tropical environment, the use of Arbor Acre genetic type as well as a placement density of 14.3 birds/m(2) appeared to be more profitable.

Effect of oleic and conjugated linoleic acid in the diet of broiler chickens on the live growth performances, carcass traits and meat fatty acid profile

Olive oil and CLA enriched olive oil were compared with each other in a growth trial with broiler chickens, as energy supplements to the diet. A commercial CLA blend was used at the level of 1 kg per 100 kg mixed integrated feed.Two hundred and forty commercial hybrid broilers (Ross 308) were randomly subdivided and allotted to 8 pens of 30 birds each. Four pens of birds were fed the olive oil diet and considered the control group; the other 4 pens were fed the olive oil supplemented with CLA and considered the treated group. The experiment lasted 47 days.The live performance of the treated birds resulted different from the performance of the control ones: the final body weight was slightly lighter (2.544 kg vs 2.639 kg; P≤0.05) with a lower feed intake (4.886 kg feed vs 4.998 kg, P≤0.05) and, of course, an almost perfectly overlapping feed/gain ratio (1.90 vs 1.91).The fatty acid composition of the breast fat of the CLA treated birds resulted enriched by the two major CLA isomers, trans 10 cis 12 and cis 9 trans 11, whereas oleic acid and the linoleic, linolenic and arachidonic polyunsaturated acids showed a decrease (P≤0.05).CLA appears a recommendable ingredient in the diets of broilers as it improves the beneficial characteristics of poultry meat.

Quality Indicators of Chicken Broiler Raw and Cooked Meat Depending on Their Sex

The objective of this study was to compare the quality indicators of chicken breast meat depending on sex, to evaluate individual quality indicators and to find relationships between them. Three groups (A, B and C) of commercial meat-type hybrid broilers ROSS 308 (10 males and 10 females from each group) were used for colour measurement (CIE L*a*b*), pH, chemical analysis (amount of dry matter, fat and collagen) and texture (shear force, hardness, cohesiveness). Cooked meat indicators (texture, colour, pH and chemical indicators) were measured after heat treatment (80 °C, 30 min). In all groups we were able to prove raw meat differences between sexes only in the following indicators: carcass weight (A group P &lt; 0.01, B and C group P &lt; 0.001), breast weight (A group P &lt; 0.01, B and C group P &lt; 0.001) and pH value (A group P &lt; 0.05, B group P &lt; 0.001, C group P &lt; 0.01). Differences were found (P &lt; 0.05) between sexes in texture indicators (hardness or cohesiveness), breast meat of males was more tender. The cooked breast meat was significantly (P &lt; 0.05) lighter, redder and more yellow than the raw meat. Raw meat pH had a significant negative correlation (r = -0.41, P &lt; 0.001) with raw meat lightness. Cooked meat pH had a significant correlation with cooked colour indicators. The amount of collagen had significant correlations with shear force (P &lt; 0.001), hardness (P &lt; 0.001) and cooking loss (P &lt; 0.01).

Effect of Cinnamomum zeylanicum Essential Oil on Antioxidative Status in Broiler Chickens

The experiment was conducted to investigate the effects of Cinnamomum zeylanicum essential oil on antioxidant status of chickens. Thirty-two female Ross 308 hybrid broilers were fed one of four diets supplemented with 0%, 0.1%, 0.05% and 0.025% of essential oil for 38 days. Blood, liver, kidney and duodenal epithelium were collected for the subsequent evaluation of antioxidant status. Feeding of adiet supplemented with 0.1% of essential oil significantly decreased the concentration of malondialdehyde (MDA) in plasma and duodenal mucosa in comparison with the control group (0%). The activities of glutathione peroxidase (GPx) were significantly higher in blood of chicks fed the diet containing 0.1% of essential oil. Diets containing 0.05% and 0.025% of essential oil reduced alanine amino transferase (ALT) activity in plasma in comparison with the control group. Blood phagocytic activity significantly increased in chickens fed the diet supplemented with 0.1% and the index of phygocytic activity was affected by the diet containing 0.025% of essential oil in comparison with the control group. The present investigation shows that Cinnamomum zeylanicum essential oil exhibits a significant antioxidant activity in fattening chickens and can be used as a source of antioxidant in dietary supplement.

Amino Acid Profile of Protein from Pelvic Limb Long Bones of Broiler Chickens

The objective of the study was to determine the amino acid profile in protein from long bones of the pelvic limb (femur, tibiotarsus) in ROSS 308 hybrid broiler chickens, and to examine whether it is sex-dependent.The study material was obtained from 120 Ross 308 broiler chickens (60 males and 60 females) at the end of the fattening (40 days of age). The average weight of birds was 2 694 ± 32.6 g for cockerels and 2 345 ± 23.9 g for pullets. The study birds did not show any clinical signs of leg diseases. The long bones of the right pelvic limbs (femur and tibiotarsus) were collected after bird slaughter and after removal of soft tissues, they were used for laboratory analyses. The crude protein content and the amino acid (AA) composition were determined and the obtained values were recalculated to 100% dry matter. The chemical score (CS) and the essential amino acid index (EAAI) were calculated for each AA. As a standard, the hen egg ovalbumin was used. The crude protein content in 100% dry matter shows that the content of crude protein was significantly higher (P ⪬ 0.01) in the femur (405.3 ± 17.21 g/kg) compared to the tibiotarsus (393.5 ± 12.68 g/kg). The same trends were found with regard to sex. Both males and females had significantly (P ⪬ 0.01) higher crude protein content in the femur (406.6 ± 19.34 g/kg and 404.1 ± 15.09 g/kg, respectively) than in the tibiotarsus (395.0 ± 12.16 g/kg and 392.1 ± 13.21 g/kg, respectively). Both bones showed the highest contents of Gly, Glu and Pro, and the lowest contents of Met, Tyr and His. The same trends were found with regard to chicken sex. Collagenous protein has lower contents of most AA in comparison to the standard protein - ovalbumin; especially contents of Ser, Val, Met, Ileu and Phe are substantially lower. On the other hand, collagenous protein had higher contents of Gly, Pro, His and Arg. The collagenous protein EAAI for the femur and the tibiotarsus was 59.0% and 57.4%, respectively. The knowledge of amino acid composition in protein from long bones of the pelvic limb in broiler chickens is important because it can help us understand the origin of bone disorders.

The influence of baical skullcap root (Scutellaria baicalensis radix) in the diet of broiler chickens on the chemical composition of the muscles, selected performance traits of the animals and the sensory characteristics of the meat

The aim of this study was to evaluate the effect of the baical skullcap root (&lt;I&gt;Scutellaria baicalensis radix&lt;/I&gt;) on the performance, chemical composition of the muscles and sensory characteristics of the meat of broiler chickens. 120 one-day old Hubbard Hi-Y broiler hybrids were assigned to four groups of 30 each and fed either a basal diet (control) or a basal diet supplemented with 0.5%, 1.0% or 1.5% ground root of skullcap. The body weight, weight gain, feed consumption and feed : gain ratio were calculated after 42 days. The addition of the ground baical skullcap root to the fodder had no effect on the quality or chemical composition of the breast and leg muscles of the broiler chickens. However, it positively influenced some of the performance characteristics of the chickens.

Effects of deoxynivalenol and zearalenone on oxidative stress and blood phagocytic activity in broilers

Effects of dietary contamination with various levels of deoxynivalenol (DON) and zearalenone (ZEA) were investigated on Ross 308 hybrid broilers of both sexes. After hatching, all chickens were fed an identical control diet for two weeks. Then chickens of Group 1 received a diet contaminated with DON and ZEA, both being 3.4 mg · kg−1, while Group 2 received DON and ZEA at 8.2 and 8.3 mg · kg−1, respectively. The diet of the control group contained background levels of mycotoxins. Samples of blood and tissues were collected after two weeks. Intake of both contaminated diets resulted in a significantly decreased activity of glutathione peroxidase (GPx) and increased level of malondialdehyde (MDA) in liver tissue, while in kidneys the concentration of MDA was significantly increased only in Group 1. On the other hand, activities of blood GPx and plasma γ-glutamyltransferase (GGT) were elevated in Group 2 only. Activities of thioredoxin reductase in liver and GPx in duodenal mucosa tissues, superoxide dismutase (SOD) in erythrocytes as well as levels of MDA in duodenal mucosa and α-tocopherol in plasma were not affected by dietary mycotoxins. Blood phagocytic activity was significantly depressed in Group 1 and 2. These results demonstrate that diets contaminated with DON and ZEA at medium levels are already able to induce oxidative stress and compromise the blood phagocytic activity in fattening chickens.

Effect of diazepam on some physiological and productive traits of Cobb hybrid broiler chickens

Effect of diazepam on some physiological and productive traits of Cobb hybrid broiler chickens

Effects of different salinity levels in drinking water on growth of broiler chickens

During breaks in supply of treated water, farmers turn to surface and underground sources such as wells and boreholes. Though seemingly wholesome, such water usually contains dissolved salts of various kinds that may affect productivity in poultry and other farm livestock. Fifteen 2-week-old, imported broiler hybrid chicks were fed a common ration, but offered drinking water from one of three sources for 21 days to investigate any effects of water quality on productivity. Three treatments (water source), each with five replicates (individually penned birds), were tested in a completely randomised designed experiment. The treatments were (i) water from the tap (TAP), (ii) water from first borehole (B1), and (iii) water from second borehole (B2). The birds were raised in battery cages, offered water and feed ad libitum, and weighed weekly. Water samples from the three sources were analyzed weekly for quality (i.e., conductivity, salinity, dissolved oxygen, pH, and total dissolved solids). Mean water salinity levels were 0.00, 0.70 and 3.80 per cent for TAP, B1 and B2, respectively. Water treatment had no significant effects (P>0.05) on feed intake (110.8, 95.3 and 106.1 g bird-1 day-1), weight gain (45.0, 43.6 and 43.0 g bird-1 day-1), feed conversion ratio (46.8, 50.0 and 47.2%), and final weight of birds after 21 days (1.33, 1.30 and 1.32 kg) for TAP, B1 and B2, respectively. Water intake by birds was, however, significantly (P

Effect of age upon retention of mercury in chickens with a different growth rate

Retention of total mercury was examined in groups of 95 slowly-growing laying type chickens and 52 fast-growing broiler hybrids in 47 subsequent balance periods from 1 to 100 days of age. Chickens were fed &lt;I&gt;ad libitum&lt;/I&gt; on a diet containing 5.41 µg of Hg per kilogram. Until Day 4 the values of coefficients of apparent retention of Hg were negative or very low. They were influenced by excretion of endogenous nutrients originating primarily from the yolk sac. When evaluating the period of 4 to 100 days of age, the dependence of Hg retention coefficients upon age was highly significant (&lt;I&gt;P&lt;/I&gt; &lt; 0.01). The course of this dependence was expressed by parabolas for laying type chickens with the maximum value at Day 61 of age and for broilers with the minimum value at Day 53. In fast growing chickens, Hg content in body gain decreased until Day 14 and then increased while in slow growing chickens it was linearly increasing for the whole experimental period. The average coefficients of Hg retention from the feed mixture were 48.18 ± 0.719 (mean ± SEM) and 47.90 ± 1.057% and Hg retained per g of live body gain were 7.494 ± 0.4682 and 6.775 ± 0.6233 ng in laying and meat type cockerels, respectively. The difference between hybrids was insignificant (&lt;I&gt;P&lt;/I&gt; &gt; 0.05). The growth rate of total amount of Hg in the body was lower (&lt;I&gt;P&lt;/I&gt; &lt; 0.01) than that of body weight of chickens, allometric coefficients were 0.706 and 0.747 for slow and fast growing chickens, respectively.

COMPARISON THE PRODUCTIVE PERFORMANCE OF TOW BROILER HYPRIDS

This study was conducted in the Agricultural Research Center of American University of Beirut from 11/3 to 21/4/2005 to evaluated the performance of two commercial broiler hybrids ( Cobb 500 and Hubbard Classic )for investigating the more respond one of these hybrids to breeding within environment conditions under control .400 of one- day- aged unsexed birds were used ( 200 for each hybrid ). The results of the statistical analysis of data collected during the experiment period from 1_21 and 22_42 days-old showed that the performance of the Cobb 500 hybrid was significantly ( P ≤ 0.05 ) superior to that of Hubbard Classic . The live body weight for Cobb 500 was heavier in that , the mean reached ( 690.5 and 2210 g ) at 21 and 42 day age respectively , while Hubbard weights ( 618.75 and 2095.75 g ) at both ages respectively. The type of hybrid as well had significant effect ( P ≤ 0.05 ) on the feed conversion where the birds of hybrid Cobb 500 were superior in this trait than those of Hubbard Classic , the feed conversion coefficient of two types of hybrids were (1.495 and 1.548 g feed intake / g weight gain ) during the starter period and ( 2. 067 and 2.120 g feed intake/ g weight gain ) during the growth period for both hybrid respectively.The mortality percentage was significantly low in Cobb 500 hybrid than Hubbard Classic during the total breeding period where was (2.89 and 14.88 % ) for both hybrids respectively .The results of yield factor of the total breeding period showed that significant differences to hybrid Cobb 500 vs Hubbard Classic revealed and were (269.8 and 214.42 ) for both respectively . According we can conclude that the hybrid Cobb 500 was superior in all essential production indicatory than Hubbard Classic .