SEARCH · PubMed Health

Results for “Broilers”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources

PubMed2000

Effect of clinoptilolite on performance of broiler chickens during experimental aflatoxicosis.

1. The amelioration of aflatoxicosis in broiler chickens was examined by feeding 2 concentrations of natural zeolite (clinoptilolite). Clinoptilolite (CLI), incorporated into the diet at 15 and 25 g/kg, was evaluated for its ability to reduce the deleterious effects of 2.5 mg total aflatoxin (AF; 76.40% AFB1, 16.12% AFB2, 6.01% AFG1 and 1.47% AFG in diet on growing broiler chicks from 1 to 21 d of age. A total of 360 broiler chicks were divided into 6 treatment groups (6 replicates of 10 broilers each): control, AF, CLI (15 g/kg), AF plus CLI (15 g/kg), CLI (25 g/kg), and AF plus CLI (25 g/kg). 2. Compared to controls, the treatment had significantly decreased body weight gain from week 1 onwards. The adverse effect of AF on food consumption (8.0%) and food conversion ratio (8.3%) was also shown over the entire 21-d feeding period. 3. The addition of CLI (15 g/kg) to an AF-containing diet significantly reduced the deleterious effects of AF on food consumption and body weight gain. Food conversion ratio was also slightly improved by adding CLI (15 g/kg) to AF-containing diets. Food consumption, body weight gain and food conversion ratio values were rendered numerically intermediate between AF and control groups by the addition of CLI (25 g/kg) to the AF-containing diet. 4. The addition of CLI (both 15 and 25 g/kg) to the AF-free diet did not produce any significant changes compared with the controls, except for decreased total food consumption in the CLI (25 g/kg)-alone group. 5. These results suggest that CLI (15 g/kg) addition effectively diminished the detrimental effects of AF on the values investigated. Also, the lower dietary concentration of CLI (15 g/kg) was more effective than the greater concentration against the adverse effects of AF on the variables investigated in this study.

Aflatoxins↗

PubMed2001

The effect of supplementary dietary L-carnitine on the growth performance, serum components, carcase traits and enzyme activities in relation to fatty acid beta-oxidation of broiler chickens.

1. This study investigated the effects of supplementary dietary L-carnitine on the performance, serum components, carcase traits and specific activities of hepatic enzymes related to beta-oxidation of fatty acids in broiler chickens. One hundred and eighty 1-d-old broilers were divided into 2 groups, each with 3 replicates, and given diets supplemented with 0 and 160 mg L-carnitine/kg for 6 weeks. 2. Experimental results indicated that supplementary carnitine did not significantly influence the performance and carcase characteristics of the broilers. 3. The serum triacylglycerol (TG) and nonesterified fatty acid (NEFA) concentrations in the carnitine supplemented group were significantly lower than that in the control group (P < 0.05). However, the effect on serum cholesterol, phospholipids concentrations and lipoprotein profiles were not significant (P > 0.05). 4. Carnitine palmitoyl transferase activity in the carnitine-supplemented group was significantly (P < 0.05) higher than in the control; however, carnitine supplementation did not significantly affect the activities of other fatty acid beta-oxidation enzymes. 5. The results in this study demonstrated that supplementary carnitine facilitated fatty acid transportation and did not influence the performance or carcase characteristics of broilers.

Animal Feed↗

PubMed2000

Quinolone resistance among Salmonella enterica from cattle, broilers, and swine in Denmark.

This study was conducted to determine the susceptibility to nalidixic acid and fluoroquinolones of Salmonella Dublin, S. Enteritidis, and S. Typhimurium isolates from cattle, broilers, and pigs over time in Denmark and to characterise the gyrA, gyrB, and parC genes in quinolone-resistant isolates. A total of 584 S. Typhimiurium and 573 S. Dublin isolates from cattle during 1984 through 1999, and 241 S. Enteritidis and 131 S. Typhimurium from broilers and 452 S. Typhimurium from pigs isolated during 1997-1999 were tested. All isolates from cattle from the period 1984 through 1992 were susceptible to quinolones. A single (1.1%) S. Typhimurium isolate from 1995 and three (5.9%) from 1998 were resistant to nalidixic acid. Six (9.0%) S. Dublin isolates from 1996, four (4.2%) from 1997, and one (1.7%) from 1998 were resistant to nalidixic acid. Resistance was not observed among isolates from cattle in 1999. All broiler isolates from 1997 except for one were susceptible to nalidixic acid, whereas seven (6.2%) S. Enteritidis and two (6.3%) of the S. Typhimurium isolates from 1998 and 9 S. Enteritidis (26.5%) from 1999 were resistant. Among isolates from pigs, four isolates from 1997, three from 1998, and one from 1999 were resistant to nalidixic acid. All the nalidixic acid-resistant isolates had reduced susceptibility to fluoroquinolones. Sequence analysis of the gyrA gene in 37 nalidixic-resistant isolates identified two different base substitutions at codon serine-83 and two at aspartate-87. The base substitutions in serine-83 were TCC (Ser)-->TAC (Tyr), and TCC (Ser)-->TTC (Phe). The base substitutions in aspartic-87 were GAC (Asp)-->AAC (Asn), and GAC (Asp)-->GGC (Gly). Sequence analysis of the gyrB and parC genes revealed no mutations in 27 selected isolates. This study showed that quinolone-resistant isolates have emerged in recent years among food-producing animals, especially among S. Enteritidis from broilers in Denmark, and that the resistance mainly is associated with mutations in gyrA.

4-Quinolones↗

PubMed2004

Antimicrobial resistance in Campylobacter strains isolated from French broilers before and after antimicrobial growth promoter bans.

OBJECTIVES: The antimicrobial susceptibility of Campylobacter strains isolated from standard and free-range broilers in 1992-1996 and 2001-2002 was studied. METHODS: Strains were isolated from caeca or skin samples collected from standard or free-range broilers arriving in slaughterhouses. The MICs of ampicillin, nalidixic acid, enrofloxacin, tetracycline, erythromycin and gentamicin were determined by agar dilution and compared according to species (Campylobacter jejuni or Campylobacter coli), production system and sampling period. RESULTS: Results showed that all chickens harboured Campylobacter. An increase over time of the C. coli/C. jejuni ratio for standard chickens occurred. A wide range of MICs was observed among isolates from the same broiler or from the same farm. Strains collected on entry to the slaughterhouse and after storage showed no significant difference in their antibiotic resistance. C. coli was more resistant than C. jejuni to tetracycline and erythromycin during the first period and to all tested molecules (except gentamicin) during the second period. Strains isolated from standard chickens were also more often resistant than those isolated from free-range broilers. The percentage of C. jejuni strains resistant to ampicillin decreased from 1992-1996 to 2001-2002, whereas no change could be observed for the other antimicrobial agents. However, for C. coli the resistance to ampicillin, nalidixic acid, enrofloxacin, tetracycline and erythromycin significantly increased. CONCLUSION: There was an increase in the incidence of antibiotic resistance of C. coli between 1992-1996 and 2001-2002.

Animal Feed↗

PubMed1995

The differences in intestinal viscosity produced by barley and beta-glucanase alter digesta enzyme activities and ileal nutrient digestibilities more in broiler chicks than in cocks.

The objectives of this study were to determine whether intestinal viscosity caused by mixed linked barley beta-glucan depresses ileal nutrient digestibility and digestive enzyme activities and to determine the interaction of intestinal viscosity, digestive enzyme activities and ileal nutrient digestibility in different ages of poultry. In Experiments 1 and 2, 1-d-old broiler chicks and 1-y-old cocks, respectively, were fed diets with 60% corn, low and high viscosity barley with or without beta-glucanase, for 3 wk. A 3 x 2 factorial design was used. Comparisons were made only within the same age group. In Experiment 3, 1-d-old broiler chicks were fed high viscosity barley with and without beta-glucanase to measure fecal nutrient and ileal and fecal amino acid digestibility. Broiler chicks fed barley ate less and gained less weight than those fed corn; added beta-glucanase resulted in increases in both food consumption and weight gain for the barley-fed chicks (P < 0.05). Relative pancreas weight was higher (P < 0.05) in chicks fed barley than in those fed corn, and lower with beta-glucanase (P < 0.05). Digesta from barley-fed birds had the highest viscosities, which were decreased (P < 0.05) by beta-glucanase. Amylase and lipase were lower in broiler chicks fed high viscosity barley compared with corn (P < 0.05), and beta-glucanase increased both activities and that of trypsin as well (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1999

All-rac-alpha-tocopherol acetate is a better vitamin E source than all-rac-alpha-tocopherol succinate for broilers.

The difference in bioavailabilities of the acetate and succinate esters of all-rac-alpha-tocopherol was investigated in a feeding experiment with broilers. The experiment was initiated with 96 12-d-old male Cobb broilers and lasted for 4 wk. The two sources of vitamin E were fed to eight groups of broilers at four different dietary levels (50, 100, 150 and 200 mg/kg feed, including the naturally occurring alpha-tocopherol). A total collection of droppings for determination of apparent tocopherol absorption were performed at two separate time periods (d 28-34 and d 35-41). There were no differences among the eight experimental groups with respect to animal performance or feed intake. At all dietary levels, the apparent absorption coefficient for all-rac-alpha-tocopherol succinate was significantly lower than that of the acetate ester. The mean (+/- SD) apparent absorption coefficient for all-rac-alpha-tocopherol succinate was 58.0 +/- 5.4 compared with 70. 8 +/- 5.6 for all-rac-alpha-tocopherol acetate. Furthermore, the apparent absorption coefficients for both esters was significantly lower in the first collection period (d 28-34) than in the second collection period (d 35-41). This difference in the apparent absorption coefficient between the succinate and the acetate ester was accompanied by significant differences in alpha-tocopherol concentrations in plasma, breast muscle, liver and adipose tissue of the broilers, which were lower in those fed the succinate ester. Based on a comparison of plasma and tissue responses, the succinate ester was utilized only 69-76% as efficiently as the acetate ester. In vitro studies showed a significantly higher capacity of pancreatic carboxyl ester hydrolase to hydrolyze alpha-tocopherol acetate compared to alpha-tocopherol succinate. This difference in intestinal hydrolysis of the two vitamin E sources may explain the observed differences in biopotency.

Animal Feed↗

PubMed1997

Effects of beta-carotene and canthaxanthin on aflatoxicosis in broilers.

In 2 x 3 factorial experiments, 240 broiler chicks were fed diets containing 0, 0.01, and 0.02% beta-carotene or canthaxanthin with or without 5 ppm aflatoxin to determine the effects of these two carotenoids on the health and well-being of broilers subjected to aflatoxin poisoning. Neither beta-carotene nor canthaxanthin was effective at overcoming the growth-depressing effects of aflatoxin. Relative liver weights were significantly higher in broilers receiving dietary aflatoxin in the presence of beta-carotene but not canthaxanthin. beta-Carotene and canthaxanthin had no effect on antibody production against infectious bursal disease (IBD). Interestingly, secondary antibody production against IBD was enhanced by the presence of aflatoxin in the diet. Canthaxanthin significantly increased the concentrations of cholesterol, total protein, uric acid, and triglyceride, all of which were significantly depressed by aflatoxin. beta-Carotene did not effect any of the measured blood analytes. There was a significant interaction between canthaxanthin and aflatoxin with respect to creatine kinase activity. Creatine kinase activity decreased as dietary canthaxanthin increased in the presence of aflatoxin. The data suggest that beta-carotene is not effective at ameliorating aflatoxicosis in broiler chickens but that canthaxanthin may be somewhat effective with respect to certain clinical blood chemistry indicators.

Aflatoxins↗

PubMed1997

The use of competitive exclusion in broilers to reduce the level of Salmonella contamination on the farm and at the processing plant.

The effect of a competitive exclusion (CE) product, Broilact, on Salmonella contamination of broiler chickens was studied on the farm and at the processing plant. In the first part of the study, two flocks per week, a CE-treated and an untreated control flock, were placed in similar broiler houses. The CE treatment was administered in the hatchery using a modified spray vaccination cabinet. Salmonella was analyzed from the paper pads of the transport boxes on arrival at the farm and from fecal samples taken 2 wk before slaughter. The results of Salmonella sampling were received for 67 flocks. The other 141 flocks of the company that were reared during the trial period were also sampled for Salmonella and the results were compared to those of treatment and control groups. Broiler performance, including mortality, weight, and feed conversion, was recorded for the trial flocks. In the second part of the study, Salmonella contamination of neck skin samples taken at the processing plant from 18 CE-treated and 28 control flocks was compared. The Broilact-treatment significantly reduced Salmonella contamination both on the farm and at the processing plant. At the level of the farm, the percentage of Salmonella-positive flocks was essentially the same in the control flocks and in other flocks reared during the trial period. An improvement in broiler performance was indicated, although the difference was not significant.

Animal Husbandry↗

PubMed1997

Feather retention force in broilers ante-, peri-, and post-mortem as influenced by carcass orientation, angle of extraction, and slaughter method.

Stunning and slaughter trials were conducted to evaluate the influence of carcass orientation (inverted or supine), angle of feather extraction (parallel or perpendicular to the carcass surface), and slaughter method (exsanguination without or with spinal cord transection) on feather retention force (FRF) in commercial broilers sampled ante-, peri-, and post-mortem. The pectoral, sternal, and femoral feather tracts were sampled before and after stunning contralaterally, with a maximum indicating force gauge, from broilers suspended on a shackle (inverted) or laying on a table (supine). For all trials and sample periods FRF was consistently greater in the femoral area (547 to 679 g) than in the pectoral area (273 to 391 g), with the sternal feather tract requiring the least force at 246 to 343 g. Feathers extracted parallel to the carcass resulted in consistently greater FRF (9 to 29%) than feathers extracted at a perpendicular angle, at all sample periods. Broilers suspended on shackles ante- and peri-mortem had higher FRF values (5 to 30%) than those restrained in shackles in a supine position on a table. Other parameters resulted in minor and inconsistent alterations in FRF. Electrical stunning, when not followed by bleeding, resulted in small reductions in FRF (up to 7%). Bleeding after stunning without or with spinal cord transection resulted in variable peri-mortem FRF changes (+7 to -11% and +11 to -11%, respectively). Only in the pectoral feather tract was there a significant increase (5 to 6%) in FRF as broilers went from the ante- to peri-mortem state. At 2 and 6 min after stunning and initiation of exsanguination, post-mortem FRF was unaffected by carcass orientation for the pectoral and femoral tracts.

Abattoirs↗

PubMed1997

The effect of using different levels of shrimp meal in broiler diets.

The objective of this study was to measure the effect of substituting different levels of shrimp meal (SM) for soybean meal (SBM) in broiler diets. In Experiment 1, 0, 10, 20, 30, and 40% of the crude protein contributed by the SBM in broiler diets was substituted by crude protein from SM. In Experiment 2, 0, 60, 80, and 100% of the crude protein contributed by SBM in broiler diets was replaced by crude protein from SM. Body weight, cumulative feed consumption, and feed conversion (feed:gain) were determined on a weekly basis for 49 d in Experiment 1 and 42 d in Experiment 2. Mortality was reported daily. Carcass weight and percentage yield were determined on a prechilled basis. In Experiment 1, no significant differences were found for body weight, feed consumption, feed conversion, mortality, carcass weight, or yield. In the second experiment, body weight was found to be significantly higher (P < 0.01) at 21, 28, 35, and 42 d of age in treatments in which SM was introduced at a 100% substitution for SBM. Growth responses to SM were also seen at lower levels of substitution at 21, 28, and 35 d. No significant differences were observed for feed consumption, feed conversion, mortality, or carcass yield for any of the treatments. Carcass weight increased significantly by 12.1% when SM was substituted 100% for SBM. Results of the present study show that the particular SM used in this study could partially or totally replace SBM in broiler diets without negatively affecting performance or carcass quality.

Analysis of Variance↗

PubMed1997

The bioefficacy of zinc bacitracin in practical diets for broilers and laying hens.

Two balance trials were conducted to examine the response in metabolizable energy and metabolizability of both fat and amino acids to graded levels of zinc bacitracin (ZnB; Albac registered trade name of Alpharma, Oslo, Norway) in practical broiler and layer diets varying in their nutrient density. Broiler diets were supplemented with either 0, 20, or 50 mg ZnB/kg and layer diets were supplemented with either 0, 50, or 100 mg ZnB/kg. Each experimental diet was fed to five replicates of four broiler chicks each or nine replicates of individually housed laying hens, respectively. All balance parameters were significantly influenced by nutrient density, age, and dietary ZnB level. No significant interactions between ZnB by nutrient density were found. Addition of ZnB resulted in a lower excreta:feed ratio and an improved N retention; there was a nearly linear relationship between these effects and dietary ZnB levels. Moreover, dietary MEn content was linearly enhanced by ZnB supplementation. As a consequence, the bioefficacy of ZnB can be expressed in terms of MEn units: the average MEn equivalency of ZnB was 2,080 and 1,184 Mcal/kg, for broiler chicks and laying hens, respectively.

Amino Acids↗

PubMed1997

Comparative evaluation of three commercial broiler stocks in hot versus temperate climates.

Hot climate is a major limiting factor of broiler production in tropical and subtropical regions. The use of standard stocks in hot climates may result in large economic losses because genotypes selected in temperate climates may respond differently to the high ambient temperatures in hot regions or seasons. The summer and fall in Izmir, Turkey, provided the natural hot and temperate climates, respectively, for this study. Broiler chicks were obtained from three commercial stocks, all bred in temperate climates. Male and female chicks, 60 per pen, were housed in four pens per stock per season. Individual BW was determined at hatch, and at 4 and 7 wk of age. Feed consumption and efficiency were determined per pen. Feathering was scored at 4, 5, and 6 wk of age. Body temperature was measured twice on three birds per sex per pen, 16 h and immediately before slaughter, and feather weight was determined for each of these birds. The two seasons clearly differed in ambient temperature at the broiler house, and consequently, BW at 7 wk was significantly lower in the summer than in the fall in all stocks, with an average reduction of 23%. The season effect was largest (33.5%) on BW gain from 4 to 7 wk, along with 23 and 15% reductions in feed consumption and efficiency, respectively, during these 3 wk. A significant season by stock interaction was detected for BW gain from 0 to 4 wk and 4 to 7 wk. The three stocks exhibited similar 4- to 7-wk BW gains under the temperate fall climatic conditions, but differed significantly in the summer. These differences were not related to normal differences in feather coverage or body temperature, suggesting that standard broiler stocks must be tested in hot climates in order to find the one most suited to these conditions.

Analysis of Variance↗

PubMed1998

Evaluation of minimally invasive indices for predicting ascites susceptibility in three successive hatches of broilers exposed to cool temperatures.

Broilers from three consecutive hatches were exposed to cool temperatures to amplify the incidence of pulmonary hypertension syndrome (PHS, ascites). The largest apparently healthy individuals on Day 42 were evaluated using minimally invasive diagnostic indices [percentage saturation of hemoglobin with oxygen, hematocrit (HCT), heart rate, electrocardiogram (ECG) Lead II, body weight), then they were subjected to the ongoing pressures of fast growth and cool temperatures to determine which of these indices are predictive of the subsequent onset of PHS. Approximately 20% of the males and females evaluated on Day 42 subsequently developed PHS by Day 51. When data for all hatches were pooled and broilers that subsequently developed ascites were compared with those that did not (nonascitic), body weights, heart rates, and percentage saturation of hemoglobin with oxygen were lower on Day 42 for ascitic than for nonascitic males, and HCT was higher in ascitic males and females than in nonascitic males and females, respectively. Comparisons of the ECG Lead II wave amplitudes for all hatches pooled indicated that RS-wave amplitude was larger in ascitic than in nonascitic males, and that S-wave amplitude was more negative in ascitic males and females than in nonascitic males and females. Necropsies conducted on Day 51 revealed higher right:total ventricular weight ratios in ascitic than in nonascitic broilers, whereas normalizing the left ventricle plus septum weight for differences in body weight generated similar values for ascitic and nonascitic males and females, respectively. These results support a primary role for pulmonary hypertension but not cardiomyopathy in the pathogenesis of ascites triggered by cool temperatures. Values obtained for minimally invasive diagnostic indices on Day 42 also establish predictive thresholds that can be used to evaluate the PHS susceptibility of large and apparently healthy male and female broilers.

Animals↗

PubMed1998

Metabolic disturbances in male broilers of different strains. 1. Performance, mortality, and right ventricular hypertrophy.

Two trials were carried out to test the susceptibility for metabolic disturbances of different strains of male broilers. In Trial 1, 1,890 male chickens were allotted in a randomized block design with seven treatments (Arbor Acres, Avian Farms, Cobb-500, Hubbard-Peterson, ISA, Naked Neck, and Ross) and six blocks of 45 chickens. Trial 2 involved 2,184 male chickens of six strains (Arbor Acres, Avian Farms, Cobb 500, Hubbard-Peterson, ISA Naked Neck, and Ross) allotted in seven complete blocks of 52 birds. The same management system was adopted for all birds, reared up to 42 d in an open house during late winter (Trial 1) or late autumn (Trial 2). The most marked differences observed among the strains tested was the lower BW and higher feed conversion of Naked Neck broilers. Total percentage mortalities were high among the most productive broilers, being more than 50% due to sudden death (SDS) and ascites syndrome (AS). No Naked Neck birds died as a consequence of these disturbances and the total mortalities were significantly lower (P < or = 0.05) than the other strains. The ratio of right ventricle weight to total ventricle weight of the dead birds was over 0.25, except for Naked Neck birds, which presented a nonhypertrophic ratio. The two trials confirmed the relationship between high productivity and high incidence of SDS and AS and indicated that Naked Neck male broilers are resistant to these metabolic disturbances.

Animal Feed↗

PubMed1998

Further studies on the influence of genotype and dietary protein on the performance of broilers.

An experiment was conducted to quantify genetic differences in response to dietary protein level of male vs female broilers. Broilers (1 d old) from a "high-yield" strain cross (Ross x Ross 208) and a "fast-growing" strain cross (Peterson x Arbor Acres) were placed on fresh pine shavings in floor pens. From Day 0 to 18, all birds were fed a 23% CP starter diet. During Days 18 to 53 male birds were fed either a 16, 18, 20, 22, 24, or 26% CP diet (3,200 kcal ME/kg) and female birds were fed the 16, 20, or 24% CP diet. Significant differences (P < 0.05) were noted in the performance of the different strains. Ross x Ross 208 male birds had a higher body weight (3.37 vs 3.16 kg), higher feed intake (7.08 vs 6.78 kg), higher breast yield (31.76 vs 29.25%), higher carcass yield (73.90 vs 71.85%), and a lower adjusted feed conversion ratio (FCR; 2.10 vs 2.16 g:g) than Peterson x Arbor Acres males at 53 d of age. As compared to Peterson x Arbor Acres females, Ross x Ross 208 female broilers also had a higher body weight (2.68 vs 2.55 kg), higher breast meat yield (33.61 vs 30.80%), higher carcass yield (75.31 vs 73.91%), and lower adjusted FCR (1.97 vs 2.04 g:g). Qualitative differences in the response of these strains were confirmed and better qualitative data is presented that can be used to predict the important output parameters from the import inputs in broiler production.

Aging↗

PubMed1998

The effect of environmental temperature and body weight on growth rate and feed:gain of male broilers.

High environmental temperatures are detrimental to the growth and feed:gain of broilers. The objective of this research was to determine the effects of incremental differences in environmental temperature on growth and feed:gain. The data are needed for decisions about the profitability of energy inputs when managing the housing environment. In Trial 1, broiler chicks were reared as a group to 21 d on litter with constant lighting and with water and feed available for ad libitum consumption. They were then moved to 10 environmental chambers. Each chamber was set at a different temperature ranging from 21.1 C to 31.1 C in 1.11 C increments. Weight gain and feed:gain were determined when the broilers were 28, 35, and 42 d old. In Trials 2 and 3, broilers were placed in the environmental chambers, and weight gain and feed:gain were determined for the 42 to 49 d period. The data were analyzed statistically, and regression equations were obtained for growth and feed:gain. Equations were based on body weight and temperature, and the body weight equation was plotted as grams gain per bird per day. Feed:gain was plotted for that body weight and temperature. Body weight gain per day increased to a maximum with increasing weight and then declined. The body weight at the maximum rate of gain was inversely related to temperature. Feed:gain increased as body weight increased. Feed:gain was directly related to temperature at weights above 800 g and the effect of temperature increased as body weight increased. The data will be useful for the evaluation of various management scenarios to determine the inputs that are profitable.

Adaptation, Physiological↗

PubMed1998

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.

Aging↗

PubMed1998

Soybeans transformed with a fungal phytase gene improve phosphorus availability for broilers.

Male broilers (n = 416) were used to compare the efficacy of providing dietary phytase either as a commercial supplement or as a recombinant protein in transformed soybean. From 7 to 21 d of age, broilers were fed a basal diet containing 0.20% nonphytate P (nP) with additional supplementation by fungal phytase as Natuphos or as raw transformed soybeans expressing recombinant phytase at 400, 800, or 1,200 U/kg. For comparison, broilers were also fed the basal diet containing 0.08, 0.16, or 0.24 added nP. The basal diet was fed as the negative control. Diets were consumed ad libitum as a mash. All excreta were collected from each pen from 18 through 20 d of age, and the birds were killed at 21 d of age. Supplementing the basal diet with nP linearly increased body weight gain, feed efficiency, feed intake, toe ash weight and percentage, and tibia shear force and energy. Phosphorus digestibility decreased linearly as nP level increased, but P excretion increased. Dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and P digestibility, whereas excretion was decreased. Except for P digestibility, there was no difference in efficacy of responses for performance, bone mineralization, and P excretion between the two sources of phytase. It appears from this study that phytase can improve growth performance of broilers fed low nP diets when provided either as a commercial supplement or in the form of transformed seeds.

6-Phytase↗