Evaluation of wet-feeding wheat-based diets containing Saccharomyces cerevisiae to broiler chickens

1. This experiment investigated the effects of water and Saccharomyces cerevisiae added to wheat-based diets on gastrointestinal, blood and performance parameters of broiler chickens. 2. A total of 160 one-d-old male broiler chicks were given air-dry or wet diets, with or without S. cerevisiae supplementation (0 and 20 g/kg air-dry feed) ad libitum to 42 d. 3. Feeding broilers with a diet mixed with water in a ratio of 1·2 : 1·0 increased body weight, feed intake, abdominal fat, carcase weight, feed transit time and blood HDL (high density lipoprotein) (without yeast). Supplementation with S. cerevisiae increased DM digestibility but reduced ileal pH, ileal coliform population and abdominal fat content. 4. There was a significant interaction between S. cerevisiae and wet feeding, with S. cerevisiae supplementation inducing a significant increase in body weight and feed intake but a reduction of relative abdominal fat and ileal pH of broilers fed on wet diets. 5. It is concluded that wet feeding improved growth performance by increasing feed intake and that the addition of a culture of S. cerevisiae had a growth stimulating effect, as the inclusion of yeast in wet wheat-based broiler diets generated greater responses than yeast in dry-based diets.     

Evaluation of xylanase in low-energy broiler diets

The objective of the current study was to evaluate the effect of feeding a thermo-tolerant xylanase in low-energy broiler diets on performance and processing parameters. Evaluation criteria included average broiler BW, FCR, livability, carcass yield, and fat pad yields. The experimental design consisted of 3 nutrient profiles: positive control, negative control 1 (−66 kcal/kg), and negative control 2 (−132 kcal/kg). Two xylanase inclusion programs were included in the negative control 1 and 2 diets; 60 g/t was included in the starter and grower diets with either 60 or 100 g/t in the finisher and withdrawal diets, yielding a total of 7 treatment groups with 8 replicate pens per treatment each containing 42-d-old straight-run chicks per treatment (2,352 total broilers). Broilers were reared in floor pens through 45 d of age. The dietary program consisted of 5 dietary phases: starter (1–15 d), grower 1 (16–23 d), grower 2 (24–31 d), finisher (32–38 d), and withdrawal (39–45 d). Body weights and feed consumption were determined on days of dietary changes, including d 15, 23, 31, 38, and 45. On d 45, 4 male and 4 female broilers per replicate (448 total) were subjected to an 8-h feed withdrawal period and processed to obtain carcass and fat pad weights. Reducing the dietary energy level increased FCR and decreased the fat pad weight of broilers in the negative control 2 treatment compared with the positive control. Inclusion of xylanase during the starter phase increased d 15 BW and reduced FCR. The inclusion of xylanase continued to reduce FCR throughout the trial, as compared with diets without xylanase inclusion. Within this study, we have demonstrated the effectiveness of xylanase inclusion in reduced-energy diets (−66 and −132 kcal/kg) to improve FCR of broilers to that of broilers fed energy-adequate diets.     

Effects of glycine and glutamine supplementation to reduced crude protein diets on growth performance and carcass characteristics of male broilers during a 41-day production period

Glycine has been reported to be conditionally essential for broilers fed reduced crude protein diets during the starter period. Research evaluating dietary Gly responses subsequent to the starter period is sparse. This experiment was conducted to ascertain the effects of feeding reduced crude protein diets supplemented with Gly and/or L-Gln (nitrogen source) on growth performance and carcass characteristics of broilers during a 41-day production period. Eight dietary treatments were utilized with the negative control diets formulated to contain approximately 2.4 and 0.29% points lower crude protein and total Gly + Ser concentrations, respectively, than the positive control diets. The 6 other diets were formulated to contain intermediate concentrations of total Gly + Ser and/or crude protein (nitrogen) by adding Gly and/or L-Gln, respectively, to the negative control diets. Glycine appeared to have more pronounced effects than nitrogen contribution on feed conversion ratio and body weight gain of broilers during starter and grower periods, whereas Gln improved feed conversion of broilers in the finisher period. Total breast meat weight and yield of broilers provided diets with the additions of Gly and L-Gln were higher than those receiving diets with only Gly or L-Gln supplementation. The positive outcomes on growth performance and carcass characteristics suggested that providing adequate total Gly + Ser and nitrogen concentrations in diet formulation may be necessary for broilers when dietary CP content was reduced approximately by 2.4% points during a 6-week production period.     

Effect of dietary ascorbic acid supplementation level on productivity,mortality, and carcass characteristics of Venda chickens

Two experiments were carried out to determine the effect of dietary ascorbic acid supplementation levels on productivity, carcass characteristics, and mortality of indigenous Venda chickens. The first experiment determined the effect of dietary ascorbic acid supplementation levels on productivity and mortality rate of 175 unsexed Venda chickens between 1 and 6 weeks old. The second experiment determined the effect of dietary ascorbic acid supplementation levels on productivity, carcass characteristics, and mortality rate of 140 female Venda chickens between 8 and 13 weeks old. A completely randomized design was used in both experiments. Supplementation of grower diets with ascorbic acid ranged from 0 to 2,000 mg per kg DM feed in both experiments. Levels of ascorbic acid supplementation for optimum feed intake, feed conversion ratio, growth rate, live weight, and breast meat yield were determined using a quadratic equation. The optimal dietary ascorbic acid supplementation levels for feed conversion ratio, growth rate, and live weight of Venda chickens during the starter phase were 1,050, 1,301, and 1,500 mg/kg DM feed, while, at the grower phase, the optimal supplementation levels for feed conversion ratio, growth rate, live weight, and breast meat yield were 1,000, 1,250, 1,482, and 769 mg/kg DM feed, respectively. Results indicate that different levels of ascorbic acid supplementation optimized feed conversion ratio, growth rate, and live weight of Venda chickens at each growth phase. However, levels of ascorbic acid supplementation for optimum feed conversion ratio, growth rate, and live weight were higher than that for breast meat yield. These findings have implications on ration formulation for Venda chickens.     

Effect of dietary Moringa oleifera leaves on the performance,ileal microbiota and antioxidative status of broiler chickens

In this study, we investigated the effect of Moringa oleifera leaves (MOL) supplements on the performance, ileal microbiota carcass traits and biochemical and antioxidant parameters of broiler chickens. MOL was added to starter, grower and finisher diets at four levels (0%, 0.5%, 1.0% and 5.0%). A total of 320 one-day-old mixed-sex Cobb-500 broiler chicks were divided equally into four treatment groups, with 5 replicates of 16 chicks each until 42 days of age. Compared to the control group, chicks fed 0.5% and 1% MOL exhibited a higher final body weight (FBW), greater weight gain (BWG), and better average daily gain (ADG). Feed intake (FI) gradually decreased as the inclusion rate of MOL in the broilers' diet increased to 5%. The best feed conversion ratio (FCR), protein efficiency ratio (PER) and performance index (PI) were observed in broilers that were fed the MOL diet. The percentage of abdominal fat in broilers decreased significantly in response to dietary supplementation with MOL. The haematological profile in the MOL group revealed a lower WBC count and lymphocyte percentage but higher heterophil and H/L ratio without affecting haemoglobin and RBC count. The inclusion of MOL increased total serum protein, Ca and P levels but decreased glucose, cholesterol, triglycerides, AST and ALT concentrations. Moreover, dietary MOL increased the activities of GSH, CAT and SOD, GPx and GST while decreasing the TBARS level. The pH value decreased in the ileum of broilers fed the 1% and 5% MOL diet compared to the other treatments. Decreased ileal counts of E. coli, Salmonella and Staphylococcus spp. were observed whereas the total ileal Lactobacillus spp. count increased in broilers fed the MOL diet. In conclusion, the MOL supplement can enhance growth performance and antioxidant status, alter ileal microbiota and protect against enteropathogens with no deleterious effects on the broiler chickens.     

Roasted Full-Fat Soybeans in Starter,Grower, and Finisher Diets for Female Broiler Turkeys

A study was conducted to examine the growth performance and carcass composition of broiler turkeys fed graded levels of roasted soybeans processed by flame roasting. Roasted soybeans were incorporated as a partial replacement of soybean meal in starter (0 or 15% of the diet) and as a partial or complete replacement for soybean meal in grower and finisher diets (0:100, 33.3:66.6, 66.6:33.3, 100:0; roasted full-fat soybeans:soybean meal). At 21 d of age, the birds fed the starter diet with roasted soybeans ate more feed and were heavier than the controls, but feed conversion was similar. Feed consumption and feed conversion were not affected by ratio of roasted soybeans to soybean meal. However, birds fed the diet containing the 66.6:33.3 ratio were heavier than birds fed any other diet. At 84 d of age, carcass CP content of the birds fed roasted soybeans in the starter diet were similar to the control birds, whereas the carcass fat content was lower.     

Effects of dietary 1 alpha-hydroxycholecalciferol in calcium and phosphorous-deficient diets on growth performance,tibia related indices and immune responses in broiler chickens

This experiment was conducted to investigate the effect of dietary 1α-hydroxycholecalciferol (1α-OH-D₃) in calcium (Ca)- and phosphorous (P)-deficient diets on growth performance, carcass characteristics, tibia related parameters, and immune responses of broiler chickens. A total of 280 one-day-old broiler chickens (Ross 308) were assigned to 20 floor pens and 4 dietary treatments with 5 replicates. Dietary treatments consisted of starter diets (starter diet of treatment A: 1% Ca, 0.73% total phosphorus [tP]; starter diet of treatment B: 0.85% Ca, 0.64% tP + 5 μg/kg of 1α-OH-D₃; starter diet of treatment C: 0.85% Ca, 0.59% tP + 5 μg/kg of 1α-OH-D₃; starter diet of treatment D: 0.85% Ca, 0.54% tP + 5 μg/kg of 1α-OH-D₃), grower diets (grower diet of treatment A: 0.86% Ca, 0.68% tP; grower diet of treatment B: 0.73% Ca, 0.59% tP + 5 μg/kg of 1α-OH-D₃; grower diet of treatment C: 0.73% Ca, 0.55% tP + 5 μg/kg of 1α-OH-D₃; grower diet of treatment D: 0.73% Ca, 0.50% tP + 5 μg/kg of 1α-OH-D₃) and finisher diets (finisher diet of treatment A: 0.81% Ca, 0.64% tP; finisher diet of treatment B: 0.68% Ca, 0.56% tP + 5 μg/kg of 1α-OH-D₃; finisher diet of treatment C: 0.68% Ca, 0.52% tP + 5 μg/kg of 1α-OH-D₃; finisher diet of treatment D: 0.68% Ca, 0.48% tP + 5 μg/kg of 1α-OH-D₃). Results showed that body weight gain (BWG) and feed intake (FI) of broilers in treatment B were similar to those of broilers in treatment A at the end of the trial (P < 0.05). Broilers in treatments C and D had lower BWG and FI than those in treatment A during the whole trial (P < 0.05). Feed conversion ratio, carcass traits and relative weight of lymphoid organs were not affected by dietary treatments (P > 0.05). Dietary treatments had no significant effect on antibody titers against Newcastle and Influenza disease viruses as well as sheep red blood cells. Dietary treatments had no significant effects on tibia ash and tibial dyschondroplasia score. Broilers fed Ca-P deficient diets had lower tibia Ca and P than those in treatment A (P < 0.05). In conclusion, results indicated that broilers fed Ca-P deficient diets supplemented with 5 μg/kg 1α-OH-D₃ failed to achieve the same tibia Ca and P values as broilers fed nonphytate phosphorus adequate diets.     

Performance of Broiler Chickens Fed Sweet Potato Meal (Ipomoea batatas L.) Diets

Day-old Lohman broiler chicks (n = 120) were fed on five starting diets for 4 weeks in groups of 24 birds. The starting diets contained 0%, 9%, 18%, 27% and 36% sweet potato tuber as a replacement for maize. From the fifth week, the 120 birds were tested in groups of 30 on four finishing diets containing 0%, 15%, 30% and 45% sweet potato tuber as a replacement for maize. The carcass quality was significantly (p>0.05) improved due to a significant (p>0.05) reduction of abdominal fat in the birds fed on the 45% sweet potato finisher diets. However, the birds on the sweet potato diet continually passed wet dropppings, resulting in a significant (p>0.05) reduction in body weight and feed conversion efficiency. The optimum levels of inclusion of sweet potato in the diets were considered to be 27% and 30% for starting and finishing broiler chickens, respectively. Sweet potato diets may be a remedy for fatty broilers.     

Effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens

Two experiments were conducted to evaluate the effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens. The first experiment examined the effect of level of Hoodia gordonii meal supplementation at finisher stage (30 to 42 days of age) on productivity and carcass characteristics of chickens. Level of Hoodia gordonii meal supplementation had no effect (P > 0.05) on diet intake, growth rate, feed conversion ratio and live weight of chickens. Daily supplementation with 300 mg of Hoodia gordonii meal reduced (P < 0.05) fat pad weights by 40 % in broiler chickens The second experiment examined the effect of Hoodia gordonii meal supplementation interval on the productivity and carcass characteristics of broiler chickens. Hoodia gordonii meal supplementation interval had no effect (P > 0.05) on feed intake, growth rate, live weight, feed conversion ratio and all carcass characteristics except fat pad of broiler chickens. Daily supplementation with 300 mg of Hoodia gordonii meal/bird reduced fat pad weights of the chickens by 18 %. This could not be explained in terms of differences in feed intake, digestibility, or growth rate.     

Influence of a combination of formic and propionic acids added to wheat- and barley-based diets on the performance and gut histomorphology of broiler chickens

Day-old male chicks were used to test the effects of a combination of formic and propionic acids (CFP) added to wheat- and barley-based diets on the performance and gut histomorphology of broilers. The CFP, containing formic and propionic acids based on an inorganic phyllo-silicate carrier, was added to starter and grower broiler diets of standard (NRC, 1994) or lower nutrient density (LND) using different levels of wheat and barley. Body weight gain (BWG) and feed conversion ratio (FCR) of broiler chicks were significantly (P < 0.001) improved by CFP supplementation at 21 days of age regardless of nutrient density (ND). However, at 35 days of age CFP addition significantly (P < 0.001) increased BWG and FCR. Proventriculus weight was also significantly affected by the dietary treatments. Ileal viscosity was significantly (P < 0.05) affected by ND which was associated with wheat and barley contents, whereas feed viscosity was significantly (P < 0.05) affected by CFP supplementation. Villus height was significantly (P < 0.05) increased by the CFP supplementation. In the case of villus width, an interaction effect was observed: there was a significant (P < 0.05) decrease in the group fed the standard ND diet, but only a numerical decrease in the group fed the LND diet compared to control group. No significant effect of dietary treatment on the thickness of the lamina muscularis mucosae could be detected.     

Effects of different management factors on broiler performance and incidence of tibial dyschondroplasia

(1) This study was to determine the effects of two lighting programmes (continuous--24L:0D or intermittent--12L:3(1L:3D)), two feeding programmes (continuous--ad libitum or meal Jeeding--3 h feed:3 h deprivation x 4 times per d) and two ascorbic acid (AA) supplementations (0 or 150 mg/l in water) on broiler performance and incidence of tibial dyschondroplasia (TD). (2) One-day-old male commercial (Ross PM3) broiler chicks (1600) were used. The chicks were randomly divided into 8 treatment groups (2 x 2 x 2) and their replicates (2) replicates per treatment). (3) Intermittent lighting increased body weight and improved feed conversion. Body weight of broilers was decreased by meal feeding. AA supplementation had no significant effect on the body weight and feed conversion ratio. There was no lighting x feeding x supplemental AA interaction for body weight, feed conversion ratio, mortality rate and carcase weight. (4) Supplemental AA improved the cortical thickness of tibiotarsus and decreased the incidence of TD. (5) It was concluded that the application of intermittent lighting in combination with supplementation of 150 mg/l AA is a useful method to reduce TD in broilers without loss of performance.     

Impacts of calcium and phosphorus concentration,their ratio,and phytase supplementation level on growth performance,foot pad lesions,and hock burn of broiler chickens

Concerns about the environment, nutrition, and farm profits all point to the increasing importance of the phosphorus (P) content of a diet. Animals must now be fed near their P requirements. However, it is very difficult to know the exact P requirements of broilers. The objective of this study was to provide efficacy data of a 6-phytase for use in broilers at different Ca levels and Ca/P ratios. Broilers were randomly assigned to 6 treatments, each with 6 replicates. The treatments comprised diets differing in Ca and P level: 1) normal Ca and total normal phosphorus (Pt) level, 2) normal Ca and low Pt level, 3) low Ca and Pt level, and differing in phytase level (no, normal or high phytase supplementation). During the entire study, lowest BW was obtained when broilers were given the imbalanced (normal Ca and low Pt level) diet with low phytase supplementation. Among the balanced dietary treatments no significant effects on performance were observed. A higher Ca/Pt ratio decreased feed intake, whereas addition of phytase increased feed intake. For the starter period, the most favorable feed conversion was obtained when broilers were fed the imbalanced diet with a high dosage of phytase or the low Ca, low Pt diet supplemented with phytase. For the grower and finisher period, broilers with the highest weight gain had the highest feed intake resulting in comparable feed conversions between treatments. Litter quality was not affected by dietary treatments but prevalence of foot pad lesions and hock burn was significantly influenced by treatments. The highest percentage of both was seen when broilers were given the imbalanced diets. The overall results of this study emphasises the relevance of the Ca/P ratio in modern broiler feeding and P studies. It can be concluded from this study that dietary Ca and P concentrations can be reduced by 20% if done in a balanced way. If done in combination with phytase supplementation, performance results improve even more.     

Effects of dietary amino acid density and metabolizable energy level on the growth and meat yield of summer-reared broilers

The effects of dietary amino acid (AA) density and AME on the growth and meat yield of summer-reared Cobb × Cobb 700 (CCB-700) broilers were evaluated. In addition, the responses of CCB-700 and Cobb × Cobb 500 (CCB-500) broilers to dietary AME levels (with low AA) were compared. All chicks were fed through a starter, grower, finisher, and withdrawal phase program. Grow-out performance, carcass traits, meat yield, and feed cost efficiency were evaluated using 2 separate 2-way ANOVA based on 2 separate 2 × 2 factorial arrangements of treatments. Each group includes 14 replicate pens with 14 chicks/replicate. Mortality was not affected by treatment; however, as compared with birds fed other diets, feeding CCB-700 broilers a low-AME and high-AA density diet decreased feed intake and BW on d 35, 42, and 54, and decreased carcass, breast, wing, front half, and back half weights on d 55. The CCB-500 broilers consumed more feed and gained more weight as compared with CCB-700 broilers at 14, 28, and 35 d of age. However, at 55 d of age, breast weight and wing yield were observed to be higher in the CCB-700 than in the CCB-500 broilers. However, the back half (drumstick and thigh) weights were lower in the CCB-700 than in the CCB-500 broilers. In conclusion, without affecting feed costs, broiler performance and carcass yield were affected by diet in both strains. More specifically, a higher AME diet and lower AA density increased the yield of all cut-up parts, except for legs, in summer-reared CCB-700 chicks.     

Chemical composition and nutritive value of kapok seed meal for broiler chickens

1. Mechanically extracted kapok (Ceiba pentandra) seed meal (KSM) contained 324 g crude protein, 97 g ether extract, 289 g fibre, 94 g ash, 128 g available carbohydrates, 3-8 g calcium, 11 g phosphorus, 10.4 g cyclopropenoid fatty acids and 15 g tannins per kg. 2. In a 4 x 2 factorial experiment, KSM was incorporated in broiler starter and finisher feeds at 0, 30, 60 and 90 g/kg, replacing sunflower meal (SFM) w/w; without and with multi-enzyme supplementation. 3. No significant differences were noticed between treatments in body weight gain, feed consumption, feed conversion efficiency, mortality or carcase yields. 4. Multi-enzyme (amylase, endoxylanase, hemicellulase, beta-glucanase, pectinase, phytase and protease) supplementation did not improve the growth performance of broilers fed on the KSM diets.     

Effect of some antibiotics as growth promoters on performance of broiler chicks fed different protein levels

This work was carried out to study the effect of different sources of dietary antibiotics (Zinc bacitracin, Flavomycin, Virginiamycin) in rations with optimal protein levels (starter phase: 23.5%, finisher phase: 20.0%) and low protein levels (starter phase: 19.6%, finisher phase: 17.0%) on broiler performance with 8 groups of 75 broiler each. The supplement of diets, containing the optimal and low protein level, with antibiotics increased the body weight after 7 weeks of age and improved the feed conversion as compared with control groups. Virginiamycin was superior in increasing body weights after 7 weeks of age and in improving the feed conversion with rations containing low protein level when compared with zinc bacitracin and Flavomycin. When broiler rations, low in the protein content, were supplemented with antibiotics, they could not substitute the difference in optimal protein level. Antibiotics supplementation increased the value of improvement in production efficiency and this was more pronounced with Virginiamycin.     

The nutritive value of marula (Sclerocarya birrea) seed cake for broiler chickens: nutritional composition,performance, carcass characteristics and oxidative and mycotoxin status

This study was aimed at investigating the nutritive value of marula seed cake (MSC) as an alternative protein source for broilers. In a completely randomised design involving six replicate pens of five chickens assigned to each of five treatments, body weight gain (BWG), feed intake (FI), feed conversion efficiency (FCE) and carcass characteristics were measured in an experiment in which 150 28-day-old broilers were fed maize-based diets containing, respectively, 0, 5, 10, 15 and 20% MSC at finisher phase. The results showed MSC to be remarkably high in CP (470.0 g/kg DM) and EE (343.5 g/kg DM), with moderate CF (58.2 g/kg DM), ash (54.3 g/kg DM), Ca (1.1 g/kg DM) and P (11.0 g/kg DM). Whilst very poor in lysine, MSC was found to be rich in methionine, cyst(e)ine, arginine and glutamic acid; it also contains good levels of valine, glycine, threonine, isoleucine, leucine, histidine, phenylalanine, serine, proline and alanine. Also, it contained 85.24% oleic (OA), 9.65% palmitic and 5.11% stearic acids, with a high peroxide value and low levels of mycotoxins deoxynivalenol (DON) and T-2 toxin. BWG, FI and FCE of broiler chickens significantly decreased (P < 0.001) as the dietary level of MSC increased. Further, dietary MSC significantly decreased bird live weight at slaughter (P < 0.001), plucked weight (P < 0.001), dressed weight (P < 0.001) and weights of the liver (P < 0.001) and neck (P < 0.05). The results therefore demonstrate MSC to be a good source of CP, fat, Ca, P, amino acids (except lysine) and OA that can replace soya bean meal (SBM) in broiler diets. However, its use is currently limited by lipid peroxidation and presence of mycotoxins.

     

Growth response, blood characteristics and copper accumulation in organs of broilers fed on diets supplemented with organic and inorganic dietary copper sources

1. A 56-d experiment was conducted to study the comparative influence of organic and inorganic dietary copper (Cu) sources on growth, blood characteristics and copper accumulation in organs of broilers. 2. A total of 480 Arbor-Acre unsexed broilers were fed on diets containing copper sulphate (CuSO(4)) or copper proteinate (Cu Pro) at concentrations of 50, 100 or 150 mg/kg of Cu supplementation. The birds were given a broiler starter diet from 1-28 d and a broiler finisher diet from 29-56 d which contained 30·8 mg/kg and 41·1 mg/kg basal copper concentration respectively. Growth performance, blood characteristics and Cu accumulation in organs of the broilers were measured. 3. At 28 d, Cu Pro-fed birds had improved feed conversion ratio compared with CuSO(4). At 56 d, birds fed on Cu Pro diets had significantly greater body weight than CuSO(4)-fed birds. Birds fed on CuSO(4) supplemented diets had significantly better feed conversion efficiency. Feed consumptions for the two Cu sources were not significantly different. At no stage did the concentration of added Cu affect the productive traits measured. 4. Cu Pro supplementation increased haemoglobin concentration but reduced plasma triglyceride and plasma cholesterol. Plasma cholesterol decreased as Cu concentration increased. 5. There was a greater accumulation of Cu in the blood, heart, lung, liver and bone of broilers fed on Cu Pro than in those receiving CuSO(4). The liver Cu concentration increased as dietary Cu concentration increased. 6. Cu Pro was more effective in promoting growth and reducing blood cholesterol, and was more bio-available in the organs of broilers.     

Comparison of the supplemental effects of Saccharomyces cerevisiae and antibiotics in low-protein and high-fibre diets fed to broiler chickens.

Two experiments were completed to compare the supplemental effects of yeast Saccharomyces cerevisiae and sub-therapeutic antibiotics in high-fibre and low-protein diets for broiler chicks. In experiment 1, yeast was added at 1.5, 3.0 and 6.0 g kg-1 while penicillin, tylosin or neoterramycin were added at 150 mg kg-1 into different batches of a high-fibre diet containing 250 g kg-1 palm kernel meal. Saccharomyces cerevisiae and antibiotics increased BW, BWG, FCR, feed intake, carcass and breast weights above the control. Small intestine weight was reduced by antibiotics, while yeast caused a lower deposition of abdominal fat. Liver weights of different treated broilers were similar. The performance indices were superior on penicillin and 3.0 g kg-1 yeast compared to other supplements evaluated. In the second experiment, 1.5 and 3.0 g kg-1 of yeast, and 0.75 mg kg-1 of procaine penicillin, zinc bacitracin and tylosin were separately added to a 180 g kg-1 crude protein diet. Performance of the chicks with additives was compared with unsupplemented negative and positive controls containing 180 and 210 g kg-1 crude protein respectively. Broilers fed with supplements had superior BW, BWG, FCR and feed intake compared to the negative control, but carcass data were similar. Dietary penicillin increased BW, BWG, feed intake more than other supplements, but yeast stimulated higher FCR. Data from both studies indicated that Saccharomyces cerevisiae comparatively increased growth and carcass weight and reduce abdominal fat, therefore, it can serve as a natural substitute for antibiotics in broiler diet.     

Effects of varying conditioning temperature and mixer-added fat on feed manufacturing efficiency, 28- to 42-day broiler performance,early skeletal effect,and true amino acid digestibility

Three experiments (EXP) were conducted with the objective of evaluating the effects of varying steam conditioning temperatures (CT) and mixer-added fat (MAF) on a practical broiler finisher diet on feed manufacture variables (EXP 1), 28- to 42-d broiler performance (EXP 2), and early skeletal effect using 3-to 21-d broiler performance and tibiae ash measurements and true amino acid digestibility using cecectomized roosters (EXP 3). For all EXP, we used a 3 CT (74, 85, or 96°C) by 2 MAF (low or high) factorial arrangement, resulting in 6 experimental diets. Prior to EXP 2 and 3, all diets were ground to a common crumble size. In EXP 1, increasing both CT and MAF decreased relative electrical energy use at the pellet mill. In EXP 2, feeding finisher diets manufactured utilizing increased CT and decreased MAF to broilers from 28 to 42 d resulted in increased FCR. Also, CT by MAF interactions demonstrated the highest BW gain when birds were fed diets with high MAF, conditioned at 85°C. In EXP 3, feeding diets manufactured in EXP 1 to broilers from 3 to 21 d resulted in no significant effects on live performance variables. However, a significant CT by MAF interaction was observed, where chicks fed diets using low MAF conditioned at 85 and 96°C resulted in incrementally increased percent tibia ash over those with high MAF. In addition, based on true amino acid digestibility data, altering MAF and especially CT can affect the digestibility of several amino acids.     

The effects of strain and incremental improvements in feed form on d 28 to 42 male broiler performance

Feeding high-quality pellets to modern commercial broilers may maximize genetic potential; however, this typically requires an increased cost to produce feed. Therefore, it is important to determine if incremental improvements in feed form (FF) can increase performance of modern broiler strains. The current study was conducted to investigate the effects of feeding modest improvements in feed form (50, 60, 70, or 80% intact pellets; IP) to 2 commercial broiler strains (fast-growing or high-yield) on d 28 to 42 growth performance and processing variables. A common diet was manufactured to contain 80% IP, of which a portion was ground to create a total of 4 FF treatments varying in IP to ground pellet ratios: 50:50; 60:40; 70:30; and 80:20. Fast-growing (FG) birds demonstrated improvements in body weight (BW), BW gain (BWG), and feed conversion ratio (FCR) when compared to high-yield (HY) birds. For the main effect of FF, feeding 80 vs. 50% IP reduced d 28 to 42 FCR. Also, feeding birds 80% IP vs. all other FF treatments improved d 28 to 42 BWG and d 42 BW. A Strain × FF interaction established that FG broilers fed 50, 60, and 70% IP diets had higher d 43 total breast yield than HY birds fed the same FF treatments; however, both strains demonstrated similar total breast yield when 80% IP were fed, which suggests that FG broilers are less sensitive and HY broilers are more sensitive to increasing FF. These data suggest a distinct benefit for feeding improved FF from d 28 to 42 to modern broilers.