Effects of high non-phytate phosphorus starter diet on subsequent growth performance and carcass characteristics of broiler chickens

The trial was performed to investigate the effects of different concentrations of non-phytate phosphorus (nPP) in the starter and grower (with phytase inclusion) periods on carcass characteristics, organ weight and weekly variations of growth performance in the grower period. Seven hundred and twenty-day-old male broiler chickens were randomly assigned to 12 treatments in a completely randomized design. Chickens received two dietary treatments (4.5 g/kg and 6 g/kg nPP) in the starter (0-21 days) and six experimental diets (4 g/kg, 3.1 g/kg, 2.3 g/kg and 2.3 g/kg + 1000 FTU/Kg of feed phytase, 1.5 g/kg, 1.5 g/kg nPP + 1000 FTU/Kg of feed phytase) in the grower period (22-42 days). Results showed that phytase inclusion in the second and third weeks of grower period could increase feed intake significantly. Also, decrease in the concentrations of nPP to 1.5 g/kg caused to decline body weight gain markedly. Moreover, there is a significant difference between 4.5 g/kg and 6 + 4 g/kg nPP (starter+grower) and 1.5 g/kg nPP. Phytase inclusion increased carcass yield and declined liver weight significantly. Dietary treatment of 4.5 + 1.5 g/kg nPP enhanced heart and liver weight markedly. It is concluded that starter diets with increased concentration of nPP (6 g/kg nPP) had no beneficial effects on growth performance in the starter and grower period in the total (0-42 days). Also, it is possible to decrease nPP concentration of grower diets to 1.5 and 2.3 g/kg with and without phytase inclusion respectively.

Phosphorus requirements of broiler chicks six to nine weeks of age as influenced by phytase supplementation

Two trials of similar design were conducted to determine the nonphytate phosphorus (NPP) requirements for broilers from 42 to 63 d of age in diets with or without phytase supplementation. Male broilers of a commercial strain were grown to 42 d on nutritionally complete diets with NRC (1994) recommended levels of Ca and NPP. At 42 d, the birds were placed on experimental diets and fed to 63 d. The experimental treatments consisted of a 2 x 6 factorial arrangement with two levels of phytase (0 or 800 U/kg) and six levels of NPP (0.10 to 0.35% in 0.05% increments). Body weight gain, feed conversion, and mortality were determined during the period. At 49, 56, and 63 d, excreta samples were taken, and samples of birds were killed for tibia ash determination. The lowest level of NPP, with or without phytase supplementation, was sufficient for maximum BW gain, feed conversion, and livability. Using nonlinear regression, levels of NPP needed to optimize tibia ash in the absence of phytase were 0.31 +/- 0.004%, 0.23 +/- 0.02%, and 0.22 +/- 0.029% at 49, 56, and 63 d, respectively. When diets were supplemented with 800 U/kg of phytase, the NPP requirement for optimum tibia ash was 0.15 +/- 0.049% at 49 d. At 56 and 63 d, no more than 0.10% NPP (lowest level tested) was sufficient to maximize tibia ash. Compared to current NRC (1994) recommendations, the application of these reduced dietary phosphorus levels could markedly reduce excreta excretion of phosphorus by broilers.

Relationship of dietary lysine level to the concentration of all essential amino acids in broiler diets

A study was conducted to evaluate the relationship of dietary Lys and other essential amino acids (EAA) in diets for broilers. Diets were formulated based upon NRC (1994) recommendations. Within each age period, diets contained NRC recommended levels of Lys with other EAA at 100, 110, 120, or 130% of NRC. The diets were then supplemented with 0.1, 0.2, or 0.3% additional Lys, resulting in a 4 x 4 factorial arrangement with four levels of Lys (NRC, + 0.1%, + 0.2%, and + 0.3% Lys) and four levels of other EAA (100, 110, 120, and 130% of NRC). Each of the 16 treatments was fed to six replicate pens of 25 male broilers of a commercial strain. At 56 d, five birds per pen were processed to determine dressing percentage and carcass yield. There were no significant interactions between level of Lys and levels of other EAA for live performance or carcass characteristics. The BW was significantly increased at 21 and 42 d by addition of + 0.1% Lys above NRC but not at 56 d. There was no significant effect of other EAA on BW at any age. The effects of Lys on feed conversion were varied. At 21 and 42 d, addition of 0.1% Lys to diets containing the NRC Lys level significantly improved feed conversion; response to 0.2 or 0.3% Lys were varied. No significant effects of Lys on feed conversion were observed at 56 d. Increasing the level of EAA resulted in significant improvements in feed conversion at 21, 42, and 56 d, generally following a linear trend. Dietary Lys levels had no significant effects on dressing percentage, breast meat yield, or abdominal fat content. The level of other EAA significantly influenced dressed yield but had no significant influence on carcass yield. These results indicate that NRC (1994) levels of Lys and other EAA are adequate for optimum performance of male broilers processed at 56 d but may be less than adequate at younger ages.

Phosphorus requirements of broiler chicks three to six weeks of age as influenced by phytase supplementation

Two studies of identical design were conducted in battery brooders utilizing male chicks of a commercial strain. The birds were grown to 3 wk on diets with adequate P and from 3 to 6 wk were fed diets ranging from 0.10 to 0.45% nonphytate P (nPP) in increments of 0.05%, with or without supplementation with 800 units of phytase per kilogram of diet. Measurements included BW gain, feed conversion ratio (FCR), mortality, tibia ash, and fecal P content. Nonlinear regression was used to estimate nPP needs for optimizing BW gain, feed conversion, and tibia ash. In the absence of phytase, nPP levels of 0.33, 0.186, and 0.163% were required to optimize tibia ash, BW gain, and FCR, respectively. The estimated level for optimum tibia ash is in close agreement with current NRC (1994) recommendations. In the presence of 800 units of phytase per kilogram, nPP levels of 0.24, 0.151, and 0.109% were needed to optimize tibia ash, BW gain, and FCR, respectively. Fecal phosphorus levels were markedly reduced at the lower P levels. Further studies are needed to determine whether maximum tibia ash values are needed to sustain optimum production of market broilers.

Nonphytate phosphorus requirement and phosphorus excretion of broiler chicks fed diets composed of normal or high available phosphate corn with and without microbial phytase

A study was conducted to evaluate the ability of the young (0 to 3 wk) broiler chicken to utilize the P provided by a high available P corn [HAPC; 0.27% total P and 0.17% nonphytate P] in comparison with yellow dent corn (YDC; 0.23% total P and 0.03% nonphytate P), and to determine the extent to which supplementation with exogenous phytase enzyme could reduce the demands for dietary P and subsequently reduce P excretion. Diets prepared using the two types of corn differed in the amount of phytate-bound P, with the HAPC diets containing approximately 50% less phytate-bound P. Treatment diets were prepared by varying the amount of dicalcium phosphate, and ranged from 0.10 to 0.50% nonphytate P for YDC diets, and from 0.18 to 0.50% nonphytate P for HAPC diets. Sublots of each diet were supplemented with 800 units/kg phytase. Each diet was fed to six pens of five male chicks of a commercial broiler strain from 1 to 21 d of age. Regression analysis was used to estimate nonphytate P requirements for each corn type with and without phytase supplementation. The greatest need for nonphytate P was for maximum tibia ash, with requirements of 0.39, 0.29, 0.37, and 0.32% in diets with YDC, YDC plus phytase, HAPC, and HAPC plus phytase, respectively. Addition of phytase liberated approximately 50% of the phytate-bound P from each diet. These levels were sufficient to support body weight, feed conversion, and livability. Fecal P content of broilers fed diets with YDC at the NRC (1994) recommended level of 0.45% nonphytate P was 1.21%, whereas at the respective requirement points indicated above, the P content was 1.09, 0.87, 0.78, and 0.64% in feces from broilers fed diets with YDC, YDC plus phytase, HAPC, and HAPC plus phytase, respectively. Thus, fecal P output could be reduced while maintaining optimum performance by the use of reduced dietary nonphytate P, introduction of HAPC, and phytase supplementation. One of the greatest benefits of phytase supplementation appeared to be maintaining livability at lower dietary levels of nonphytate P.

Evaluation of normal yellow dent corn and high available phosphorus corn in combination with reduced dietary phosphorus and phytase supplementation for broilers grown to market weights in litter pens

A study was conducted to determine the extent fecal P levels could be reduced while maintaining performance. Various strategies were employed including the use of a high available phosphorus hybrid of corn (HAPC), supplementation with phytase enzyme, and reduced dietary P levels. The use of HAPC resulted in a 50% reduction in phytate-bound dietary P as compared with a normal yellow dent corn (YDC) diet. Dietary nonphytate P was maintained at either NRC (1994) recommendations for appropriate age periods or reduced by 0.075 or 0.15%. Portions of the diets were supplemented with 1,000 units of phytase/kg. Male chicks of a commercial strain were grown to 56 d on the test diets. Broilers fed diets with HAPC had BW, feed conversion, livability, and tibia ash that were equal to or superior to those fed diets with YDC with considerably reduced fecal P content at any dietary level of nonphytate P. Phytase supplementation enabled birds to maintain live performance at lower levels of nonphytate P, further reducing the fecal P output. One of the greatest contributions of phytase was a reduction in mortality at the lower levels of nonphytate P. Dietary P levels could be reduced by 0.075% under NRC (1994) recommendations without adversely affecting live performance; a reduction of 0.15% in conjunction with phytase supplementation maintained BW, feed conversion, and livability but reduced tibia ash. The extent to which dietary P levels can be reduced over the entire feeding program is subject to further research.

Nutritional approaches to reducing phosphorus excretion by poultry

Phosphorus is an essential mineral for growing poultry, and the consequences of a failure to provide for adequate quantities of this nutrient are physiologically and economically disastrous. Therefore, nutritionists provide a margin of safety for this mineral in their diets. However, because of growing concerns regarding the potential contribution of P in poultry excreta on eutrophication of surface waters, increasing pressure is being placed to limit the amount of excess P in diets and thus reduce fecal output. In order to significantly reduce fecal P while maintaining economic productivity, the nutritionist must establish and maintain an integrated program of activities, including an effective quality control program for incoming animal protein feeds, selection of P supplements of the highest biological value, use of phytase enzymes, and judicious selection of dietary P levels. Potential benefits of newer isomers of vitamin D and the commercial development of grains with high levels of nonphytate P offer promise in the future. Whatever measures are taken to increase the biological availability of the phytate-bound and nonphytate P portions of the diet, commensurate reductions in overall dietary P content must be made.

Effect of dietary phytase and high available phosphorus corn on broiler chicken performance

Two trials were conducted to determine the effects on broiler chicken performance and health of reducing dietary phosphorus levels by treating feed with the enzyme phytase, formulating diets using high available phosphorus (HAP) corn, or when diets were formulated with HAP corn and treated with phytase. Cobb x Cobb male broiler chickens were placed in an experimental design consisting of four dietary treatments with six replicate pens of 50 broilers per pen. The dietary treatments consisted of untreated control feed, phytase-supplemented feed (500 U/kg), diets prepared with HAP corn, and diets prepared with HAP corn and supplemented with phytase. The chickens were maintained on these dietary treatments from 1 to 49 d of age with feed and water made available for ad libitum consumption. When the two trials were combined, there was a significant (P < or = 0.05) increase in body weight in the broilers fed the phytase treated diets at 49 d of age. The serum activity of alkaline phosphatase was significantly decreased in the diets supplemented with phytase, and serum cholesterol was significantly decreased in the diets prepared with HAP corn. These data indicate that total phosphorus can be reduced by at least 11% in diets prepared with HAP corn, or in diets supplemented with phytase, without affecting the performance or health of broiler chickens. When diets are prepared with HAP corn and supplemented with phytase, the dietary addition of total phosphorus can be reduced by at least 25% without affecting broiler chicken performance or health.

Dietary arginine and lysine in Large White toms. 1. Increasing arginine:lysine ratios does not improve performance when lysine levels are adequate

A study was conducted utilizing two strains of male Large White turkeys (BUT Big 6 and Nicholas 700) to determine the effects of increasing Arg:Lys ratios on live performance and carcass composition. Diets were formulated to provide 100, 110, and 120% of NRC (1994) Lys levels, adjusted for dietary energy level, with Arg:Lys ratios of 1.0:1, 1.1:1, 1.2:1, and 1.3:1 in a 3 x 4 factorial arrangement. Eight pens of 15 poults (four pens of each strain) were fed each of the 12 test diets for an 18-wk period. Diets were changed at 3-wk intervals rather than the 4-wk interval suggested by NRC. The results of this study suggest that the Arg and Lys levels suggested by the NRC (1994) are not sufficient when diets are fed on 3-wk intervals, rather than the 4-wk intervals suggested by NRC. This conclusion is in agreement with the studies of Waldroup et al. (1997b). Increasing Arg:Lys ratios improved performance of turkeys only when the diets contained insufficient amounts of Arg in association with low levels of Lys. Increasing Arg:Lys ratios when diets contained sufficient amounts of these two amino acids was without benefit, in contrast to the report of Brake et al. (1994). Turkeys of the BUT Big 6 strain appeared to be more sensitive to marginal deficiencies of Lys and Arg than did turkeys of Nicholas 700 strain.

Utilization of spent hen meal in diets for broiler chickens

Studies were conducted to evaluate spent hen meal (SHM) produced in commercial rendering plants as a nutrient source in diets for broiler chickens. Utilizing previously determined nutrient composition values, including digestible amino acid and TMEn content, diets were formulated to include 0, 5, 10, and 15% of SHM from three different locations. In the first experiment, conducted in battery pens from 1 to 21 d posthatch, diets were formulated with digestible amino acid requirements set at 90, 95, or 100% of NRC (1994) total amino acid requirements. In the second experiment, conducted in floor pens from 1 to 49 d posthatch, diets were formulated with digestible amino acid requirements set at 95% of NRC (1994) total amino acid requirements. Samples of birds from the second experiment were processed to determine the possible influence of SHM inclusion on carcass yield. Results of the present studies indicate that SHM from commercial rendering facilities can be utilized in diets for growing broiler chickens provided adjustments are made in nutrient content and digestibility. When formulated on the basis of digestible amino acid content, levels of SHM up to 10% appear acceptable based upon body weight, feed conversion, bone ash, and carcass yield. Higher inclusion rates generally reduced performance. It is apparent that differences in nutritional quality may exist among products produced by different rendering facilities; however, evaluation of products to assess nutrient quality may be difficult under commercial conditions. As more information is generated regarding typical amino acid content and digestibility of rendered SHM, the product may be used with greater confidence in commercial diets.

An evaluation of threonine requirements of young turkeys

Two experiments were conducted to evaluate the Thr requirements of male Large White turkeys from 3 to 6 and 6 to 9 wk of age. One group of turkeys was fed to 3 wk using nutritionally adequate diets and fed test diets from 3 to 6 wk; another group of turkeys was fed to 6 wk using nutritionally adequate diets and fed test diets from 6 to 9 wk. Test diets were composed of peanut meal, soybean meal, corn, and grain sorghum as intact protein sources and were supplemented with amino acids. Peak performance of turkeys fed the test diets was equivalent to that of turkeys fed conventional corn-soybean meal diets formulated to meet NRC (1994) standards. Estimates of Thr requirements for weight gain were 0.92 and 0.86% for 3 to 6 and 6 to 9 wk, respectively. For feed conversion, estimates of Thr requirements were 0.87% and 0.84% for 3 to 6 and 6 to 9 wk, respectively. The results of the two experiments reported herein would suggest that the Thr requirements suggested by NRC (1994) for turkeys up to 9 wk of age are safe estimates; they may slightly overestimate the requirements but not by a large margin.

Effects of amino acid restriction during starter and grower periods on subsequent performance and incidence of leg disorders in two strains of male large white turkeys

Male turkeys of two commercial Large White strains (Nicholas 88, BUT 6) were subjected to growth restriction by means of reducing amino acid (AA) content of diets to a minimum of 75% of NRC (1994) suggested levels. There were three periods when diets containing 75% of NRC recommended AA for that age period were fed ad libitum: 0 to 3 wk, 0 to 6 wk, or 6 to 12 wk. A fourth (control) group was not restricted in AA content at any time. When turkeys were not fed the AA-restricted diets they were fed diets formulated to meet a minimum of 100, 110, or 120% of NRC (1994) AA recommendations, which resulted in a 3 x 4 factorial arrangement of treatments with three AA levels by four restriction times. Four pens of 12 males each were fed each AA by restriction time combination. At 18 wk, all birds were scored individually for leg condition and representative samples of turkeys were processed for parts yield. Birds fed restricted diets from 0 to 6 or 6 to 12 wk had significantly lower BW at 18 wk than control birds. Birds fed the restricted diets from 0 to 3 wk did not differ significantly in 18-wk BW compared to control birds but the magnitude of difference was similar to that observed at the end of the restriction period. Feed utilization was not improved by early AA restriction. Restricting early growth resulted in a significantly higher incidence of birds with no leg disorders and a lower incidence of birds with moderate leg disorders than control birds. Feeding higher AA levels during realimentation resulted in a greater severity of leg disorders. Breast meat yield was depressed significantly as severity of early restriction increased. Increasing dietary AA above NRC (1994) recommended levels generally improved performance during realimentation but was not able to compensate for reduced gains during restriction.

Response of two strains of large white male turkeys to amino acid levels when diets are changed at three- or four-week intervals

A study was conducted to evaluate the amino acid recommendations of the NRC (1994) when diets were changed at 3- or 4-wk intervals. Diets formulated to provide from 90 to 115% of recommended amino acid levels were fed to Nicholas (NIC) and British United Turkey (BUT) Large White males from day-old to 24 wk of age; samples of turkeys were processed at 18 and 24 wk. Results indicated that the amino acid levels suggested by NRC are adequate to support maximum body weight gain, feed conversion, and dressing percentage of Large White males grown to 18 or 24 wk when fed on 4-wk intervals. An approximately 5% higher level of amino acids was required to maximize breast yield. When feeds were changed at 3-wk intervals, higher levels of amino acids were required to maximize performance; however, there did not seem to be any difference in the response of the two strains of turkeys to different levels of amino acids in this study.

Performance and carcass composition of large white toms as affected by dietary crude protein and threonine supplements

This experiment evaluates the effect of decreasing dietary CP, in addition to the effects of dietary supplements of L-Thr to low CP diets, in Large White Nicholas toms from 0 to 18 wk of age. Toms were fed dietary treatments consisting of four levels of dietary CP as a percentage of NRC (1994) recommendations (100, 92, 84, and 76% of NRC recommendations). Additional treatments consisted of supplements of L-Thr (0.1 and 0.2% of diet) added to the 92 and 84% NRC CP treatments. All eight dietary treatments were formulated to meet a minimum of 105% of NRC (1994) recommendations for Met, TSAA, Lys, Thr, and Trp. Body weight, feed conversion, mortality, and carcass composition responses were measured. Decreasing CP to 84% of NRC resulted in 18-wk BW lower than that (P < or = 0.001) of toms fed diets containing 100 or 92% of NRC CP; however, toms fed 84% of NRC CP diet supplemented with 0.1% L-Thr had 18-wk BW equal to (P < or = 0.001) that of the 100 and 92% NRC CP treatments. Toms fed diets containing 76% of NRC CP had depressed BW and feed:gain in comparison to all other treatments. No adverse effects in cumulative feed:gain (0 to 18 wk) were noted by decreasing CP from 100 to 84% of the NRC recommendations. Mortality did not differ among treatments. Treatments had no effect on carcass fat expressed as a percentage of hot carcass weight. Breast meat yield (deboned Pectoralis major and Pectoralis minor) was highest (P < or = 0.001) in toms fed the 100 and 92% NRC CP treatments. The 84 and 76% NRC CP treatments resulted in decreased breast meat yield regardless of L-Thr supplements. These results indicate that diets containing Met, TSAA, Lys, Thr, and Trp at a minimum of 105% NRC recommendations may support favorable breast meat yield when CP is decreased to 92% of the NRC (1994) recommendation. If growth and feed conversion are the desirable traits, rather than breast meat yield, CP levels below 92% of the NRC (1994) recommendation may support favorable responses.

Evaluation of National Research Council amino acid recommendations for large white turkeys

Two trials of identical experimental design were conducted to evaluate the NRC (1994) amino acid requirements for growing turkeys. Diets were formulated for 4-wk age intervals using intact ingredients and amino acid supplements to provide 85, 90, 95, 100, 105, 110, 115, and 120% of the suggested requirements. Formulation was done in a manner to minimize excess levels of as many essential amino acids as possible. Day-old male poults of a commercial Large White strain were grown to 20 wk on the test diets with body weight and feed conversion determined at intervals throughout the test; representative samples of birds were processed to determine carcass composition and parts yield. Results suggested that diets formulated to provide 105% of the suggested NRC requirements were needed to provide maximum body weight gain, feed conversion, and breast meat yield. Ambient temperatures in the present study frequently exceeded 27 C and may have contributed to the need for somewhat greater amino acid needs than the present NRC (1994) suggestions.

Influence of dietary lysine levels and arginine:lysine ratios on performance of broilers exposed to heat or cold stress during the period of three to six weeks of age

Four trials of identical experimental design were conducted to determine the effects of temperature, dietary Lys level, and dietary Arg:Lys ratios on performance and carcass yield of male broilers. Birds of a commercial strain were grown from 21 to 42 d of age in wire-floored finishing batteries placed in environmental chambers. The chambers were programmed to provide either a constant thermoneutral temperature (21.1 C), a constant cold temperature (15.5 C), or a cycling hot diurnal temperature (25.5 to 33.3 C). Within each environment there was a factorial arrangement of three Lys levels (1.0, 1.1, and 1.2%) with four Arg:Lys ratios (1.1:1, 1.2:1, 1.3:1, and 1.4:1). Environmental temperature significantly influenced virtually every characteristic examined. Hot cyclic temperatures reduced weight gain, feed intake, and breast meat yield, and increased feed conversion, dressing percentage, leg quarter yield, and abdominal fat content. The cold environment promoted increased feed intake and mortality. Ascites and cardiomyopathy were the leading causes of death under cold exposure and thermoneutral conditions, whereas complications arising from heat exposure were the main cause of death under hot cyclic conditions. Levels of Lys affected leg quarter yield and abdominal fat content over all environments but increased breast meat yield only under cold conditions. Increasing Arg:Lys ratios improved feed conversion and dressing percentage and reduced abdominal fat content; it could not be determined whether these responses were consistent with Arg per se or were due to a nonspecific N response. As increasing Lys levels or Arg:Lys ratios did not improve weight gain, increase breast meat yield, or attenuate adverse effects due to heat or cold exposure, it is concluded that the levels of Lys and Arg suggested for 21 to 42 d by the NRC are adequate for birds of this age under the environmental conditions encountered.

Examination of the dietary methionine requirements of breeding northern bobwhite, Colinus virginianus

Adult Northern bobwhite were used to test the hypothesis that dietary methionine levels recommended by the NRC for breeding quail are excessive for wild bobwhite. We tested the hypothesis by comparing immunocompetence, reproductive performance, and chick viability of Northern bobwhite hens fed diets containing low (0.31%), moderate (0.39%), or high (0.47%) concentrations of methionine. Chick viability was determined by assessing immunocompetence, including evaluating the ability of hens to passively transfer immunity to their chicks. Hens were fed the experimental diets for 6 wk on an ad libitum basis. After 6 wk, methionine treatment had no measurable effect (P > or = 0.20) on hen phytohemagglutinin wing web indices, organ weights, or serum anti-Pasteurella multocida titer indices. Mean egg weight, percentage egg production, total cumulative egg production, yolk weight, yolk volume, and percentage fertile and percentage hatch of fertile eggs did not differ (P > or = 0.12) among diet treatments. Amount of albumen in eggs produced by hens fed the high methionine diet averaged 0.27 g more (P = 0.003) than eggs of hens fed the low methionine diet. Anti-P. multocida titer of yolks from eggs in Week 6 were not different (P = 0.36) between birds fed the high and the low methionine diets. The mortality rate of chicks after challenge with 23 cfu of P. multocida was not different (P > or = 0.05) among diets. Chicks hatched from eggs laid by vaccinated hens during Weeks 2 and 3, however, had lower (P < 0.05) mortality than chicks of unvaccinated hens. It appears a dietary methionine concentration of 0.3% may be sufficient for wild Northern bobwhite to produce viable chicks.

Utilization of hydrolyzed sucrose polyester (olestra) in broiler diets

Three experiments were conducted in which hydrolyzed olestra (HO) and hydrolyzed olestra manufacturing by-product (HBP) were compared with corn oil (CO) and a feed-grade hydrolyzed animal-vegetable fat blend (AVF) as fat supplements in diets for broilers. Various blends of HO and HBP with AVF and other fat sources were also evaluated. Results of these experiments indicate that HO or HBP may be used as energy sources in broiler diets. Use of these materials as the sole source of supplemental fat often reduced body weight gain and impaired feed utilization as compared with CO or AVF; however, when used as a component of a blended fat product typical of industry supplements, there was little if any adverse effect on live performance. Carcass fatty acid content was a reflection of dietary fat content. If the blend of fats containing HO or HBP contains a suitable ratio of unsaturated and saturated fatty acids, the product should be an acceptable source of supplemental energy in broiler diets.

Utilization of crude and refined palm and palm kernel oils in broiler diets

Four experiments were conducted to evaluate the use of crude and refined palm (PAO) and palm kernel oil (PKO) in diets for broiler chickens. In Experiment 1, refined PAO and PKO were compared with corn oil (CO) and poultry oil (PO) at levels up to 10%. In Experiment 2, refined PAO and PKO were compared with PO at levels up to 8%. In Experiments 3 and 4, crude PAO and PKO were compared with PO at levels up to 8%. Diets were formulated based on the energy level assigned to PAO; other oils were added in amounts calculated to be isocaloric with an inert filler as required. Live production variables were measured. Samples of birds were processed to determine carcass characteristics, and fatty acid composition of adipose tissue was determined. In all studies, broilers fed crude or refined sources of PAO and PKO grew as well and utilized their feed as efficiently as those fed diets with isocaloric amounts of CO or PO. There were minimal interactions of source and dietary level of oil in any of the studies. Dressing percentage and quantity of abdominal fat were not influenced by source of supplemental oil; however, the fatty acid profile of adipose tissue was altered by the source of supplemental oil. There were only minor differences in fatty acid content of adipose tissue of broilers fed PAO (either crude or refined) versus those fed PO. However, increasing levels of PKO resulted in increased deposition of saturated fatty acids, especially lauric and myristic acid, and decreased concentrations of both monoenoic and polyunsaturated fatty acids. The resulting change in hardness of adipose tissue may prove to be advantageous in marketing.

Effects of amino acid restriction during starter and grower periods on subsequent performance and incidence of leg disorders in male large white turkeys

Male Nicholas Large White turkeys were fed diets formulated to meet a minimum of 100, 110, or 120% of NRC (1984) amino acid recommendations. There were three periods when 75% of recommended standards were fed: 0 to 3 wk, 0 to 6 wk, or 6 to 12 wk. A fourth (control) group was not restricted at any time. Four pens of 12 males were fed each amino acid by restriction combination. At 18 wk, leg scores were assigned to all birds and representative samples of birds processed for parts yield. All birds fed restricted diets had significantly lower BW at 18 wk than unrestricted controls but did not differ in feed utilization. Dietary amino acid levels significantly influenced BW and feed utilization, but there was no interaction with restriction times. There were no significant effects of amino acid levels or restriction times on incidence of leg disorders. Breast meat yields (quantity and percentage of carcass) were significantly influenced by both restriction time and amino acid levels. There seemed to be little if any compensatory gain following amino acid restriction in these studies.

An evaluation of fructooligosaccharide in diets for broiler chickens and effects on salmonellae contamination of carcasses

Two similar trials were conducted to evaluate the effects of dietary inclusion of fructooligosaccharide (FOS) on live performance and carcass characteristics of broilers and on incidence and level of salmonellae on prechill broiler carcasses. The FOS was fed at two levels (0 and .375%) in a complete factorial arrangement with two levels (0 and 55 mg/kg) of bacitracin methylene disalicylate (BMD) in nutritionally complete diets. Broilers were grown to 49 days of age, and samples were processed to determine dressing percentage, abdominal fat content, and most probable number salmonellae on prechill carcasses. The addition of FOS to nutritionally complete broiler diets at .375% had little consistent effect on growth rate, feed utilization, mortality, carcass dressing percentage, abdominal fat content, or incidence or severity of salmonellae contamination of processed broiler carcasses. There appeared to be an antagonism between FOS and BMD on both live performance and salmonellae contamination of processed broiler carcasses.

Research note: does compensatory growth occur following withdrawal of salinomycin from the diet of broilers?

Two floor pen studies were conducted to determine whether compensatory growth occurs following withdrawal of the anticoccidial drug salinomycin from the feed of broilers reared to 46 days of age. There were no significant differences in weight gain or feed conversion between medicated and unmedicated birds whether overall performance or performance during the 1-wk withdrawal period was measured. Feed intake of birds given salinomycin, however, was significantly lower than that of unmedicated birds, and feed intake following withdrawal was greater than that of birds still receiving the drug.

Effects of protein and amino acid level fed zero to forty-two days on response of broilers to protein and amino acid levels fed forty-two to forty-nine days of age

Three studies were conducted to evaluate the effect of protein and amino acid (AA) levels fed 0 to 42 days posthatch on response of broiler chickens to levels of protein and AA fed during the finisher period. Birds were grown to 42 days on diets formulated to contain a minimum of 105 or 120% of recommended AA levels, and then randomly assigned to diets formulated to contain a minimum of 70, 80, 90, 100, 110, or 120% of recommended AA levels for 42 to 49 days. No minimum protein level was imposed on the diets. Body weight, feed intake, feed utilization, dressing percentage, abdominal fat content, and parts yield were determined. The protein and AA level fed 0 to 42 days had significant effects on 42- and 49-day body weight and 42- to 49-day feed intake of male but not female broilers. However, there was no interaction of protein and AA levels fed 0 to 42 days on response to protein and AA levels fed 42 to 49 days for these criteria. Weight gain, feed intake, and feed utilization of both males and females 42 to 49 days were significantly influenced by protein and AA levels fed during this time; protein and AA requirements of females during this time appeared to be equal to, or greater than, those of the male broiler. Although there were significant interactions of protein and AA levels 0 to 42 and 42 to 49 days on various carcass parameters for both male and female broilers, these followed no consistent pattern. Protein and amino acid levels fed 0 to 42 days had a significant influence on both quantity and percentage of abdominal fat in both male and female broilers processed at 49 days but not on any other carcass parameters. The protein and AA levels fed 42 to 49 days had a significant effect on both quantity and percentage of abdominal fat in male but not female broilers. The protein and AA levels fed 42 to 49 days significantly influenced quantity but not percentage of breast meat in male but not female broilers. The results of the current study indicate that there was minimal carryover effect of protein and AA levels fed 0 to 42 days on response to AA levels fed 42 to 49 days.

Effects of dietary amino acid level and duration of finisher period on performance and carcass content of broilers forty-nine days of age

Two studies were conducted to evaluate feeding reduced levels of amino acids (AA) to broilers during the finisher period. Birds grown to 42 days on nutritionally complete diets were fed diets formulated to contain a minimum of 70, 80, 90, 100, or 110% of recommended AA levels for periods of 3, 5, or 7 days prior to slaughter at 49 days of age. Body weight, feed intake, feed utilization, dressing percentage, and abdominal fat content were determined. For finisher periods of 3 to 5 days, a reduction in recommended dietary AA levels may be utilized without impairment of body weight gains of broilers. Extending the finisher period to 7 days resulted in significant (P less than .05) reduction of body weight gains on diets with AA levels less than 90% of recommended levels. Feed utilization was more sensitive to reduction in AA levels and may be affected adversely even by a 5-day withdrawal period. Dressing percentage was reduced in some instances, and abdominal fat generally increased when reduced AA levels were fed. The economics of feeding reduced AA levels must be considered in evaluating the results of the present studies.

Effects of bird density on Salmonella contamination of prechill carcasses

Two similar trials were conducted to evaluate the effects of bird density on Salmonella contamination of processed broilers. Commercial strain broiler chicks were reared in floor pens on new litter at densities of 557, 619, 697, 796, 929, and 1,115 cm2 per bird. Twenty percent of the chicks in each density were gavaged directly into the crop with .5 mL of 10(8) nalidixic-acid-resistant (NAR) Salmonella typhimurium on Day 2. Twenty percent of the uninoculated birds in each density category were processed at 42 days. Prechill carcasses were evaluated for NAR Salmonella incidence using the whole carcass rinse technique and a mechanical shaking device. The resulting NAR Salmonella contamination rates (from lowest to highest bird densities) were as follows, 55, 4.2, 35.7, 34.3, 88.9, and 20% in Trial 1; and 30, 20.8, 28.6, 50, 58.3, and 30% in Trial 2. A random sample of the prechill carcasses of gavaged birds indicated a contamination rate of 13.8% in Trial 1 and 61.1% in Trial 2. The NAR Salmonella contamination rates of the prechill carcasses did not appear to be affected by the bird densities evaluated in these trials. Feed intake and body weight at 42 days were adversely affected by the highest bird density, but feed utilization was not affected.

Effects of dietary lactose on incidence and levels of salmonellae on carcasses of broiler chickens grown to market age

Two trials were conducted to evaluate the effects of lactose in the diet of broilers grown to market weights on incidence and levels of salmonellae on the carcass. Lactose was substituted for sand in otherwise nutritionally complete diets at levels of 0, 2.5, 5, and 7.5% and fed from day-old to 49 days of age. Birds were reared on used (Trial 1) or new (Trial 2) litter and inoculated via the drinking water on Days 2, 7, and 14 with 10(8) cfu/mL Salmonella typhimurium (ATCC 14028). At 50 days, 12 (Trial 1) or 24 (Trial 2) birds per treatment were processed and prechill carcasses were evaluated for salmonellae incidence and level by the most probable number (MPN) method. Body weight of male broilers was significantly reduced by feeding diets containing up to 7.5% lactose. Feed intake of broilers fed diets containing lactose was significantly reduced and feed utilization improved, suggesting that lactose provided some metabolizable energy. The degree of litter caking was significantly increased, and cecal pH was significantly decreased as dietary lactose increased. Prechill carcases of broilers fed diets with 7.5% lactose had significantly higher levels of salmonellae than did prechill carcasses of broilers fed 0% lactose. The results of the present study suggest that supplementing poultry diets with lactose is not a viable means in itself of reducing or eliminating salmonellae incidence or levels on processed broiler carcasses.

Effect of dietary protein level and length of feeding on performance and abdominal fat content of broiler chickens

Dietary CP levels influence carcass fat content of chickens but the length of time necessary to feed higher levels in order to increase carcass fat is not known. Studies were conducted to evaluate the effects of length of feeding of different levels of dietary CP on broiler performance and abdominal fat deposition. All diets were calculated to be isocaloric at 3,200 kcal ME/kg. Broilers fed 23% CP for 0 to 21 days, 20% CP for 21 to 42 days, and 18% CP for 42 to 49 or 42 to 56 days served as the control group in each of two trials. In the first trial, broilers were fed constant levels of CP from day-old to market age with CP levels ranging from 15 to 27% (amino acids adjusted in proportion to CP level). Other broilers were fed 23% CP for 0 to 21 days and then fed either 15, 17, 19, or 21% CP to market age. In the second trial, broilers were fed constant levels of CP (18, 20, or 23%) from day-old to market age. Feeding CP levels lower than those fed the control group had a more pronounced effect on males than on females, with the primary effects being reduced body weight, poorer feed utilization, and increased carcass fat content. Feeding CP levels higher than those fed the control group generally did not increase final body weight but generally improved feed utilization and decreased carcass fat content. The economics of improved feed utilization and reduced carcass fat must be considered in determining dietary CP levels to use at different ages for growing broilers.

Comparison of different anticoccidials on processing characteristics and parts yield of broiler chickens

Broilers were grown to 42 days of age on diets supplemented with salinomycin (60 mg/kg), monensin (99 mg/kg), or halofuginone (3 mg/kg) and continued on unmedicated diets to 49 days of age. There were no significant (P greater than .05) differences among anticoccidials in final body weight, feed conversion, or mortality rates. Samples of birds were processed for dressing percentage and parts yield. Both males and females fed salinomycin had significantly higher breast meat yield as a percentage of postchill weight than those fed halofuginone but not those fed monensin; differences were not significant for breast meat yield of males or females fed monensin or halofuginone. Males fed halofuginone had significantly heavier leg quarters than those fed salinomycin but not those fed monensin. Females fed salinomycin had significantly higher water uptake during chill than those fed monensin or halofuginone. Results of the present study indicate that the anticoccidial used in growing broilers may influence some carcass yield parameters.

Research note: fumaric acid enhances performance of broiler chickens

Two studies were conducted to examine the effects of dietary inclusion of fumaric acid on performance and carcass composition of broiler chickens. Fumaric acid was added to nutritionally complete diets at levels of 0, .125, .25, and .5% and fed from 1 to 49 days under simulated commercial conditions. In one trial, samples of birds were processed to determine dressing percentage and abdominal fat content. In the first trial (mixed sex broilers), the addition of .125% fumaric acid significantly (P less than .05) improved 49-day body weight of females and average weight gain of both sexes with no effect on feed utilization. Feed consumption was significantly increased when diets contained .125 or .50% fumaric acid. In the second trial (male broilers), 49-day body weight was significantly (P less than .05) improved by the addition of .125 and .25% fumaric acid. There were no significant differences in feed consumption; feed utilization was improved by the addition of all levels of fumaric acid. Dietary fumaric acid had no adverse effects on dressing percentage, abdominal fat content, or mortality rate.

Effects of dietary amino acid levels on performance and carcass composition of broilers 42 to 49 days of age

Broilers were grown to 42 days on nutritionally complete diets. From 42 to 49 days in two trials, broilers were fed diets formulated to contain 70, 80, 90, 100, 110, or 120% of recommended amino acid (AA) values. In four additional trials, the same AA levels were fed; in addition, Met and Lys were added to diets formulated to contain 70, 80, and 90% to equal levels of the 110% AA diet. Body weight gain (BWG), feed consumption (FC), feed conversion (FCR), dressing percentage (DP), and abdominal fat (AF) were measured. From 42 to 49 days, dietary AA levels had little effect on BWG, DP, or AF of female broilers. When male broilers were fed diets containing less than 100% of the recommended AA levels, BWG was reduced and AF increased. Broiler FC increased and FCR decreased as the AA level of the diet decreased. The addition of Met and Lys to the 90% AA diet improved performance; however, the addition of Met and Lys to the 70% AA diet had no beneficial effect. Amino acid levels may be reduced in broilers diets fed from 42 to 49 days; however, male broilers are more sensitive than females to reductions in AA levels during this period.

Effects of dietary amino acid levels on bone development in broiler chickens

Studies with several species suggest that dietary protein may influence bone calcification. Six pens of six male broilers in two consecutive trials were fed from 1 to 21 days either .5 or 1.0% Ca in diets with 80, 90, 100, 110, or 120% of the amino acid (AA) standards suggested by Thomas et al. in 1986 at a constant .46% nonphytate P. The BW and feed conversion rate (FCR) were determined, and bone measurements were taken. Both AA and Ca levels influenced BW with an interaction of the two factors. The Ca level, but not AA level, influenced FCR. The lower Ca level inhibited feed intake. Increasing AA levels reduced bone ash but did not affect tibia breaking strength. There was an interaction of AA and Ca on tibia ash, tibia weight, and tibia length. The higher AA levels supported normal linear growth of the tibia but decreased rate of calcification, especially in the diets with .5% Ca. In diets with marginal Ca levels, higher AA levels may reduce bone calcification.

Efficacy of different anticoccidials against experimental coccidiosis in large white turkeys

Two trials were conducted to compare the efficacy of currently approved anticoccidials for turkeys against challenge using a field isolate of mixed Eimeria species; E. adenoides, E. gallopavonis, and E. meleagrimitis. Poults in wire-floored cages were fed unmedicated diets from day-old to 3 wk of age. Diets were supplemented with either amprolium (AMP, 125 mg/kg), butynorate (BUT, 375 mg/kg), monensin (MON-60, 60 mg/kg; MON-100, 100 mg/kg), halofuginone (HAL; 3 mg/kg), zoalene (ZOA; 125 mg/kg), or sulfadimethoxine plus ormetoprim (SUL + ORM, 62.5 mg/kg and 37.5 mg/kg, respectively). After 2 days on the test diets, poults were individually weighed and inoculated with sporulated coccidial oocysts from the field isolate. Total fecal collections were obtained for Days 0 to 5 and 6 to 10 to estimate oocyst output. At 10 days postinoculation, the birds were individually weighed and killed to determine severity of intestinal lesions. The HAL and MON were most effective and AMP, ZOA, and SUL + ORM were least effective in maintaining weight and in reducing the severity of intestinal lesions. All the coccidiostats tested reduced oocyst passage, but poults fed HAL produced fewer oocysts. The results demonstrated differences in efficacy among anticoccidials with the more recently approved drugs providing the best protection against coccidiosis.

Effects of different coccidiostats on performance of large white turkeys

Two trials were conducted to evaluate the effects of feeding various anticoccidial products to turkeys to 8 wk and then growing to market age (16 wk for hens and 20 wk for toms). Anticoccidials evaluated in the first trial included amprolium at 187.5 mg/kg for 0 to 4 wk and 125 mg/kg for 4 to 8 wk; butynorate at 375 mg/kg for 0 to 8 wk; monensin at both 60 (MON-60) and 100 mg/kg for 0 to 8 wk; zoalene at 187.5 mg/kg for 0 to 4 wk and 125 mg/kg for 4 to 8 wk; and halofuginone at 3 mg/kg for 0 to 8 wk. In the second trial, MON-60 was replaced by a combination of sulfadimethoxine (62.5 mg/kg) plus ormetoprim (37.5 mg/kg) for 0 to 8 wk. In each trial each treatment was fed to four pens of 16 hens and four pens of 12 toms. Several of the anticoccidials significantly influenced the weight of both hens and toms by producing lower weights at the end of the 8-wk feeding period than birds in other treatments. However, after removal of the anticoccidials, compensatory gains were observed in almost every instance. Significant effects of previous anticoccidial feeding were noted on body weight of hens at 16 wk but not on weights of toms at 20 wk.

Effects of formic acid or calcium formate in feed on performance and microbiological characteristics of broilers

Three experiments were conducted to determine the effects of feeding broilers formic acid (FA) or calcium formate (CF) on performance and microbiological characteristics of broilers. Live bird performance was not adversely affected by feeding up to 1.0% FA or 1.45% CF. In Experiment 1, levels of salmonellae in carcass and cecal samples were significantly reduced by feeding birds .36% CF. Salmonellae were not isolated from any of the carcasses of birds fed .36% CF. Similar reductions were not noted for total organisms or presumptive coliforms. In Experiment 2, feeding .36% CF nonsignificantly reduced levels of salmonellae in carcass and cecal samples, but again, levels of total organisms and coliforms were not reduced. In Experiment 3, salmonellae in the ceca or in the carcass rinse fluid were not reduced by feeding .36% CF.

Effects of different antibiotics on performance, processing characteristics, and parts yield of broiler chickens

Broilers were grown to 49 days of age on diets supplemented with bambermycins (BAM, 2.2 ppm), bacitracin methylene disalicylate (BMD, 27.5 ppm), virginiamycin (VM, 11 ppm), or an unmedicated control. Samples of birds were processed for dressing percentage and parts yield. There were no significant (P greater than .05) effects of antibiotics on final body weight, feed conversion, or mortality. In male broilers, BMD and VM significantly (P less than or equal to .05) increased dressing percentage and percentage yield and reduced the skeletal rack as a percentage of postchill weight compared to those fed the nonmedicated control. All antibiotics significantly increased breast skin weight and breast skin as a percentage of postchill weight of as compared with those fed the unmedicated control. In female broilers, BAM and BMD significantly increased dressing percentage and percentage yield and increased breast weight and breast as percentage of postchill weight as compared with those fed the unmedicated control diet. Females fed BMD also had significantly heavier leg quarters and breast skin than those fed the unmediated control. Females fed VM had increased breast skin weight and breast skin as a percentage of postchill weight than those fed the unmedicated control. The results of the present study indicate that antibiotics may influence dressing percentage and parts yield in the absence of improvements in body weight gain or feed utilization.

The effects of energy and amino acid levels on performance and carcass quality of male and female broilers grown separately

Studies were conducted to evaluate the response of male and female broiler chickens to diets containing different levels of energy and amino acids. Two energy series were compared: 3,080, 3,135, and 3,190 kcal of ME/kg ("low") and 3,190, 3,245, and 3,300 kcal of ME/kg ("high") in pelleted starter, grower, and finisher diets. Diets provided a minimum of 85, 90, 95, 100, 105, and 110% of suggested amino acid recommendations for the broiler male except for Met and TSAA, which were kept at 105%. Modifications were made in feeding periods, recognizing the differences in rate of gain and marketing ages of the two sexes. Feeding periods were 0 to 21, 21 to 42, and 42 to 56 days for males and 0 to 18, 18 to 35, and 35 to 49 days for females. Four floor pen trials utilizing 9,600 male and 9,600 female broilers were conducted. Birds were processed to determine dressing percentage and abdominal fat pad weights. Energy content of the diets had no significant (P greater than .05) effect on body weight or feed efficiency for male or female broilers. Carcass dressing percentage of females, but not males, was significantly (P less than .05) increased on the high energy series. Abdominal fat pad was not influenced by energy for either sex. For both sexes, increasing dietary amino acid levels resulted in significant (P less than or equal to .05) linear improvements in live weights and feed utilization and a reduction in abdominal fat pad weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of feeding lasalocid on performance of broilers in moderate and hot temperature regimens

Three trials were conducted in environmental chambers to study the effects of feeding lasalocid on broiler performance. Birds were randomly assigned at 31 or 35 days of age to one of four treatment groups: hot cyclic (26.7 to 37.8 C and 90 to 40% RH) with basal diet; hot cyclic with lasalocid diet (88 mg/kg); moderate constant (21 C and 50% RH) with basal diet; or moderate constant with lasalocid diet. All birds were killed and processed 2 wk after the start of each trial. Percentage of carcass yield and fat pad weight were determined. In the moderate temperature regimen, lasalocid feeding caused a depression in the 2nd wk gain (469 versus 486 g) but not in the final 2-wk gain. In the hot temperature regimen, birds fed lasalocid gained significantly more weight in the 2nd wk than those fed the basal diet (341 g versus 325 g) and had a significantly better feed conversion in the 2nd wk (2.04 versus 2.61) and overall (2.07 versus 2.32) than those fed the basal diet.

The effect of zinc bacitracin and roxarsone on performance of broiler chickens when fed in combination with narasin

Six trials were conducted at various locations to determine the response of broiler chickens to combinations of zinc bacitracin and roxarsone when fed in the presence of narasin. The addition of zinc bacitracin at 55 mg per kg significantly improved growth rate and feed utilization when data from all locations were combined. There was no effect of roxarsone fed at 50 mg per kg on BW or feed utilization, nor was there an interaction of roxarsone and zinc bacitracin on BW. There was a significant interaction of roxarsone and zinc bacitracin for feed utilization; addition of zinc bacitracin significantly improved feed utilization both in the presence and absence of roxarsone, but the improvement was greater in the absence of roxarsone.

Effects of a buffered propionic acid in diets on the performance of broiler chickens and on microflora of the intestine and carcass

A buffered propionic acid (BPA) was added to broiler diets fed in floor pens with litter. The BPA was fed continuously at 0, .2, .4, and .8% in Trial 1 and at 0 and .4% in Trial 2. The BPA was also fed at .4% for the last 7 days in Trial 2. Natural salmonellae exposure versus periodic dosage with Salmonella typhimurium was compared in Trial 2. In Trial 1, the BPA supplement had no adverse effects on growth, feed utilization, or abdominal fat with a significant (P less than or equal to .05) increase in the female dressing value at .8% of buffered propionic acid. The total number of coliforms and of Escherichia coli in the duodenum were significantly reduced by .4% BPA; in the jejunum, by all levels used in the trials; and in the ileum, by .4% and .8% of buffered propionic acid. The intestinal pH was not influenced by the BPA addition. In Trial 2, the BPA at .4% fed continuously had no adverse effect on growth, feed utilization, the abdominal fat of females, or the dressing percentage of males while significantly reducing the abdominal fat for males and increasing the dressing percentage for females. Feeding .4% BPA for the last 7 days had no effect on any of these parameters. Periodic dosage with S. typhimurium had no effect on body weight, feed utilization, or abdominal fat and significantly increased the dressing percentage. There was a significant interaction between the Salmonella dosage and the time of feeding BPA on dressing percentage.(ABSTRACT TRUNCATED AT 250 WORDS)

Production and Processing Studies to Reduce the Incidence of Salmonellae on Commercial Broilers 1, 2

A series of experiments have been conducted at the University of Arkansas over the last two years in efforts to decrease the incidence of salmonellae on commercial broilers. These experiments have concentrated on feeding trials in efforts to alter intestinal microflora, and processing trials in which chemical additives have been evaluated. A buffered propionic acid compound was fed at various concentrations for specific time periods and the cecal tonsils, small intestine, litter, and processed carcasses were tested for salmonellae and other organisms. In a separate series of trials a variety of chemicals were added to the scald, chill, scald and chill, or used as pre- or post-chill dips or sprays in efforts to decrease carcass contamination with salmonellae and extend product shelflife. Feeding trials indicate that the addition of a buffered propionic acid can alter intestinal microflora and decrease contamination of the processed carcass without adversely affecting live bird performance. Processing trials indicate that certain chemicals such as lactic acid can be used in a variety of ways to either decrease or eliminate salmonellae from the carcass and extend shelflife of processed broilers. However, some chemicals at high concentrations may produce undesirable organoleptic characteristics.

Effects of ethoxyquin feed preservative and peroxide level on broiler performance

Rancidity development in feeds and feed ingredients reduces the feeds' nutritive value and produces toxic peroxides. This investigation was conducted to determine the effects of different levels of peroxide on broiler performance and to determine the effectiveness of ethoxyquin in ameliorating the adverse effects of peroxides. Poultry fat was oxidized to contain 0, 50, 100, and 175 meq peroxide/kg and added to diets to provide 0, 2, 4, or 7 meq peroxide/kg feed, respectively. Liquid ethoxyquin was incorporated into the diets at 0, 62.5, and 125 ppm. Each of the 12 diets was fed to 8 replicate pens with 35 males and 35 females/pen. Body weights at 21 and 42 days of age were significantly lower in birds fed diets containing 4 or 7 meq peroxide/kg feed. At 49 days of age, the reduction in body weight was significant only at the 7 meq/kg level. Reductions in feed efficiency showed a similar pattern, but the depression was significant only at the highest peroxide level. Supplementation of 62.5 and 125 ppm ethoxyquin resulted in significantly heavier birds at 49 days of age but had no significant effect on feed efficiency. Beneficial effects of ethoxyquin supplementation were evident at higher peroxide levels. The study showed that at least 4 meq peroxide/kg feed was required to significantly affect bird performance, and that the addition of ethoxyquin could alleviate the deleterious effects of dietary peroxide.

Estimation of the tryptophan requirement of male broiler chickens

Three experiments were conducted to determine the response of the male broiler chick to tryptophan (TRP) supplementation. Chicks were fed from 7 to 18 or 7 to 20 days posthatch either a grain sorghum-soybean meal diet containing .16% TRP, supplemented with 0, .02, .04, .06, .09, or .11% L-TRP, or a corn-soybean meal positive control diet containing .25% TRP. Levels of TRP in all diets were confirmed by ion-exchange chromatography using an alkaline hydrolysis. The test diet contained 15.34% CP (N x 6.25) from intact ingredients and 20% CP (N x 6.25) when supplemented with other amino acids to 110% of National Research Council recommendations in 1984. No improvement in gain or feed efficiency was observed with chicks fed the grain sorghum-soybean meal diet at any level of TRP supplementation. Feed utilization but not weight gain of the chicks fed the TRP-supplemented test diets was significantly poorer than that of chicks fed the corn-soybean meal positive control diets. These results suggest that the TRP requirement of the young (0 to 21-day-old) broiler chicken is no greater than .16% of a diet containing 3,200 kcal ME/kg.

Ascorbic acid and acetylsalicylic acid (aspirin) in the diet of broilers maintained under heat stress conditions

Male broiler chicks were grown to 21 days of age under normal conditions, then placed in environmental chambers maintained under constant (24 C) or cyclic (24 to 35 C) heat conditions. Chicks were acclimated for 1 wk on a standard grower basal diet. Standard grower basal diets were fortified with 0, 125, 250, 500, or 1,000 ppm coated ascorbic acid (AA) or 0, 125, 250, or 500 ppm acetylsalicylic acid (ASA). Test diets were fed for 14 days in two separate studies. Cyclic heat conditions reduced feed intake and significantly reduced weight gains in both trials. Feed efficiency was not significantly affected by heat stress. Neither AA or ASA had beneficial effects on broiler growth or feed efficiency.

Use of organic acids in broiler diets

Two feeding trials were carried out to determine the potential use of fumaric acid and calcium formate in diets for broiler chickens. In the first study using male broiler chicks fed to 21 days of age, fumaric acid was added at 0, .5, 1.0 and 1.5% and calcium formate was added at 0, .72, 1.48, 2.20, and 2.89%. All combinations of fumaric acid and calcium formate were evaluated in a 4 x 5 factorial arrangement of treatments. Addition of .5 or 1.0% fumaric acid significantly (P less than .05) improved body weights of broilers but did not influence feed utilization. Addition of calcium formate at levels greater than .72% significantly reduced both body weight and feed utilization. There was no significant interaction between levels of fumaric acid and calcium formate. In a second trial, male and female broiler chicks were grown to 49 days of age using diets containing 0, .5, 1.0, and 1.5% calcium formate. Addition of .5 or 1.0% calcium formate had no significant effect on weight gains or feed utilization. Addition of 1.5% calcium formate significantly reduced body weights of both males and females at 21 and 42 days. At 49 days of age, body weights of males fed 1.5% calcium formate did not differ from those of males fed the control diet, but were significantly less than those of males fed diets with .5 or 1.0% calcium formate. Female body weights at 49 days of age were significantly depressed by addition of 1.5% calcium formate.

Performance and yields of broilers fed extruded grain amaranth and grown to market weight

A trial was conducted to determine the effects of feeding extruded grain amaranth (Amaranthus cruentus) on performance of male broilers grown in batteries to 49 days of age. Practical corn-soy rations were supplemented with 0, 10, 20, 30, 40, or 50% amaranth and formulated to meet nutrient requirements for the starter (0 to 21 days), grower (21 to 42 days), and finisher (42 to 49 days) periods. Each diet was fed to six replicate pens of 10 male birds each. No differences were observed for feed utilization (P greater than .05), but at Day 49, birds fed 50% amaranth weighed significantly less and had significantly lighter dressed carcass weights than those fed the control diet. For dressing percentages, no significant differences among diets were observed. Dietary differences in fat pad weights were not detected, but significant differences between diets were observed for fat pad weights expressed as a percentage of the total carcass weight (% OTC). Significant and positive linear responses existed when liver weight, liver weight as % OTC, and fat pad weight as % OTC were regressed upon amaranth inclusion. No treatment differences were observed for heart or pancreas weights or for their weights as % OTC. Gizzard weight and gizzard weight as % OTC decreased linearly with amaranth inclusion. Giblet weights (heart + liver + gizzard) were significantly different among diets, but giblet weight appeared to be unrelated to amaranth level. Birds fed the diet with 50% amaranth had giblets of equal size to birds fed the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of extruded grain amaranth as a feed ingredient for broilers. 2. Apparent amino acid availability values

Apparent amino acid availabilities (AAAA) were determined for grain amaranth in two experiments using broilers. Total collection method (TCM) and acid-insoluble ash (AIA), as a marker, were used for these determinations. Individual amino acid availabilities for the extruded grain were calculated both by regression analysis and by difference from the basal diet. From the linear regression equations, TCM produced more accurate results than did the AIA method, based on standard errors of the intercept and coefficient of determination. Predicted AAAA, based on linear regression equations, from the TCM were 92.4, 79.9, and 89.4% for methionine, lysine, and arginine, respectively. Using the TCM and calculation by difference, average AAAA on an as-fed basis were 85.0, 79.1, and 92.9% for methionine, lysine, and arginine, respectively. The AAAA of 11 other amino acids were also determined.

Assessment of extruded grain amaranth as a feed ingredient for broilers. 1. Apparent metabolizable energy values

Two trials were conducted to determine the apparent metabolizable energy (AME) and nitrogen-corrected AME (AMEn) of extruded grain amaranth (Amaranthus cruentus). Procedures for these determinations were the total collection method (TCM) and the use of acid-insoluble ash (AIA) as a marker. The AME and AMEn values for the grain were determined both by regression analysis and by calculations based on differences from the basal diet. Based on standard errors of the predicted values and coefficients of determination of the regression equations, TCM produced more accurate results than did AIA. Using regression analysis, the predicted values from the TCM were 3,382 kcal/kg of AME and 3,267 kcal/kg of AMEn on an as-fed basis. When expressed on a dry-matter basis, these values were 3,646 and 3,522 kcal/kg for AME and AMEn, respectively. When the difference method was used to calculate the ME of the extruded grain on an as-fed basis, the values of 3,295 kcal/kg of AME and 3,164 kcal/kg of AMEn were obtained. When the results were expressed on a dry-matter basis, 3,556 kcal/kg of AME and 3,415 kcal/kg of AMEn were determined.

Feather meal as a nonspecific nitrogen source for abdominal fat reduction in broilers during the finishing period

Earlier studies have shown that excessive abdominal fat deposition in broilers can be overcome by feeding feather meal (FM) during the finishing period (7 or 14 days prior to slaughter). Studies were conducted to determine if the observed fat reduction in FM-fed birds was due to factors other than supplying excess protein. The FM was added at levels of 4, 6, and 8% and glycine at levels of .125, .25, and .5%, similar to amounts contributed by corresponding levels of FM. Corn-soybean diets were also formulated at protein levels corresponding to those of FM diets. All experimental diets were fed from 35 to 49 or from 42 to 49 days of age. There were no significant differences in weight gain and feed efficiency of treatment and control groups during the study. The addition of glycine resulted in a significant (P less than .05) reduction in abdominal fat content and appeared to be partially responsible for the observed reduction in FM-fed birds. Increasing the dietary protein level also significantly (P less than .05) reduced abdominal fat deposition regardless of protein source. The study indicates that lower quality protein sources such as FM can be effectively used as a nonspecific nitrogen source for reducing abdominal fat deposition during the finishing period.

Response of broiler chickens to dietary supplementation with roxarsone and bacitracin methylene disalicylate in diets containing narasin

Six trials were conducted at different locations to examine the response of broiler chickens to roxarsone and bacitracin in the form of bacitracin methylene disalicylate (BMD) in the presence of the anticoccidal narasin. All diets contained narasin (80 mg/kg) and were fortified with a factorial arrangement of roxarsone (0 to 50 mg/kg) and BMD (0 or 55 mg/kg). Broilers were grown to market weights with narasin and roxarsone removed from the diets for the final 5 days. Addition of both roxarsone and BMD resulted in significant (P less than .05) improvements in body weight and feed utilization. Response to roxarsone for feed utilization was influenced to some extent by the presence or absence of BMD. Although the response to roxarsone was always positive, the degree of response was lessened by the presence of BMD. This resulted in a significant (P less than .10) interaction between roxarsone and BMD for feed utilization but not for body weight.