Effect of feeding low-oil distillers dried grains with solubles on the performance of broilers.

Manufacturers of distillers dried grains with solubles (DDGS) are changing practices to extract corn oil from DDGS in the process of ethanol production. The resulting product is called low-oil DDGS (LO-DDGS) and may be included in broiler diets. Two LO-DDGS and one unextracted DDGS were used in a broiler performance trial to determine maximum levels of inclusion without detrimental effects. Corn- and soybean meal-based mash diets were used with different DDGS samples included at 10 or 20%. Six hundred thirty Cobb 500 male by-product chicks were randomly assigned to 6 replicate pens containing 15 chicks each and fed diets from 0 to 18 d of age. There was a significant interaction between source and level on BW at d 11 and 18 when 10 and 20% of LO-DDGS was included compared with the control group. There was also a significant effect of source and level interaction on BW at d 18 (P < 0.05). Feed efficiency from d 0 to 18 was improved when 10% LO-DDGS was used compared with 20% inclusion. Abdominal fat pad weights were higher when LO-DDGS samples were included at 10 or 20% compared with the control group. There was a significant effect of DDGS source and level on fat pad weights (P < 0.05). Producers may achieve an increase in performance when including 10% LO-DDGS in broiler diets. Up to 20% inclusion levels may have no detrimental effects on performance parameters compared with a standard corn-soybean diet.

Amino acid digestibility and metabolizable energy of genetically selected soybean products.

To determine the ME and amino acid digestibility of 5 soybean meal (SBM) samples, a precision-fed rooster assay and a chick assay were conducted. The 5 samples were cold-pressed (extruded) soybean meals or solvent-extracted (defatted) soybean meal. Of the cold-pressed varieties (unheated), there was an ultra-low trypsin SBM, a low-trypsin SBM, and a heated and unheated commodity SBM. The solvent-extracted SBM was a heated commodity blend. The TME and AME values were compared between each category: cold-pressed and defatted, as well as between the 2 assays. Semipurified diets containing dextrose as the main energy source were formulated to meet the bird's nutrient requirements, with each diet containing a different SBM product. The TME rooster assay was a precision-fed rooster assay in which 5 birds per diet were fasted for 24 h, crop intubated with 35 g of the test diet containing 46.58% cold-pressed or defatted SBM, and excreta was then collected for 48 h. The total aromatic amino acids rooster assay followed the same protocol, but cecectomized birds were used. For the chick assay, 480 one-day-old chicks were fed a standard corn-SBM starter diet until 17 d of age, and on d 18, the chicks were allowed ad libitum access to the SB-dextrose diets. Excreta were collected on d 22, dried, ground, and analyzed for gross energy and CP to determine ME. The SBM samples that were genetically selected to have lower trypsin inhibitor levels and higher protein had higher ME values and increased amino acid digestibility than the commodity cold-pressed SBM samples. Genetic selection of soybeans for certain traits can have positive effects on the ME value and amino acid digestibility for roosters and chicks.

Tolerance and efficacy of tribasic manganese chloride in growing broiler chickens.

These studies were designed to determine the relative bioavailability and tolerance of tribasic Mn chloride (TBMC) for growing broiler chickens. In experiment 1, birds were fed a basal diet (starter, 102 ppm; grower, 209 ppm) or the basal diet supplemented with 3,600, 4,500, or 5,400 ppm Mn from either TBMC or manganese sulfate (MnSO(4)), and BW, feed intake, and plasma Mn were measured. In experiments 2 and 3, diets included the basal diet (45 and 43 ppm Mn, respectively) and the basal diet supplemented with graded levels of either TBMC or MnSO(4) ranging from 30 to 240 ppm Mn. Body weight and feed intake were measured and tibia, bile, and liver were collected for mineral analysis; heart samples were taken for manganese superoxide dismutase activity, protein, and relative mRNA abundance. In experiment 1, BW differed among treatments, with higher Mn leading to lower BW (P < 0.05). Birds from all treatments showed higher plasma Mn than birds fed the basal diet. Birds supplemented with the highest level of MnSO(4) had the highest level of plasma Mn (P < 0.05). In experiment 2, tibia and liver Mn increased with higher dietary Mn regardless of source (P < 0.05). Liver Mn increased up to the 60 ppm diets whereas Mn in the tibia was highest with the 130 ppm diets. Bile Mn increased with increasing dietary Mn, but these differences were not significant. In experiment 3, manganese superoxide dismutase activity, protein, and relative mRNA abundance were not affected by diet. The calculated bioavailabilities of TBMC and MnSO(4) did not differ significantly (P > 0.20). Together, these results indicate that TBMC is as effective as and better tolerated than MnSO(4) and that supplementing Mn at the lowest level used in this study may be sufficient for normal development of broiler chickens.

Effect of dietary nucleotide supplementation on performance and development of the gastrointestinal tract of broilers.

1. Two experiments were conducted to determine the effects of dietary nucleotide supplementation on broiler performance, and physical and morphological development of the gastrointestinal tract. 2. Experiment 1: A total of 180 one-d-old male chicks were placed in battery brooders in 3 × 6 replicate pens containing 10 chicks each. Chicks were randomly assigned to one of the three dietary treatments; a maize-soyabean meal based diet supplemented with 0, 0·25, and 0·50% Torula yeast RNA (as a source of nucleotides) from 0 to 16 d of age. 3. Experiment 2: A total of 1344 one-d-old male chicks were placed in floor pens and reared on recycled wood shavings (two flocks) under a high stocking density (0·068 m(2)/bird). Chicks were randomly assigned to one of the 4 dietary treatments (0, 0·25% Torula yeast RNA, 2% and 6% Nupro®) for the starter period (0 to 14 d of age) with 6 replicate pens containing 56 chicks each. All the birds were fed on the same common grower diet with no supplementation of nucleotides from 15 to 32 d of age. 4. Experiment 1: Supplementing the diets with up to 0·50% Torula yeast RNA did not affect broiler performance, or relative intestinal tract weight and length of broilers at any periods measured. 5. Experiment 2: From 0 to 14 d of age, broilers fed on the diets supplemented with 0·25% Torula yeast RNA and 2 and 6% Nupro® were significantly heavier and had improved feed conversion (feed:gain) ratios as compared with the birds fed on the control diet. Supplementing the starter diet only with 2% Nupro® supplementation significantly improved body weight (BW) gain as compared with the control diet over the entire experiment (0 to 32 d of age). Broilers fed on the diets supplemented with 2 and 6% Nupro® from 0 to 14 d of age had better feed conversion (feed:gain) ratios over the entire experiment (0 to 32 d of age) as compared with the birds fed on the control diet, even though the birds were only fed on the diets supplemented with Nupro® from 0 to 14 d of age. The broilers fed on the diets supplemented with 0·25% Torula yeast RNA and 2% Nupro® had higher villus height and an improved villus height-to-crypt depth ratio as compared with birds fed on the control or 6% Nupro® diet at 14 d of age. 6. It is generally assumed that nucleotides are not an essential nutrient; thus there is no need to supplement the diets of broilers reared under normal conditions. However, dietary nucleotide supplementation may be important to maintain maximum growth performance when birds are exposed to stress conditions, such as high stocking density combined with dirty litter.

Evaluation of the bacterial community and intestinal development of different genetic lines of chickens.

The gastrointestinal tract (GIT) of each animal species provides a unique niche for specialized intestinal bacterial communities to thrive, and in poultry this is no exception. However, little is known about how the bacterial community varies among these different genetic lines of chickens, especially of those with various growth rates. Therefore, an experiment was conducted to observe and evaluate the changes in the bacterial community and GIT development of a modern multipurpose strain, high-yield strain, and a historic strain, Athens Canadian Random Bred (ACR), of broilers. All birds were fed a standard nonmedicated corn-soybean meal broiler starter diet ad libitum from 0 to 35 d of age. Intestinal measurements and bacterial analysis of the ileum were conducted at 4, 8, 14, 21, and 35 d of age. Bacterial DNA was isolated from the digesta, and the distribution of bacterial 16S rRNA sequence polymorphisms was analyzed by a combination of denaturing gradient gel electrophoresis and terminal restriction fragment length polymorphisms. The multipurpose chicks performed the best from 0 to 14 d of age; however, overall performance was similar for the multipurpose and the high-yield broilers. The ACR birds had the poorest performance at all periods measured. The overall relative weight of the jejunum and ileum was not different between the 3 genetic lines, but the ACR birds had the longest relative jejunum and ileum lengths. Furthermore, the multipurpose birds had the longest villi height, whereas the ACR birds had the shortest villi height in the jejunum and ileum at all measuring periods. Based on denaturing gradient gel electrophoresis, the multipurpose and high-yield broilers had similar bacterial communities at all ages. Regardless of the genetic line of broiler, the bacterial community changed with age. Performance, GIT measurements, and bacterial community of the ACR differed compared with the modern broilers. The results indicate that the different genetic lines of broilers have varying rates of intestinal development, which may affect performance and the bacterial community.

The effect of gender on the bacterial community in the gastrointestinal tract of broilers.

The effect of gender on the growth, carcass yield, and nutritional requirements of chickens has been well documented, but little is known about how the sex of a chicken affects the bacterial population of the gastrointestinal tract. Therefore, our objective was to evaluate the biodiversity of the bacterial community in the gastrointestinal tract of male and female broilers. An experiment was conducted with Cobb 500 broiler chicks that were vent sexed at 0 d of age and allocated to 8 pens of 25 chicks per gender. All birds were fed a nonmedicated corn-soybean meal starter diet from 0 to 21 d of age. At 3, 7, 14, and 21 d of age, chicks were randomly selected and ileums were taken for bacterial sampling. Bacterial DNA was isolated from the digesta of the ileum, and denaturing gradient gel electrophoresis was used to examine PCR-amplified fragments of 16S ribosomal DNA. Denaturing gradient gel electrophoresis analyses revealed that the bacterial communities separated into 2 gender-specific groups, with less than 30% similarity between populations. Furthermore, as the birds aged, the similarity of the intestinal bacterial community decreased within each gender. Although ileal bacterial population differences within and between genders were noted as early as d 3, differences in growth rate between males and females were not noted until d 21 (data not shown). This suggested that non-growth-related factors influenced the composition of intestinal bacterial communities.

The effect of supplemental glutamine on growth performance, development of the gastrointestinal tract, and humoral immune response of broilers.

Two experiments were conducted to evaluate the effect of supplemental Gln on growth performance, development of the gastrointestinal tract, and humoral immune response of broilers. Immediately after hatch 6 replicate pens of 6 chicks were randomly assigned to 1 of 7 (experiment 1) or 5 (experiment 2) dietary treatments for 21 d. On d 4, 7, 14, and 21, twelve chicks per treatment (2 chicks/pen) were killed for thymus, spleen, bursa, duodenum, jejunum, ileum, bile, and blood sample collections and weights. In experiment 1, the effect of 1 or 4% Gln addition to the feed, water, or both was compared with a corn-soybean meal (SBM) control diet. All diets were formulated to be isocaloric and isonitrogenous. Weight gain improved significantly (P < 0.05) when chicks were fed diets with 1% Gln as compared with chicks fed the control diet (11% average improvement). The addition of 4% Gln to the diet or water depressed (P < 0.05) growth performance. Based on the results from experiment 1, 1% Gln supplementation to the diet was determined to be ample and most practical. Thus in experiment 2, diets supplemented with 1% Gln were fed for 4, 7, 14, or 21 d after which time chicks were fed the corn-SBM control diet until the experiment was terminated at 21 d. Weight gain improved significantly (P < 0.05) when chicks were fed diets supplemented with 1% Gln throughout the 21-d study. In both experiments, chicks fed diets supplemented with 1% Gln for 21 d had higher concentrations of bile, intestinal, and sera IgA and sera IgG (P < 0.05). Chicks fed diets with 1% Gln had heavier intestinal relative weights and longer intestinal villi (P < 0.05) as compared with the chicks fed the corn-SBM diet. Our results indicate that the addition of 1% Gln to the diet of broiler chicks improves growth performance and may stimulate development of the gastrointestinal tract and humoral immune response.

Variations in the digestible sulfur amino acid requirement of broiler chickens due to sex, growth criteria, rearing environment, and processing yield characteristics.

Four experiments (Exp.) were conducted with Cobb 500 chicks to evaluate variations in the estimated digestible sulfur amino acid (DSAA) requirement of broilers due to rearing environment, sex, or growth performance during the starter period (7 to 19 d), and live performance response and carcass yield characteristics during the grower period (21 to 42 d). In the first 3 experiments conducted during the starter period, chicks were allocated to battery or floor pens, and in the fourth experiment birds were reared in floor pens. For Exp. 1, 2, and 3 a sulfur amino acid deficient corn-soybean meal-corn gluten meal basal diet and for the grower experiment a corn-soybean meal-peanut meal basal diet was formulated to be isocaloric and isonitrogenous within experiment. Graded levels of DSAA ranged from 0.54 to 0.94% in Exp. 1, 0.53 to 1.03% in Exp. 2, 0.49 to 0.89% in Exp. 3, and 0.43 to 0.83% in Exp. 4. True digestibility of the diets was determined using the precision-fed rooster assay. The DSAA requirements were estimated using 1-slope broken-line methodology. During the starter period, the average DSAA requirement of males and females was similar when based on the gain to feed ratio (G:F; 0.71 and 0.71%, respectively) and BW gain (BWG; 0.67 and 0.67%, respectively). In Exp. 3 involving battery and floor pens, males and females had similar DSAA requirement estimates, but the DSAA requirement based on maximal G:F (0.68%) was higher than the maximal BWG requirement (0.61%). In the grower period, the estimated DSAA requirement for males based on G:F was higher than that based on BWG, but the BWG and G:F requirements were similar for females. The DSAA requirement estimates were similar for males and females based on BWG (0.55%), but the DSAA requirement based on G:F was higher for males than females. The DSAA requirement for maximum breast meat yield was similar for males (0.55%) and females (0.56%), and the requirement for maximal breast meat yield was similar to that for maximal BWG. The DSAA requirements were similar based on sex, rearing environment, or both; however, there was a difference in the estimated DSAA requirements between growth and carcass responses.

A comparison of methods to determine amino acid digestibility of feed ingredients for chickens.

Two experiments were conducted to compare standardized ileal amino acid (AA) digestibility in 7- and 21-d-old chicks and true AA digestibility as determined by the precision-fed cecectomized rooster assay for several ingredients used in poultry feeds. Diets were formulated to contain soybean meal, cottonseed meal, poultry by-product meal, and fish meal in experiment 1 and corn, wheat, soybean meal, poultry by-product meal, feather meal, and fish meal in experiment 2 as the sole sources of protein. Celite, used as an indigestible marker, was added at 1.5% of the diet. The test diets were fed ad libitum to broiler chicks from 0 to 7 d of age in experiment 1 and from 4 to 7 and 17 to 21 d of age in experiment 2. Ileal digesta samples were collected after euthanizing the birds at 7 d of age in experiment 1 and at 7 and 21 d of age in experiment 2. Additionally, cecectomized, Single-Comb White Leghorn roosters were used for crop intubation of the test diets for determination of true AA digestibility. In experiment 1, AA digestibility of all ingredients tested was significantly lower at 7 d of age than when determined by the rooster assay. In experiment 2, no differences were detected between AA digestibility at 7 or 21 d of age in the chick assay for the majority of the indispensable AA. However, the AA digestibility coefficients obtained by the chick assay at 7 d and, in some cases, at 21 d of age, were significantly lower than those obtained by the rooster assay. In conclusion, there were differences in the AA digestibility coefficients obtained through the chick and the rooster assays. Such discrepancies could be associated with an age effect or the methodological differences between both methods.

Variations in the digestible lysine requirement of broiler chickens due to sex, performance parameters, rearing environment, and processing yield characteristics.

Four experiments were conducted to evaluate variations in the digestible lysine (DLYS) requirement estimates of broilers due to rearing environment, sex, or growth performance during the starter period (7 to 21 d) and due to sex, growth, and carcass yield characteristics during the grower period (21 to 38 d). In the first 3 experiments, chicks were allocated to either battery or floor pens. The fourth experiment was conducted during the grower period with birds reared in floor pens only. All the studies used a lysine-deficient corn-soybean meal-corn gluten meal basal diet formulated to be isonitrogenous and isocaloric. Treatments consisted of 5 graded levels of DLYS varying from 0.70 to 1.21% in the first 3 experiments and from 0.73 to 1.13% in the fourth experiment. The DLYS requirement was estimated by broken-line methodology based on body weight gain (BWG) and gain:feed ratio (G:F) for the starter period, and the same variables plus breast meat yield for the grower period. During the starter period, the average DLYS requirement of males based on BWG was slightly higher than that of females reared in battery (0.96 vs. 0.94%) or floor pens (0.98 vs. 0.93%). However, based on G:F, the average DLYS requirement of females was slightly higher than that of males reared in both battery (0.99 vs. 0.96%) and floor pens (1.01 vs. 0.99). The DLYS requirement based on G:F was higher than that based on BWG only for females in both rearing environments. Rearing environment did not affect the DLYS requirement of broilers during the starter period. In the grower period, the DLYS requirement of males was higher than that of females based on BWG (0.97 vs. 0.93%), but for G:F it was similar for both sexes (0.96%). The DLYS requirement for females based on G:F was higher than that based on BWG. The DLYS requirement for maximum breast meat yield of males (0.98%) or females (0.90%) was similar to the estimate for maximal growth performance.

Changes in the digestible lysine and sulfur amino acid needs of broiler chicks during the first three weeks posthatching.

Four experiments were conducted to study the changes in the digestible lysine (DLYS) and sulfur amino acid (DSAA) requirements of broilers during the first 21 d posthatching. Cobb 500 by-product male broilers were fed corn-corn gluten meal-soybean meal diets formulated to be isocaloric and isonitrogenous. Five graded levels of either Lys or SAA were used, varying from 0.78 to 1.28% DLYS (experiments 1 and 2) and from 0.61 to 1.08% DSAA (experiments 3 and 4). Body weight gain (BWG) and gain:feed ratio (GF) were calculated at 4, 7, and 21 d. The DLYS requirements based on BWG varied from 0.98 at 4 d of age to 1.01% at 21 d in experiment 1 and from 0.95 at 4 d of age to 0.99% at 21 d, in experiment 2. Based on GF, the DLYS requirement varied from 1.08 to 1.10% in experiment 1, and from 0.98 to 0.94% in experiment 2 at 4 and 21 d, respectively. The estimated DSAA requirements for BWG varied from 0.83 to 0.88% or from 0.71 to 0.75% for 4 and 21 d in experiments 3 and 4, respectively. For GF, the DSAA decreased slightly from 0.88% at 4 d to 0.83% at 21 d in experiment 3, but did not change in experiment 4 (0.81%). Minimal changes in the DLYS or DSAA estimated requirements occurred during the first 21 d of age, which suggests that the recommended DLYS and DSAA levels determined at 21 d of age appear to be adequate to meet chick needs for the first week of age.

The bioavailability of lysine and phosphorus in distillers dried grains with solubles.

Five experiments were conducted to determine Lys and P bioavailabilities of distillers dried grains with solubles (DDGS), which was derived from corn fermentation in a modern nonbeverage ethanol plant. In experiment 1, we used the precision-fed cecectomized rooster assay and estimated the true digestibility of Lys in DDGS to be 75%. In experiments 2, 3, 4, and 5 the relative bioavailabilities of Lys and P were assessed using slope-ratio chick growth experiments. In experiments 2 and 3, Lys-deficient basal diets containing 0.40 or 0.60% digestible Lys respectively, were formulated. A linear growth response (P < 0.05) was observed from the addition of 0.10 and 0.20% L-Lys from L-Lys x HCl and 10 and 20% DDGS to the basal diets. Body weight gain was regressed on Lys intake from L-Lys x HCl and DDGS, and the ratio of the slopes indicated the relative bioavailable Lys in DDGS. The values as a percentage of total Lys (0.83) in DDGS yielded availability estimates of 80% for experiment 2 and 100% for experiment 3. In experiments 4 and 5, a P-deficient basal diet containing 0.12% nonphytate P was formulated. A linear growth and tibia bone ash (%) response (P < 0.05) were observed from the addition of 0.05 and 0.10% P from K2HPO4 and 2 levels of DDGS (5 and 10% for experiment 4 and 7 and 14% for experiment 5). Tibia bone ash (%) was regressed on P intake from K2HPO4 and DDGS, and the ratio of slopes indicated the relative bioavailability of P in DDGS. The values as a percentage of total P (0.74%) in DDGS yielded availability estimates of 68% for experiment 4 and 54% for experiment 5.

Evaluation of distillers dried grains with solubles as a feed ingredient for broilers.

Two experiments were conducted to evaluate the use of distillers dried grains with solubles (DDGS) from modern ethanol plants in broiler diets. Experiment 1 was a 2 x 2 factorial experiment with diets containing 2 levels of DDGS (0 and 15%) and 2 diet densities (high and low). The high- and low-density diets were formulated to contain 22% CP and 3,050 kcal MEn/kg and 20% CP and 3,000 kcal MEn/kg, respectively. Eight pens of 6 chicks were fed an experimental diet from 0 to 18 d of age. Weight gain and feed efficiency (gain:feed ratio) of the chicks receiving the high-density diets were (P < 0.05) better than those of chicks fed the low-density diets. However, within the 2 density levels there was no difference in performance of chicks fed diets with 0 or 15% DDGS. In experiment 2, 6 replications of 50 chicks were fed 1 of 4 dietary treatments for 42 d. The diets were formulated to be isocaloric and isonitrogenous and contained 0, 6, 12, or 18% DDGS. There was no significant difference in performance or carcass yield throughout the 42 d experiment except for a depression in BW gain and feed conversion when chicks were fed diets with 18% DDGS in the starter period. These studies indicate that DDGS from modern ethanol plants is an acceptable feed ingredient for broiler diets and can be safely used at 6% in the starter period and 12 to 15% in the grower and finisher periods.

Utilization of various carbohydrate sources as affected by age in the chick.

In 3 experiments, New Hampshire x Columbian male chicks were fed carbohydrate-soybean meal (SBM) or casein diets from 0 to 21 d of age, and MEn was determined at 0 to 2, 3 to 4, 7, 14, and 21 d of age. Carbohydrate sources evaluated in experiment 1 were dextrose (D-glucose), conventional cornstarch, dextrinized cornstarch, corn-syrup solids, pregelatinized unmodified cornstarch, pregelatinized tapioca starch, tapioca dextrin, high-amylose starch, and polycose (mixed glucose polymers). Carbohydrate sources evaluated in experiments 2 and 3 were conventional corn, waxy corn, high-oil corn, corn flour, rice flour, dextrose, and sucrose. In experiment 1, chicks fed the dextrose diet had the highest weight gains, and the chicks fed high-amylose starch and pregelatinized unmodified cornstarch diets had the lowest weight gains. The MEn values varied among carbohydrate sources with MEn being highest for the dextrose diet and lowest for the high amylose starch diet. In experiment 2, chicks fed waxy corn, high-oil corn, or dextrose-SBM diets had (P < 0.05) higher growth rates than chicks fed conventional corn, corn flour, or rice flour. The MEn values increased with age for all diets except the dextrose-SBM, which was consistently high at all ages. In experiment 3, the dextrose diets (SBM or casein) yielded higher growth performance and MEn values than the sucrose-diets, and the differences were greater at younger ages. The MEn values were also much higher for the casein than the SBM diets, and MEn of the SBM diets increased with increasing age. The results of this study indicate that MEn, varies among carbohydrate sources and increases with age for most carbohydrate-SBM diets.

Minimum phosphorus requirement of one-cycle and two-cycle (molted) hens.

In experiment 1 (one cycle), hens were fed diets containing 0.10, 0.115, 0.125, 0.135, 0.15, or 0.45% available P (AP) from 40 to 56 wk of age, with the last diet being a positive control. Egg production, egg mass, and BW were reduced (P < 0.05) by all lower AP levels except 0.15% AP when compared with the 0.45% AP treatment. In the second experiment (two cycles with a molt), hens were initially fed diets containing 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, or 0.45% AP from 21 to 63 wk of age. Diets containing 0.10, 0.12, and 0.14% AP were terminated at 35, 39, and 50 wk, respectively, due to low egg production and increased mortality. Hens fed 0.16% AP also had significantly lower production performance than hens fed 0.45% AP during the first cycle. Hens on the 0.16 to 0.45% AP treatments were induced molted at 64 wk of age by 10 d of feed removal. The hens were then returned to the same AP layer diet they had been fed from 21 to 63 wk. For the 68 to 108 wk postmolt second-cycle period, hens fed the 0.16 to 0.20% AP diets (166 to 209 mg/d) had significantly lower egg production, egg mass, and feed efficiency than hens fed 0.45% AP. The results of our study indicated that first-cycle hens required approximately 0.18% AP or 198 mg AP/hen per day, and molted hens in their second cycle had a requirement that was greater than 0.20% AP or 209 mg AP/hen per day.

Efficacy of high available phosphorus corn in laying hen diets.

Our objective was to determine if high available phosphorus corn would provide sufficient available phosphorus (AP) to laying hens fed corn-soybean meal diets from 57 to 69 wk of age. Six replications of 12 Dekalb Sigma Leghorn hens were fed a normal yellow dent (YD) corn-soybean meal diet or high available phosphorus (HAP) corn-soybean meal diet without and with 0.04% supplemental inorganic P. The unsupplemented YD diet was calculated to contain 17% CP, 3.8% Ca, and 0.10% AP, and the unsupplemented HAP diet contained 17% CP, 3.8% Ca, and 0.16% AP. In addition, a positive control, YD diet (17% CP, 3.8% Ca, 0.45% AP) was also fed. The HAP corn was directly substituted for YD on a weight basis, and the amount of soybean meal was kept constant in all diets. Egg production, hen body weight, egg weight, egg mass, feed consumption, and feed efficiency were measured. The YD and the YD + 0.04% P treatments were terminated at 61 and 65 wk of age, respectively, due to severe depressions in egg production. Egg production and egg mass for hens fed HAP diets were not different (P > 0.05) from those of hens fed the 0.45% AP diet; however, hens fed the unsupplemented HAP diet did have lower hen body weights and feed intake (P < 0.05) compared to hens fed the positive control diet. Our results indicate that HAP corn contains more available P than normal YD corn and that hens can be fed HAP corn-soybean meal diets containing little or no P supplementation with only minimal effects on production performance.

Utilization of different soy products as affected by age in chicks.

Two experiments were conducted to evaluate the utilization of several different soy products at different ages in New Hampshire x Columbian male chicks. Six pens of eight chicks were fed dextrose-protein source diets (23% CP) containing 1 of 10 different protein sources from 0 to 21 d of age. Excreta were collected at 0 to 2, 3 to 4, 7, 14, and 21 d of age, and AMEn and amino acid (AA) digestibility were determined using acid-insoluble ash as a marker. Protein sources evaluated were as follows: Experiment 1--casein, soybean meal (SBM), soy protein concentrate (SPC), and soy protein isolate (SPI); Experiment 2-raw soyflakes, SBM, Williams 82 soybeans, heated Williams 82 soybeans, Kunitz-free soybeans (reduced trypsin inhibitor), lectin-free soybeans, and Kunitz/lectin-free soybeans. In Experiment 1, when comparing the MEn and AA digestibility values among diets at the same age, the ranking (from highest to lowest) for the four diets was casein, SPI, SPC, SBM. The MEn values increased (P < 0.05) with age for all four diets, with the increase being much smaller for the casein diet (3%) than the soy diets (mean increase of 13%). In Experiment 2, the SBM diet yielded the highest (P < 0.05) growth performance, MEn and AA digestibility values. The MEn and AA digestibility values of the Williams 82 soybeans, Kunitz-free soybeans, and lectin-free soybeans diets were much lower than those for the SBM diet. In general, the Kunitz/lectin-free soybeans yielded higher growth performance and MEn values than the Williams 82 soybeans, Kunitz-free soybeans, and lectin-free soybeans. The MEn values increased with age for most diets, and AA digestibility increased with age for the soyflake and Kunitz/ lectin-free soybean diets. Our results suggest there may be some potential benefits of feeding SPC or SPI during the first 1 to 3 wk posthatching and that underprocessed (under heated) soybeans should not be included in the diets of very young chicks.

Effects of age on development of digestive organs and performance of chicks fed a corn-soybean meal versus a crystalline amino acid diet.

Changes in growth performance and physical and morphological development of the digestive organs were examined in chicks fed a crystalline amino acid (AA) diet compared to chicks fed a corn-soybean meal (SBM) diet. Six pens of eight New Hampshire x Columbian male chicks were assigned to one of three dietary regimens: (1) corn-SBM diet from 0 to 21 d of age; (2) cornstarch-crystalline AA diet from 0 to 21 d of age; and (3) corn-SBM diet from 0 to 7 d of age followed by the crystalline AA diet from 8 to 21 d of age. Weight gain was significantly reduced by feeding a crystalline AA diet from 0 to 21 or 8 to 21 d of age. Feeding a crystalline AA diet for the first 7 d of age depressed absolute weight of the small intestine, pancreas, liver, gizzard, and proven-triculus, and continual feeding through 21 d of age further depressed growth of these organs compared with birds fed a corn-SBM diet for 21 d. When expressing organ weight on a relative basis (g/100 g of BW), reductions were observed at 7 d of age due to feeding a crystalline AA diet but not at 21 d of age. Feeding a crystalline AA diet for the first 7 or 21 d of age depressed intestinal villi height and crypt depth. However, chicks fed the crystalline AA diet only from 8 to 21 d of age had further depressed villi height and crypt depth but greater villi width compared with chicks fed the crystalline AA or corn-SBM diet continually from 0 to 21 d of age. These results indicate that the reduced growth of chicks fed a crystalline AA diet is due in part to slower growth and development of the gastrointestinal tract.

Effect of fasting versus feeding oasis after hatching on nutrient utilization in chicks.

Two experiments were conducted to determine the effects of fasting, feeding Oasis, or feeding a corn-soybean meal (SBM) or dextrose-casein diet immediately after hatching on growth performance, MEn and apparent amino acid (AA) digestibility. In each experiment, five or six pens of eight chicks were assigned to one of five treatments: feeding a corn-SBM or dextrose-casein diet immediately after hatching, fasting for 48 h (no feed or water) after hatching, or feeding Oasis for 24 or 48 h (no water) after hatching. The fasting and feeding Oasis treatments were followed by feeding the corn-SBM diet for 21 d. Excreta were collected at 0 to 2, 3 to 4, 7, 14, and 21 d on feed for determination of MEn and AA digestibility. Fasting chicks for 48 h posthatching significantly depressed weight gains compared to all other treatments at 21 d of age. Although weight losses were not significantly different at 48 h posthatching, chicks fed Oasis for 48 h had significantly (P < 0. 05) higher weight gains at 1 and 3 wk of age than did chicks fasted for 48 h. Chicks fed the dextrose-casein diet had significantly (P < 0.05) higher weight gains at 48 h and 7 d posthatching than chicks fed the corn-SBM diet immediately after hatch in Experiment 2. As time on feed increased from 3 to 21 d, MEn increased substantially (25%) for all the treatments in which chicks were fed the corn-SBM diet. In addition, the MEn of the corn-SBM diet for chicks fed Oasis was significantly (P < 0.05) higher for than chicks fasted for 48 h. The MEn of the dextrose-casein diet was high immediately after hatching and increased only slightly (2%) with increasing age. Digestibility of most AA increased with increasing age for all the corn-SBM treatments, and the digestibility values were similar among treatments. However, AA digestibility values for the dextrose-casein diet were consistently high at all ages and much higher (P < 0.05) than the other dietary treatments. Our results indicated that feeding Oasis (compared to fasting) had a beneficial effect on growth performance and subsequent energy utilization of a corn-SBM diet and that Oasis may stimulate early gut development even though very early growth (0 to 48 h) is not affected.

Ideal ratio (relative to lysine) of tryptophan, threonine, isoleucine, and valine for chicks during the second and third weeks posthatch.

Six bioassays were conducted to determine the ideal ratios of several amino acids relative to Lys. Young male crossbred chicks were fed diets based on corn gluten meal and synthetic amino acids that could be made singly deficient in Lys, Trp, Thr, Ile, or Val. Diets for all assays contained 3,400 kcal ME/kg, and L-glutamic acid was used to make all diets (within and among assays) equal in crude protein at 22.5% of the diet. True digestibility assessment of corn gluten meal in cecectomized roosters facilitated dose-titration studies so that least squares fitted one-slope broken-lines and quadratic regression equations could be calculated to establish inflection points for weight gain and gain:feed. Four battery pens of four chicks were fed one of six amino acid levels from 8 to 21 or 22 d posthatching. Weight gain and gain:feed responded quadratically (P < 0.01) to increasing doses of digestible Lys (0.68 to 1.28%), Trp (0.09 to 0.24%), Thr (0.41 to 0.81%), Ile (0.45 to 0.95%), and Val (0.51 to 1.06%). Broken-line least squares analysis predicted breakpoints for gain and gain:feed, respectively, of: Lys (0.85, 0.96%), Trp (0.16, 0.16%), Thr (0.53, 0.53%), Ile (0.59, 0.58%), and Val (0.74, 0.74%). The intercept of the quadratic regression curve and the plateau of the broken line predicted digestible Lys requirements for gain and gain:feed, respectively, of 0.95 and 1.03%. Similar calculations predicted digestible Trp requirements of 0.18% for gain and gain:feed, digestible Thr requirements of 0.59% for gain and 0.60% for gain:feed, digestible Ile requirements of 0.68% for gain and gain:feed, and digestible Val requirements of 0.81% for gain and 0.82% for gain:feed. Regardless of curve-fitting method, gain:feed requirements for Lys were much higher than weight gain requirements. Using the higher of the broken-line requirement estimates for gain and gain:feed, ideal ratios (% of Lys) were as follows: Lys (100), Trp (16.6), Thr (55.7), Ile (61.4), and Val (77.5).