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Developmental changes in hepatic methionine adenosyltransferase, cystathionine β-synthase, cystathionase, and glycine N-methyltransferase were determined in broiler chick embryos and hatched chicks by using radiometric and spectrometric methods. Hepatic free methionine, S-adenosylmethionine, S-adenosylhomocysteine, homocysteine, cystathionine, and cysteine levels were also investigated. Results showed an increase in hepatic MAT activity from E10 to E21 during embryogenesis, suggesting greater transmethylation rates throughout the rapid embryonic growth and development period. A strong positive correlation between embryo BW and MAT activity also supports this idea. The MAT specific activity continued to increase after hatching, but there was a negative correlation between chick BW and MAT activities from D1 to D49. This may indicate different MAT isozymes exist for chick embryo hepatic tissue compared to hepatic tissue of hatched chick and growing broilers. The developmental pattern of MAT isozymes could be critical for methionine metabolism to cope with the demand imposed on the embryo, chicks, and growing broilers. Additionally, the specific activity of hepatic CBS in chick embryos was determined to be lower compared to that observed in older broilers (35 and 49 days). Since liver CBS specific activity is at the lowest point from D1-7 in young chicks, the ability to convert adequate homocysteine to cysteine through transsulphuration may be limiting for cysteine synthesis at this time. Steady-state hepatic homocysteine levels in chick embryos and chicks may be a function of the rates of homocysteine formation, remethylation, and catabolism via the transsulphuration pathway. The present study indicates young chicks from D1 to D7 may have a limited ability for adequate transsulphuration; therefore, dietary cystine may be needed for optimum performance.

The remethylation of homocysteine to methionine is important for chick embryos to sustain the S-adenosylmethionine transmethylation reactions, which are essential for the rapid proliferation of cells. Developmental changes in hepatic 5-methyltetrahydrofolate-homocysteine methyltransferase (MFMT), betaine-homocysteine methyltransferase (BHMT) and hepatic serine hydroxymethyltransferase (SHMT) were determined in E10-21 Cobb 500 broiler chick embryos and hatched chicks from D1-49. Hepatic levels of free serine, glycine, putrescine, spermidine and spermine levels were also determined. Analyses showed hepatic MFMT-specific activity doubled from E10 to E12, with remaining embryo development experiencing small fluctuations in activity through E21. Hepatic MFMT doubled immediately after hatch, with peak activity occurring at D3. Afterwards, hepatic MFMT-specific activity steadily declined from D7-49. Hepatic BHMT activity was higher from E10 to E16 of embryogenesis, decreased rapidly at E17 and remained lower through E21 (p < .05). Hepatic BHMT-specific activity was also lower in chicks, with the exception of a peak in specific activity on D7. BHMT activity returned to lower levels by D21. Throughout embryogenesis, hepatic SHMT activity in chick embryos remained relatively constant except for a decrease at 13E, followed by an increase at 14E. Maximal activity of SHMT was found the first day post-hatch. Additionally, SHMT activity was significantly lower in growing chicks than that in embryos. Hepatic-free serine and glycine levels were negatively correlated with SHMT in hatched chicks. Hepatic polyamine, putrescine and spermidine shared a similar development pattern: peak level in the middle of incubation, low at late embryogenesis and lowest during the post-hatch period except an increase within one week after hatch. The sharp increase in hepatic concentrations of glycine, serine and putrescine, along with increased specific activities of MHMT, BHMT and SHMT from D1-7, suggests that methionine conservation (remethylation from homocysteine) and glycine/serine is critical for young chicks for organ growth, maturation, and development.

Three isotopic tracers ([2,3,3-2H3]-L-serine, [2H11]-L-betaine, and [1-13C]-L-methionine) were administered by amnion injection into 18-day-old chick embryos to investigate the kinetics of methionine metabolism. The embryos utilized were from eggs collected from 34-week-old Cobb 500 broiler breeders that were fed either a control diet containing folic acid (1.25 mg/kg diet) and pyridoxine HCl (5 mg/kg diet) or diets devoid of supplemental pyridoxine or folic acid. Intermediate metabolites of methionine metabolism and polyamines were analyzed in 18-day-old chick embryos. There were no differences in hepatic [2H2] methionine or [2H3] cysteine enrichments or in physiological concentrations of sulfur amino acids for chick embryos from breeders fed the control diet and embryos from breeders fed diets containing no pyridoxine or folic acid. Supplementation of B6 or folic acid did not affect the production of methionine and cysteine in chick embryos. However, breeders fed the control diet with both folic acid and pyridoxine supplementation produced embryos with a two-fold reduction of hepatic homocysteine and increased spermine compared with embryos from breeders fed diets containing no supplemental pyridoxine or folic acid (P

Digestibility coefficients of nutrients, metabolizable energy (ME), net energy (NE) and the ratio of NE to ME (NE/ME) of 20 diets were measured in broiler chickens (1 to 21 d). Dietary nutrients were formulated to keep similar ME/nutrient ratios, except for dietary protein, fat, and fiber using corn, soybean meal, animal protein blend, barley, poultry oil and an enzyme mixture of xylanase, glucanase, and phytase. Digestibility coefficients of nutrients and ME were measured in battery cages under free-access of feed, while NE was measured in floor pens feeding 75% of recommended ME intake each day. NE for maintenance was calculated on basis of mean metabolic weight using a coefficient from a previous study and NE for gain was calculated by body protein and fat gains using dual-energy x-ray absorptiometry. Digestibility coefficients of protein and neutral detergent fiber (NDF) were curvilinearly related to dietary protein and NDF, respectively, while digestibility coefficients of fat and starch were linearly correlated to dietary fat and starch, respectively. The inclusion of enzymes increased the digestion coefficient of NDF to predict the digestibility of protein, NDF, fat, and starch. MEn/gross energy ratio averaged 72.5% and was correlated to protein, fat, NDF, and starch. ME values were accurately predicted from chemical characteristics, where best equations were obtained from digestible nutrients. Energetic efficiencies of ME were 72% (NE/MEn) and 68% (NE/ME) and varied by about 20 and 18%, respectively. Ratios of energetic efficiency were 68% for digestible carbohydrates; 86% for digestible fat; and 76% (NE/MEn) and 59% (NE/ME) for digestible protein. According to the lowest residual standard deviation the best nutrient components to predict energy were digestible nutrients for predicting ME values (41 kcal/kg); digestible protein intake, fecal organic matter, and body fat and protein for predicting heat increment values (111 kcal/kg); and combination of ME and crude nutrient for predicting NE values (140 kcal/kg).

The effects of 3 dietary amino acid (AA) profiles during lay on reproductive performance of broiler breeders were investigated. A flock of 2,376 Ross 708 female broiler breeders were randomly divided into 3 treatments with 12 replicates of 66 females per replicate, and fed 2 breeder feed phases (breeder 1: 25 to 36 wk; breeder 2: 37 to 60 wk) which were formulated to 3 different AA densities (Aviagen advice = control; 10% increased AA in Aviagen advice = high-AA; and estimated AA needs for maintenance, growth, and egg mass = estimated-AA). No differences in total or hatching egg production due to dietary treatments were observed. Hens fed high-AA had a higher incidence of double-yolk eggs. During the second phase of lay, hens fed estimated-AA had lower livability compared to the other treatments. Hens fed estimated-AA also laid smaller eggs compared to control and high-AA fed birds. Back feather cover deteriorated as hens grew older, and hens fed the estimated-AA diets had poorer feather cover from 41 wk onward. Overall, these results suggest that feeding higher AA levels than Aviagen recommendations presented no benefit in reproductive performance or feather quality. The estimated-AA feeding approach supported laying performance similar as other treatments, although affected egg weight and back feather cover.

A study was conducted to determine the effect of different feeding programs and energy intakes on the body composition of broiler breeders (BB) from 22 wk of age to 65 wk of age. Cobb 500 BB that had been reared using three growth curves: (1) the control group followed Cobb 500 guidelines (SBW) for target body weights (BW), (2) the second group target BW was 20% heavier (HBW) than the SBW group, and (3) the third group target BW was 20% lighter (LBW) than the SBW group. At 21 wk of age, pullets from each growth curve were assigned to be fed one of six treatments. Diets were formulated and allocated to provide 330, 360, 390, 420, 450, or 480 kcal ME/hen/d and 24 g protein/hen/d, at peak intake. Body composition (lean mass, fat mass, and mineral content) was measured by dual-energy x-ray absorptiometry throughout the production period. Significantly, greater (P0.05) amounts of fat mass and lower amounts of lean mass were evident at the beginning of the production period for HBW hens compared with SBW and LBW hens. Higher levels of energy intake also affected body composition. Namely, fat deposition was greatest throughout the production period in hens consuming 480 kcal/d at peak intake (P0.05). Critically, fluctuations to lean and fat mass throughout the production period are suggestive of underlying regulatory processes. Specifically, hens appears to maintain consistent lean mass throughout the production period with a coefficient of variation of12% across all birds. The results of this study provide important BB body composition information from management and nutrition studies that showed the dynamics of body composition change during the production period.

An isotope dose technique was utilized (i) to determine endogenous amino acid (AA) and protein losses and (ii) to propose adjusted values for AA requirements. The endogenous flow rate was calculated from the pool of enrichment in plasma AA, assuming similitude to enrichment of endogenous AA. In experiment 1, chicks were orally administered D4-lysine at 2% of estimated lysine intake from 16 to 24 days to find the isotopic steady state of the atom percent excess (APE) of lysine for plasma and jejunal and ileal digesta. The APE of D4-lysine in plasma, jejunal digesta and ileal digesta reached the isotopic steady state at 5.5, 3.4 and 2.0 days, respectively, by using the broken-line model. It was assumed that the isotopic steady state at 5 days identified for D4-lysine is also representative for the 15N-labeled AA. In experiment 2, chicks were fed diets from 1 to 21 days with increasing levels of fat (6%, 8%, 12%, 13% extract ether), protein (26%, 28.5%, 31% CP) or fiber (14%, 16%, 18% NDF) by adding poultry fat, soybean meal, blended animal protein or barley. Chicks were orally administered 15N-threonine, 15N-cysteine, 15N-methionine, 15N-lysine and 15N-leucine at 2% of estimated daily intake for 5 days from 17 to 21 days of age. Dietary nutrients influenced endogenous losses (EL), where dietary fat stimulated EL of lysine (P=0.06), leucine and protein (P=0.07); dietary protein enhanced EL of leucine and protein; and finally the dietary fiber increased EL of leucine. Dietary nutrients also affected apparent ileal digestibility (AID). Dietary fat increased AID of cysteine but decreased AID of lysine. Dietary protein reduced AID of protein, threonine, lysine and leucine, and similarly dietary fiber decreased AID of protein, threonine, methionine, lysine and leucine. In contrast, dietary fat or protein did not affect real ileal digestibility (RID) of protein and AA except threonine and leucine. The dietary fiber reduced the RID of protein, threonine and leucine. This indicate that variations of some endogenous AA and protein losses due to dietary nutrients almost eliminates the effects of RID, and thus the EL coming from the body should be utilized to adjust the AA requirement instead of changing the true digestible nutrients of ingredients. The present data suggest that 5 days’ feeding labeled AA was enough to reach the isotopic steady state and AA requirements should be adjusted when additional dietary protein, fat or fiber is fed.

A study was conducted to determine the effects of dietary energy and protein intake on the partitioning of lysine in broiler breeder hens. One hundred twenty-six broiler breeders were randomly assigned to 1 of 6 dietary treatments in a 2 (390, 450 kcal/d) × 3 (22, 24, 26 g of CP/d) fashion. Thirty-six hens were administered a daily oral dose of 15 mg of 15 N-Lys for a period of 2 wk or until first egg. After the 2-wk enrichment period, no isotopes were given for 2 d. After 2 d, a daily oral dose of 15 mg of 2 D4-Lys was administered until the 2nd, 3rd, and 4th egg (saved) after the initial 2 D4-Lys was given, at which point pectoralis muscle was sampled. Weeks 25, 29, and 45 were assessed. Isotopic enrichment of pectoralis muscle, egg yolk, and albumen was determined via gas chromatography-mass spectrometry. The 15 N-Lys was intended to represent endogenous lysine, whereas the 2 D4-Lys was intended to represent dietary lysine. Greater than 78% of all labeled lysine (15 N and 2 D4-Lys) was found in breast muscle. Endogenous muscle was the main source of lysine for yolk formation at wk 25 and 45. Diet was the main source of lysine for albumen formation at wk 25 and 29. A consistent decrease in the 15 N-Lys in breast muscle from the 2nd to the 3rd egg was observed, while also seeing an increase in the 15 N-Lys in the egg from the 3rd to the 4th egg. No difference in the partitioning of lysine was determined by energy or protein intake at levels typical for the current poultry industry. Rather, age, and possibly rate of production, appear to be the main drivers of lysine partitioning in the broiler breeder hen.

Cotton seed meal (CSM) is an alternative ingredient in poultry diets but its use is limited due to the presence of gossypol and the potential effects of gossypol on digestibility of nutrients. Glandless cottonseed is available and contains very low gossypol but there has been a limited amount of poultry nutritional studies completed with glandless cottonseed meal (GCSM). The TMEn, proximate analysis, amino acid content and amino acid (AA) digestibility of a glandless (GCSM) and a commercial (CCSM) cottonseed meal were determined with broilers. Thirty 42-day old Cobb 500 male broilers were precision-fed 30g of CCSM, GCSM and glucose and excreta collected during a 48 h period. Glucose was fed to serve as a control (no nitrogen or AA content). The chemical composition, gossypol content, True metabolizable energy (TMEn) and digestibility coefficients for AA were calculated for both meals. The crude protein and fat content of GCSM was higher than the CCSM (54 and 51%, 6 and 2%, respectively). Both meals were similar in calcium, total phosphorus and phytic acid contents. The CCSM had a higher content of total and free gossypol (1.52 and 0.161%, respectively) when compared to GCSM (0.02 and .003%, respectively). The TMEn for the GCSM provided approximately one thousand kcal more per energy/ kg than the CCSM. The essential AA content (g/kg; 90% DM) was determined for both cottonseed meals and was generally higher for GCSM compared to CCSM but both types of CSM contained higher levels of key essential AA than reported values for AA in the literature. The most extreme differences were for methionine and cystine; % methionine content was approximately 2 fold higher than values in the literature and the % cystine was 74 to 93% higher. The true digestibility coefficients for essential AA ranged from the low of 73.9% for isoleucine to 91.8% for arginine, for CCSM; the amino acid digestibility coefficients for GCSM were all higher than 90% for the essential AAs.

The contribution of dietary, mobilized, or newly synthesized fatty acids in yolk formation at different periods of egg production was determined. In an initial experiment, a single dose of 13C-linoleic acid was administered to pullets at the onset of egg production and their presence in follicles determined over the subsequent 10 days. In a second experiment, pullets were fed a daily 15 mg dose of U-13C-glucose beginning 2 wk prior to sexual maturity through the end of the experimental period. A 50 mg meal of U-13C-linoleic acid was orally administered approximately 10 d prior to sexual maturity (defined as first egg) representing body linoleic acid. Upon each hen's first egg, each bird received a 25 mg meal of 2D31-linoleic acid representing dietary linoleic acid. All eggs were collected for the next 10 days. The incorporation of labeled linoleic acid and palmitic acid in egg yolk was then determined using GC-MS. This process was repeated at peak production and at 45 wk of age. At sexual maturity, the deposition of labeled palmitic acid in the yolk was higher compared with its deposition at peak production and 45 wk of age. The deposition of both 13C- and 2D31-linoleic acid increased with hen age. These results suggest that dietary and tissue linoleic acid is utilized to a greater extent in older hens and that lipogenesis (synthesis of palmitic acid) plays a larger role at sexual maturity in the young hen.

3 Abstract: Traditionally, body composition data for poultry is determined by grinding /homogenizing the whole bird and obtaining a sample for wet chemistry analysis. The overall process is slow, requires a large amount of freezer space and the time-lag required for determining body composition reduces the opportunity to use data in real- time situations. Two studies were conducted to evaluate Dual-energy X-ray Absorptiometry (DEXA) as a means of measuring body composition in broilers and broiler breeders. In Trial 1, two hundred and forty Cobb 500 broilers were reared from day-old to 60 days of age. Broilers were extracted from the flock every 3 days during the 60 day grow-out in order to obtain a variety of body weights and body composition for developing the body composition equations. The birds were weighed and scanned using the small animal software mode of the DEXA scanner (LunarProdigy, GE ). DEXA provides measurements in grams of Bone ® Mineral Content (BMC), Fat Mass (FM) and Lean Mass (LM). It was assumed that the sum of BMC+FM+LM represented the total body mass. After the scan was performed, the carcasses were frozen for further chemical analysis. Prior to chemical analysis, the carcasses were thawed, autoclaved at 110°C with 1 atm pressure for 1-5 h depending upon Body Weight (BW) and homogenized in a heavy duty blender (Waring Laboratory, Blender LBC15, Model CB15). Samples of the homogenized carcasses were freeze dried, weighed, ground and analyzed for total ash, ether extract and crude protein. The measurements obtained from the DEXA scans were compared with the whole body chemical analysis for each broiler. Regression analysis of DEXA values (BMC, FM, LM) and chemical analysis (ash, ether extract and protein) were utilized to determine possible correlations. Prediction equations were then developed to adjust the original DEXA results to more accurately predict BMC, fat tissue and lean mass. The R values for the prediction equations 2 using DEXA values were 0.999, 0.99, 0.96 and 0.99 for total mass, BMC, fat and lean mass (P

Various recommendations exist for formulating broiler diets. In this study, diet specifications were compared for four different scenarios which included U.S. Poultry Industry average, recommendations by two major breeders and Brazilian recommendations. For each of these, amino acid specifications were adjusted to a percent per Mcal basis as the various recommendations utilize different energy levels. Performance of birds formulated to different nutrient recommendations varied depending primarily upon the relative levels of crude protein, amino acids and metabolizable energy. Feeding diets higher in crude protein and amino acids tended to result in faster growth, especially in early stages, but were less efficient in conversion of crude protein and amino acids into body weight gain. Feeding diets higher in metabolizable energy tended to result in better feed conversion, however effects of dietary energy on calorie conversion were somewhat variable. Over the entire 49 d feeding period there were no significant differences among the various treatments for caloric efficiency. No economic analysis was made of the present study, as relative costs of energy and amino acids vary over time. However it is obvious that when protein costs are high relative to energy, feeding systems which recommend lower protein and amino acid levels should be mor e economical, while perhaps resulting in a small sacrifice in body weight gain, while feeding systems that recommend higher protein and amino acid levels might be more economical when protein is relatively lower in comparison to dietary energy costs. Because overall calorie utilization was similar among nutrient programs at the conclusion of the study, this could be used as an overall indication of economic efficiency when comparing the different nutrient programs.

Nutritional models for comparison of environmental conditions on responses to dietary energy using data from literature were evaluated to formulate broiler diets by maximum profit feed formulation with real or simulated prices of corn and soybean meal. These diets were formulated based on Corn and Soybean Meal (C-SBM) or with Wheat and Cottonseed Meal (+W-CM) as alternative sources of energy and protein. Average body weight gain or feed intake slopes at normal temperature were significantly higher than those at heat stress. The rate of gain per calorie was two times higher at normal compared to heat stress and the rate of feed intake per calorie was half as high at normal than did at heat stress. At real or simulated prices, the economic energy content in most cases was reduced by heat stress compared to those at normal temperature. For real prices the energy reductions from normal temperature to heat stress were from 3.254 to 3.015 kcal/g for diets based on C-SBM or from 3.2 to 2.961 kcal/g for diets based on +W-CM. These economic energy reductions were around 7% from real prices, up to 10% from simulated corn prices and up to 9% from simulated SBM prices. The inclusion of +W-CM reduced the economic energy content and increased the profitability compared to those based on C-SBM diets. These data indicate that broiler diets fed during heat stress should be formulated with reduced economic energy content due to decreased rate of gain or feed intake per calorie compared to those at normal temperature.

Empirical nutritional models were developed for comparison of the effects of two feed forms on responses to dietary energy using data from literature to formulate broiler diets by maximum profit feed formulation with real or simulated prices of corn and soybean meal. Broiler diets were formulated based on Corn and Soybean Meal (C-SBM) and or with Wheat and Cottonseed Meal (+W-CM) as alternatives sources. Estimated average body weight gain or feed intake slopes of birds fed mash feed were significantly greater than that of birds fed pelleted feed. The rate of gain per calorie of mash-fed birds was three times higher than that of pellet-fed birds and the rate of feed intake per calorie for pellet-fed birds was six times smaller than for mash-fed birds. The economic energy content in most cases was decreased by pelleted feed compared to mash feed at real or simulated prices. For real prices the energy reductions from mash feed to processed feed were from 3.254 to 3.015 kcal/g for diets based on C-SBM or from 3.2 to 2.961 kcal/g for diets based on +W-CM. These economic energy reductions were around 7% from real prices, up to 10% from simulated corn prices and up to 11% from simulated SBM prices. Broiler diets formulated with +W-CM decreased the economic energy content and increased the profitability compared to those based on C-SBM diets. These data indicate that broiler diets fed as pellets should be formulated with reduced economic energy content due to decreased rate of gain or feed intake per calorie compared to those at mash feed.

The present study was conducted to investigate the effects of dietary Crude Protein (CP), lysine and amino acid balance in male broiler diets on performance (weight gain and feed conversion, feed efficiency, protein efficiency ratio). Five test diet series were used: 1) the 23% CP diet; 2) the 21% CP diet; 3) the 21% CP diet plus additional amino acids (21.68% total CP) to provide at least as much of the essential amino acids as present in the 23% CP diet; 4) the 19% CP diet and 5) the 19% CP diet plus additional amino acids (20.31% total CP) to provide at least as much of the essential amino acids as present in the 23% CP diet. For each of the five test diets series, additional Lys was added to provide total Lys levels of 1.10, 1.15, 1.20, 1.25, 1.30, 1.35 and 1.40%. This resulted in a total of 35 final experimental treatments in a 5 x 7 factorial arrangement. Each treatment was fed to 6 replicate pens of 6 male broilers in electrically heated battery brooders from 1-18 days of age. Birds fed the low-protein diets (21%) supplemented with EAAs (21.68% total CP) showed significantly the highest BW and best FCR and FE. There were no significant differences in BW between birds fed control diet (23%) and 19% CP or 19% plus EAAs (20.31% total CP) and 21% CP. FC and PER were significantly affected by dietary protein levels. FCR and FE were significantly improved and BW increased significantly by increasing dietary lysine levels up to 1.25%. An interactions of CP with or without EAAs with dietary lysine level were significant for BW. FCR, FE, FC and PER not significantly influenced by interaction. Thus, our results suggest that maximum body weight could be obtained with a 21% low-CP plus EAA supplementation which was the same as that of the chicks fed high protein diet (23% CP). Optimum dietary lysine level for performance was affected by dietary protein level and amino acid balance.

SUMMARY Differently sized dies were used to pellet broiler starter diets formulated to meet typical commercial standards. From 0 to 13 d of age, birds in floor pens were assigned different feed forms, such as mash, crumble, or pellets made by using 1.59- and 3.17-mm dies, followed by common grower and finisher diets pelleted with a 4.76-mm die fed to 41 d. During the first 13 d, birds fed the crumble diet and the 1.59- and 3.17-mm die diets had greater BW and more efficient feed conversion than did birds fed the mash feed; however, when all birds were placed on a common pelleted feed from 13 to 41 d, these positive effects dissipated as the birds grew older. Significant differences in feed intake were observable only at 13 d. Birds fed the diet pelleted with a 1.59- or 3.17-mm die had higher feed consumption than did birds fed the mash feed, but the feed intake was similar when birds were fed either the crumble or mash diet. Significant linear regressions were observed between BW or feed intake at 13 d and at 34 or 41 d. According to these correlations, the numerical differences in BW or feed intake at 7 d were maintained up to 34 or 41 d. It was likely that a 3.17-mm die diet was suitable for the starter diet because these birds became accustomed to a larger pellet size, thereby increasing the feed intake in subsequent periods. These data indicate that the small pellet diameters could be beneficial during the starter period and on subsequent performance.

Two trials with identical experimental design were conducted approximately 20 months apart to evaluate the response of broiler chickens to the addition of NuPro®, a yeast product rich in nucleotides. In both trials, four dietary treatments were compared. The first treatment contained no NuPro®. For the second treatment, the diet with 2% NuPro® was fed only the first 7 days of life while for the third treatment, 2% NuPro® was fed for the first 14 d. For the fourth treatment, 2% NuPro® was fed for the first 7 days and also during the finisher period of 35-42 d of age. In both studies, each treatment was fed to six replicate groups of 60 male broilers of a commercial strain. Response to the addition of NuPro® varied between the two experiments. In the first study, addition of 2% NuPro® to the diet resulted in improvement in feed conversion. Response varied by age of bird and time during which the NuPro® was fed. At 7 d of age, there were no significant differences between birds that had been fed NuPro® and those fed the negative control diet. At 14 d of age, there were no significant differences in feed conversion among birds fed the various treatments, but feed conversion was numerically better for those birds that had been fed NuPro® for the first 7 or 14 d. At 35 d, birds that had been fed NuPro® for the first 7 d had significantly better feed conversion than those fed the control diet with birds fed NuPro® for the first 14 d being intermediate between these two groups. At 42 d, birds fed diets with 2% NuPro® for the first 7 d or for the first 7 d followed by feeding from 35-42 d had significantly lower feed conversion than those fed the control, with those fed NuPro® for the first 14 d being intermediate between these groups. However, in the second trial there was no significant effect of inclusion of NuPro on any of the parameters evaluated. There may be nutritional differences between batches of the product that influence the response of chicks.

The effect of different dietary levels of amino acids, calcium and phosphorus as influenced by phytase supplementation was evaluated in broiler chickens. The experimental design consisted of a 3 x 4 x 2 factorial arrangement with three levels of digestible lysine (1.10, 1.30 and 1.50%), four levels of calcium (0.50, 0.70, 0.90 and 1.1%) and diets containing 0.35% AP with and without phytase for a total of 2 4 treatments. Remaining amino acids levels were adjusted with respect to the digestible lysine level using the ideal ratios suggested by Rostagno et al. (2005). Each experimental diet was fed to six replicates pens of five male chickens during 21 days. Body weight, FCR, feed intake, bone development (TD), bone mineralization (toe ash), and phosphorus excretion as Total Phosphorus in excreta (TP), Water Soluble Phosphorus in excreta (WSP) and the WSP/TP ratio were evaluated. Birds fed lysine levels higher than 1.1% expressed better body weight in a non-linear trend. Feed intake was decreased by increasing the lysine level while feed conversion improved as lysine level increased. Increasing levels of Ca decreased feed intake, the 1.1% Ca level was detrimental for body weight. Phytase supplementation was effective to alleviat e widened-suboptimal Ca:P ratios in terms of feed intake and body weight. The 1.5 % digestible lysine level improved toe ash; however, high levels of lysine were also related to a higher incidence of TD. Ca levels equal or greater than the NRC (1994) recommendation were adequate for optimum bone mineralization. Increasing levels of Ca reduced the incidence and severity of TD. Moreover, Ca levels greater than those suggested by NRC (1994) were adequate to assimilate higher lysine levels without compromising bone development. The higher lysine levels fed reduced TP in excreta but increased the WSP/TP ratio. The supplementation of phytase increased WSP and the WSP/TP ratio. Increasing levels of Ca reduced WSP and the WSP/TP ratio in excreta. Furthermore, high levels of Ca were also effective to overcome the increased WSP and WSP/TP ratio caused by the supplementation of phytase.

Maximum Profit Feed Formulation (MPFF) is proposed as a new approach to formulation of broiler diets which predicts the best profit for given ingredient and broiler prices, nutrient requirements and performance. Absolute and relative equations for body weight and feed intake as a function of Dietary Nutrient Density (DND) were developed and included into the objective function of Maximum Profit Programming 3.0. Maximum performance and profitability were compared in terms of DND. Factors such as livability , temperature, processing cost, ingredient and broiler prices, starting and ending broiler prices as well as comparisons of two dynamic models, Body Weight (BW) or cut-up parts (CW), were evaluated to determine changes in DND and to compare the profitability between MPFF and Least-cost Feed Formulation (LCFF). Starter, grower and finisher DND were calculated from the mean of DND obtained by the MPFF. The maximum performances for cut-up parts and body weight were 3.250 and 3.300 ME kcal/g of DN D respectively using simulations of the calculated equations, whereas the maximum profits for them were at 3.169 and 3.177 ME kcal/g respectively using the MPFF. Livability slightly decreased the DND, while temperature and processing cost did not affect the DND. However, the ingredient and broiler prices did affect the DND. As broiler meat or corn price increased, the DND was also increased but as the price of soybean meal or poultry oil increased, the DND tended to decrease. For the above variables, use of the MPFF resulted in better profits than did use of LCFF. As expected, the use of ending broiler prices produced better profitability than use of starting broiler prices. If the starting broiler prices were used, the MPFF resulted in higher profits than with LCFF and had similar pattern in profits as ending prices. The dynamic model CW estimated a narrower range of DND compared with those of dynamic model BW. Both dynamic models were more profitable than those of the LCFF model. Starter, grower and finisher DND decreased as the bird aged. This new formulation method can be used to complement least cost formulation to get the best profitability and is recommended for Ross male lines (on which the performance data was developed) with the static nutrient requirement and ingredients used. Requirements for other strains should be quantified by dose - response.

Four economic nutritional models including a constant calorie-nutrient ratio (C-E:P), a variabl e calorie-protein ratio (V-E:Pg), a constant protein-amino acid ratio (DBP) and a variable calorie-protein ratio for the finisher period (V-E:Pd) were compared in terms of relative performance, economic nutrient requirements and profitability based on relative performance expressed as a function of nutrients, relative or real prices of feedstuffs and broilers and maximum profit feed formulation. The relative body weight or feed intake in response to nutrient contents tended to increase or decrease respectively with particular differences for each model. The economic nutrient requirements were different for each model such as 3.139 Mcal/kg for C-E:P, 2.968 Mcal/kg and 20.7% of protein for V-E:Pg model, 22.44% of protein for DBP model, 3.167 Mcal/kg for V-E:Pd and 3.134 Mcal/kg for C-E:P-3.15 model. As the price of broilers or corn increased, the energy or protein content was increased for C-E:P, V-E:Pg and DBP models except the energy level of V-E:Pg model. However, as the Soybean Meal (SBM) or poultry oil price increased, the energy or protein content was reduced for the three models indicated above except the energy level of V-E:Pg model. Energy levels of the V-E:Pd model were kept almost constant as the broiler or ingredient price raised. Under relative price of feedstuffs and broilers the best profits depended on the model used, being more economical when the broiler or corn price increased for the C-E:P or DBP models respectively. The best profitability using real price of broiler, corn or SBM for twelve months came from the C-E:P model followed by the DBP model. From the two models, V-E:Pd and C-E:P-3.15 models, the V-E:Pd model had the best benefit but with a narrow range of growth response and economic conditions. These data suggest that the C-E:P model is the best method of formulation to maximize performance or profitability; however, for some corn price variation the DBP model can be more profitable though the carcass quality can be negatively affected.

SUMMARY Differently sized dies were used to pellet broiler starter diets formulated to meet typical commercial standards. From 0 to 13 d of age, birds in floor pens were assigned different feed forms, such as mash, crumble, or pellets made by using 1.59- and 3.17-mm dies, followed by common grower and finisher diets pelleted with a 4.76-mm die fed to 41 d. During the first 13 d, birds fed the crumble diet and the 1.59- and 3.17-mm die diets had greater BW and more efficient feed conversion than did birds fed the mash feed; however, when all birds were placed on a common pelleted feed from 13 to 41 d, these positive effects dissipated as the birds grew older. Significant differences in feed intake were observable only at 13 d. Birds fed the diet pelleted with a 1.59- or 3.17-mm die had higher feed consumption than did birds fed the mash feed, but the feed intake was similar when birds were fed either the crumble or mash diet. Significant linear regressions were observed between BW or feed intake at 13 d and at 34 or 41 d. According to these correlations, the numerical differences in BW or feed intake at 7 d were maintained up to 34 or 41 d. It was likely that a 3.17-mm die diet was suitable for the starter diet because these birds became accustomed to a larger pellet size, thereby increasing the feed intake in subsequent periods. These data indicate that the small pellet diameters could be beneficial during the starter period and on subsequent performance.

A trial was conducted to evaluate high levels of distillers dried grains with solubles (DDGS) in broiler diets throughout a 49 d growing period. Diets were formulated based on digestible amino acid content to contain 0, 10, 20, 30, 40, or 50% DDGS. Diets were formulated to be optimum nutrient density commensurate with approximately 1% supplemental poultry oil. Each dietary treatment was assigned to four replicate pens with 25 commercial male broiler chicks. Starter (0-14 d) and grower (14-35 d) diets were fed as pellets with finisher (35-49 d) diets fed as mash. Bulk density (mass/volume) was determined on all the diets. Body weights and feed consumption were determined at 14, 35, 42 and 49 d of age. At the conclusion of the study, five representative birds per pen were processed to determine dressing percentage and parts yield. Generally, the bulk density of pellet or mash diets in all different growth periods decreased as DDGS inclusion rates increased, especially in mash diets. Level of DDGS had little effect on body weight at any age until up to 20% inclusion, after which body weight declined significantly. Feed intake was not significantly affected by level of DDGS during all the periods except of 0-14 d. For the whole period (0-49 d), the estimated metabolizable energy intake by chickens was less as DDGS inclusion increased. Increasing DDGS levels significantly increased calorie conversion ratio (CCR, calorie/gain ratio), especially during the period of 0-42 and 0-49 d. Dressing percentage decreased linearly with increasing DDGS levels from 0-50%. There was a significant reduction in breast meat or leg quarter yield as a percentage of live weight with increasing DDGS inclusion, while birds fed higher levels of DDGS had higher wings as percentage of live weight. These results indicate that up to 30% DDGS could be used in broiler diets if price was justified. Inclusion of high levels of DDGS reduces the bulk density and pellet quality and may be a major reason for reduced performance. Low energy density of DDGS diets is probably the limiting factor in meeting the energy needs of the chick.

A feeding trial was conducted in various levels of corn distillers dried grains with solubles (DDGS) were fed in broiler diets formulated to be either isocaloric using metabolizable energy levels similar to current U.S. poultry industry levels or formulated to contain optimum density commensurate with 1% supplemental poultry oil. In each diet type, levels of 0, 15 and 30% DDGS were incorporated. This resulted in six dietary treatments with four pens of 25 males per treatment. Diets were developed for starter (0-14 d), grower (15-28 days) and finisher periods (29-42 days) and were formulated to meet digestible amino acid specifications of a major poultry breeder, adjusted to the energy content of the diet. Bulk density and pellet quality of mixed feeds were determined. At the end of the study, five representative birds per pen were processed for dressing percentage and parts yield determination. Pellet quality decreased with increasing level of DDGS used. There was little difference in pellet quality between diets with 0 or 15% DDGS but quality deteriorated severely in diets with 30% DDGS. Diets formulated to optimum energy had better pellet quality due to lower supplemental poultry oil. Over the 42 days study, birds fed diets with 30% DDGS had significantly lower body weight and significantly higher feed conversion than did birds fed the control diet with no DDGS. Birds fed diets with 15% DDGS did not differ significantly in 42 days BW or feed conversion from birds fed the control diet with no DDGS nor with the birds fed diets with 30% DDGS. It appeared that a portion of the reduced performance associated with the higher level of DDGS might have been associated with the reduced pellet quality and the bulk density of the diet, rather than any nutritional deficiency. Therefore, approaches to feed manufacturing that enhance pellet quality may enhance usage of higher levels of DDGS in broiler diets.

Two consecutive experiments compared different concentrations of inorganic trace minerals in broiler production under different ambient temperature. Both experiments had six treatments, consisting of 100, 80, 60, 40, 20 and 0% of normal trace mineral premix (TMP) inclusion rate with eight and four replicates of sixty male broilers in the first and second experiments, respectively. Experiment 1 began on January 9th and finished on February 20th while Experiment 2 began on July 19th and finished on August 29th. Body weight and feed consumption were determined at 14, 35 and 42 days. At 42 day two birds per pen were nd killed and the tibia removed for bone ash determination. In Experiment 2, cohort birds were fed in battery pens from 35 to 37 days. with excreta samples collected for trace mineral analysis. In Experiment 1, birds with no TMP had significantly decreased body weight over all growth periods. Birds fed diets with 20% of normal TMP did not differ in performance from those fed higher levels up to 100% of normal addition rates. There was no difference in any growth variables in Experiment 2 when higher environmental temperatures were in effect. Reduction of TMP in broiler diets could reduce mineral excretion to environment. Levels of Fe, Cu, Mn and Zn in broiler excreta decreased when mineral premix levels were reduced.

2 Abstract: An experiment was conducted to evaluate the use of distillers dried grains with solubles (DDGS) combined with glycerin in broiler diets. In a 3×2 factorial arrangement, 600 one-day-old commercial strain Cobb 500 broilers were randomly assigned to experimental diets with 0, 15 and 30% DDGS of know n composition; within each level of DDGS the diets contained 0 or 5% glycerin, respectively, from 0-42 days of age. Diets were formulated to meet digestible amino acid requirements and were fed in pelleted form. Each dietary treatment was replicated 4 times. Body weight gain and feed consumption were measured and carcass characteristics were evaluated at 42 days of age. Inclusion of 30% DDGS had no adverse effect on body weight of chicks; however birds fed diets with 30% DDGS had greater feed intake and poorer feed conversion than birds fed the control diet at most age periods. This was highly correlated to the reduced pellet quality of diets containing the high levels of DDGS. Birds fed diets with 30% DDGS also had significantly reduced dressing percentage compared to birds fed the control diet with no DDGS. However, there was no adverse effect on breast meat yield related to the higher levels of DDGS inclusion. Addition of 5% glycerin from biodiesel production to the diets had no significant effect on body weight, feed intake, or feed conversion. There was no significant effect of the addition of glycerin on dressing percentage or yield of various carcass parts. With one minor exception, there was no significant interaction between addition of glycerin and level of DDGS in the diet, even though pellet quality declined when glycerin was added to the diets. Overall, the results of this study demonstrates that 15% DDGS of known nutritional quality can be utilized in diets for growing broilers with no adverse effects provided diets are formulated on a digestible amino acid basis and meet the nutritional requirements of the broiler. Higher levels may be tolerated but there may be a loss in feed conversion unless pellet quality can be improved. A loss in dressing percentage at higher levels of DDGS has been consistently noted in this and previous studies. Incorporation of 5 % glycerin from biodiesel production as a source of energy appears satisfactory.

Male broilers from 11 to 49 days of age were assigned to one of four feeding treatments: Single diets (control), a choice of starter and finisher diets, a choice of high energy and high protein diets in relation to amino acid: lysine ratio and a choice of high energy and high protein diets in relation to amino acid: protein ratio. Birds fed both energy-protein treatments had worse body weight, feed conversion and carcass characteristics than did birds fed single diets or starter and finisher diets. The high energy-protein diets formulated in relation to lysine had the poorest carcass characteristics for all parameters except for wing and leg quarter yields. Birds given the choice feeding systems selected more high energy diet than high protein diet especially during the period of 11 to 22 days of age. Choice-fed broilers of both energy-protein treatments consumed less protein (total intake or percentage of consumed feed) for all periods, whereas these birds consumed similar energy intake at all age periods except for 42 to 49 days of age and higher energy density than did birds fed the other two feeding systems. As the choice-fed birds grew older, the selected energy content tended to wane while the selected protein contents tended to increase. These data indicate that the high protein diet formulated with amino acids in relation to lysine did not overcome the failure of choice feeding with high energy and high protein diets to sustain productivity since energy may be the driving force for feed selection.

A st udy was conducted utilizing a 2 x 2 x 4 x 4 factorial arrangements in which a nutritionall y adequate diet was fed with and without 1200 FTU/kg of phytase and with or without 69 µg/kg of 25 - hydroxycholecalciferol, four levels of nonphytate phosphorus (NPP) (0.35, 0.40, 0.45, and 0.50%) and four levels of calcium (2:1 Ca:NPP ratio, 0.2% Ca less than the 2:1 ratio, 0.2% Ca more than the 2:1 ratio, and 0.4% Ca more than the 2:1 ratio) for a total of 64 treatments, each fed to two replicate pens of five male broilers in wire-floored battery brooders. At 14 d of age excreta samples were collected, frozen, freeze dried, and analyzed for total P (TP), Ca, and water-soluble P (WSP). The ratio of WSP/TP was calculated from these data. The TP, Ca and WSP in excreta increased as the NPP content of the diet increased. Phytase supplementation reduced TP and Ca but increased WSP concentration and the WSP/TP ratio; this effect might be reversed if levels of NPP lower than those evaluated in the present study are utilized to account for the improvement on phytate phosphorus digestion. The addition of Hy-D reduced TP and Ca concentration in broiler excreta. The most remarkable effect was seen by increasing dietary calcium levels above the 2:1 Ca:NPP ratio typically used in the poultry industry. As the dietary Ca increased, there were significantly reduced excreta levels of TP, WSP and the WSP/TP ratio was significantly reduced. Compared to chicks fed diets with the 2:1 Ca:NPP ratio, the WSP in excreta was reduced 40% by adding 0.20% more Ca and 54% by adding 0.40% more Ca. As the WSP fraction of broiler litter is the primary concern in eutrophicatio n, increasing the dietary Ca level in conjunction with feeding closer to the P requirement should be a cost- effective means of combating the adverse effects of broiler litter on pastures.

This study was conducted to evaluate the use of moderate to high levels of DDGS in broiler diets and to evaluate the effects of rapid and multiple changes in level of DDGS during the growth period. Diets were formulated to contain 0, 15, or 30% DDGS with diets formulated on the basis of digestible amino acids to meet levels typical of the U.S. broiler industry. Groups of birds were fed diets with these three levels of DDGS on a constant basis from 0 to 42 d of age. Other groups were fed 0 and 15% or 0 and 30% DDGS on alternate week basis, with one group starting with diets containing no DDGS and other groups starting with diets containing 15 or 30% DDGS. Four pens of 25 male broilers were fed each of the dietary treatments. At the conclusion of the study five representative birds per treatment were processed to determine dressing percentage and carcass yield. Birds fed diets containing 15% did not differ significantly in live performance or carcass characteristics from birds fed diets with no DDGS, whether fed on a continuous basis or alternated weekly between 0 and 15% DDGS. Birds that were continuously fed diets with 30% DDGS had significantly reduced body weight and feed intake at 35 and 42 d compared to birds fed the control diet with no DDGS and had reduced breast meat yield. When birds were fed diets with 0 or 30% DDGS alternating on a weekly basis live performance was approximately midway between that of birds fed diets with 0 or 30% continuously and similar to that of birds fed 15% DDGS on a constant basis, but breast meat yield tended to be reduced. The results of the study demonstrated the effective use of diets with 15% DDGS when formulated on a digestible amino acid basis and showed that abrupt removal of this level of DDGS did not adversely affect performance of broilers. Further studies are suggested to quantify reasons for reduced performance when fed diets containing 30% DDGS.

Chickens from two broiler strains known to differ in growth rate and feed conversion (GROWTH) and in high breast meat yield (YIELD) were grown to 10 days of age on a common starter diet and from 11 to 49 days were provided single diets (control), a choice between high energy and high protein diets, or a choice between starter and finisher diets. Overall the YIELD strain had greater body weight, feed intake and breast yield than did GROWTH strain. However, the YIELD strain had better feed conversion only when offered a choice of starter and finisher diets. Birds fed single diets and Starter-Finisher diets had better body weight, feed intake, feed conversion and breast yield than those birds fed Energy-Protein diets. Birds fed both choice feeding systems selected more high energy diets than high protein diets especially during the period of 11 to 22 d of age. The YIELD strain had a preference for the high protein diet and consequently had greater protein intake and average dietary protein content than did the GROWTH strain, while the former ate more energy intake but less energy content than did the latter. Birds given choice of the energy and protein diets had less protein intake and content for all periods, whereas these birds chose less energy intake for the period of 22 to 42 d of age and a higher energy level than did birds fed the other two feeding systems. These data indicate that choice feeding systems can identify differences in performance according to the selected nutritional needs for new strains of broilers.

A study was conducted to evaluate the use of constant or increasing levels of Distillers Dried Grains with Solubles (DDGS) in diets for broilers. Diets were formulated for starter (0-14 d), grower (14 to 35 d) and finisher (35 to 42 d) periods to contain 0, 15, or 30% DDGS. Diets were formulated on digestible amino acid basis to meet current U.S. poultry industry nutrient levels and were maintained isocaloric and isonitrogenous. Varying levels of DDGS were fed during the study; with some birds receiving a constant level while others received increasing amounts as the bird aged. The DDGS levels used in the study were as follows (starter-grower-finisher, %): 1) 0-0-0; 2) 0-15-15; 3) 0-15-30; 4) 0-30-30; 5) 15-15-15; 6) 15-15-30; 7) 15-30-30; 8) 30-30-30. Starter diets were crumbled, while grower and finisher diets were pelleted. Each of the dietary treatments was fed to four replicate pens of 25 birds each. Body weights and feed consumption were determined at 14, 35 and 42 d of age. At the conclusion of the study five representative birds per pen were processed for dressing percentage and parts yield. The results indicated that increasing DDGS levels had a trend to reduce the weight:volume ratio and visually decreased pellet quality. Diets containing 15% DDGS could be fed throughout the entire feeding period of 1 to 42 d of age with no adverse effects on live performance or carcass composition when diets were formulated on a digestible amino acid basis. Inclusion of 30% DDGS in the diet reduced the weight:volume ratio and markedly reduced pellet quality. Birds fed diets with 30% DDGS during the starter or grower periods had reduced body weight, elevated feed conversion and typically had reduced breast meat yield, compared to birds fed diets with 15% DDGS or birds fed the control diet with no DDGS. Feeding DDGS for the last seven days prior to slaughter after being fed diets with 15% during starter or grower period might possibly be acceptable in terms of body weight gain and feed conversion but still resulted in a significant reduction in breast meat yield. It is possible that some of the essential amino acids that were not considered in the formulation of the diets may become marginal or deficient in diets with 30% DDGS. Further studies are suggested to evaluate needs for these amino acids in diets with high levels of DDGS.

The rapid increase in production of ethanol from corn and other grains has resulted in growing quantities of byproducts, primarily distillers dried grains with solubles (DDGS). The use of DDGS in poultry diets is not new, but the supply of product encourages the use of higher percentages than has typically been used in the past. As greater quantities are used in the diet, it becomes increasingly essential that accurate nutrient values be assigned to the product. This review attempts to summarize results from various laboratories to provide a nutrient matrix that can be used to evaluate the potential use of DDGS in poultry feeds.

An experiment was conducted to evaluate different levels of "new generation" distillers dried grains with solubles (DDGS) in broiler diets throughout a 49 d growing period, based a standardized nutrient matrix derived from a composite of literature values. Diets were formulated based on digestible amino acid content to typical U.S. poultry industry standards to contain 0, 5, 10, 15, 20, or 25% DDGS. Each dietary treatment was assigned to four replicate pens of 25 male chicks of a commercial broiler strain. Starter diets (0 to 14 d) were fed as crumbles; grower (14 to 35 d) and finisher (35 to 49 d) diets were fed as pellets. Bulk density (mass/volume) was determined on the crumbled or pelleted feeds. Body weights and feed consumption were determined at 14, 35 and 49 d of age. At the end of the study five representative birds per pen were processed to determine dressing percentage and parts yield. Increasing the DDGS in the diet generally reduced the weight per volume of feed. There were no significant effects of DDGS level on body weight; however chicks fed diets with 25% DDGS consumed significantly more feed and had poorer feed conversion compared to chicks fed the control diet with no DDGS. Birds fed 15 and 25% DDGS had significantly lower dressing percentage than did birds fed the control diet with no DDGS. Birds fed diets with 25% DDGS had significantly lower breast weight when expressed as percentage of live weight but not when expressed as a percentage of the carcass weight, compared to birds fed the control diet with no DDGS. Wing weight as percent of live weight and carcass weight was significantly greater for birds fed diets with 15% DDGS as compared to the control, while wing weight as percent of the carcass was significantly increased for birds fed the diet with 25% DDGS as compared to those fed the control diet with no DDGS. These results indicate that good quality DDGS could be used in broiler diets at levels of 15 to 20% with little adverse effect on live performance but might result in some loss of dressing percentage or breast meat yield.

This study was conducted to evaluate the bioavailability of an organic copper source, MINTREX ® concentration. Overall, there was no effect of Cu source or dietary Cu concentration on feed conversion or mortality. At 14 d the birds in the MINTREX treatment weighed significantly more than the birds in the Cu sulfate treatment. High Cu concentration s markedly decreased (p

Glycerine from biodiesel production was used as a pure energy source in broiler diets formulated to meet typical commercial standards. In the first experiment, glycerine was added at 0, 5, and 10% of the diet while in the second experiment glycerine was added at 0, 2.5, and 5%. Glycerine was assigned a metabolizable energy value of 3527 ME kcal/kg in formulating the diets. In each experiment the various treatments were assigned to eight replicate pens of 60 male broilers each. In the first experiment, birds fed diets with 5% glycerine did not differ significantly in performance from birds fed the control diet with no glycerine. Birds fed diets with 10% glycerine consumed significantly less feed than did those fed diets with 0 or 5% glycerine and consequently had significantly reduced body weight. It is felt that this was due in large part to reduced flow rate in the feeders used in this study as previous researchers have shown acceptance of higher levels of glycerine. In the second study, birds fed diets with 2.5 or 5% glycerine had growth rate and feed conversion that did not differ significantly from that of birds fed the diet with no glycerine. Breast yield as a percent of the dressed carcass was significantly greater for birds fed diets with 2.5 or 5% glycerine as compared to those fed the diet with no glycerine. These data indicate that glycerine from biodiesel can be a useful energy source for use in broiler diets. Concerns remain regarding acceptable levels of residual methanol resulting from separation of the fatty acids in biodiesel production.

Inconsistencies in expected performance have been noted from feeding exogenous enzymes. Several explanations may exist but it is possible that when feeding diets with exogenous enzymes a metabolic feedback system limits or regulates endogenous digestive enzyme expression, synthesis, and secretion. Labeled amino acids may be an advantage over other methods for measuring endogenous losses because the isotope technique may be used with practical diets. Endogenous amino acid secretions have been shown to be affected by dietary protein, types of fats, and fiber (Siriwan et al., 1989; Danicke et al., 2000) and digestible amino acid requirements should be corrected for the endogenous amino acid losses. The objectives of the present study were to determine endogenous amino acid losses from broilers fed various levels of protein, fat, and fiber with and without added Rovabio MaxTM.

Energy utilization is a key component of animal production. The study of the mechanisms by which lipids and carbohydrates are mobilized and deposited in the egg, can give us clues about how breeders utilize energy during the production period. Is the dietary energy directly utilized during yolk formation or is there a dynamic metabolic system that consistently provides nutrients to the egg at the expense of body tissue? Are the fatty acids in the yolk derived from direct intestinal absorption, endogenous synthesis, or maternal body stores? Do the systems change as the breeder ages and egg production decreases? The aim of the present studies was to better understand the mechanisms of energy partitioning in broiler breeder hens.

Among the regulators of protein turnover, amino acids play a critical role. Lysine, leucine and isoleucine were found to alter protein synthesis, degradation and its regulation (Yoshizawa, 2004; Nakashima et al., 2005; Tesseraud et al., 2008). Furthermore, Tesseraud et al. (2000) reported that differences in the fractional degradation rates (FDR) between fast-growing and slow-growing birds are observed in young birds but not older ones, suggesting a possible age effect.

The extensive use of an NE system has not been accepted by the poultry industry because NE feed evaluation is laborious, values have a high variability and the process is expensive. Productive energy (PE), developed by Fraps and Carlyle (1939), was used commercially from 1946-1960 and was unfortunately related to NE. The methodology for the determination of PE is considered the cause for the high variability. De Groote (1968) used one plane of feed intake along with an independent NEm and showed similar variability between ME and NE energy systems. High energy feed costs have caused the poultry industry to dramatically increase the use of exogenous feed enzymes during the past 5 years. The objectives of this study were to compare the ME and NE systems for variability, predicted performance and to determine the extra energy content due to an enzyme complex.

A study was conducted to determine the changes that occur to proteolysis and related genes due to age, protein, and energy intake in high-yield broiler breeder hens (Gallus gallus). Cobb 700 broiler breeders were randomly assigned to one of six diets in a 2 × 3 factorial fashion. Two levels of energy (390 and 450 kcal/day) and three levels of protein (22, 24, and 26 g CP/day) were utilized. Protein turnover was determined in the left pectoralis at 22, 26, 31 and 44 weeks. Relative mRNA expression of calpain 2 (CAPN2), proteasome C2 subunit (PSMA1), and F box protein 32 (FBXO32) were determined via RT-PCR at 20, 25, and 44 weeks. Contrasts indicate fractional synthesis rate (FSR) and FBXO32 increase to a maximum at 25–26 weeks and a decrease thereafter. A significant drop in PSMA1 and FBXO32 was observed between 25 and 44 weeks and matched the decrease observed in FBR. No differences were detected in the levels of fractional synthesis and degradation, or the expression of CAPN2, PSMA1, and FBXO32, due to protein or energy intake. In summary, protein turnover was upregulated during the transition into sexual maturity and decreased thereafter. The observed changes in degradation appeared to be mediated by the ubiquitin–proteasome pathway.

A 3 × 2 × 2 factorial experiment, consisting of 52 hens per treatment, was conducted to determine the effects of pullet BW, dietary nonphytate phosphorus (NPP), and feeding regimen on performance, progeny quality, and bone remodeling. Cobb 500 broiler breeder pullets were reared to 3 different growth curves: 20% under, Cobb standard, and 20% over. Body weights were recorded weekly and feed adjustments made accordingly. At 21 wk, 624 hens were fed one of 2 breeder diets differing only in the amount of dietary NPP: 0.15 or 0.40%. A normal feeding regimen was appropriate for the particular growth curve; an alternative regimen considered the 3 growth curves together as a flock. At 24, 26, and 29 wk, blood was collected from 5 hens per treatment every 4 h over a 24-h period. Plasma samples were analyzed for total alkaline phosphatase, tartrate-resistant acid phosphatase, parathyroid hormone-related peptide, Ca, and inorganic P. Eggs per hen housed were diminished in hens fed the low dietary NPP and by low pullet target weight. Hens fed low dietary NPP also had lower egg weights but better eggshell quality. Mortality was significantly higher in hens fed low dietary NPP. Breeder tibia relative strength and ash were also significantly lower in hens fed low dietary NPP, regardless of the quantitative amount. Progeny tibia ash was not affected by any treatment. Total alkaline phosphatase responded to pullet BW, however by wk 29, total alkaline phosphatase also became sensitive to dietary NPP. The NPP by pullet BW interaction for tartrate-resistant acid phosphatase levels became significant by 29 wk, and pullet BW was significant at wk 24. The NPP by pullet growth curve interaction was also critical for plasma inorganic P levels throughout the sampling period. In summary, both 0.15% dietary NPP and reared pullets 20% under standard BW negatively affect egg production but do not impair progeny productivity. Body composition appears to be a main contributor in bone remodeling mechanisms, especially during the transition into egg production.