Assessment of meat quality attributes of four commercial broiler strains processed at various market weights.

As the demand for poultry meat continues to rise, industry production is constantly challenged with obtaining consumer needs. Integrators have answered this increasing demand by improving the growth rate of broilers allowing for increased production efficiently. The resulting broiler produces higher yields and a larger quantity of fresh poultry to satisfy consumer needs. However, this increase in efficiency has cost integrators as new quality issues continue to manifest through global production. Therefore, the objective of the current experiment was to evaluate the effect of genetic strain (standard and high yielding) and target weight on meat quality attributes such as pH, water holding capacity (WHC), and tenderness, alongside meat quality defects such as breast and tender myopathies. In the current study, 1,800 broilers from 4 commercial strains (2 high breast yielding (HY) and 2 standard yielding (SY) were raised sex separate to evaluate meat quality trends over time at 6 previously defined market weights. Birds were processed at weights ranging from 2,043 to 4,313 g in 454 g increments. HY strains produced higher breast and tender yields than those of SY strains (P < 0.05). There was an increase in breast and tender yield as target weight increased (P < 0.05) for both HY and SY strains. Differences were observed between strains for all fillet dimensions (P < 0.05); however, these measurements increased as target weight increased as expected. Woody breast (WB) had a higher severity (P < 0.05) in HY strains over SY strains, for both males and females. Differences were observed in white striping (WS; P < 0.05) for females in both strains, but no differences were observed in males. A main effect of target was noticed for both WB and WS (P < 0.05), expressing increased severity as target weight increased. Shear values were influenced more by target weight (P < 0.05), but inconsistent differences were observed between HY and SY groups. Meullenet-Owens Razor Shear (MORS) energy values increased slightly as target weights increased (P < 0.05) from 2,951 to 4,313 g in both males and females, but differences were minor and inconsistent with the smaller carcass weights. The MORS peak counts generally increased as target weight increased for both sexes. While strain had minimal effects on meat quality attributes, processing weight had a greater influence on quality, specifically muscle myopathies, WHC, and shear properties.

Meat quality attributes of male and female broilers from 4 commercial strains processed for 2 market programs.

In recent times, meat quality has become a key aspect of poultry production. In the current study, 2,400 sex separate broilers from 4 commercial strains were placed in 6 replications to evaluate various meat quality characteristics when grown to 2 market weights. Broilers were fed 1 of 2 diets with varying degrees of amino acid inclusion to evaluate meat quality of broiler raised on varying planes of nutrition. Birds were processed to meet 2 specified target weights (2.5 and 3.8 kg) representing small bird and big bird debone markets in the United States, respectively. Birds were processed using commercial methods, deboned at 3-h postmortem, and meat quality was assessed. Myopathies (woody breast, white striping, spaghetti meat, along with tenderloin quality), fillet dimensions, color, water-holding capacity (e.g., drip loss, cook loss), and Meullenet Owens Razor Shear was determined. Data were analyzed using the Mixed Model platform of JMP Pro 15.2 (SAS Institute, Cary, NC). Diet had no effect (P > 0.05) on the key quality responses; data were then pooled resulting in main effects of sex, strain, and target weight (noted as carcass size). On the day of processing, high yielding (HY) strains produced higher breast and tender yields (P < 0.05) when compared to standard yielding (SY) strains. In addition, and as expected, females exhibited higher breast and tender yields (P < 0.05) than males. However, males had significantly thicker (P < 0.05) and longer (P < 0.05) fillets, higher incidences (P < 0.05) of white striping, and higher (P < 0.05) cook loss when compared to females. Differences were also observed in tenderness as SY strain A produced the lowest shear values, whereas SY strain B produced the highest shear values across parameters (P < 0.05). SY strains in the small bird (SB) market performed better than SY strains in the big bird (BB) market as indicated by lower incidences of breast and tender myopathies white striping, woody breast, spaghetti meat, woody-like tender, and tender feathering and improved quality attributes (P < 0.05). Similar trends were observed (P < 0.05) in HY strains as SB carcasses produced a better overall product than BB. Differences in carcass size directly impacted quality (P < 0.05) as SB markets showed improvements in most parameters assessed, but broilers representing BB markets had greater breast yield. Although strain had minimal impacts on quality measures, carcass size, and sex had a greater impact on muscle myopathies, water-holding capacity, and shear properties.

Characterization of growth patterns and carcass characteristics of male and female broilers from four commercial strains fed high or low density diets.

Over the last few decades, the poultry industry has seen the emergence of various market segments that are beneficial for rearing various flock sizes. Two concurrent experiments consisting of 1,200 broilers each were conducted to evaluate the effects of broiler size and diet on the performance of four commercially available broiler strains, including 2 standard yielding (SY) and 2 high yielding (HY) strains. Within each experiment (Experiment 1: males, Experiment 2: females), a small bird (38 and 40 d processing) and big bird (47 and 54 d processing) debone market were targeted to give variable carcass size. Two polyphasic diets were fed based on varying of amino acid densities. The low-density diet (L) consisted of 1.20, 1.10, 1.00, and 0.96% digestible Lys and the high-density diet (H) consisted of 1.32, 1.21, 1.10, and 1.06% across the 4-phases, respectively, with similar essential amino acid to digestible Lys ratios between the L and H diets in each phase. Weekly BW, BW gain, feed intake, and feed conversion ratio were assessed, as well as processing yields during both experiments. Broilers fed the H diets responded better than those fed the L diets, regardless of sex, with increased BW and decreased FCR (P < 0.05). Male HY strains provided the highest carcass yields (P < 0.05) compared to SY strains, with no differences observed in females (P > 0.05). High density diets (Diet H) also produced increases in carcass, breast, and tender yield (P < 0.05) for males, but that trend was not present in carcass yield for females (P < 0.05). Overall, strain impacted performance traits and carcass yields. Therefore, the use of specific strains and amino acid density for various market segments is beneficial for integrators to maximize return.

A comparison of formic acid or monoglycerides to formaldehyde on production efficiency, nutrient absorption, and meat yield and quality of Cobb 700 broilers.

After being banned by the European Commission in 2018, the use of formaldehyde as a feed amendment in the United States has come into question. Therefore, this study was conducted to explore alternatives to formaldehyde, such as formic acid and monoglycerides, and their effects on poultry production. In total, 1,728 Cobb 700 broilers were randomly assigned to 96-floor pens on day of hatch (18 birds/pen). Using a randomized complete block design (4 blocks), treatments were assigned to pens with blocking based on location within the barn, with the eastern half of the barn designated for digestibility and the western half designated for production (per experiment: 8 control pens and 10 pens per treatment). All diets were based on a negative control (NC), basal diet. Dietary treatments consisted of: NC, NC + 0.25% formalin (F), NC + 0.25 and 0.50% Amasil NA (AML and AMH; 61% formic acid and 20.5% Na-formate), and NC + SILO Health 104L (SILO; mixture of monoglycerides; 0.5% from 0 to 14 d, 0.4% from 14 to 28 d, and 0.2% from 28 to 42 d). Water and feed were provided ad libitum. Performance data were collected during feed changes on d 0, 14, 28, and 42, with digestibility data collected at d 14 (2 per pen) and carcass quality (6 per pen) assessed at d 46 with a randomly selected group of broilers. A one-way ANOVA followed by Dunnett's multiple comparison, where treatments were evaluated against F were conducted using JMP 14.0 (P ≤ 0.05). Main effect of treatment was significant for performance, nutrient digestibility, and carcass quality. Differences in body weight and ADG were observed from d 14 to d 28, resulting in a trending improvement in lysine digestibility on d 14 and carcass quality on d 46 of birds fed AML and AMH in comparison to those fed F (P < 0.05). Whereas birds fed SILO had reduced digestibility of methionine on d 14 and a decrease in meat quality on d 46 in comparison to those fed F (P < 0.05). Therefore, Amasil NA at 0.25 or 0.50% may be an effective alternative to formaldehyde as a feed amendment for poultry production.

Progress of amino acid nutrition for diet protein reduction in poultry.

There is growing interest among nutritionists in feeding reduced protein diets to broiler chickens. Although nearly a century of research has been conducted providing biochemical insights on the impact of reduced protein diets for broilers, practical limitation still exists. The present review was written to provide insights on further reducing dietary protein in broilers. To construct this review, eighty-nine peer reviewed manuscripts in the area of amino acid nutrition in poultry were critiqued. Hence, nutritional research areas of low protein diets, threonine, glycine, valine, isoleucine, leucine, phenylalanine, histidine, and glutamine have been assessed and combined in this text, thus providing concepts into reduced protein diets for broilers. In addition, linkages between the cited work and least cost formation ingredient and nutrient matrix considerations are provided. In conclusion, practical applications in feeding reduced protein diets to broilers are advancing, but more work is warranted.

Dietary branched-chain amino acid assessment in broilers from 22 to 35 days of age.

BACKGROUND: Valine and isoleucine are similar in chemical structure and their limitation in broiler chicken diets. To evaluate their limitation and interactive effects, multivariate assessment nutrition studies for the branched-chain amino acids (BCAA) are needed. A three level (- 1, 0, + 1), three-factor Box-Behnken design study was conducted to assess dietary BCAA ratios to lysine of 65, 75, and 85 for valine, 58, 66, and 74 for isoleucine, and 110, 130, and 150 for leucine in male and female Lohman Indian River broilers from 22 to 35 d of age. RESULTS: Live performance of male broilers was not affected by BCAA level. However, male broilers fed increasing isoleucine had improved (P = 0.07) carcass yield as leucine and valine were reduced. Female broilers had improved body weight gain (P = 0.05) and feed conversion (P = 0.003) when leucine and isoleucine were at their lowest levels, independent of valine, but increasing leucine impaired live performance and warranted concomitant increases in isoleucine to restore responses. Increasing dietary isoleucine and valine in female broilers increased breast meat yield (P = 0.05), but increasing leucine tended to diminish the response. CONCLUSION: The female Lohman Indian River broiler is more sensitive to BCAA diet manipulation than males. Specifically, as dietary leucine is increased in female broilers, dietary isoleucine increases were needed to offset the negative effects. Both increases in dietary valine and isoleucine improved breast meat yield in female broilers, but only when birds were fed the lowest dietary leucine.

Effect of pullet body weight and hen dietary amino acid treatments on their progeny fed high and low amino acid diets.

Four studies were conducted on Cobb 700 broilers to evaluate the dietary protein and any maternal effects on live production and processing parameters. Day-old Cobb 700 broiler breeder pullets were reared to conform to 2 different BW curves (control BW and increased BW) with 8 replicate pens per treatment. Birds were fed common diets from 1 d of age until first egg (24 wk). At 24 wk, 12 pens of each pullet treatment were given different amino acid (AA) diets (low = 14% CP, high = 15% CP). The performance of female and male progeny from 32 and 45 wk hens were evaluated on low AA and high AA density diets. The 4 progeny trial designs were identical factorial 2 × 2 × 2 designs, with 2 pullet BW curves (control BW and increased BW), 2 dam CP diet levels (low and high), and 2 progeny CP diets (low and high), with 6 replicates each containing 18 birds, for a total of 108 broiler progeny per treatment. Broiler chickens on the higher AA density feed exhibited consistent improvement in mid-growth BW and FCR and white meat yield percentage. Some maternal effects were noted, including increased carcass yield in female broilers from 32 wk old hens. There were 3-way interactions of pullet BW × hen dietary AA × progeny dietary AA treatments for female progeny carcass yield (from 32-week-old hens) and male tender yield (from 45-week-old hens). There were 2-way interactions of pullet BW x hen dietary AA treatments effect on female and male progeny drumstick yield from 32-week-old hens, pullet BW × progeny dietary AA treatments effect on male 27 d BW from 32-week-old hens, and hen dietary AA × progeny dietary AA treatments effect on male thigh yield from 45-week-old hen. The epigenetic effects of maternal pullet BW and dietary AA treatments were seen in processing yields suggesting, the need of dietary CP changes of the progeny.

Determining the 4th limiting amino acid in low crude protein diets for male and female Cobb MV × 500 broilers.

1. Four experiments were conducted to determine the 4th limiting amino acid (AA) in maize-soybean meal-based diets. 2. Deletion assay methodology was used to quantify performance and carcase trait responses to potential deficiencies in essential and conditionally essential AA caused by reductions in dietary crude protein of maize-soybean meal-based diets from 202.9 to 186.5 g/kg. 3. The deletion of Val, Phe and Gly + Pro resulted in negative effects on live performance and carcase traits for male broilers, whereas AA deletion only affected wing weights for females with no response on live performance. 4. Further experimentation could not duplicate a response to Phe or Pro in male broilers. 5. Valine was identified as the potential 4th limiting AA in maize-soybean meal-based diets and was not found to be co-limiting with Ile.

Evaluation of carryover effects of dietary lysine intake by Cobb 500 broiler breeder hens.

Two experiments were conducted to examine the progeny performance of broiler breeder (BB) hens fed diets differing in digestible lysine (dLys). A total of 240 Cobb 500 BB pullets and 40 cockerels, 20 wk of age, were used for each of 2 experiments. In experiment 1, treatment diets were fed from 35 to 45 wk of age. Treatment 1 and 2 diets were formulated with common feed ingredients and BB had dLys daily intakes of 1,200 (IDL-1,200) and 1,010 mg/hen per d (ID-1,010), respectively. Treatments 3 and 4 were composed of semipurified diets formulated to dLys intakes of 1,010 (SPL-1,010) and 600 mg/hen per d (SP-600), respectively. In experiment 1, chick weight at hatch was lower (P < 0.05) for those that came from the SP-600 and SPL-1,010-fed hens, but 42 and 56 d BW was similar for all treatments. Improvements (P < 0.10) in feed conversion ratio were seen at 42 and 56 d for chicks from ID-1,010-fed hens compared with IDL-1,200 hens. For experiment 2, diets were fed to BB hens from 24 to 42 wk of age. Treatment 1 was composed of corn-soybean meal and formulated to a dLys intake of 1,000 mg/hen per d (CS-1,000). Treatments 2, 3, and 4 had inclusion of 25% distillers dried grains with solubles (DDGS) with dLys intake levels of 1,000 (DDGS-1,000), 800 (DDGS-800), and 600 (DDGS-600) mg/hen per d, respectively. Progeny performance was evaluated from eggs collected at wk 26, 31, and 36. Chick hatch weight was similar for all 3 hatches. Chicks from 26-wk-old BB hens and fed DDGS-600 diets resulted in lower (P < 0.05) BW, carcass weight, and breast weight, and higher (P < 0.05) back half (drumsticks and thighs) yield, at 42 d of age. Growout studies performed on eggs laid during wk 31 and 36 revealed no effect on growth or carcass parameters. In conclusion, the results from experiments 1 and 2 may not be comparable, and therefore, the impact on progeny performance needs to be further evaluated.

Determination of the fourth and fifth limiting amino acids in broilers fed on diets containing maize, soybean meal and poultry by-product meal from 28 to 42 d of age.

1. Valine (Val) is considered the 4th limiting amino acid for broilers fed on diets containing ingredients from vegetable origin. However, Val and Isoleucine (Ile) may be co-limiting for broilers fed on diets containing animal protein meals. An experiment was conducted to examine growth responses and meat yield of broilers provided diets varying in digestible Val (dVal) and digestible Ile (dIle) concentrations from 28 to 42 d of age. 2. Eight experimental diets varying in dVal (dVal to dLys ratios from 0·66 to 0·76) and dIle (dIle to dLys ratios from 0·57 to 0·67) were studied; digestible Lysine (Lys) was formulated to 9·9 g/kg in all diets. 3. Broilers fed on a negative control (NC) diet supplemented with crystalline Val (L-Val) and crystalline Ile (L-Ile), dVal to dLys = 0·76 and dIle to dLys = 0·67, grew faster and had higher breast meat yield than birds fed on NC + L-Ile (dVal to dLys = 0·66 and dIle to dLys = 0·67), NC + L-Val (dVal to dLys = 0·76 and dIle to dLys = 0·57), and NC + reduced L-Val and L-Ile (dVal to dLys = 0·71 and dIle to dLys = 0·62). 4. Feeding broilers on the NC + L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67) diets gave similar BW gain, carcase weight and yield and total breast meat weight and yield to birds fed on the positive control-fed broilers with no added L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67). 5. These results indicate that Val and Ile are co-limiting in diets containing poultry by-product meal.

Dietary limitation of isoleucine and valine in diets based on maize, soybean meal, and meat and bone meal for broiler chickens.

1. The dietary limitation of isoleucine (Ile) and valine (Val) was evaluated in broilers. Common diets were given to all broilers from 0 to 28 d of age. Experimental diets were provided from 28 to 42 d of age. 2. The experimental test diet was based primarily on maize, soybean meal, and meat and bone meal, and formulated to satisfy all nutrient recommendations with the exception of Ile and Val. 3. Diets were supplemented with L-Ile and L-Val at either 0·5 or 1·0 g kg⁻¹ of diet, alone or in combination. A diet composed only of commercially available amino acids and formulated to satisfy all nutrient requirements served as a positive control. 4. Body weight gain was depressed by the test diet, but recovered to a weight similar to birds fed on the positive control when Val was added to the test diet either alone or in combination with Ile. Feed efficiency improved when Val and Ile were simultaneously supplemented. 5. Abdominal fat yield was reduced with the combined supplementation of Val and Ile. Breast meat yield appeared to be more sensitive to Ile supplementation than to Val. 6. The results suggest that live performance may be more sensitive to Val, while breast meat yield was maximised with Ile supplementation. However, their combination is required for optimised growth and meat yield.

Digestible lysine requirements of male broilers from 28 to 42 days of age.

Research addressing digestible Lys requirement data of modern broilers from 4 to 6 wk of age is limited. Male broilers (1,632 Ross×Ross TP16 and 3,000 Cobb×Cobb 700) were used in separate experiments to determine the digestible Lys requirements from 28 to 42 d. In each experiment, 2 diets (dilution and summit) consisting of corn, soybean meal, animal protein meal, and peanut meal were formulated to be adequate in all other amino acids. The dilution and summit diets were blended to create 9 titration diets. A control diet formulated to contain corn, soybean meal, and animal protein meal as the primary ingredients was used for comparison with the titration diets. Body weight gain, feed intake, digestible Lys intake, digestible Lys intake:BW gain, feed conversion, mortality, carcass yields, and physiological measurements were assessed during experimentation. Digestible Lys requirements were estimated using a quadratic broken-line model. In experiment 1, the digestible Lys requirement for male Ross×Ross TP16 broilers was determined at 0.988, 1.053, 0.939, and 0.962%, respectively, for BW gain, feed conversion, carcass weight, and total breast meat weight. In experiment 2, the digestible Lys requirement for male Cobb×Cobb 700 broilers ranged from 0.965, 1.012, 1.029, 0.987, and 0.981%, respectively, for 28- to 42-d BW gain, feed conversion, carcass weight, total breast meat weight, and total breast meat yield. Digestible Lys requirements for male Ross×Ross TP16 and Cobb×Cobb 700 broilers were estimated at 1.001 and 0.995%, respectively, based upon averages of live performance and meat yield responses. Both strains required the highest requirement estimate of digestible Lys to optimize feed conversion.

Digestible and metabolizable energy content of crude glycerin originating from different sources in nursery pigs.

The energy value of crude glycerin from different biodiesel production facilities was determined in nursery pigs (initial BW of 10.4 kg) to predict apparent DE and ME based on the composition of crude glycerin. Dietary treatments consisted of a basal diet, or diets containing crude glycerin from various biodiesel production facilities supplemented in the diet at approximately 9.1%. Because of bulk density differences, 2 glycerin products were supplemented at either 7.7 or 6.9%. In addition, soybean oil and lard were included at 6.7% as 2 dietary treatments to serve as positive controls. Each diet was fed twice daily to pigs in individual metabolism crates. After a 6-d adjustment period, a 4-d balance experiment was conducted. During the collection period, feces and urine were collected daily and stored at 0 degrees C until analysis. The GE of each test ingredient and diet and of urine and fecal samples from each pig were determined by isoperibol bomb calorimetry. The DE and ME values of crude glycerol were estimated by difference, whereby the DE and ME content of the basal diet was subtracted from the complete diet containing the test ingredient. Gross energy, DE, and ME of US Pharmacopeia grade glycerin were determined to be 4,325, 4,457, and 3,682 kcal/kg, respectively. In contrast, GE of the crude glycerin samples ranged from 3,173 to 6,021 kcal/kg, DE ranged from 3,022 to 5,228 kcal/kg, and ME ranged from 2,535 to 5,206 kcal/kg, reflecting the content of glycerol, methanol, and FFA in the crude glycerin. The GE, DE, and ME of soybean oil and lard were determined to be 9,443, 8,567, and 8,469 kcal/kg, and 9,456, 8,524, and 8,639 kcal/kg, respectively. The stepwise regression prediction of the ME in crude glycerin exhibited R(2) of only 0.41 [ME, kcal/kg (as-is basis) = (37.09 x % of glycerin) + (97.15 x % of fatty acids)], whereas prediction of GE achieved an R(2) of 0.99 [GE, kcal/kg (as-is basis) = -236 + (46.08 x % of glycerin) + (61.78 x % of methanol) + (103.62 x % of fatty acids)]. On average, the ME of crude glycerin was 85.4% of its GE (SE 5.3) and did not differ by glycerin source. The data provided in these experiments indicate that crude glycerin is a valuable energy source, with its GE concentration dependent on the concentration of glycerin, methanol, and fatty acids, and with ME as a percentage of GE averaging 85.4%.

Limitations of dietary isoleucine and valine in broiler chick diets.

The purpose of this study was to understand the needs and relationship of Ile and Val, the most likely candidates to become fourth limiting amino acids in practical broiler formulas. Broiler chicks were fed a diet adequate in all nutrients that served as positive control (PC). A second diet served as negative control (NC), was formulated to resemble the nutrient amounts of the PC, and was supplemented with various crystalline amino acids but not with l-Ile and l-Val, and therefore, no nutrient minimums were given to Ile or Val in the formula. The other treatments fed were as follows: NC plus 0.15% Ile, NC plus 0.15% Val, NC plus 0.075% Ile and 0.075% Val, and NC plus 0.15% Ile and 0.15% Val. Diets were fed in crumble form from placement until 21 d of age. A total of 1,080 Ross x Ross 708 males chicks were randomly allotted into 72 floor pens (15 chicks/pen), and each treatment was replicated 12 times. Individual supplementation with Val, but not Ile, to the NC diet resulted in BW gain of chicks equal to those fed the PC diet (P<0.005). Feed conversion values of chicks supplemented with Val or Ile, or both, resulted in an improvement, but for this variable it would appear that Val and Ile were both equally needed (P<0.001). Responses observed for plasma concentrations of total protein and albumin suggest that Val may be warranted before Ile (P<0.02). Overall responses indicate that Val was the fourth limiting amino acid under these dietary conditions but may reach a point where Ile becomes co-limiting judging by the response observed with feed conversion.

Digestible lysine requirements of male and female broilers from fourteen to twenty-eight days of age.

There is little research data available on the digestible Lys requirement of broilers from 2 to 4 wk of age. Two experiments were conducted to determine the digestible Lys requirements of male and female Ross x Ross TP16 broilers from 14 to 28 d. Two diets (dilution and summit) consisting of corn, soybean meal, poultry by-product meal, and peanut meal were formulated to be adequate in all other amino acids. The dilution and summit diets were blended to create 9 titration diets. A control diet containing adequate Lys was used for comparison with the titration diets. A true Lys digestibility assay was conducted with cecectomized roosters to determine the values for the dilution (low) and summit (high) diets. True digestible Lys of the low and high dose-response diets were determined to be 0.84 and 1.21%, respectively. Body weight gain, feed intake, digestible Lys intake, digestible Lys intake:BW gain, feed conversion, and mortality were assessed during experimentation. Digestible Lys requirements were estimated using a quadratic broken-line model and a quadratic regression equation based on 95% of the optimum response. In experiment 1, the digestible Lys requirement for male Ross x Ross TP16 broilers was determined to be between 1.07 and 1.09% and 1.10 and 1.15%, for BW gain and feed conversion, respectively. In experiment 2, the digestible Lys requirement for female Ross x Ross TP16 broilers was estimated as 0.98% for BW gain determined with a quadratic broken-line model and 1.03 and 0.99% for feed conversion, respectively, using a quadratic regression equation based on 95% of the optimum response and the quadratic broken-line model. Digestible Lys requirements for male and female Ross x Ross TP16 broilers were estimated at 1.10 and 1.00%, respectively, based upon BW gain and feed conversion averaged for both statistical models.

Dietary digestible lysine requirements of male and female broilers from forty-nine to sixty-three days of age.

Experiments were conducted to evaluate digestible (dig) Lys requirements of male and female broiler chickens from 49 to 63 d of age. A dose-response diet consisting of corn, soybean meal, and corn gluten meal was formulated to be adequate in dig amino acid concentrations with the exception of Lys. L-Lysine . HCl was added to the dose-response diet to create 7 experimental diets. Concentrations of dig Lys of experimental diets ranged from 0.50 to 1.04% in increments of 0.09%. Variables measured consisted of standardized dietary Lys digestibility, feed intake, dig Lys intake, BW gain, feed conversion, mortality, abdominal fat weight and percentage, carcass weight and yield, and total breast meat weight and yield. In experiment 1, dig Lys of the dose-response diet was determined as 0.51% with cecectomized roosters. In experiment 2, dig Lys requirements of male broilers for BW gain, feed conversion, breast meat weight, and breast meat yield were 0.86, 0.88, 0.90, and 0.90%, respectively, based on 95% of the responses. From 49 to 63 d of age, male broilers optimized growth and meat yield measurements with approximately 3.0 g of dig Lys intake. In experiment 3, dig Lys requirements of female broilers were estimated as 0.79 and 0.83%, respectively, for BW gain and feed conversion. Digestible Lys intake necessary to optimize growth performance was 2.8 g/bird during 49 to 63 d of age. These results indicate that dig Lys requirements for male broilers were 0.87 and 0.90% of the diet, respectively, for growth performance and breast meat yield. Conversely, the dig dietary Lys requirement for females was 0.81% based only on growth performance.

Apparent metabolizable energy of glycerin for broiler chickens.

Three energy balance experiments were conducted to determine AMEn of glycerin using broiler chickens of diverse ages. In experiment 1, two dietary treatments were fed from 4 to 11 d of age. Dietary treatments consisted of a control diet (no added glycerin) and a diet containing 6% glycerin (94% control diet + 6% glycerin). Four dietary treatments were provided in experiment 2 (from 17 to 24 d of age) and 3 (from 38 to 45 d of age). Diets in experiment 2 and 3 were 1) control diet (no added glycerin); 2) 3% added glycerin (97% control diet + 3% glycerin); 3) 6% added glycerin (94% control diet + 6% glycerin); and 4) 9% added glycerin (91% control diet + 9% glycerin). Diets in experiment 1 and 2 were identical, but the diet used in experiment 3 had reduced nutrient levels based on bird age. In experiments 2 and 3, broilers were fed 91, 94, 97, and 100% of ad libitum intake so that differences in AMEn consumption were only due to glycerin. A single source of glycerin was used in all experiments. Feed intake, BW, energy intake, energy excretion, nitrogen intake, nitrogen excretion, AMEn, and AMEn intake were determined in all experiments. In experiment 1, AMEn determination utilized the difference approach by subtracting AMEn of the control diet from AMEn of the test diet. In experiments 2 and 3, AMEn intake was regressed against feed intake with the slope estimating AMEn of glycerin. Regression equations were Y = 3,331x -72.59 (P < or = 0.0001) and Y = 3,348.62x -140.18 (P < or = 0.0001) for experiments 2 and 3, respectively. The AMEn of glycerin was determined as 3,621, 3,331, and 3,349 kcal/kg in experiments 1, 2, and 3, respectively. The average AMEn of glycerin across the 3 experiments was 3,434 kcal/kg, which is similar to its gross energy content. These results indicate that AMEn of glycerin is utilized efficiently by broiler chickens.

Valine nutrient recommendations for Ross x Ross 308 broilers.

Studies delineating the dietary Val needs of modern commercial broilers are sparse. Three studies were conducted to determine the dietary Val nutrient needs of Ross x Ross 308 male broilers. Three time periods were evaluated independently, 0 to 14 d (starter), 14 to 28 d (grower), and 28 to 42 d (finisher) of age. Corn- and peanut meal-based diets for each feeding phase served to titrate the Val dose-response levels. Dietary Val (total basis) was supplied from 0.75% up to 1.15% in 0.08% increments for the starter phase; from 0.73% up to 1.08% in 0.07% increments for the grower phase; and from 0.64% up to 0.99% in 0.07% increments for the finisher phase. Regression analysis was used to calculate the Val nutrient recommendations. These estimates were 1.00% for the starter, 0.95% for the grower, and 0.85% total Val for the finisher period. Dietary Val data obtained for all the feeding periods evaluated exhibited the expected decline with age, characteristic of all amino acids and most nutrients. Total dietary Val needs of 1.00, 0.95, and 0.85% for the starter, grower, and finisher phase, respectively, should provide nutritionists with a guide for nutrient minimums, particularly for their use in Ross x Ross 308 broilers. These values translate into calculated true digestible Val needs of 0.91, 0.86, and 0.78% for the starter, grower, and finisher feeding phases, respectively.

Digestible and metabolizable energy of crude glycerol for growing pigs.

The apparent DE and ME values of crude glycerol for growing pigs were determined in 5 experiments using crude glycerol (86.95% glycerol) from a biodiesel production facility, which used soybean oil as the initial feedstock. Dietary treatments were 0, 5, or 10% glycerol addition to basal diets in Exp. 1; 0, 5, 10, or 20% glycerol addition to basal diets in Exp. 2; and 0 and 10% crude glycerol addition to the basal diets in Exp. 3, 4, and 5. Each diet was fed twice daily to pigs in individual metabolism crates. After a 10-d adjustment period, a 5-d balance trial was conducted. During the collection period, feces and urine were collected separately after each meal and stored at 0 degrees C until analyses. The GE of each dietary treatment and samples of urine and feces from each pig were determined by isoperibol bomb calorimetry. Digestible energy of the diet was calculated by subtracting fecal energy from the GE in the feed, whereas ME was calculated by subtracting the urinary energy from DE. The DE and ME values of crude glycerol were estimated as the slope of the linear relationship between either DE or ME intake from the experimental diet and feed intake. Among all experiments, the crude glycerol (86.95% glycerol) examined in this study was shown to have a DE of 3,344 +/- 8 kcal/kg and an ME of 3,207 +/- 10 kcal/kg, thereby providing a highly available energy source for growing pigs.

Nitrogen-corrected apparent metabolizable energy value of crude glycerol for laying hens.

An experiment was conducted with laying hens to determine the AME(n) value of crude glycerol, a coproduct of biodiesel production. Crude glycerol (87% glycerol, 9% water, 0.03% methanol, 1.26% Na, and 3,625 kcal/kg of gross energy) was obtained from a commercial biodiesel production facility (Ag Processing Inc., Sergeant Bluff, IA). A total of forty-eight 40-wk-old laying hens (Hy-Line W-36) were placed in metabolic cages (2 hens/ cage) and given free access to the experimental diets. A corn and soybean meal-based basal diet (18% CP, 2,875 kcal/kg of AME(n), 4.51% Ca, 0.51% nonphytate P) was formulated with 15% glucose.H(2)O and 1% Celite. Four dietary treatments were created by substituting 0, 5, 10, or 15% crude glycerol for glucose.H(2)O (3,640 kcal/kg of AME(n)). After 7 d of dietary adaptation, excreta were collected twice daily for 3 d, freeze-dried, and analyzed for contents of DM, Kjeldahl N, acid-insoluble ash, and gross energy. Egg production was recorded daily, and eggs were collected on d 7 and 8 of the experiment for calculation of egg mass (egg production x egg weight). Feed consumption was measured over the 10-d experimental period. Egg-production data were analyzed by ANOVA with 4 treatments and 6 replications in a completely randomized experimental design. The AME(n) value of crude glycerol was estimated as the slope of the linear relationship between the inclusion rate of dietary crude glycerol and the glucose-corrected AME(n) value of the experimental diets. No significant treatment effects (P > 0.1) were apparent for egg-production rate (93.0%), egg weight (56.1 g), egg mass (52.2 g/d), or feed consumption (104 g/d). Linear regression analysis (P < 0.001, r(2) = 0.92, n = 24) revealed that the AME(n) value of the crude glycerol used in this study was 3,805 +/- 238 kcal/kg (mean +/- SEM; as-is basis) for laying hens.