A. Corzo

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.

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.

Effects of feeding distillers dried grains with solubles to broilers from 0 to 28 days posthatch on broiler performance, feed manufacturing efficiency, and selected intestinal characteristics

This study evaluated the effect of 2 levels (0 vs. 8%) of distillers dried grains with solubles (DDGS) in a starter broiler diet (0 to 14 d; 45 replicates/treatment) after these same birds were subsequently fed a grower diet (14 to 28 d) with either 0, 7.5, 15, 22.5, or 30% DDGS (9 replicates/treatment). Ross×Ross 308 male broilers were used in this experiment, and evaluation criteria consisted of feed mill parameters, broiler growth, relative liver weight, ileal viscosity, and cecal content count of Clostridium perfringens and Escherichia coli analyzed by both selective media and real-time PCR. Increased inclusion of DDGS resulted in a nonlinear response for production rate (P<0.05), conditioner energy usage (P<0.01), and pellet mill energy usage (P<0.05). Increasing DDGS resulted in a linear decrease in pellet quality (P<0.001) and an increase (P<0.001) in total fines. Inclusion of DDGS decreased (P<0.001) energy usage at the pellet mill and decreased (P<0.05) bulk density of the diets. The DDGS levels fed during the starter phase (0 vs. 8%) had no effect on the broilers at 14 or at 28 d of age. Increasing DDGS inclusion levels during the grower phase resulted in a linear decrease (P<0.001) in BW gain and liver relative weight (P<0.001). A DDGS starter×grower interaction (P<0.05) was observed for feed consumption, in which birds that consumed no DDGS during the starter phase exhibited a decrease in feed consumption with the higher inclusion levels of DDGS during the grower phase, whereas birds that received 8% DDGS during the starter phase were unaffected by DDGS inclusion level in the grower phase. Feed conversion, mortality, ileal viscosity, and cecal C. perfringens and E. coli concentrations were unaffected by DDGS level in the grower diet. The feed intake response suggests a beneficial effect of exposing broiler chicks to DDGS if inclusion levels of 22.5% or higher are to be fed after 14 d of age. However, the data suggest that the young broiler can be negatively affected with inclusion levels of 15% DDGS or higher up to 28 d of age.

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 inclusion level effects of distillers dried grains with solubles on broiler meat quality.

A completely randomized design with 7 replications (n = 7, treatments = 5 with 8 subsamples per treatment) was used to evaluate the effects of feeding various levels of distillers dried grains with solubles (DDGS; 0, 6, 12, 18, and 24%) on broiler breast and thigh meat quality. Broilers were harvested in a pilot scale processing plant with commercial prototype equipment at 42 d of age. The right half of each breast was evaluated for pH, instrumental color, cooking loss, proximate analysis, and tenderness. The left half of each breast was used for consumer acceptability testing. Thigh meat was evaluated for proximate composition, fatty acid composition, and TBA reactive substances. Breast meat from broilers that were fed DDGS had a higher (P < 0.05) pH than those from the control diet. In addition, the 18 and 24% DDGS treatments yielded breast meat with higher (P < 0.05) pH values than the 6% DDGS treatment. No differences existed (P > 0.05) among breast meat from the different treatments with respect to cooking loss, instrumental color, and consumer acceptability, but breast meat from the control (0% DDGS) treatment had slightly lower (P < 0.05) shear force than breast meat from the 18 and 24% DDGS treatments. In addition, no differences (P > 0.05) existed among proximate composition of breast and thigh meat from the control and DDGS treatments. As DDGS concentration increased, there was a linear increase (P < 0.05) in linoleic and polyunsaturated fatty acids, which indicates a greater potential for lipid oxidation. The TBA reactive substances values were greater (P < 0.05) for the 18 and 24% DDGS treatments at d 5 when compared with the control and 6% DDGS treatments, which indicates increased oxidation. Overall, data suggest that all treatments yielded high-quality breast meat and that thigh meat quality was similar among treatments containing 0 to 12% DDGS, but higher inclusion levels led to thigh meat that was more susceptible to oxidation.

Protein expression of pectoralis major muscle in chickens in response to dietary methionine status

The present study evaluated the effect of dietary methionine on breast-meat accretion and protein expression in skeletal muscle of broiler chickens in vivo. All broilers received a common pre-test diet up to 21 d of age, and were subsequently fed either a methionine-deficient (MD) or -adequate (MA) diet (3.1 v. 4.5 g/kg diet) from age 21 to 42 d. Dietary cystine levels were 3.7 v. 3.6 g/kg diet for the MD and MA diet, respectively. Detrimental effects on carcass yield (P=0.004), abdominal fat percentage (P=0.001), and breast-meat weight (P=0.001), yield (P=0.001), and uniformity (P=0.002) were observed and validated in birds fed MD diets. Via tandem MS, a total of 190 individual proteins were identified from pectoralis major (PM) muscle tissue. From the former composite, peptides from three proteins were observed to be present exclusively in breast muscle from those chickens fed the MD diet (pyruvate kinase, myosin alkali light chain-1, ribosomal-protein-L-29). No proteins were observed to be uniquely expressed in chickens fed MA diets. Research is warranted to further explore the possibility of the proteins pyruate kinase, myosin alkali light chain-1, or ribosomal protein L-29, as potential biological indicators of differences in protein expression of PM of chickens in response to a dietary methionine deficiency.

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 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.

Effects of in ovo injection of L-carnitine on hatchability and subsequent broiler performance and slaughter yield

Effects of in ovo injection of L-carnitine on the hatchability, grow-out performance, and slaughter yield of Ross x Ross 308 broilers from a young breeder flock were determined through 48 d of age. Fertilized eggs were injected in the amnion with L-carnitine (0.5, 2.0, or 8.0 mg dissolved in 100 microL of a commercial diluent) on d 18 of incubation using an automated egg injector. Three control groups (noninjected and injected with or without diluent) were also included. Hatchability and hatch rate of fertilized eggs were assessed. Furthermore, subsequent mortality, BW gain, feed intake per bird, and feed conversion were determined through 46 d posthatch. On d 47, live body, carcass, and abdominal fat pad weights, along with the weights of all major commercial cuts including the thigh, drumstick, wings, and breast muscles, were determined. Individual doses of supplemental L-carnitine had no significant effect on the hatchability or rate of hatch of fertilized eggs; however, significant trends were noted for increased hatchability and length of egg incubation in conjunction with increases in L-carnitine dose. Nevertheless, there were no significant treatment effects on any of the grow-out performance or slaughter yield parameters investigated. In conclusion, although increasing the levels of L-carnitine added to commercial vaccine diluent between 0.5 and 8.0 mg/100 microL for commercial in ovo injection did not significantly influence subsequent broiler grow-out performance or slaughter yield, L-carnitine dosages above those used in this study have the potential for significantly increasing incubation length and hatchability of broiler hatching eggs.

Effects of in ovo injection of l-carnitine on subsequent broiler chick tissue nutrient profiles

Effects of in ovo injection of L-carnitine on BW and the moisture and nutrient biochemical concentrations of various organs and muscles of Ross x Ross 308 broiler chicks, hatched from eggs laid by a 28-wk-old breeder flock, were determined through 48 d posthatch. Eggs containing live embryos were injected in the amnion with L-carnitine (0.5, 2.0, or 8.0 mg dissolved in 100 microL of a commercial diluent) on d 18 of incubation using an automated egg injector. Three control groups (noninjected and injected with or without diluent) were also included. On d 0, 3, 10, 28, and 48 posthatch, bird BW and the proportional weights and moisture concentrations of various organs and muscles were determined. Glycogen, glucose, protein, and fat concentrations were also determined in certain tissue samples. Bird BW; proportional liver weight; breast, thigh, and gastrocnemius muscle moisture; liver glycogen, glucose, and protein concentrations; and breast and thigh muscle fat and protein concentrations changed with posthatch bird age. Liver glucose on d 0 and pipping muscle moisture on d 3 posthatch were significantly affected by treatment. In comparison to eggs injected with commercial diluent with no added L-carnitine, liver glucose was reduced by the injection of diluent containing either 0.5 or 8.0 mg of L-carnitine, and pipping muscle moisture was increased by the injection of commercial diluent containing either 0.5 or 2.0 mg of L-carnitine. The modified concentrations of the 2 parameters in response to these treatments were not different from those in noninjected control eggs. In conclusion, L-carnitine added to commercial vaccine diluent at levels between 0.5 and 8.0 mg/100 microL for the commercial injection of broiler hatching eggs may decrease liver glucose and increase pipping muscle moisture concentrations of chicks on d 0 and 3 posthatch, respectively, so that their levels are commensurate with noninjected controls.