Evaluation of protein and energy quality of rendered spent hen meals

Standardized amino acid digestibility and protein quality in extruded canine diets containing hydrolyzed protein using a precision-fed rooster assay

Protein hydrolysate has become a choice of alternative protein source in canine diets as it showed greater digestibility, lower allergenic responses, and various functional properties when compared with intact proteins. The objective of the study was to determine the effect of hydrolyzed protein inclusion on amino acid digestibility and protein quality in extruded canine diets when compared with a traditional protein source for adult dogs. Five treatment diets were formulated to have similar compositions except for the main protein source. The control diet was formulated with chicken meal (CM) as the primary protein source. Test hydrolyzed proteins, chicken liver and heart hydrolysate (CLH) and chicken hydrolysate (CH) were used to partially or completely substitute CM. The diets were: CONd: CM (30%) diet; 5%CLHd: 5% CLH with 25% CM diet; CLHd: CLH (30%) diet; 5%CHd: 5% CH with 25% CM diet; CHd: CH (30%) diet. A precision-fed rooster assay was used to determine standardized amino acid digestibility for the ingredients and diets. In addition, Digestible Indispensable Amino Acid Score (DIAAS)-like values were calculated for the protein ingredients. All protein ingredients had higher than 80% of digestibility for all indispensable amino acids with no difference among sources (P > 0.05). From the DIAAS-like values referencing AAFCO nutrient profile for adult dogs, CLH and CH did not have any limiting amino acid; on the other hand, CM has a lower DIAAS-like value (93.3%) than CLH and CH (P < 0.05) with tryptophan being the first-limiting amino acid. The DIAAS-like values were often lower when the amino acid combinations methionine + cysteine and phenylalanine + tyrosine were included in the calculation. When referencing NRC recommended allowances and minimal requirements, methionine was the first-limiting amino acid for all protein sources. Amino acid digestibility was mostly above 80% and comparable among the treatment diets. Regarding the digestible indispensable amino acid concentrations in the diets, all of them met the AAFCO nutrient profile for adult dogs at maintenance. In conclusion, both protein hydrolysates were highly digestible, high-quality protein sources, and a full substitution from CM to protein hydrolysate could result in greater protein quality, according to the DIAAS-like values of the ingredients, when compared with CM in extruded canine diets.

Exogenous protease supplementation of poultry by-product meal-based diets for broilers: Effects on growth, carcass characteristics and nutrient digestibility

An experiment was conducted to investigate the effects of three levels (0%, 3% and 6%) of poultry by-product meal (PBM) with or without protease on broiler growth, carcass characteristics and nutrient digestibility from 1 to 35 days. Two hundred and forty birds (n = 240) were fed equi-caloric and equi-nitrogenous (ME 2850 kcal/kg; CP 20%) diets throughout the experiment. The enzyme supplementation increased feed intake (p < .01) and body weight gain (p < .01), but feed:gain remained unaffected (p > .05) from 1 to 21 days. Increasing level of PBM decreased feed intake (p < .05), but body weight gain was improved (p < .05) at 3% PBM level during 1 to 21 days. The feed:gain was improved (p < .05) in birds fed diets containing 3% PBM. The feed:gain was also improved in birds fed diets containing 3% PBM from 1 to 35 days. However, feed intake and body weight gain in birds fed diets containing PBM remained unaffected. An interaction (p < .01) on feed intake between enzyme and PBM was noticed during 1 to 21 days. However, no interaction was recorded for body weight gain and feed:gain. The per cent carcass yield improved (p < .01) in birds fed diets supplemented with enzyme. The per cent breast meat yield was depressed (p < .005) in birds fed diets containing PBM. Apparent metabolizable energy (p < .001), nitrogen retention (p < .01), apparent metabolizable energy corrected for nitrogen (p < .001), and apparent digestibility coefficient for nitrogen (p < .01) improved in birds fed diets containing enzyme; however, a reverse was noticed in those fed diets containing only PBM. In conclusion, inclusion of 3% PBM along with supplementation of exogenous protease improved performance and nutrient digestibility in broilers.

Alternative methods for disposal of spent laying hens: evaluation of the efficacy of grinding, mechanical deboning, and of keratinase in the rendering process

Besides the challenges of mortality and litter disposal, the poultry industry must find economical means of disposing of laying hens that have outlived their productive lives. Because spent hens have low market value and disposing of them by composting and burial is often infeasible, finding alternative disposal methods that are environmentally secure is prudent. The feasibility of grinding or mechanically deboning spent hens with and without prior mechanical picking was evaluated for the production of various proteinaceous by-product meals. The end products were analyzed for nutrient content and found to be high in protein (35.3-91.9% CP) and, with the exception of the feathers, high in fat (24.1-58.3%), making them potentially valuable protein and energy sources. After considering physical and economic feasibility, mechanical deboning was determined to be a logical first step for the conversion of spent hens into value-added by-product meals. Because the hard tissue fraction (primarily feathers, bones, and connective tissue) generated by mechanically deboning the hens presents the greatest challenge to their utilization as feedstuffs, attention was focused on technologies that could potentially improve the nutritional value of the hard tissue for use as a ruminant protein source. Traditional hydrolysis of this hard tissue fraction improved its pepsin digestibility from 74% to 85%; however, subsequent keratinase enzyme treatment for 1h, 2h, 4h, or 20 h after steam hydrolysis failed to improve the pepsin or amino acid digestibility any further (P>0.10). Enzyme hydrolysis did, however, increase the quantities of the more soluble protein fractions (A: 45.5, 46.6, 52.8, 51.6, and 55.8% of CP; B(1): 3.2, 9.8, 6.0, 4.6, and 4.1% of CP; B(2): 11.7, 18.1, 22.8, 29.6, and 22.0% of CP for 0, 1h, 2h, 4h, and 20 h, respectively) and reduced quantities of the less soluble fractions (B(3): 30.2, 18.1, 10.8, 5.5, and 10.2% of CP; C: 9.4, 7.5, 7.6, 8.8, and 7.9% of CP for 0, 1h, 2h, 4h, and 20 h, respectively). The protein digestibility of the steam hydrolyzed hard tissue fraction from the mechanical deboning of spent hens was found to be comparable to the digestibility of feather meal, but post-hydrolysis keratinase treatment did not improve feeding value for ruminants.

Protein quality of poultry by-product meal manufactured from whole fowl co-extruded with corn or wheat

Three experiments were conducted with turkey poults to characterize the protein quality of a novel poultry by-product meal composed of aged fowl extruded with either corn (CHM) or wheat (WHM). In Experiment 1, a growth assay was conducted to determine a dietary protein response range for semipurified diets containing CHM or WHM as the sole sources of dietary protein. Diets contained 12, 15, and 18% CP, and there was a linear increase in BW with no significant differences between the 2 sources. The same dietary protein levels were used to determine the protein efficiency ratio (PER), net protein ratio (NPR), and apparent amino acid digestibility of CHM and WHM in Experiments 2 and 3. In Experiment 3, WHM and CHM were also compared with soybean meal (SBM) and meat and bone meal (MBM). In Experiment 2, there were no significant differences between CHM and WHM in PER or NPR, but the variability between levels of CP did account for a significant level of CP x source interaction (P < 0.05). In Experiment 3, there were no significant protein level effects on PER or NPR, but the values for MBM were consistently lower than those for CHM, WHM, and SBM. The apparent amino acid digestibility coefficients for MBM were also consistently lower than those for CHM and WHM. In conclusion, the extruded WHM and CHM products have acceptable protein quality and were better than MBM as single sources of dietary protein.

Content and relative bioavailability of phosphorus in distillers dried grains with solubles in chicks

Total phosphorus analysis was performed on 20 samples of corn distillers dried grains with solubles (DDGS), and three experiments were conducted to determine the bioavailability of P in different samples of DDGS varying in Lys digestibility and heat processing (autoclaving). Relative bioavailability of P was estimated from tibia ash using the slope ratio method after chicks were fed a P-deficient corn-soybean meal diet supplemented with 0.05 or 0.10% P from KH2PO4 or supplemented with 2 levels of the test DDGS (7 to 25%). The mean total P value for the 20 DDGS samples was 0.73 +/- 0.04% (SD), with an average dry matter value of 88 +/- 0.8% (SD). In experiment 1, the bioavailability coefficient for P in a random sample of DDGS relative to KH2PO4 was 69%. In experiment 2, the relative bioavailabilities of P in low digestible Lys DDGS 1, low digestible Lys DDGS 2, and high digestible Lys DDGS 3 were 102, 82 and 75%, respectively (P < 0.05). For experiment 3, the P bioavailability coefficients for a light-colored nonautoclaved DDGS and the same DDGS autoclaved at 121 degrees C and 124 pKa were 75 and 87%, respectively (P < 0.05). Our results showed that the total P content of DDGS was similar to the 0.72% value reported by the NRC (1994), but the relative P bioavailability is higher than the value estimated from NRC (1994) based on table values for total and nonphytate P content. Our results also indicated that there is substantial variability in P bioavailability among different DDGS samples and suggest that increased heat processing may increase the bioavailability of P in DDGS.

Effects of inclusion of poultry by-product meal and enzyme-prebiotic supplementation in grower diets on performance and feed digestibility of broilers

1. Two experiments were conducted to determine the effects of level of inclusion of poultry by-product and enzyme-prebiotic supplementation on grower diet digestibility and the performance of broilers. 2. Six grower diets were formulated to provide a similar nutrient profile with the exception of using three graded levels of poultry by-product, namely 0, 25, 40 g/kg of the diet with and without supplementation of enzyme preparation at the rate of 1 kg per tonne of feed and prebiotic preparation at the rate of 2 kg per tonne of feed. The experimental diets were used from 3 to 6 weeks of age. 3. Body weights, feed intake and feed conversion efficiency were not affected by poultry by-product; however, enzyme-prebiotic had a significant positive effect on feed conversion efficiency at 0 to 6 weeks in experiment 1. 4. Crude protein digestibility was decreased by feeding the diet containing poultry by-product while ether extract digestibility was increased by poultry by-product at the rate of 25 g per kg of feed only. Dry matter retention, crude fibre digestibility and organic matter retention were not affected by poultry by-product. Dry matter and organic matter retentions, crude protein, ether extract and crude fibre digestibilities were not affected by enzyme-prebiotic. 5. Protein efficiency ratio (PER) values were increased by poultry by-product at the rate of 40 g per kg of feed and addition of enzyme-prebiotic.

Evaluation of a rendered poultry mortality–soybean meal product as a supplemental protein source for pig diets123

Dehydrated/rendered broiler mortality-soybean meal products (DPS) were evaluated in two trials as high-protein feedstuffs for pig diets. Broiler mortalities, collected and frozen on-farm and transported to a central facility, were minced, blended with soybean meal, and dried with a final product temperature of 120 to 130 degrees C. The final DPS products used contained approximately 30 and 45% (DM basis) dried broiler mortality for the first and second trials, respectively (DPS1 and DPS2). The first trial involved 50 young, growing pigs (9 to 26 kg) and the second, 72 growing and finishing pigs (27 to 111 kg). The trials compared corn-based diets containing either soybean meal (SBM; 48%) or DPS products as the supplemental protein source. The DPS products averaged 50% CP and 2.9% total lysine; crude fat content of DPS used in the first trial was 8%, and for the second, 14.6% (as-fed basis). The ADG of pigs fed the DPS diets in either trial was similar to that of pigs fed the SBM control diets. In the second trial, pigs fed DPS2 had an overall average G:F ratio that was 9% better (P < 0.01) than that of pigs fed the SBM control diets. Carcass characteristics and pork quality from pigs of the growing-finishing trial were not affected by dietary treatment. Subjective carcass fat firmness scores indicated slightly softer fat (P < 0.05) from pigs fed DPS2. The mincing, blending with SBM, and dehydration of frozen stored on-farm broiler mortalities produced a safe and nutritious protein feedstuff for pigs, while also offering a viable disposal option.

Nutritional evaluation of dried tomato seeds

Two samples of tomato seeds, a by-product of the tomato canning industry were evaluated to determine proximate analysis, amino acid content, and digestibility, TMEn, and protein efficiency ratio. Tomato seeds were also used to replace corn and soybean meal (SBM) in a chick diet on an equal true amino acid digestibility and TMEn basis. Tomato seeds were found to contain 8.5% moisture, 25% CP, 20.0% fat, 3.1% ash, 35.1% total dietary fiber, 0.12% Ca, 0.58% P, and 3,204 kcal/kg of TMEn. The total amounts of methionine, cystine, and lysine in the tomato seeds were 0.39, 0.40, and 1.34%, respectively, and their true digestibility coefficients, determined in cecectomized roosters, were 75, 70, and 54%, respectively. The protein efficiency ratio (weight gain per unit of protein intake) value when fed to chicks at 9% CP was 2.5 compared to 3.6 for SBM (P < or = 0.05). When corn-SBM diets were formulated on an equal true amino acid digestibility and TMEn basis, up to 15% tomato seeds could replace corn and SBM without any adverse affects on chick weight gain, feed intake, or gain:feed ratio from 8 to 21 d posthatch. Tomato seeds at any level in the diet did not significantly affect skin pigmentation. Although the protein quality of tomato seeds may not be as high as SBM, tomato seeds do contain substantial amounts of digestible amino acids and TMEn. When formulating diets on a true digestible amino acid and TMEn basis, tomato seeds can be supplemented into chick rations at up to 15% without any adverse affects on growth performance.

Early postmolt performance of laying hens fed a low-protein corn molt diet supplemented with spent hen meal

We used a total of 504 commercial Single Comb White Leghorn hens (69 and 65 wk of age) in each of two experiments, and hens were induced to molt by feed withdrawal only. Feed withdrawal lasted for 12 and 11 d, and hens lost 26 and 25%, body weight in Experiments 1 and 2, respectively. All hens were then weighed, and seven replicate groups of 12 hens each were assigned to molt diet treatments. In Experiment 1, diets consisted of a corn basal diet (7.9% CP) or corn basal diet supplemented with 7.5 or 10% spent hen meal (SHM) each from two different sources. In Experiment 2, the corn basal diet or this diet supplemented with 5 or 10% SHM alone or 5% SHM plus Met, Lys, and Trp was evaluated. A molt diet of 16% CP corn-soybean meal was used as a positive control in both experiments. Molt diets were fed for 15 d in both experiments, at which time all hens were fed a 16% CP layer diet. Performance was measured for 8 wk following the beginning of feeding the layer diet. Feeding the low-protein corn molt diet supplemented with 5 to 10% SHM improved early postmolt egg production performance and body weight gain compared with hens fed the corn basal diet alone. The 7.5 and 10% SHM diets yielded early postmolt performance that was not significantly different (P > 0.05) from that of hens fed the high-protein (16% CP) diet. Supplementing the 5% SHM diet with amino acids generally did not significantly improve performance. The present study thus indicates that improved early postmolt performance may be achieved by supplementation of a low-protein corn molt diet with 5 to 10% SHM.

Nutritional evaluation of low phytate and high protein corns

Three chick experiments and two cecectomized rooster experiments were conducted to determine P bioavailability and amino acid (AA) digestibility in two low phytate corns (LP), a high protein corn (HP), and a corn containing both low phytate and high protein content (HP/LP) compared with conventional corn (CONV). From 8 to 20 or 21 d of age, 1-wk-old New Hampshire x Columbian chicks were fed a cornstarch-dextrose-soybean meal (SBM) basal diet containing 0.10% available P or the basal diet supplemented with two concentrations of P (0.05 or 0.06% and 0.10 or 0.12%) from KH2PO4 or two concentrations of the corns (20 or 21% and 40 or 42%). Bioavailability of P based on tibia bone ash was much higher for LP than for CONV; values ranged from 21 to 40% for CONV and from 59 to 95% for LP. Digestibility of AA in cecectomized roosters indicated no significant differences (P > 0.05) between CONV and HP in the first rooster experiment. Digestibilities of eight AA, including lysine, methionine, and arginine, in LP and HP/LP were higher (P < 0.05) than those in CONV in the second rooster experiment. The results of this study indicated that the P in LP was two to three times more bioavailable than the P in CONV and that the digestibilities of AA in HP/LP were equal to or higher than those in CONV.

Nutritional value of enzyme- or sodium hydroxide-treated feathers from dead hens

Two feather digestion processes to remove the feathers from the carcasses of dead hens were evaluated for their impact on the nutritional quality of the resulting feather meal. There were three treatments: control (untreated feathers), a feather-digesting enzyme, and NaOH treatment. Both enzyme- and NaOH-treated feathers were easily separated from the hen carcasses. The CP level of enzyme-treated feathers after autoclaving (49.90%) was significantly less than the control and NaOH-treated feathers (94.48 and 87.31%, respectively) because of elevated ether extract levels resulting from skin and abdominal fat release during the 12-h enzyme incubation. Before autoclaving, pepsin digestibilities of enzyme- and NaOH-treated feathers were significantly higher than the control. However, after autoclaving, no significant difference was found in pepsin digestibility between the control and enzyme treatments or control and NaOH treatments. The typical limiting amino acids, methionine, lysine, and histidine, in feathers were present at greater levels in the resulting enzyme-feather meal (E-FM) compared with the NaOH-feather meal (N-FM) or control-feather meal (C-FM) on a percentage of CP basis. Cystine levels, however, were significantly lower in the E-FM and N-FM compared with that of the C-FM. In chick bioassays, no significant differences were found in protein efficiency ratio (PER) and net protein ratio (NPR) among C-FM, E-FM, and N-FM. The AMEn of E-FM (4.52 kcal/g) was significantly higher than the C-FM (3.58) or N-FM (2.79). These findings indicated that although enzyme treatment could improve the nutritional quality of feathers from dead hens, NaOH treatment was a more rapid means of separating feathers from the carcass.

Dietary formulation with rendered spent hen meals on a total amino acid versus a digestible amino acid basis

Previous results indicated that performance of chicks fed a high level (15%) of rendered spent hen meal (SHM) was lower than performance of chicks fed a corn-soybean meal (SBM) diet. The latter difference was hypothesized to be due to variation in digestible amino acid (AA) levels among the diets. This study evaluated diets containing SHM formulated on an equivalent total AA basis vs an equivalent digestible AA basis compared to a corn-SBM diet. Three SHM (A, B, and C), produced in commercial rendering plants, were evaluated. Mean true digestibility coefficients (percentages) for 17 AA in SHM A, B, and C were 73.1, 63.4, and 75.5, respectively. In two chick trials, 1-wk-old New Hampshire x Columbian male chicks were fed from 8 to 20 d of age a corn-SBM diet or diets containing 15% SHM formulated to be equal in total or digestible AA to the corn-SBM diet. All diets contained 21.5% CP and 3,200 kcal TME(n)/kg. Chicks fed 15% SHM (A, B, or C) diets formulated on a total AA basis had significantly lower (P < 0.05) weight gain and feed efficiency than chicks consuming the corn-SBM diet. Formulating diets containing SHM B or SHM C on a digestible AA basis yielded growth performance equivalent to chicks fed the corn-SBM diet. Growth performance of chicks fed the SHM A diet formulated on a digestible AA basis was greater (P < 0.05) than that obtained from the SHM A diet formulated on a total AA basis but was still lower than performance of chicks consuming the corn-SBM diet. Additional AA and energy supplementation of the SHM A diet formulated on a digestible AA basis only partially alleviated the latter performance difference. The results of this study indicated that formulation of diets containing SHM on a digestible AA basis is superior to formulation on a total AA basis and that 15% inclusion of two of the three SHM in chick diets had no detrimental effects on performance if the diets were formulated to contain adequate levels of digestible AA.

Utilization of spent hen meal in diets for broiler chickens

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