Protein Source For Broiler Chickens Research Articles

Dried crickets (Gryllus sigillatus) or black soldier fly (Hermetia illucens) larvae meal for broiler chickens: nutrient composition and digestibility

Abstract This study explores the potential of cricket meal and black soldier fly larvae meal (BSFLM) as alternative protein sources in broiler chicken diets. With the use of the substitution method, using diatomaceous earth as an external marker, we investigated the nutrient availability and apparent metabilizeable energy content of oven-dried full-fat cricket meal (OD-CM), freeze-dried full-fat cricket meal (FD-CM), and defatted BSFLM in a feeding trial involving 320 Ross 308 broilers housed in 32 pens (8 replicates / treatment; 8 birds / pen). Feed intake, daily weight gain, and feed conversion ratio were measured between days 15 and 21. Excreta collected on days 19, 20, and 21 were analyzed for nutrient content. Both cricket treatments were high in crude protein. Additionally, FD-CM demonstrated the highest fat content, surpassing OD-CM. OD-CM displayed a significantly higher apparent digestibility coefficient for crude protein compared to BSFLM (). FD-CM had the highest apparent digestibility coefficient for gross energy (). The nitrogen-corrected apparent metabolizable energy of OD-CM and FD-CM were significantly higher than that of BSFLM (). Furthermore, OD-CM exhibited a significantly higher available crude protein content compared to BSFLM and FD-CM (). This research sheds light on the potential of OD-CM and FD-CM as valuable alternative protein sources for broiler chickens, providing critical insights for the poultry industry’s sustainable future. This research is important as the apparent digestibility coefficients, as well as available nutrients calculated for the three ingredients may be used to accurately formulate poultry diets on an available nutrient basis.

Evaluation of Clostridium autoethanogenum protein as a new protein source for broiler chickens in replacement of soybean meal.

The object of this study was to investigate the effect of replacing soybean meal with Clostridium autoethanogenum protein (CAP) in broiler diets on growth performance, blood indicators, antioxidant capacity, and immune function. A total of 180 Arbor Acres broilers were randomly divided into three treatments, each treatment with six replicates and 10 broilers per replicate for a 42-day feeding trial. The control group (CON) was fed corn-soybean meal based diet. The CAP-1 and CAP-2 groups were considered to use CAP to replace 25% or 50% of soybean meal in the diet, respectively. The average daily gain and average daily feed intake of broilers at 1-21 d, 22-42 d, and 1-42 d were measured, and the feed conversion ratio was calculated. At the 42nd day of age, two broilers with similar weights and fasted for 12h were selected in each replicate for blood collection from the brachial wing vein. The blood routine indicators, serum biochemical indicators, serum antioxidant capacity, and immunoglobulin content of broiler chickens were measured. Replacement of soybean meal with 25% (CAP-1) and 50% (CAP-2) CAP significantly increased the average daily gain of 22-42 d and 1-42 d and decreased the average daily feed intake and feed conversion rate (p<0.05). The CAP-1 group, and CAP-2 group significantly increased hemoglobulin in the blood of broilers, while the CAP-2 group increased hematocrit content (p<0.05). Compared with the control group, the contents of superoxide dismutase and immunoglobulin A in serum of the CAP-2 group were significantly increased, while the contents of malondialdehyde in CAP group were significantly decreased (p<0.05). Replacing soybean meal with CAP led to significant improvements in the growth performance, antioxidant capacity, and immunoglobulin content of broilers.

Nutritional Value of Duckweed as Protein Feed for Broiler Chickens—Digestibility of Crude Protein, Amino Acids and Phosphorus

Duckweed is gaining attention in animal nutrition and is considered as a potential alternative protein source for broiler chickens. In order to evaluate the nutritional value of duckweed, three individual batches were investigated. They consisted of a mixture of Lemna minuta and Lemna minor (A, 17.5% crude protein), Spirodela polyrhiza (B, 24.6% crude protein) and Lemna obscura (C, 37.0% crude protein). Treatment diets contained 50% batch A, 50% batch B, and 25, 50 and 75% of batch C. All diets were fed to broiler chickens (Ross 308) from an age of 21 to 27 days. Diets with a share of 50 and 75% of batch C led to decreased feed intake (109.3 and 74.9 g/day, respectively) compared to the control. Standardized ileal digestibility of crude protein and amino acids differed significantly between duckweed batches, at values for methionine between 49.9 and 90.4%. For all amino acids, batch A consistently had the lowest and batch C the highest digestibility. Batches had different tannin contents of 2943, 2890 and 303 mg/kg for batches A, B and C, respectively. The apparent ileal digestibility of phosphorus differed significantly between all batches (50.8-78.9%). Duckweed can be used as a protein feed for broiler chickens. However, a defined and stable biomass composition optimized for the requirements of broiler chickens is needed.

Meat quality in broiler chickens fed on cowpea (Vigna unguiculata [L.] Walp) seeds

The study aimed to evaluate the effects of a diet containing untreated cowpea (CWP; Aura 26 variety) seeds as a protein source on quality parameters of chickens’ breast (PM; Pectoralis major) and thigh muscles (BF; Biceps femoris). A total of 240 Ross 308 broiler chickens were randomly allotted to two groups: a control group fed with soybean meal (SBM) and an experimental group fed with CWP included at 200 g/kg as a replacement of SBM. Each group consisted of six pens as replicates, with 20 chicks per pen. At 6 weeks of age, twelve birds/group were slaughtered. Compared to SBM group, the group fed CWP had higher (P < 0.0001) lightness (L*) and redness (a*) values of PM and BF muscles, the latter had also higher yellowness (b*, P < 0.0001). The collagen and protein contents were significantly higher in CWP group in both PM and BF muscles, while fat was lower (P < 0.001) only in BF muscle. The use of CWP into broilers’ diets did not negatively impact the textural properties, i.e., hardness, adhesiveness, cohesiveness, springiness, gumminess, chewiness, and resilience of PM and BF, showing similar values in both groups. Also, PM and BF muscles of birds fed CWP had significantly higher (P < 0.05) levels of C:18:3n-3 and C:20:5n-3 compared with birds fed SBM. The n-6/n-3 PUFA ratio was significantly lower in CWP group (11.72 and 7.00) compared to SBM (13.47 and 12.63) for both PM and BF muscles. These results indicate that CWP can be considered a promising protein source for broiler chickens’ feed.

Effects of eri silkworm (Samia ricini) pupae inclusion in broiler diets on growth performances, health, carcass characteristics and meat quality.

ObjectiveThe objective of this study was to determine the appropriate amount of eri silkworm pupae meal (Samia ricini) to add to the broiler diet.MethodsTwo hundred 1-day-old male chicks with initial weight at 50.03±0.56 g/chick were divided into four groups (five replicates per group and ten chicks per replicate): a control group fed a corn-soybean diet and experimental groups supplemented with 5%, 10%, or 15% eri silkworm pupae meal. All experimental diets were isocaloric and isonitrogenous and formulated respecting nutrient requirements. Growth performances were collected during the experimental period and other parameters were collected at the end of experiment when broilers reached thirty-eight days old.ResultsA higher cold carcass weight and skin yellowness in the broilers fed 10% eri silkworm pupae meal compared with the other groups (p<0.05). Therefore, supplementation with 10% eri silkworm pupae meal is suggested for the broiler diet formulation because it did not cause any serious negative consequences on growth performance, health status, carcass characteristics and meat quality. However, the usage of eri silkworm pupae meal at 15% is not recommend because it led to negative outcomesConclusionThe addition of eri silkworm pupae at 10% can be used as an alternative protein sources for broiler chickens which provided benefits on cold carcass weight and skin yellowness without adverse effects.

Standardized ileal amino acid digestibility of protein sources for broiler chickens is influenced by the feed form

The aim of present study was to determine the influence of the feed form (FF) on standardized ileal digestibility (SID) of nitrogen (N) and amino acids (AA) in 3 protein sources (PS) for broiler chickens. Six diets were tested in a 3 × 2 factorial arrangement of treatments involving 3 PS (meat and bone meal [MBM], soybean meal [SBM], and canola meal [CM]) in mash and pelleted forms. The basal endogenous N and AA losses were determined by offering a N-free diet in the mash form. From day 1 to 18, the birds were offered a broiler starter diet. The diets and the N-free diet were randomly assigned to 6 replicate cages (8 birds per cage) and fed from day 19 to 23. The ileal digesta were collected on day 23. The SID of N was higher (P < 0.05) in SBM followed by MBM and CM. The average SID of AA in SBM and MBM were similar (P > 0.05), and greater (P < 0.05) than that in CM. The FF had no influence (P > 0.05) on the SID of indispensable AA, the only exception being His, which was reduced (P < 0.05) by pelleting. Pelleting, however, resulted in reduction (P < 0.001) in the SID of all dispensable AA and average of AA. The AA most affected by pelleting was Cys, with a 15.4% decrease in the SID. The standardized ileal digestible contents of protein and the average of indispensable AA and dispensable AA were higher in MBM than in SBM, with CM being the lowest. Pelleting decreased (P < 0.05) the digestible protein and total digestible AA contents. These findings reveal that the FF has a substantial impact on AA digestibility estimates of feed ingredients and it must be considered in AA digestibility assays of ingredients with high protein and AA contents.

Yellow mealworm, Tenebrio molitor (Col: Tenebrionidae), larvae powder as dietary protein sources for broiler chickens: Effects on growth performance, carcass traits, selected intestinal microbiota and blood parameters.

This study was conducted to evaluate the effects of dietary Tenebrio molitor larvae meal (TM meal) inclusion on the performance, carcass traits, caecum microbiota and blood parameters of broiler chickens. A total of 180-day-old chickens were allocated to three dietary groups with five replicate pens (12birds/pen). Experimental diets were included a corn-soybean basal diet, and two diets with 2.5% and 5% TM. TM-included diets have been administered for periods of starter (1-10days) and grower (11-25days). A regular finisher diet was given to all groups during the 26-42days of age. Diets containing TM meal did not influence feed intake and mortality percentage. Feed conversion ratio was lower with the 2.5% TM meal diet compared with the control group at starter period (p<.05). Besides, broiler chickens fed TM meal included diet had a higher body weight gain than the control group during 1-10days of age (p<.05). The carcass characteristics and length and weight of different parts of small and large intestines were not influenced by diets. TM meal inclusion decreased the albumin-to-globulin ratio compared with the control group (p<.05). Additionally, lower total count of aerobic and Escherichia coli bacteria was observed in response to diet inclusion of 5% TM meal. Overall, the inclusion of TM meal in broilers' diet improved body weight gain and feed conversion ratio in the starting period, decreased albumin-to-globulin ratio and E.coli bacteria content.

Cyberlindnera jadinii yeast as a protein source for broiler chickens: effects on growth performance and digestive function from hatching to 30 days of age

Europe is heavily dependent on imported feed protein sources such as soybean meal (SBM); thus, investigating local sustainable alternatives is crucial to increase self-sufficiency. This study evaluated the effects of the inactivated yeast Cyberlindnera jadinii grown on local lignocellulosic sugars on the growth performance and digestive function of Ross 308 broiler chickens. A total of 1,000 male chicks were allocated to 20 pens. There were 5 replicate pens with 50 birds each, from 1 to 30 D after hatch. The birds were offered one conventional wheat–oat–SBM–based control diet and 3 diets with increasing levels of C. jadinii replacing 10, 20, and 30% of dietary crude protein (CP), whereas SBM levels were gradually decreased. The feed intake and weight gain of the birds decreased linearly, and feed conversion ratio increased linearly (P < 0.01) with increasing dietary levels of C. jadinii. Nevertheless, growth performance and feed intake were similar between the birds fed with control diets and diets containing 10% CP from C. jadinii in the starter and grower periods. The apparent ileal digestibility (AID) of dry matter, crude fat, organic matter, and carbohydrates was higher in control diets than in diets with 30% C. jadinii CP (P < 0.05) and decreased (P < 0.01) with incremental levels of dietary C. jadinii. Regardless, the AID of CP, starch, ash, and phosphorus was unaffected. Ileal villus height on day 10 was maintained in birds fed with diets containing 30% C. jadinii CP compared with the birds fed with control diets but was lower for birds fed with diets containing 10 and 20% C. jadinii protein (P < 0.05). To conclude, up to 10% C. jadinii CP can replace SBM CP in broiler chicken diets, maintaining growth performance and digestive function, whereas higher levels of C. jadinii may decrease bird performance. Altogether, this suggests the potential of C. jadinii as a local-based protein source in broiler chicken diets, contributing to a more sustainable feed.

Black soldier fly defatted meal as a dietary protein source for broiler chickens: effects on carcass traits, breast meat quality and safety

Finding insect meals as alternative sources of poultry feedstuffs is a recent research topic; therefore, the present study aimed to evaluate the effects of defatted black soldier fly (Hermetia illucens L., HI) larvae meal in broiler chicken diets on the carcass characteristics and meat quality parameters, proximate composition, fatty acid profile and the heavy metal content of the breast meat. Four dietary treatments were designed: a control diet (HI0) and three experimental diets (HI5, HI10 and HI15), corresponding to 50, 100 and 150 g/kg HI inclusion levels, respectively. The inclusion of 50, 100 and 150 g HI meal per kg feed supply 16.56%, 33.01% and 49.63% of required crude protein. The broilers were slaughtered at day 35, the carcasses were weighed and the breast muscles were excised from 16 birds per each feeding group (two birds per replicate pens) and used for meat quality evaluation. Linear and quadratic responses were observed, for increasing HI meal levels, in the live and carcass weights (maximum for HI10). As far as the colour of the breast meat is concerned, redness (a*) showed a linear response, while yellowness (b*) linearly decreased with increasing HI meal levels (minimum for HI15). As the HI larvae meal increased in the diets, the moisture content linearly decreased and the protein content increased. The total saturated fatty acid and total monounsaturated fatty acid proportions rose to the detriment of the polyunsaturated fatty acid fraction. The HI larvae meal, used in the current study, represents a valuable protein source for broiler chickens when included by up to 100 g/kg in their diets, as an improved slaughtering performance was observed without any detrimental effects on meat quality parameters or heavy metal residues in the meat.

Black soldier fly defatted meal as a dietary protein source for broiler chickens: Effects on growth performance, blood traits, gut morphology and histological features

BackgroundThe present study has evaluated the effects of different inclusion levels of a partially defatted black soldier fly (Hermetia illucens L.; HI) larva meal on the growth performance, blood parameters and gut morphology of broiler chickens. A total of 256 male broiler chickens (Ross 308) were reared from d 1 to d 35 and assigned to 4 dietary treatments (8 replicates/treatment and 8 birds/replicate). HI larva meal was included at increasing levels (0, 5%, 10% and 15%; HI0, HI5, HI10 and HI15, respectively) in isonitrogenous and isoenergetic diets formulated for 3 feeding phases: starter (1–10 d), growing (10–24 d) and finisher (24–35 d). Two birds per pen were slaughtered at d 35 and morphometric investigations and histopathological alterations were performed.ResultsThe live weight (LW) showed linear and quadratic responses to increasing HI larva meal (maximum for HI10 group). Average daily gain (ADG) showed a linear and quadratic responses to HI meal (maximum for HI10 group) during starter and growing periods. A linear decrease was observed for ADG during the finisher period. The daily feed intake (DFI) showed a linear and quadratic effect during the starter period (maximum for HI10 group). Linear and quadratic responses were observed for the feed conversion ratio (FCR) in the growing period and for the whole period of the experiment. The FCR showed a linear response in the finisher period (maximum for HI15). No significant effects were observed for the blood and serum parameters, except for the phosphorus concentration, which showed linear and quadratic responses as well as glutathione peroxidase (GPx) activity, the latter of which showed a linear response. The HI15 birds showed a lower villus height, a higher crypt depth and a lower villus height-to-crypt depth ratio than the other groups.ConclusionsIncreasing levels of dietary HI meal inclusion in male broiler chickens may improve the LW and DFI during the starter period, but may also negatively affect the FCR and gut morphology, thus suggesting that low levels may be more suitable. However, no significant effects on the haematochemical parameters or histological findings were observed in relation to HI meal utilization.

Effects of dietary Tenebrio molitor meal inclusion in free-range chickens.

Insects are currently being considered as a novel protein source for animal feeds, because they contain a large amount of protein. The larvae of Tenebrio molitor (TM) have been shown to be an acceptable protein source for broiler chickens in terms of growth performance, but till now, no data on histological or intestinal morphometric features have been reported. This study has had the aim of evaluating the effects of dietary TM inclusion on the performance, welfare, intestinal morphology and histological features of free-range chickens. A total of 140 medium-growing hybrid female chickens were free-range reared and randomly allotted to two dietary treatments: (i) a control group and (ii) a TM group, in which TM meal was included at 75g/kg. Each group consisted of five pens as replicates, with 14 chicks per pen. Growth performance, haematological and serum parameters and welfare indicators were evaluated, and the animals were slaughtered at the age of 97days. Two birds per pen (10 birds/treatment) were submitted to histological (liver, spleen, thymus, bursa of Fabricius, kidney, heart, glandular stomach and gut) and morphometric (duodenum, jejunum and ileum) investigations. The inclusion of TM did not affect the growth performance, haematological or serum parameters. The morphometric and histological features were not significantly affected either, thus suggesting no influence on nutrient metabolization, performance or animal health. Glandular stomach alterations (chronic flogosis with epithelial squamous metaplasia) were considered paraphysiological in relation to free-range farming. The observed chronic intestinal flogosis, with concomitant activation of the lymphoid tissue, was probably due to previous parasitic infections, which are very frequently detected in free-range chickens. In conclusion, the findings of this study show that yellow mealworm inclusion does not affect the welfare, productive performances or morphological features of free-range chickens, thus confirming that TM can be used safely in poultry diets.

Effect of protein on performance and haematology of broilers fed cassava peel-based diets

A experiment was conducted to investigate the influence of the protein source on the performance and haematology of broiler chickens on cassava peel-based diets using fishmeal and groundnut cake as protein sources. In a 42 days feeding trial, a total of 192 Anak, four weeks old, unsexed broiler chickens with average initial body weight of 0.685±0.0027 (mean±SD) were divided into two groups of diets containing 0, 5, 10 and 15% dried cassava peel meal. Birds in one group had fishmeal as protein source while the other had groundnut cake. Each diet was offered to three pens of 8 birds each. Final live weight, weekly weight gain, feed and protein intake, feed conversion and protein efficiency ratios, haematology and corpuscular indices were not significantly affected by protein source. Fishmeal inclusion resulted in higher (p 0.05) serum cholesterol than groundnut cake inclusion. It was concluded that groundnut cake could serve as protein source for broiler chickens without any adverse effect on performance indices.

A study on feeding hazelnut kernel oil meal as a protein source for broiler chickens

An experiment was conducted to evaluate the effect of substituting different levels of hazelnut kernel oil meal (HKM) for soybean meal (SBM) in diets for broiler. A total of 450 one-day-old female Ross 308 broiler chicks were allocated randomly to three treatment groups of 150 birds each in a randomized design. Each treatment group consisted of five replicates each of 30 chicks. All diets (in mash form) were formulated to meet nutrient concentrations recommended for broilers. The experiment lasted for six weeks. In the experiment, an SBM control (SBM) diet was compared to two HKM diets, replacing 50 (50HKM) and 100% (HKM) of SBM protein, respectively. Body weight gain, feed intake and feed conversion ratio of broilers were adversely affected (P < 0.05) by the HKM diets at 42 days of age. Broilers fed 50HKM and HKM had growth performances similar (P > 0.05). The carcass yield and abdominal fat pads of birds fed diets with SBM were higher (P < 0.05) than those of chicks fed the 50HKM and HKM diets. The edible inner organ weight of chicks fed diets with HKM was the heaviest (P < 0.05). It is concluded that SBM cannot be replaced even up to 50% with HKM in commercial broiler diet.

Evaluation of Shrimp Waste Meal as a Probable Animal Protein Source for Broiler Chickens

Sixty unsexed Anak broiler chickens were used to evaluate the effect of dietary inclusion of Shrimp waste meal (swm) in broilers diet. They were randomly allotted to four treatment diets which were both isocaloric and isonitrogenous. The text ingredient was included in the four diets at 0.0%, 10%, 20% and 30% respectively for diets 1, 2, 3 and 4, both at the starter and finisher phases. There were 15 birds per treatment and 5 birds per replicate. The trial lasted 8 weeks. The result showed that the dietary treatments had significant (p 0.05) influenced at the finisher phase. At the starter and finisher phases, average body weight gain ranged from 446.56 to 600.00g/bird and 1096.67 to 1166.67g/bird with corresponding average total feed intake which ranged from 1318.00 to 1462.42g/bird and 2712.00 to 2880.00g/bird. Birds fed diets 1 and 2 had statistically comparable weight gain while those fed diets 3 and 4 were depressed at the starter phase. At the finisher phase all the diets were comparable. The study revealed that swm is a valuable animal protein source for broilers and can be included up to 10% in both starter and finisher broiler diets.

Valores de energia metabolizável de alimentos para pintos de corte na fase pré-inicial

Um experimento foi realizado no Setor de Avicultura da Universidade Federal de Lavras (UFLA), com duração de 6 dias, para determinar os valores energéticos de fontes protéicas para pintos de corte na fase pré-inicial. Utilizaram-se 480 pintos machos, Cobb, com 1 dia de idade que foram submetidos à metodologia de coleta total de excretas e distribuídos em 9 tratamentos com 6 repetições. Os tratamentos foram compostos por 4 alimentos protéicos de origem vegetal (farelo de soja, soja integral tostada, soja micronizada e farelo de glúten de milho) que substituíram a ração referência (RR) em 30% e 4 alimentos protéicos de origem animal (farinha de carne e ossos 40% e 45% de PB, farinha de peixe e farinha de vísceras), que substituíram a RR em 20%. Simultaneamente, 6 repetições de 8 aves foram colocadas em jejum para a determinação das perdas endógenas. As variáveis estudadas foram energia metabolizável aparente (EMA), verdadeira (EMV) e as EMA e EMV corrigidas para balanço de nitrogênio (EMAn, EMVn). Os alimentos de origem vegetal obtiveram valores de energia inferiores aos obtidos nas tabelas usuais de composição dos alimentos e os alimentos de origem animal, valores superiores.

The effect of bacterial protein grown on natural gas on growth performance and sensory quality of broiler chickens

Bacterial protein meal (BPM) produced from natural gas by Methylococcus capsulatus (Bath), Alcaligenes acidovorans, Bacillus brevis and Bacillus firmus was studied as a protein source for broiler chickens. Three experiments from day-old to slaughter at 35 d were carried out. In exp. 1, BPM was fed at 0, 20, 40, 60, 80 and 100 g kg-1 diet (as fed) replacing soybean meal protein. Levels of BPM up to 60 g kg-1 had no effect on 0-5 wk gain, while the 80 and 100 g kg-1 levels significantly reduced gain, especially in the 0–2 wk period. In exp. 2, chickens were fed diets containing 0, 30, 60 and 90 g kg-1 BPM and two protein levels, 23 and 21 g kg-1. The highest level of BPM significantly reduced growth, independent of protein level, whereas growth responses to lower levels of BPM were similar to the control diet. In exp. 3, 90 g kg-1 BPM in diets containing 23 g kg-1 protein had no negative effect on growth, but significantly reduced the abdominal fat pad. Overall, substitution of soybean meal protein with increasing levels of BPM significantly lowered feed-to-gain ratio during the last part of the feeding period. Sensory analysis of thigh meat after 2 mo of frozen storage (exp. 1) showed that meat from 35-d-old chickens fed 60 and 100 g kg-1 BPM had less odor intensity and less rancid flavor than meat from control animals fed no BPM. Other sensory attributes were not affected by treatment. Key words: Bacterial protein meal, chicken, growth performance, feed:gain ratio, feed conversion, sensory quality

Studies on Feeding Peanut Meal as a Protein Source For Broiler Chickens

Four experiments were conducted to compare the performance of broilers fed soybean meal (SBM) versus peanut meal (PNM) as protein sources. Ross × Ross 208 broiler chickens were placed in battery brooders (Experiments 1 to 3, four replicates of 8 chicks per treatment) and floor pens (Experiment 4, four replicates of 34 chicks per treatment). In Experiment 1, addition of 0, 0.1, 0.2, and 0.3% Thr to a corn-PNM-based diet increased 0 to 18 d BW gain (BWG; 0.374c vs. 0.495b vs. 0.508b vs. 0.508b kg, respectively) and decreased feed conversion ratio (FCR; 2.09c vs. 1.63b vs. vs. 1.54b vs. 1.54b g/g, respectively) compared to the corn-SBM-based control diet (BWG = 0.593a and FCR = 1.36a). In Experiment 2, diets were formulated with the same amino acid minimums, and as the percentage of PNM increased in the diets (0, 10, 20, and 32%), BWG decreased (0.560a vs. 0.532a vs. 0.521a vs. 0.458b kg, respectively) and FCR increased (1.72b vs. 1.71b vs. 1.79bc vs. 1.86c g/g, respectively). In Experiment 3, addition of Thr to a corn-PNM-based diet increased BWG (-Thr = 0.284c vs. +Thr = 0.397b kg) and decreased FCR (-Thr = 1.60b vs. +Thr = 1.54b g/g). The BWG and FCR were best for the corn-SBM-based control diet (0.499a kg and 1.38a g/g, respectively). In Experiment 4, during the growing period (18 to 42 d), significant interactions occurred between protein source (PNM vs. SBM) and protein level (16 and 20% vs. 24%) for BW and FCR but not for carcass, breast, or leg quarter yield or fat pad weights (P < 0.05) at 42 d of age. Technical (not economic) performance of birds fed PNM was similar to SBM at the highest protein levels fed. PNM could be used as a protein source for broilers under appropriate economic conditions.