Comparative growth performance, gizzard weight, ceca digesta short chain fatty acids and nutrient utilization in broiler chickens and turkey poults in response to cereal grain type, fiber level, and multienzyme supplement fed from hatch to 28 days of life

Abstract

Growth performance, gizzard weight, ceca digesta short-chain fatty acids (SCFA), and apparent retention (AR) of components were investigated in broilers and turkeys in response to cereal grain type, fiber level, and multienzyme supplement (MES) fed from hatch to 28 d of life. 480-day-old male broiler chicks and equal number of turkeys were placed separately in metabolism cages (10 birds/cage) and allocated to 8 diets. The species-specific diets were a corn or wheat-based basal diet without (LF) or with 10% corn DDGS or wheat middlings (HF) and fed without or with MES. This effectively created a 2 (grain types) × 2 (fiber levels) × 2 (MES) factorial arrangement of treatments. The diets had TiO₂ as an indigestible marker. Body weight, feed intake, and mortalities were recorded to calculate body weight gain (BWG) and feed conversion ratio (FCR). Excreta samples were collected on d 25 to 27 for AR, and all birds were necropsied for gizzard weight and ceca digesta on d 28. The interaction between grain and MES in broilers was such that wheat diets with MES had the lowest (P = 0.005) FCR. In broilers, LF diets had better (P = 0.010) FCR than HF diets. The wheat diets had the highest (P = 0.006) concentration of butyric acid in broilers. Broilers fed HF and corn diets had heavier gizzard than broilers-fed LF and wheat diets. The MES improved (P < 0.05) AMEn in HF, corn, and wheat diets in broilers. The turkeys fed wheat diets had the lowest (P = 0.019) FCR. Turkeys fed HF wheat diets had the heaviest (P < 0.001) gizzard. In turkeys, the MES improved AMEn in HF and LF corn diets, and only in LF wheat diets compared to respective controls. Treatments had no effect on turkeys cecal SCFA. In conclusion, grain type, fiber, and MES did not affect growth in both species. However, species exhibited differing FCR, gizzard, and energy utilization to fiber and MES.

INTRODUCTION

Broiler chickens and turkeys have been genetically selected to produce greater quantities of meat with reduced feed consumption and age at slaughter (Havenstein et al., 2007, Zampiga et al., 2019, Tallentire et al., 2016). However, although both species have been bred for high meat yield, turkeys grow more slowly, whereas broiler chickens are fast growing. A previous study demonstrated that young broiler chickens and turkeys (first 4 wk of life) fed corn or wheat-based diets designed to suit their nutritional needs without or with multienzyme supplement (MES) exhibited variable performance responses (Sanchez et al., 2021). Specifically, broiler chickens fed corn diets were heavier compared with those fed wheat diets; in contrast, turkey fed wheat diets were heavier than those fed corn diets (Sanchez et al., 2021). However, this study did not determine whether the differences in utilization of corn and wheat diets in broiler chickens and turkeys were linked to nutrients digestion.

At the same physiological age, broiler chickens have a much lower protein (amino acids) requirement than turkeys (NRC, 1994). Young birds have inadequate capacity for effective digestion of protein feedstuffs due to low gastric acid and enzymes secretions (Mateos et al., 2012; Kiarie et al., 2021). It has been suggested that structural materials such as fiber can stimulate gastrointestinal development and physiology in particular gizzard in poultry (Hetland et al., 2003; Mateos et al., 2012). However, the type and inclusion level of fiber is critical for nutrient utilization and growth performance in poultry (Mateos et al., 2012; Kiarie et al., 2014, 2017). Adding 10% corn distillers dried grain's with solubles (DDGS) or wheat middlings in corn or wheat-based diets for turkeys and broilers diets tended to reduce growth in broilers but had no effects on growth in turkeys (Sanchez et al., 2021). Interestingly, whereas turkeys fed diets with corn DDGS, and wheat middlings tended to have heavier gizzards, this effect was not seen in broiler chickens (Sanchez et al., 2021). It appears that turkeys and broilers have different capacities for utilization of fiber, yet there are limited comparative studies at similar physiological ages.

The use of feed enzymes is a well-accepted practice in poultry production (e.g., Kiarie et al., 2014; Goodarzi Boroojeni et al., 2018; Muchiri et al., 2023). However, there is still variability in the data due to differences associated with the nature of the enzyme used individually or in combination, the inclusion rates of the enzymes, the extent of reduction in nutrient density in the control diet, and the source of dietary fiber and enzymes could influence the responses seen in animals (Ravindran, 2013, Slominski, 2011). There are limited studies comparing the response of broiler chickens and turkeys to supplemental enzymes when fed diets formulated with similar ingredients. In our previous study, MES improved growth in broiler chickens fed 10% corn DDGS but had no effects in broilers fed 10% wheat middlings, or turkeys fed diets containing 10% corn DDGS or wheat middlings (Sanchez et al., 2021). However, we did not determine whether the differences in MES response could be explained by changes in lower gut fermentation rather than small intestine digestibility. This information may be useful in assigning accurate energy values within and among species presumably due to differences in digestive and fermentation capacities.

The hypotheses tested were that the addition of fibrous feed ingredients would reduce nutrient utilization in diets differing in base cereal grain. Supplementation with MES will enhance utilization of fibrous ingredients in broilers and turkeys. The overall objective of the present study was to compare the responses of broiler chickens and turkey poults to cereal grain types, fiber levels, and MES during the first 28 d of life. The fiber levels were created by adding 10% corn distillers dried grains with solubles or wheat middlings in corn or wheat-based diets, respectively. Growth performance, gizzard weight, ceca digesta short chain fatty acids, and nutrients utilization were the response criteria.

MATERIAL AND METHODS

The University of Guelph Animal Ethics Committee reviewed and approved the experimental protocols and the use of animals (AUP# 3521). The Canadian Code of Practice for the Care and Use of Animals for Scientific Purposes was followed when caring for broiler chickens and turkey poults (CCAC, 2009).

Experimental Diets

All feed ingredients were procured from a commercial feed mill (Floradale Feed Mill Ltd., Floradale, Canada) and delivered to the University of Guelph Feed mill for processing and diets preparation. Basal diets were formulated with either corn or wheat without (low fiber, LF) or with 10% corn DDGS or wheat middlings (high fiber, HF), respectively. The iso-caloric and iso-nitrogenous basal diets met or exceeded the recommended requirements for Ross 708 broiler chickens or Hybrid Turkey (Hybrid converter, Hendrix Genetic, Kitchener, Canada) (Table 1). The INRA-CIRAD-AFZ Feed Tables (INRA, 2020) were used for the ingredient specifications. Each basal diet was split into 2 portions: one portion, the control, and the other supplemented with MES (500 g of product per metric ton). The MES supplied the main activity of xylanase and β-glucanase and other minor activities, including invertase, protease, cellulase, amylase, and β-mannanase. The targeted activity level for xylanase and β-glucanase was 800 U/kg and 160 U/kg of feed, respectively. CBS BioPlatforms Inc. (Calgary, Canada) provided the MES and assay procedures. All diets contained 0.25% TiO₂ as an indigestible marker and were fed in crumble form. The temperature of the processing condition was 60°C to 65°C and steam pressure of 30 psi.

Table 1.

Composition of the basal diets, as fed basis.

	Species	Broiler diets				Turkey diets
	Grain type	Corn diets		Wheat diets		Corn diets		Wheat diets
Item, %	Fiber level	Low	High	Low	High	Low	High	Low	High
Corn		62.1	57.9	-	-	49.8	44.8	-	-
Wheat		-	-	64.1	56.2	-	-	53.5	45.3
Corn DDGS		-	10.0	-	-	-	10.0	-	-
Wheat middlings		-	-	-	10.0	-	-	-	10.0
Soybean meal (48%)		29.8	24.2	24.3	22.3	36.3	31.4	29.3	27.6
Pork meal		3.00	3.00	3.00	3.00	10.4	9.83	12.0	11.7
Soy oil		1.07	0.87	4.17	4.05	0.20	0.20	2.06	2.02
Monocalcium phosphate		1.35	1.11	1.26	1.31	1.10	0.97	0.65	1.00
Limestone		0.61	0.76	0.81	0.77	0.08	0.30	-	-
Vitamin and trace minerals premix1		1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00
DL-methionine		0.31	0.30	0.32	0.38	0.42	0.41	0.44	0.49
L-lysine HCL		0.29	0.45	0.41	0.51	0.51	0.65	0.64	0.72
L-threonine		0.14	0.18	0.20	0.25	0.16	0.20	0.23	0.28
Sodium chloride		0.25	0.16	0.18	0.15	0.20	0.12	0.13	0.10
Sodium bicarbonate		0.10	0.10	0.14	0.19	0.01	0.08	0.02	0.08
Tryptophan		-	-	-	-	0.01	0.02	0.05	0.03
Titanium dioxide		0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25
Calculated provisions
AME, kcal/kg		3,000	3,000	3,000	3,000	2,850	2,850	2,850	2,850
Crude protein, %		21.0	21.0	21.0	21.0	27.5	27.5	27.5	27.5
Crude fat, %		3.76	3.40	5.97	6.09	3.25	3.00	4.65	4.81
Neutral detergent fiber, %		7.75	9.96	9.16	12.02	7.06	9.26	8.25	11.1
SID Lys, %		1.15	1.15	1.15	1.15	1.62	1.62	1.62	1.62
SID Met, %		0.59	0.59	0.58	0.61	0.76	0.77	0.77	0.80
SID Met + Cys, %		0.85	0.85	0.85	0.85	1.05	1.05	1.05	1.05
SID Trp, %		0.22	0.20	0.23	0.21	0.28	0.28	0.28	0.28
SID Thr, %		0.77	0.77	0.77	0.77	0.96	0.96	0.96	0.96
Calcium, %		0.92	0.92	0.92	0.92	1.40	1.40	1.40	1.40
Total phosphorous, %		0.76	0.74	0.77	0.85	1.08	1.06	1.07	1.16
Available phosphorous, %		0.46	0.46	0.46	0.46	0.75	0.75	0.75	0.75
Sodium, %		0.16	0.16	0.16	0.16	0.16	0.16	0.16	0.16
Chloride, %		0.23	0.23	0.23	0.23	0.24	0.24	0.24	0.24
Analyzed provisions
Dry matter, %		87.2	87.1	87.2	87.4	87.5	88.2	87.7	87.4
Gross energy, kcal/kg		3,959	4,093	4,178	4,129	4,084	4,179	4,094	4,130
Crude protein, %		22.1	20.9	22.4	21.1	26.6	26.4	28.1	28.3
Crude fat, %		3.82	4.12	5.21	5.74	3.19	4.12	4.13	4.22
Starch, %		36.4	35.0	34.1	32.00	32.0	29.5	30.1	27.4
Neutral detergent fiber, %		8.01	10.6	9.11	11.0	8.01	9.13	8.86	10.6

¹Provided per kilogram of diet: transretinol, 2.64 mg; cholecalciferol, 83 µg; dl-α-tocopherol, 36 mg; cyanocobalamin, 12.0 mg; menadione, 3.3 mg; niacin, 50.0 mg; choline, 1,200.0 mg; folic acid, 1.0 mg; biotin, 0.22 mg; pyridoxine, 3.3 mg; thiamine, 4.0 mg; calcium pantothenic acid, 15.0 mg; riboflavin, 8.0 mg; manganese, 70.0 mg; zinc, 70.0 mg; iron, 60.0 mg; iodine, 1.0 mg; copper, 10 mg; and selenium, 0.3 mg.

Birds and Housing

A total of 480 day-old male broiler chicks (Ross 708) were procured from a commercial hatchery (Maple Leaf Foods, New Hamburg, Canada). Likewise, 480 day-old Tom turkeys (Hybrid converter, Hendrix Genetics, Kitchener, Canada) were obtained from a local commercial hatchery (Cuddy Farms Ltd., Strathroy, Canada). The birds were placed in cages (10 birds per cage per species) based on body weight (BW). The cages were all housed in one environmentally controlled room. Each cage (105 × 62 cm) had a feeder trough and nipple drinkers. On d 0, the room temperature was set at 32°C and progressively reduced to 29°C by d 13, then to 24°C by d 21. The lighting program consisted of 23 h of light (20 lux) from d 0 to 3, followed by 20 h of light (10–15 lux) in the subsequent days. The room had a total of 96 cages installed in 2 rows separated by a 36 inches walkway and cages stacked in 2 tiers of 24 cages each side. The broiler chickens and turkeys were placed in different rows.

Experimental Procedures and Sample Collection

The 8 diets were assigned within species in a completely randomized design to give 6 replicates per diet by species. The birds had free access to feed and water throughout the study. On d 24, collection trays were installed in all cages and fresh grab excreta samples were collected from d 25 to 27 and stored at −20°C until further analyses. The BW and feed intake (FI) were recorded on d 0 and 28 for the calculation of body weight gain (BWG) and feed conversion ratio (FCR). Mortalities were recorded as they appeared for the calculation of adjusted FCR. On d 28, 2 birds per cage were randomly selected, individually weighed, and euthanized via cervical dislocation. The gizzard was dissected, content emptied, blotted dry with paper towel and empty weight recorded. The ceca digesta was collected and immediately frozen at −20°C until required for analysis.

Sample Processing and Chemical Analyses

The excreta samples were thawed, pooled by the cage, and oven-dried at 65°C for 72 h. Diet and dried excreta samples were finely ground and stored in airtight plastic containers at 4°C for further analyses. All samples were analyzed for dry matter (DM), gross energy (GE), neutral detergent fiber (NDF), nitrogen, crude fat (CF), and titanium. Method 930.15 (AOAC, 2004) was used for DM analyses. The gross energy (GE) was determined using an adiabatic bomb calorimeter (IKA Calorimeter System C 6000; IKA Works, Wilmington, NC). The NDF was determined using ANKOM 200 fiber analyzer (ANKOM Technology, Fairport, NY) according to van Soest et al. (1991). Nitrogen (N) was determined using the LECO machine (LECO Corporation, St. Joseph, MI) using method 968.06 (AOAC International, 2005), and crude protein (CP) values were derived by multiplying the N value by 6.25. Crude fat content was determined using ANKOM XT 20 Extractor (ANKOM Technology, Fairport, NY). The titanium content was determined according to Myers et al. (2004). The short-chain fatty acids (SCFA) concentration (propionic, lactic, acetic, iso-butyric, and butyric) were measured in thawed ceca digesta (Leung et al., 2018). Briefly, in a microcentrifuge tube, 0.1 g of digesta was resuspended in 1 mL of 0.0025 mol/L H₂SO₄ (1:10, wt/vol), firmly closed, and vortexed quickly until the material was completely dissolved. After centrifuging the tubes at 11,000 g for 15 min, 400 µL of supernatant was transferred to a high-performance liquid chromatography vial and topped with 400 µL of 0.0025 mol/L H₂SO₄ buffer. Following this, the digesta fluid was analyzed for SCFA using high-performance liquid chromatography (Hewlett Packard 1100, made in Germany) with Rezex ROA-Organic Acid LC column, 300 mm 7.8 mm from Phenomenex, and Refractive Index detector at 400°C (Agilent 1260 Infinity RID from Agilent Technologies, made in Germany) (De Baere et al., 2013). Starch concentration in the basal diets was determined in a commercial laboratory (SGS Canada Inc., Guelph, Canada). Xylanase activity in diets was assayed using Xylazyme AX tablets (Megazyme International Ltd., Bray, Ireland). One unit of xylanase was defined as the quantity of the enzyme that liberated 1 μmoL of xylose equivalent per min. The particle sizes of the diets were determined using a RO-TAP Sieve Shaker (model RX-30 E; W.S. Tyler, Mentor, OH).

Calculations and Statistical Analyses

The apparent retention (AR) of components, apparent metabolizable energy (AME) and AME corrected for nitrogen (AMEn) were calculated as described by Mwaniki and Kiarie (2019). The digestible crude protein conversion ratio (CPCR g/kg BWG) and calories conversion ratio (CCR mcal/kg BWG) were calculated according to Mohammadigheisar et al. (2021).

$$\text{CCR}=\left(\text{Feed}\text{intake}\times \text{AMEn}\right)/\left(\text{Body}\text{weigt}\text{gain}\right)$$

$$\text{CPCR}=\frac{\left(\text{Aparent}\text{retention}\text{of}\text{crude}\text{protein}\times \text{crude}\text{protein}\text{intake}\right)}{\text{Body}\text{weigt}\text{gain}}$$

The cage was considered the experimental unit. Outliers were assessed using the PROC UNIVARIATE in the SAS studio. Any value above or below the mean ±3 standard deviations was identified and removed as an outlier. The data were subjected to PROC GLIMMIXX procedures of SAS. For each species, the model had fixed effects of grain type, fiber level, MES, and associated interactions. Tukey method was used for LSmeans separation when interaction effects and t test was used for the main effects. The P < 0.05 was used to determine the significance of treatment differences.

RESULTS

The particle sizes (geometrical mean diameter ± standard diameter, µm) for the broiler chicken basal diets were 460.37 ± 14.53, 477.59 ± 14.40, 481.05 ± 13.52, and 461.81 ± 16.56 for LF corn, HF corn, LF wheat, and HF wheat, respectively. The corresponding values for the turkeys’ diets were 528.94 ± 3.95, 523.75 ± 5.64, 502.99 ± 16.52, and 532.30 ± 5.74, respectively. Xylanase activity was determined to confirm accuracy of inclusion of MES and feed mixing. The analyzed xylanase activities (U/kg of feed) for the broiler chicken diets were 189, 206, 554, 543, 274, 209, 1,189, and 1,408 for LF corn, HF corn, LF corn + MES, HF corn + MES, LF wheat, HF wheat, LF wheat + MES, HF wheat + MES, respectively. The corresponding values for the turkey diets were 185, 191, 513, 762, 255, 250, 1,344, and 1,784, respectively. The analyzed chemical composition of the basal diets is shown in Table 1. Within species, the concentrations of GE, CP, and starch were comparable. Wheat diets for broilers had higher concentration of CF in alignment with higher soy oil inclusion to balance for energy. In broilers basal diets, the concentration of NDF was 1.32- and 1.21-fold higher in HF corn and wheat diets relative to respective LF corn and wheat diets. The corresponding concentrations in turkey diets were 1.14- and 1.20-fold higher, respectively.

Broiler Chickens

Day-old broiler chicks were, on average, 35.7 ± 0.32 g/bird and turkey poults were 65.7 ± 1.04 g/bird. There were no (P > 0.05) 3-way interactions between grain, fiber level, and MES on BW, BWG, FI, and FCR (Table 2). There were no (P >0.05) 2-way interactions between grain and fiber, and fiber and MES or main effects of grain and MES on BW, BWG, and FI. There was also no fiber main effect on FI. However, a 2-way interaction (P = 0.005) between grain and MES on FCR, was observed, whereby, relative to respective controls, MES improved FCR in wheat diets and not in corn diets. There were fiber main effects on BW and FCR, in which case broilers fed LF diets had a higher BW (1,419 vs. 1,378 g/bird), and BWG (1,382 vs. 1,341 g/bird) than HF diets. There was no 3- or 2-way interactions (P >0.05) between grain, fiber, and MES or MES main effect on gizzard weight (Table 2). But there was grain and fiber main effect (P ≤ 0.001) on gizzard weight. In this context, broilers fed corn diets and those fed HF diet had heavier gizzard than broilers fed wheat and LF diets, respectively.

Table 2.

Growth performance and gizzard weight in broiler chickens in response to cereal grain type, fiber, and multienzyme supplement (MES) fed from hatch to 28 d of life.

Grain type	Fiber level	MES1	FBW, g/d	BWG, g/b	FI, g/b	FCR, g/g	Gizzard weight, g/kg BW
Corn			1,393	1,358	1754	1.303a	15.88a
Wheat			1,402	1,367	1759	1.282b	14.68b
	Low		1,419a	1,382a	1770	1.281b	14.21b
	High		1,378b	1,341b	1742	1.304a	16.35a
		-	1,395	1,359	1745	1.292	15.05
		+	1,402	1,366	1768	1.294	15.50
SEM			15.72	15.72	15.24	0.01	0.03
Corn	Low		1,430	1,394	1782	1.291	14.79
Corn	High		1,358	1,322	1726	1.316	16.96
Wheat	Low		1,408	1,371	1759	1.272	13.62
Wheat	High		1,397	1,361	1760	1.293	15.73
Corn		-	1,404	1,369	1735	1.289ba	15.62
Corn		+	1,383	1,347	1773	1.317a	16.13
Wheat		-	1,384	1,348	1755	1.294ba	14.48
Wheat		+	1,421	1,385	1763	1.270b	14.87
SEM			21.95	21.95	21.92	0.01	0.05
P-value
Grain			0.587	0.591	0.731	0.021	0.001
Fiber			0.013	0.013	0.082	0.010	<0.001
MES			0.657	0.651	0.134	0.827	0.202
Grain*Fiber			0.059	0.058	0.074	0.846	0.946
Grain*MES			0.071	0.070	0.324	0.005	0.862
Fiber*MES			0.824	0.823	0.844	0.826	0.717
Grain*Fiber*MES			0.738	0.741	0.178	0.090	0.910

Abbreviations: BWG, body weight gain; cFCR, mortality corrected feed conversion ratio; FBW, final body weight; FI, feed intake; IBW, initial body weight; SEM, standard error of means.

Within a factor of analyses, response criteria with means with different superscripts are significantly different, P < 0.05.

¹MES: multienzyme supplement supplied the main activity of xylanase and β-glucanase and other minor activities including invertase, protease, cellulase, amylase, and mannanase. The targeted activity level of xylanase and β-glucanase were 800 and160, U/kg of feed, respectively.

There were no (P >0.05) 3- or 2-way interactions between grain, fiber, and MES on ceca digesta concentration of SCFA (Table 3). The main effect of grain was only observed on butyric (P = 0.006) with wheat diets showing higher concentration of this acid than corn diets. There was no main effect of fiber and MES on concentration of ceca digesta SCFA.

Table 3.

The concentration of short-chain fatty acids (SCFA, mmol/g) in ceca digesta of broiler chickens in response to cereal grain type, fiber, and multienzyme supplement (MES) fed from hatch to 28 d of life.

Grain type	Fiber level	MES1	Lactic	Acetic	Propionic	Iso-butyric	Butyric	Total SCFA
Corn			22.36	58.20	5.73	13.76	22.13b	122.2
Wheat			25.02	60.31	5.35	12.41	26.98a	129.9
	Low		22.79	60.34	5.70	12.68	25.85	128.0
	High		24.60	58.18	5.38	13.49	23.26	124.1
		-	23.98	59.00	5.71	12.35	24.20	124.4
		+	23.41	59.51	5.37	13.82	24.91	127.7
SEM			1.70	2.40	0.37	0.87	1.66	4.21
P-value
Grain			0.127	0.385	0.309	0.132	0.006	0.074
Fiber			0.294	0.375	0.401	0.360	0.126	0.354
MES			0.738	0.834	0.374	0.101	0.671	0.440
Grain*Fiber			0.610	0.523	0.491	0.747	0.641	0.267
Grain*MES			0.614	0.077	0.387	0.543	0.834	0.197
Fiber*MES			0.211	0.839	0.296	0.626	0.682	0.939
Grain*Fiber*MES			0.840	0.712	0.315	0.473	0.163	0.378

Within a factor of analyses, response factors with means with different superscripts are significantly different, P < 0.05.

¹MES: multienzyme supplement supplied main activities of xylanase and β-glucanase and other minor activities including invertase, protease, cellulase, amylase and mannanase. The targeted activity level of xylanase and β-glucanase were 800 and 160, U/kg of feed, respectively.

There were 3-way interactions (P ≤ 0.038) between grain, fiber, and MES on AR of CP, CF, NDF, and retainable CPCR (Table 4). Supplementation of MES increased AR of CP in broilers fed HF and LF diets relative to respective control diets. However, the magnitude of MES effect on AR of CP was larger for the HF corn diet (65.72 vs. 58.59%) than LF corn diet (68.17 vs. 66.94%). The MES also improve the AR of NDF in HF and not LF corn diets. Broilers fed HF wheat diet with MES had higher AR of CP and NDF than birds fed LF wheat diet without MES and LF wheat diets without or with MES. However, MES improved AR of CF in birds fed HF wheat diets (85.89 vs. 82.70%) and not in LF wheat diets (85.37 vs. 84.86%). A 2-way interaction between grain and fiber, and fiber and MES on AR of GE was such that HF reduced GE while MES improved the GE in both LF and HF diets relative to their respective controls. There were also a 2-way interactions between grain and fiber, grain and MES and fiber and MES on AR of AMEn. As such, HF improved the AMEn in wheat diets and not in corn diets, MES improved AMEn in corn, wheat, LF, and HF diets relative to their respective controls. There were 3-way interactions between grain, fiber, and MES on CPCR (Table 4). In this context, MES improved CPCR in LF and HF corn and wheat diets compared to their respective controls. There were 2-way interactions between grain and fiber, and MES main effect on CCR (Table 4). Low-fiber and HF corn being similar (4.60 vs. 4.59) and HF wheat diets being greater than LF wheat diets (4.45 vs. 4.20) and MES improving CCR in broilers (4.54 vs. 4.38).

Table 4.

Apparent retention of components, metabolizable energy corrected for nitrogen (AMEn), crude protein, and calories conversion in broiler chickens in response to cereal grain type, fiber, and multienzyme supplement (MES) fed from hatch to 28 d of life.

Grain	Fiber level	MES1	Apparent retention, %					AMEn, mcal/kg DM	Conversions
			Dry matter	Crude protein	Crude fat	NDF	Gross energy		CCR2 mcal/kg BWG	CPCR3 g/kg BWG
Corn			69.90a	64.85a	90.19a	27.11b	75.06a	3.55a	4.60a	181.63a
Wheat			66.65b	61.10b	84.71b	32.39a	71.72b	3.42b	4.32b	167.65b
	Low		67.95b	63.66a	87.85a	29.40	73.46	3.49	4.40b	178.72a
	High		68.59a	62.29b	87.04b	30.10	73.32	3.49	4.52a	170.57b
		-	67.39b	61.28b	87.31	26.56b	72.59b	3.46b	4.38b	168.69b
		+	69.16a	64.67a	87.58	32.93a	74.19a	3.51a	4.54a	180.60a
SEM			0.14	0.33	0.22	0.48	0.14	0.01	0.06	2.00
Corn	Low		71.08a	67.55a	90.59	30.37b	76.45a	3.60a	4.60a	190.97a
Corn	High		68.71b	62.15b	89.79	23.85d	73.68b	3.50b	4.59a	172.29b
Wheat	Low		64.82c	59.78c	85.12	28.43c	70.47d	3.38d	4.20b	166.47b
Wheat	High		68.47b	62.42b	84.30	36.36a	72.96c	3.47c	4.45a	168.84b
Corn		-	69.19b	62.76b	90.84a	23.74	74.38	3.54b	4.50	173.79
Corn		+	70.60a	66.94a	89.54b	30.48	75.75	3.57a	4.69	189.48
Wheat		-	65.58d	59.79c	83.78d	29.38	70.81	3.39d	4.27	163.58
Wheat		+	67.71c	62.40b	85.63c	35.40	72.62	3.46c	4.37	171.72
	Low	-	67.70b	62.85b	88.04a	28.16c	73.23b	3.48b	4.33	173.94
	Low	+	68.20b	64.48a	87.67ba	30.64b	73.69b	3.49b	4.47	183.51
	High	-	67.07c	59.70c	86.58b	24.97d	71.96c	3.44c	4.43	163.43
	High	+	70.11a	64.87a	87.50ba	35.24a	74.68a	3.53a	4.60	177.70
Corn	Low	-	71.15	66.94ba	91.22a	30.25b	76.34	3.60	4.53	186.45a
Corn	Low	+	71.02	68.17a	89.96ba	30.49b	76.56	3.60	4.67	195.50a
Corn	High	-	67.24	58.59e	90.46ba	17.23d	72.41	3.47	4.46	161.12c
Corn	High	+	70.18	65.72bc	89.11b	30.46b	74.94	3.53	4.72	183.46ba
Wheat	Low	-	64.26	58.77ed	84.86c	26.06c	70.12	3.37	4.14	161.43c
Wheat	Low	+	65.38	60.78d	85.37c	30.79b	70.82	3.39	4.27	171.51bc
Wheat	High	-	66.90	60.82d	82.70d	32.71b	71.51	3.41	4.41	165.74c
Wheat	High	+	70.04	64.02c	85.89c	40.01a	74.41	3.52	4.48	171.94bc
SEM			0.33	0.65	1.35	0.89	0.28	0.01	0.12	4.33
P-value
Grain			<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
Fiber			<0.001	0.001	0.013	0.150	0.302	0.678	0.044	<0.001
MES			<0.001	<0.001	0.385	<0.001	<0.001	<0.001	0.010	<0.001
Grain*Fiber			<0.001	<0.001	0.978	<0.001	<0.001	<0.001	0.030	<0.001
Grain*MES			0.013	0.020	<0.001	0.459	0.136	0.021	0.411	0.066
Fiber*MES			<0.001	<0.001	0.044	<0.001	<0.001	<0.001	0.763	0.247
Grain*Fiber*MES			0.070	<0.001	0.033	<0.001	0.844	0.227	0.410	0.038

Abbreviation: SEM, standard error of means.

^a-gWithin a column LSmeans with different superscripts differs, P < 0.05.

¹MES: multienzyme supplement supplied main activity of xylanase and β-glucanase and other minor activities including invertase, protease, cellulase, amylase and mannanase. The targeted activity level of xylanase and β-glucanase were 800 and160, U/kg of feed, respectively.

²CCR: calories conversion ratio.

³CPCR: crude protein conversion ratio.

Turkeys

There were no (P > 0.05) 3- and 2-way interactions between grain, fiber level, and MES on BW, BWG, FI, and FCR (Table 5). There were no (P > 0.05) main effects of fiber and MES on BW, BWG, FI, and FCR. However, main effects of grain were only observed (P < 0.001) on FI and FCR, with broilers fed wheat diets having a lower FI and FCR. There were no (P > 0.05) 3-way interactions between grain, fiber level, and MES on gizzard weight (Table 5). There were also no 2-way interactions between grain and MES or fiber level and MES on gizzard weight. However, turkeys fed HF wheat diet had heavier gizzard than those fed LF wheat. In contrast, turkeys fed LF corn diets had a heavier gizzard than those fed HF corn diets. There was MES main effect (P = 0.003) on gizzard weight. Regarding this, turkeys fed diet without MES had heavier gizzard than turkeys fed diets with MES.

Table 5.

Growth performance and gizzard weight in turkey poults in response to cereal grain type, fiber, and multienzyme supplement (MES) fed from hatch to 28 d of life.

Grain type	Fiber level	MES1	FBW, g/d	BWG, g/b	FI, g/b	FCR, g/g	Gizzard weight, g/kg BW
Corn			1343	1278	1739a	1.363a	16.08b
Wheat			1338	1272	1661b	1.308b	17.39a
	Low		1337	1272	1718	1.353	16.69
	High		1344	1278	1682	1.317	16.77
		-	1327	1262	1692	1.343	17.40a
		+	1354	1288	1708	1.328	16.07b
SEM			22.48	22.51	31.42	0.02	0.04
Corn	Low		1334	1269	1768	1.395	16.88ba
Corn	High		1352	1287	1709	1.330	15.27b
Wheat	Low		1340	1274	1667	1.311	16.50b
Wheat	High		1335	1269	1655	1.305	18.28a
Corn		-	1317	1251	1715	1.372	16.67
Corn		+	1370	1304	1763	1.353	15.48
Wheat		-	1338	1272	1669	1.314	18.12
Wheat		+	1337	1271	1653	1.302	16.65
SEM			31.79	31.83	44.43	0.03	0.06
P-value
Grain			0.807	0.795	0.018	0.019	0.004
Fiber			0.766	0.771	0.268	0.122	0.846
MES			0.250	0.259	0.610	0.497	0.003
Grain*Fiber			0.606	0.605	0.458	0.198	<0.001
Grain*MES			0.238	0.241	0.322	0.861	0.742
Fiber*MES			0.439	0.439	0.490	0.947	0.934
Grain*Fiber*MES			0.708	0.712	0.292	0.418	0.492

Abbreviations: BWG, body weight gain; cFCR, mortality corrected feed conversion ratio; FBW, final body weight; FI, feed intake; IBW, initial body weight; SEM, standard error of means.

Within a factor of analyses, response criteria with means with different superscripts are significantly different, P < 0.05.

¹MES: multienzyme supplement supplied the main activity of xylanase and β-glucanase and other minor activities including invertase, protease, cellulase, amylase and mannanase. The targeted activity level of xylanase and β-glucanase were 800 and160, U/kg of feed, respectively.

There were no (P > 0.05) 3- and 2-way interactions between species, grain, fiber, and MES on ceca digesta concentration of SCFA (Table 6). There were also no main effects of grain, fiber, and MES on concentration of ceca digesta SCFA. However, high fiber tended to increase the concentration of lactic acid (29.86 vs. 25.641).

Table 6.

The concentration of short-chain fatty acids (SCFA, mmol/g) in ceca digesta of turkey poults in response to cereal grain type, fiber, and multienzyme supplement (MES) fed from hatch to 28 d of life.

Grain type	Fiber level	MES1	Lactic	Acetic	Propionic	Iso-butyric	Butyric	Total SCFA
Corn			26.59	50.26	4.03	10.35	23.00	116.63
Wheat			28.91	51.47	4.04	10.99	23.22	119.25
	Low		25.64	49.38	3.86	10.72	21.91	113.41
	High		29.86	52.33	4.22	10.62	24.31	122.47
		-	27.90	51.81	4.07	10.78	23.71	119.38
		+	27.60	49.91	4.00	10.56	22.51	116.49
SEM			2.21	3.68	0.25	0.74	1.45	6.60
P-value
Grain			0.298	0.744	0.982	0.393	0.879	0.694
Fiber			0.063	0.427	0.159	0.889	0.104	0.178
MES			0.895	0.610	0.789	0.768	0.411	0.664
Grain*Fiber			0.681	0.213	0.602	0.347	0.704	0.481
Grain*MES			0.553	0.833	0.872	0.953	0.228	0.608
Fiber*MES			0.275	0.360	0.753	0.291	0.092	0.386
Grain*Fiber*MES			0.871	0.139	0.806	0.583	0.387	0.166

Within a factor of analyses, response factors with means with different superscripts are significantly different, P < 0.05.

¹MES: multienzyme supplement supplied main activities of xylanase and β-glucanase and other minor activities including invertase, protease, cellulase, amylase and mannanase. The targeted activity level of xylanase and β-glucanase were 800 and 160, U/kg of feed, respectively.

There were 3-way interactions (P <0.05) between grain, fiber, and MES on AR of DM, CP, CF, NDF, and AMEn (Table 7). The main effects and 2-way interactions between grain, fiber, and MES on AR of components are shown in Supplementary Table 1. Relative to respective controls, MES improved DM, CF, NDF, and GE in HF and not LF corn diets. In contrast, MES improved the AR of DM, CF, NDF, and GE in LF and not HF wheat diets. The MES improved the AR of CP in HF (55.20 vs. 48.07) and not LF (51.32 vs. 53.77) corn diets, and in LF and HF wheat diets. The MES also improved AMEn in LF and HF corn diets and LF wheat diets in turkeys (Table 7). There were no 3- and 2-way interactions between grain, fiber, and MES or their main effects on CCR (Table 7). There were 3-way interactions between grain, fiber, and MES on CPCR (Table 7). In this context, MES improved CPCR in HF and LF corn diets relative to their respective controls. The MES also improve the CPCR in LF and only to a small magnitude in HF wheat diets compared to their respective controls.

Table 7.

Apparent retention of components, metabolizable energy corrected for nitrogen (AMEn), crude protein and calories conversion in turkey poults in response to cereal grain type, fiber, and multienzyme supplement (MES) fed from hatch to 28 d of life.

Grain	Fiber level	MES1	Apparent retention, %					AMEn, mcal/kg DM	Conversion
			Dry matter	Crude protein	Crude fat	NDF	Gross energy		CCR2 mcal/kg BWG	CPCR3 g/kg BWG
Corn			59.96b	52.09b	86.19	25.11b	66.34b	3.18b	4.21	179.23b
Wheat			61.55a	54.18a	85.63	34.28a	67.57a	3.29a	4.33	199.15a
	Low		59.58b	52.04b	84.64b	27.84b	65.94b	3.19b	4.28	184.85b
	High		61.93a	54.23a	87.17a	31.55a	67.97a	3.27a	4.26	193.53a
		-	59.46b	51.98b	85.31	25.97b	65.46b	3.17b	4.29	187.70
		+	62.05a	54.29a	86.51	33.42a	68.45a	3.29a	4.25	190.68
SEM			0.15	0.34	0.49	0.41	0.16	0.01	0.07	4.14
Corn	Low		59.10d	52.55b	83.61c	23.99d	65.49	3.15c	4.26	181.52b
Corn	High		60.83b	51.63b	88.77a	26.23c	67.20	3.21b	4.17	176.94b
Wheat	Low		60.05c	51.53b	85.67b	31.70b	66.40	3.24b	4.29	188.18b
Wheat	High		63.04a	56.82a	85.58b	36.86a	68.74	3.34a	4.36	210.13a
Corn		-	58.09c	50.92	85.97	19.81d	64.24c	3.09c	4.22	178.88
Corn		+	61.83a	53.26	86.40	30.41c	68.45a	3.27b	4.21	179.58
Wheat		-	60.82b	53.04	84.64	32.13b	66.69b	3.26b	4.36	196.53
Wheat		+	62.27a	55.31	86.61	36.43a	68.44a	3.32a	4.30	201.78
	Low	-	58.84c	52.00b	83.92	26.33c	64.90d	3.14d	4.34	186.50
	Low	+	60.31b	52.08b	85.37	29.36b	66.98b	3.24b	4.22	183.20
	High	-	60.08b	51.96b	86.70	25.61c	66.03c	3.20c	4.24	188.91
	High	+	63.79a	56.49a	87.65	37.48a	69.92a	3.35a	4.28	198.16
SEM			0.22	0.48	0.70	0.57	0.22	0.01	0.11	5.79
Corn	Low	-	59.07d	53.77bc	84.12c	23.48d	65.05dc	3.12d	4.37	188.74ba
Corn	Low	+	59.13d	51.32de	83.09c	24.50d	65.92c	3.18c	4.16	174.30b
Corn	High	-	57.12e	48.07f	87.82ba	16.15e	63.42e	3.06e	4.08	169.01b
Corn	High	+	64.53a	55.20b	89.71a	36.32ba	70.98a	3.36a	4.26	184.86ba
Wheat	Low	-	58.61d	50.23fe	83.71c	29.18c	64.75d	3.17c	4.31	184.25bba
Wheat	Low	+	61.50c	52.83dc	87.64ba	34.22b	68.04bb	3.31b	4.28	192.10ba
Wheat	High	-	63.03b	55.85ba	85.58bc	35.08b	68.63b	3.34ba	4.41	208.81a
Wheat	High	+	63.05b	57.79a	85.58bc	38.64a	68.85b	3.33ba	4.31	211.45a
SEM			0.30	0.67	0.99	0.81	0.32	0.01	0.14	8.19
P-value
Grain			<0.001	<0.001	0.264	<0.001	<0.001	<0.001	0.143	<0.001
Fiber			<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.872	0.043
MES			<0.001	<0.001	0.020	<0.001	<0.001	<0.001	0.604	0.477
Grain*Fiber			<0.001	<0.001	<0.001	<0.001	<0.052	0.019	0.282	0.003
Grain*MES			<0.001	0.919	0.127	<0.001	<0.001	<0.001	0.752	0.587
Fiber*MES			<0.001	<0.001	0.614	<0.001	<0.001	0.003	0.296	0.138
Grain*Fiber*MES			<0.001	<0.001	0.001	<0.001	<0.001	<0.001	0.133	0.039

Abbreviation: SEM, standard error of means.

^a-gWithin a column LSmeans with different superscripts differs, P < 0.05.

¹MES: multienzyme supplement supplied main activity of xylanase and β-glucanase and other minor activities including invertase, protease, cellulase, amylase and mannanase. The targeted activity level of xylanase and β-glucanase were 800 and160, U/kg of feed, respectively.

²CPCR: crude protein conversion ratio.

³CCR: calories conversion ratio.

DISCUSSION

Although broiler chicks were approximately half the weight of poults at placement, they grew faster and were, as such heavier at d 28 than turkeys. This is because at 28 d of life, broiler chickens are more physiologically mature than turkeys (Palander et al., 2010). The better FCR in broilers fed HF diets relative to LF diets may be linked to the effect of HF diets increasing the gizzard weight. When turkeys and broiler chickens are fed highly viscous diets with or without MES, turkeys are more affected by the viscous diets than broiler chickens. For example, in a study conducted by Palander et al. (2010) in which 3- or 6-wk-old turkeys and broiler chickens were fed diets based on wheat and dehulled barley (WB), oats, or a mixture of WB and oats supplemented with enzymes, viscosity decreased with age in broilers. But it remained high and increased at some points in turkeys, particularly in 6-wk-old turkeys. In our previous study, turkeys fed wheat-based diets consumed 4% less feed than those turkeys fed corn-based diets (Sanchez et al., 2021). In the present study, wheat diets reduced feed intake in turkeys but did not affect broiler feed intake; on the other hand, corn diets did not affect broiler and turkey feed intake. Although the present study did not measure dietary soluble fiber or digesta viscosity, wheat diets may have reduced turkey feed intake because they have more soluble fiber than corn diets, which might have increased viscosity in the gut, thus decreasing gut transit time and feed intake in the 28-day-old turkeys (Slominski, 2011).

The effects of fiber on gizzard development depend on its source, its level in the diet, and physiological status and health of the bird (Mateos et al., 2012). Turkeys grow more slowly than broilers, and thus their digestive systems develop differently. During the first 12 d posthatch, the relative weights of gizzard and spleen are almost constant in turkeys (Uni et al., 1995, 1999). In the current study, broilers fed HF diets had the heaviest gizzards, indicating that the fiber sources effectively promoted gizzard development. Similarly, HF wheat diets increased turkey gizzard weight. However, HF corn diets reduced turkey gizzard weight. A moderate amount of insoluble fiber has been shown to increase gizzard weight (Hetland and Svihus, 2001). However, a higher amount may increase the movement of feeds from the gizzard into the small intestine, thus reducing the mechanical stimulation of the gizzard (Kiarie et al., 2014). The turkey diets in the present study had a similar inclusion level of corn DDGS to broiler's diets, but the soybean meal was higher. Both corn DDGS and soybean meal are a source of insoluble fiber which might have increased the amount of insoluble fiber, consequently increasing the gut transit time thus reducing the turkey gizzard weight (Bach Knudsen, 1997; Kiarie et al., 2014).

Wheat diets perform poorly compared to corn diets when fed to broiler chickens due to highly viscous water-soluble non-starch polysaccharides (Rodríguez et al., 2012). The present study agrees with these observations as the broiler chickens fed LF corn diet retained more components and AMEn than those fed LF wheat diet. In contrast, the turkeys fed LF wheat diets retained a higher AMEn than LF corn diets. When co-products such as corn cDDGS and wheat bran are added to corn and wheat-based diets, respectively, wheat diets can outperform corn diet because corn DDGS increases insoluble fiber in the diet (Kiarie et al., 2014). For example, Kiarie et al. (2014) fed broiler chickens with either corn + corn DDGS or wheat + wheat bran and despite the 2 diets having similar AMEn and wheat diet having 53.55% (3.94 vs. 1.83) more soluble non-starch polysaccharides, the wheat diet performance was better than corn diet. The present study found that broiler chickens fed a corn-based diet with corn DDGS had reduced AMEn and AR of components relative to the control. This can be linked to corn DDGS increasing gastrointestinal tract emptying time. Adding MES to corn diets containing corn DDGS increased the AR of DM, CP, GE, and AMEn, indicating that MES effectively improved performance in both turkeys and broiler chickens. The effect of MES on improving energy retention was also reflected in CE, as turkeys and broiler chickens fed MES diets had higher CE than those fed non-MES diets. In previous studies, young (4 wk old) and mature (11–21 wk old) turkeys utilized wheat better than corn-based diets (Waldroup et al., 1967; Persia et al., 2002; Sanchez et al., 2021). In the present study, turkeys fed LF wheat diets had 1.58% more AMEn than turkeys fed LF corn diets (3.17 vs. 3.12) and adding wheat middlings to the wheat diet (HF) improved AMEn by 8.38% compared to the HF corn diets (3.34 vs. 3.06). In contrast, the AMEn of broiler fed corn diets was higher than that of broiler fed wheat diets. The effect of grain type on turkey performance suggests that wheat grain may positively stimulate their gastrointestinal development and physiology better than corn. The performance of turkey fed wheat-based diets was better than those fed corn-based diets despite both being supplemented with enzymes (Persia et al., 2002). This is due to the differential in antinutritional components between the 2 cereals, with wheat having more than corn (Persia et al., 2002).

It is important to note that MES did not improve AMEn in broilers fed LF corn diets and turkeys fed HF wheat diets, which was unexpected. These results may concur with a trend observed by Adeola and Cowieson (2011), which showed that multicarbohydrase enzymes are more responsive when the control diet is less energy dense and has more antinutritional factors. Adebiyi and Olukosi (2015) also found no AMEn improvement when multicarbohydrase enzymes were added to high energy wheat DDGS fed to broilers and turkeys. Protein utilization efficiency is usually determined by the ratio of AMEn to digestible crude protein (Gous et al., 2018). As a result of their high protein requirements, prestarter broiler chickens and starter turkeys are in energy-dependent phase due to the high protein in their diets (Gous et al., 2018). The current study found a high CPCR ratio in turkeys fed wheat diets and turkeys fed HF diets. This is due to turkeys being able to obtain more AMEn from wheat as a source of energy, which helped to improve the ratio of AMEn to CP. Regardless of species, including MES in HF corn, LF and HF wheat diets improved crude protein utilization efficiency. Because CPCR has 2 phases, energy intake dependent and protein-dependent, it may appear that MES are more effective at maintaining this ratio in viscous grain such as wheat than corn. In the present study, supplementation of MES in LF corn diets reduced CPCR by 1.43% (187.59 vs. 184.90) while at the same time being increased in HF wheat diets by 6.53% (181.8 vs. 169.93).

As the birds matures, the amount of fermentable carbohydrates in the cecum decreases while the diversity of cecal microbiota increases (Adebiyi and Olukosi, 2015). In turn, this lowers the level of lactic acid while raising the level of other SCFA like propionic, butyric, and acetic acids (González-Ortiz et al., 2019). The acetic and propionic acids are indications of the fermentation of undigested carbohydrates, while branched SCFA like iso-butyric acid are indications of fermentation of nitrogenous compounds such as crude protein (Lee et al., 2017). In the present study, wheat promoted cecal lactic acid concentration, and acetic and propionic acids were highest in broiler chickens. Broilers fed corn diets had the highest amount of iso-butyric acid, indicating that there was more nitrogen fermentation. Broilers fed wheat diets had the highest amount of butyric acid, indicating wheat diets promoted a population of healthy microorganisms. The higher total SCFA concentration in the current study is a sign that the broilers were more mature than the turkeys and that the type of substrates flowing from the distal ileum and the gut microbiota were different. These findings concur with those of González-Ortiz et al. (2020), who fed broiler chickens and turkeys diets that met their nutritional requirements from d 0 to 28 of life and found that the broiler chickens had the highest levels of total SCFA. These researchers also suggested that the observed variations were due to broiler chicken gastrointestinal tract being more mature than that of turkeys.

In conclusion, adding fibrous feedstuffs to corn or wheat basal diets did not affect the growth performance of both broiler chickens and hybrid tom turkeys. However, HF increased gizzard weight in broilers fed any diet and turkey fed wheat diet. Supplementation of MES improved AMEn in broilers fed HF diets and in turkeys fed corn diets irrespective of fiber level and LF wheat diets. There were minimal effects of grain, fiber level, and MES on SCFA; however, broilers had higher concentrations of ceca SCFA.