Effects of Bedding Materials on Growth Performance, Footpad Dermatitis, Blood Parameters, and Economic Outcomes in Broiler Chickens

Abstract

A 42-day trial compared rice hulls and rubberwood shavings as broiler litter applied at an equal rate (7.5 kg/m²) in a house equipped with an evaporative cooling system. A total of 552-day-old male Ross 308 broiler chicks were randomly assigned to two treatments, with 12 replicate pens per treatment and 23 birds per pen. Body weight, feed intake, and feed conversion ratio (FCR) were assessed during the starter (0–14 d), grower (15–35 d), and finisher (36–42 d) phases. Footpad dermatitis (FPD), litter moisture, and complete blood counts were evaluated on days 14, 35, and 42, whereas infectious bronchitis (IB) antibody titers were measured on days 14 and 35. Rubberwood shavings increased body weight and feed intake during the grower and finisher phases and improved FCR during days 36–42 (p < 0.01). The FPD scores were lower with rubberwood shavings on days 35 and 42 (p < 0.05), although litter moisture was numerically higher on day 42. Hematological responses were transient, and IB antibody titers were unaffected. Economic analysis showed higher net profit (p < 0.01) and marginally higher return on investment in broilers reared on rubberwood shavings, with the economic advantage becoming more evident after footpad downgrade loss was considered.

1. Introduction

Litter material is a critical component of broiler production systems, influencing bird performance, welfare, and economic outcomes [1,2,3,4]. In tropical environments, maintaining litter quality is particularly challenging due to high moisture accumulation, which can impair growth, increase ammonia emissions, and predispose birds to footpad dermatitis (FPD) [5,6,7]. Keeping litter moisture below ~30% can minimize FPD severity [8]. Beyond moisture content, the physical characteristics of litter such as particle size, friability, and structural resilience play a key role in determining its functionality and impact on bird health [9,10].

Previous studies have shown that litter type can influence body weight and feed intake without consistently affecting FCR [11,12,13,14]. Footpad lesions can lead to the downgrading or rejection of chicken paws, which represent a high-value export product in many markets [15,16,17]. Selecting appropriate bedding material may improve not only production efficiency but also carcass value and overall profitability [18,19]. Therefore, in addition to performance and welfare, litter quality has important economic implications.

In Southeast Asia, rice hulls are widely used as a conventional bedding material due to their availability and low cost; however, their tendency to compact and form abrasive surfaces under wet conditions may increase the risk of FPD and associated economic losses [9,20]. In addition, global warming and increasing environmental pressures are expected to reduce rice yields in tropical regions [21,22], potentially affecting the long-term availability and sustainability of rice hulls as a standard bedding material. In contrast, wood-based materials, including wood shavings, have been reported to provide a softer and more resilient surface, thereby improving footpad condition and, in some cases, growth performance [20,23,24].

Southeast Asia is a major global producer of both rice and natural rubber, and countries such as Thailand are also key contributors to global broiler production [21,22]. Under the prevailing warm and humid environmental conditions, litter quality can deteriorate rapidly, further exacerbating welfare and performance challenges [5,25]. Given the abundant availability of rubberwood by-products in the region, rubberwood shavings may represent a promising alternative to rice hulls for poultry litter [2].

Studies comparing litter materials have reported inconsistent effects on growth performance [14,20], as also noted in a systematic review [13]. Information on their effectiveness under commercial broiler production systems remains limited, particularly in warm, humid climates and regarding integrated outcomes, including growth performance, welfare, health status, and economic returns. Therefore, the objective of this study was to evaluate the effects of rubberwood shavings compared with rice hulls, applied at the same rate (7.5 kg/m²), on growth performance, FPD, hematological responses, immune status, and economic outcomes in broilers reared in an evaporative-cooled, tunnel-ventilated house.

2. Materials and Methods

2.1. Animals, Diets, and Experimental Design and Management

The experiment was conducted at Sun Broiler Farm, Ban Na District, Nakhon Nayok, Thailand (license no. U1-02246-2558), under the approved Kasetsart University Animal Ethics protocol (ACKU68-AGR-023). Birds were monitored at least twice daily, with no additional humane endpoints beyond routine commercial practices. A total of 552 one-day-old male Ross 308 broilers were obtained from a single commercial hatchery (Sun Food International Co., Ltd., Saraburi, Thailand). Chicks were feather-sexed at hatch by trained personnel, and all originated from the same 49-week-old breeder flock and a single hatch run.

The initial body weight at placement was recorded as the overall flock mean (40.94 ± 0.19 g), with a coefficient of variation of 0.46%, before allocation to the two experimental treatments. Birds were allocated to two experimental treatments and group-housed in floor pens (23 birds per pen), with 12 replicate pens per treatment (24 pens in total). This corresponded to 276 birds per treatment (23 birds × 12 pens). The pen was the experimental unit for treatment allocation and statistical analysis. The stocking density was 23 birds per 2 m² (11.5 birds/m²). The required number of replicate pens (n) per treatment was estimated using a two-sample comparison, assuming a significance level (α) of 0.05 and a power (1 − β) of 0.80. The sample size was determined based on the following formula:

$$n={\displaystyle \frac{\mathbf{2}\left({\mathbf{Z}}_{\raisebox{1ex}{$\mathsf{\propto }$}\!\left/ \!\raisebox{-1ex}{$\mathbf{2}$}\right.}\mathbf{+}{{\mathbf{Z}}_{\mathsf{\beta }}}^{\mathbf{2}}\right)\mathbf{·}{\mathsf{\sigma }}^{\mathbf{2}}}{{\mathsf{\delta }}^{\mathbf{2}}}}$$

where ${\mathbf{Z}}_{{\displaystyle \raisebox{1ex}{$\mathsf{\propto }$}\!\left/ \!\raisebox{-1ex}{$\mathbf{2}$}\right.}}$ is the critical value for a 5% level of significance (1.96), ${\mathbf{Z}}_{\mathsf{\beta }}$ is the value for 80% power (0.84), $\mathsf{\sigma }$ represents the expected standard deviation derived from previous studies, and $\mathsf{\delta }$ is the minimum biologically relevant difference to be detected [26]. Based on these and expected variation, 10 replicate pens per treatment were considered sufficient; however, 12 replicate pens (23 birds per pen) were utilized to further enhance the statistical sensitivity of the study.

No separate acclimatization period was applied; day-old chicks were placed directly into experimental pens under standard brooding and commercial management conditions. A randomized complete block design (RCBD) was used to account for potential airflow effects on body weight. Chicks were vaccinated in ovo against Newcastle disease and infectious bursal disease, followed by infectious bronchitis vaccination at day 1 and 17, and a booster infectious bursal disease vaccination at day 20, according to manufacturer recommendations. Birds were housed in floor pens (2 m²) on a concrete floor with bedding, and equipped with nipple drinkers and standard feeders.

Environmental management followed the Ross 308 management guide (2018) [27]. Birds received 23 h of light during the first 7 days, followed by 4–6 h of darkness thereafter. House temperature was targeted at 30 °C at placement and gradually reduced to 21 °C by day 21, then maintained. However, under tropical conditions, environmental parameters during the grower phase (days 21–42) exceeded recommended levels, with a mean daily temperature of 26.49 ± 0.76 °C (min: 22.92 ± 1.68 °C; max: 30.06 ± 1.30 °C) and relative humidity of 53.38 ± 1.60%.

Litter remained unchanged throughout the experiment, with no topping, removal, or turning. Diets were formulated to meet Ross 308 nutrient specifications (2019) [28] and were based on corn, broken rice, and wheat, with wheat bran, full-fat soybean, and soybean meal as major ingredients under Thai commercial conditions (

Table 1. Composition and nutrient level of the basal diet.

Ingredients (kg)	Starter	Grower	Finisher
Corn	33.12	49.13	43.15
Broken rice	10.00	10.00	-
Wheat	10.00	-	20.00
Wheat bran	2.00	-	-
Full-Fat Soy	10.00	10.00	12.00
Soybean meal 44%	31.46	27.63	20.16
Acid oil	-	0.25	2.15
Mono-Dicalcium Phosphate (MDCP)	0.95	0.85	0.10
Lime stone	1.20	1.05	0.60
Sodium bicarbonate	0.20	0.20	0.30
Choline	0.03	0.03	0.00
DL-methionine	0.35	0.30	0.26
L-Lysine	0.18	0.13	0.14
L-threonine	0.10	0.07	0.06
Valine	0.01	-	-
Phytase	0.01	0.01	0.01
NSP Enzyme	0.01	0.01	0.01
Salt	0.25	0.20	1.00
Mineral Broiler 1	0.10	0.10	0.03
Vitamin Broiler 2	0.04	0.04	0.03
Total	100.00	100.00	100.00

Note: NSP: Non-starch polysaccharides. ¹ The mineral premix supplied the following per kg of complete feed: Cu, 16 mg; Zn, 120 mg; Fe, 20 mg; Mn, 120 mg; I, 1.25 mg; Selenium, 0.30 mg. ² The vitamin premix supplied the following per kg of complete feed: vitamin A, 11,500 IU; vitamin K3, 3.60 mg; vitamin B1, 4 mg; vitamin B2, 8 mg; vitamin B12, 0.025 mg; vitamin E, 65 IU; biotin, 0.28 mg; folic acid, 2.00 mg; pantothenic acid, 25 mg; niacin, 65 mg.

and

Table 2. Feed nutrient composition.

Nutrients by Calculation	Starter	Grower	Finisher
Metabolizable Energy, Kcal/kg	3000.00	3100.00	3200.00
Crude protein, %	23.50	21.50	19.50
Fiber, %	3.10	2.92	3.05
Fat, %	4.13	4.65	6.95
Methionine, %	0.56	0.51	0.47
Methionine + Cystine, %	1.08	0.99	0.90
Lysine, %	1.44	1.29	1.15
Threonine, %	0.97	0.88	0.78
Valine, %	1.11	1.00	0.89
Isoleucine, %	0.97	0.89	0.80
Arginine, %	1.52	1.37	1.21
Tryptophan, %	0.23	0.21	0.18
Calcium, %	0.96	0.88	0.78
Total phosphorus, %	0.72	0.67	0.62
Available phosphorus, %	0.48	0.44	0.39
Na, %	0.23	0.23	0.20

). Birds were housed in an environmentally controlled facility with evaporative cooling and horizontal ventilation, and feed and water were provided ad libitum throughout.

2.2. Experimental Design and Litter Treatments

A randomized complete block design was used with two litter treatments (24 pens; 12 replicates per treatment; 23 birds per pen). Sample size was determined a priori based on a two-sample framework (α = 0.05; power = 0.80) using ADG as the primary outcome, with 10–12 replicates per treatment considered sufficient from previous studies. Feed intake and FCR were secondary outcomes. Pens were blocked by airflow zone (high vs. low velocity) to minimize variation, and treatments were balanced within each block. ANOVA was applied, and given the balanced design, was considered robust to moderate deviations from normality.

Two bedding materials were compared: rice hulls and rubberwood shavings, both applied at 7.5 kg/m². This resulted in initial depths of approximately 6 cm and 4 cm, respectively, due to the higher bulk density of rubberwood shavings. The rubberwood shavings, derived from Hevea brasiliensis, consisted of fine particles similar to coarse sawdust. Treatments were standardized on a weight-per-area basis rather than litter depth due to differences in density and particle structure.

2.3. Data and Sample Collection

2.3.1. Productive Performance

Growth performance was evaluated over three phases: starter (0–14 d), grower (15–35 d), and finisher (36–42 d). On days 14, 35, and 42, birds and residual feed were weighed per pen. Body weight, weight gain, cumulative feed intake, and FCR (feed intake/body weight gain) were calculated by phase and for the overall period (0–42 d). The pen served as the experimental unit (n = 12 per treatment). Mortality was recorded daily, and dead bird weights were used to adjust FCR as needed. The European Production Efficiency Factor (EPEF) was calculated using standard formulae incorporating body weight, livability, age, and FCR.

2.3.2. Economic Evaluation

Economic evaluation combined biological performance with technical and price data from the commercial system. Litter cost per bird was calculated from litter price, application rate, and stocking density, while feed cost per bird was based on cumulative feed intake and average feed price during the study period. Fixed costs (e.g., chick and vaccination) were excluded as they were identical between treatments; thus, only variable costs (feed and litter) were included in ROI calculations. Revenue per bird was derived from final body weight and the farm-gate live bird price.

All monetary values are reported in Thai baht (THB) and converted to U.S. dollars (USD) using the OANDA exchange rate on 22 January 2026 (1 USD = 31.24290 THB). Economic evaluation was conducted on a per-bird basis. Revenue was calculated from final body weight and live bird price, while feed and litter costs were derived from feed intake, feed price, litter price, application rate, and stocking density. Footpad dermatitis (FPD) loss was expressed as downgrade loss per bird, based on the proportion of downgraded birds and the price difference between Grade A and downgraded feet relative to average foot weight.

Profit was estimated under two scenarios: (1) excluding FPD loss (revenue minus feed and litter costs) and (2) including FPD loss (revenue minus FPD loss, feed, and litter costs). Return on investment (ROI) was calculated as ROI (%) = (profit/total cost) × 100. Prices and technical coefficients are presented alongside the economic results.

$$\mathrm{European}\mathrm{Production}\mathrm{Efficiency}\mathrm{Factor}(\mathrm{EPEF})={\displaystyle \frac{\mathrm{B}\mathrm{w}\mathrm{f}\mathrm{i}\mathrm{n}\mathrm{a}\mathrm{l}\times \%\mathrm{l}\mathrm{i}\mathrm{v}\mathrm{e}\times 100}{\mathrm{A}\mathrm{g}\mathrm{e}\times \mathrm{F}\mathrm{C}\mathrm{R}}}$$

$$\mathrm{Litter}\mathrm{cost}(\mathrm{baht}/\mathrm{bird})={\displaystyle \frac{\mathrm{L}\mathrm{i}\mathrm{t}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{p}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{e}(\mathrm{b}\mathrm{a}\mathrm{h}\mathrm{t}/\mathrm{k}\mathrm{g})\times \mathrm{a}\mathrm{p}\mathrm{p}\mathrm{l}\mathrm{i}\mathrm{c}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e}(\mathrm{k}\mathrm{g}/{\mathrm{m}}^3)}{\mathrm{S}\mathrm{t}\mathrm{o}\mathrm{c}\mathrm{k}\mathrm{d}\mathrm{e}\mathrm{n}\mathrm{s}\mathrm{i}\mathrm{t}\mathrm{y}(\mathrm{b}\mathrm{i}\mathrm{r}\mathrm{d}/{\mathrm{m}}^2)}}$$

Feed cost (baht/bird) = FI × Feed price (baht/kg)

Footpad downgrade loss (baht/bird) = Proportion of birds downgrade × Economic loss per downgrade bird (baht/bird)

Total cost (baht) = Litter cost + Feed cost

Revenue (baht/bird) = BW × Live bird price (baht/kg)

Revenue (with footpad downgrade loss) = Revenue − Footpad downgrade loss

Profit (baht) = Revenue − (Feed cost + Litter cost)

$$(\mathrm{Return}\mathrm{on}\mathrm{investment})\mathrm{ROI}\%={\displaystyle \frac{\mathrm{P}\mathrm{r}\mathrm{o}\mathrm{f}\mathrm{i}\mathrm{t}}{\mathrm{T}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}\mathrm{C}\mathrm{o}\mathrm{s}\mathrm{t}}}\times 100$$

2.3.3. Footpad Dermatitis Scoring

At 14, 35, and 42 days of age, FPD was assessed as a welfare indicator in six pens per treatment selected to represent the range of pen mean body weight (BW), including two pens with the lowest mean BW, two pens closest to the treatment mean BW, and two pens with the highest mean BW to ensure representation of the full performance range. The pen was the sampling unit (n = 6 pens per treatment per time point). All birds within each selected pen were scored individually according to the Welfare Quality® protocol (2009) [29] as follows:

Score 0: no or very mild superficial lesions;

Score 1: discoloration, superficial lesions, or dark papillae;

Score 2: severe lesions, scabs, bleeding, or swollen footpads.

2.3.4. Quality Assessment

At 14, 35, and 42 days of age, litter moisture was measured in the same subset of pens used for FPD assessment (n = 6 pens per treatment per time point). Approximately 400 g of bedding was collected per pen from areas beneath the drinker and feeder lines and separated by depth (upper, middle, and lower layers). Moisture content was determined by oven-drying using a hot-air oven (Memmert GmbH + Co. KG, Schwabach, Germany) at 103 ± 2 °C for 6 h.

2.3.5. Blood Sampling, Hematology and Infectious Bronchitis Serology

To assess health status, blood samples were collected at 14, 35, and 42 days of age from the same subset of pens used for the footpad dermatitis (FPD) assessment (six pens per treatment). On each sampling date, three birds per pen representing the lower, median, and higher ranges of body weight were selected, resulting in 18 birds per treatment per time point.

Approximately 2–3 mL of blood was collected from the wing vein into EDTA-coated syringes and tubes. Whole blood was used for complete blood counts, including RBC, WBC, and differential leukocyte counts (heterophils, lymphocytes, monocytes, eosinophils, and basophils), following standard avian hematology procedures. Blood smears were prepared and Wright-stained when required for microscopic evaluation. The heterophil-to-lymphocyte ratio was calculated as an indicator of physiological stress [30,31].

Infectious bronchitis (IB) antibody titers were measured at 14 and 35 days of age using serum from birds sampled for hematology (six pens per treatment; three birds per pen; n = 18 per treatment per time point). These time points were selected to reflect the serological response to the routine vaccination program, with day 14 representing the primary response to day-old vaccination and day 35 the post-booster response following revaccination at day 17 [32,33]. No further monitoring was conducted as the birds were slaughtered at 42 days of age.

Serum was separated and analyzed using a haemagglutination-inhibition (HI) test for Mass-type IB antigen (IBV Antigen Massachusetts 41; GD Animal Health, Deventer, The Netherlands) and a commercial ELISA kit for Arkansas-type IB virus (BioChek IBV Antibody Test Kit; BioChek BV, Reeuwijk, The Netherlands), following the manufacturers’ instructions. Both ELISA and HI are widely used for routine serological monitoring of IBV vaccination response [34]. Titers were interpreted based on internal laboratory reference ranges and vaccine-producer guidelines [35].

2.3.6. Chemical Analysis

At days 0 and 42, bedding material samples (400 g) of rice hulls and rubberwood shavings were collected from all pens within each treatment and pooled to obtain one composite sample per treatment, with day 42 representing the poorest litter quality. Fiber fractions (crude fiber, NDF, ADF, and ADL) were determined using a FOSS Fibertec 8000 (FOSS Analytical A/S, Hillerod, Denmark) and a Gerhardt Fiber Apparatus (C. Gerhardt GmbH & Co. KG, Königswinter, Germany) according to AOAC [36,37]. Ash content was measured using a Thermo Scientific F6010 furnace (Thermo Fisher Scientific Inc., Asheville, NC, USA) [38], and nitrogen content was analyzed using a Foss Kjeltec™ 8100 (FOSS Analytical A/S, Hillerod, Denmark) [39]. As analyses were conducted on a single pooled sample per treatment, the data were descriptive only, and no statistical analysis was performed.

2.3.7. Bulk Density of Bedding Materials

Bulk density was determined using a 1 L straight-wall cylinder following the 1 L litter bulk density procedure described by [40]. The cylinder was filled by pouring litter from a constant height without compaction, and the mass per unit volume was recorded (n = 5 samples per bedding material).

2.4. Statistical Analysis

All statistical analyses were performed using SAS® University Edition (v9.4; SAS Institute Inc., Cary, NC, USA). Productive performance, litter moisture, and blood profiles were analyzed by ANOVA under a randomized complete block design (RCBD). Model assumptions were assessed using the Shapiro–Wilk test (normality, based on residuals) and Levene’s test (homogeneity of variance). Categorical welfare outcomes (e.g., footpad dermatitis scores) were analyzed using chi-square tests (df = 2). Bulk density was compared between bedding materials using one-way ANOVA under a completely randomized design (CRD) (n = 5 per material).

The pen was the experimental unit; thus, pen-based variables are presented as pen means. Productive performance and economic outcomes were analyzed using all pens (12 per treatment), while litter moisture and footpad dermatitis were assessed in a subset (6 pens per treatment). Footpad dermatitis scores were compared using chi-square tests. Blood parameters and IB antibody data were obtained from the same subset (three birds per pen; n = 18 per treatment per time point), with pen means used for analysis.

Laboratory samples were anonymized, and personnel were blinded to treatment identity and study objectives. Complete on-farm blinding was not feasible; however, assessors followed standardized procedures and were not informed of study hypotheses. Statistical analyses were independently performed and cross-checked by two investigators, with results confirmed upon concordance. Statistical significance was set at p < 0.05.

Y_ij = µ + T_i + P_j + ε_ij; i = 1, 2, …, t; j = 1, 2, …, b;

Y_ij = any observation for which i is the treatment factor and j is the blocking factor

µ = the population mean;

T_i = the effect for being in treatment i;

P_j = the effect for being in block j;

ε_ij = the corresponding error term j that received treatment i.

3. Results

3.1. Growth Performance and Economic Outcomes

In the first 14 days, bedding type made little difference to chick growth. Both rubberwood shavings and rice hulls resulted in similar feed intake and FCR, and mortality was low (<1%). Birds on rubberwood shavings were heavier than the rice hull (p < 0.01) (

Table 3. Effects of the bedding material on productive performance for 0–14 days, 15–35 and 36–42 days of age.

	Rice Hull	Rubberwood Shavings	SEM	p-Value
0–14 days
BW (g)	493.50	515.19	4.26	<0.01
BWG (g)	452.49	471.93	4.11	<0.01
FI (g)	555.99	570.63	5.73	0.66
FCR	1.23	1.21	0.01	0.26
Mortality (%)	0.73	0.36	0.30	0.80
15–35 days
BW (g)	2122.44	2246.54	41.04	<0.01
BWG (g)	1643.07	1746.02	39.39	<0.01
FI (g)	2616.90	2763.06	34.54	<0.01
FCR	1.62	1.60	0.03	<0.01
Mortality (%)	1.67	2.00	0.59	0.19
36–42 days
BW (g)	2604.17	2874.25	51.56	<0.01
BWG (g)	478.48	618.17	30.86	0.07
FI (g)	1128.78	1316.77	33.07	<0.01
FCR	2.70	2.19	0.20	0.35
Mortality (%)	10.00	6.33	1.68	0.43

Note: BW: body weight, BWG: body weight gain, FI: feed intake, FCR: feed conversion ratio. Data are presented as means ± SEM. Each treatment had 12 replicate pens (n = 12), and the pen was the experimental unit for statistical analysis.

).

From 15 to 35 days, birds raised on rubberwood shavings had higher body weight, weight gain, and feed intake than those on rice hulls. FCR was also significantly better (p < 0.01), showing efficient feed conversion to growth rather than maintenance or stress (Table 3).

During the finisher phase (36–42 days), birds raised on rubberwood shavings had higher body weight and feed intake than those on rice hulls. At 42 days, average body weight was 2.874 kg with rubberwood shavings and 2.604 kg with rice hulls (p < 0.01). Feed intake was greater in the rubberwood shavings group, but overall FCR from 0 to 42 days was similar between both treatments.

Over the entire 0–42-day period, birds on rubberwood shavings therefore achieved higher total body weight gain than birds on rice hulls, while overall feed efficiency and mortality remained comparable between bedding types. This indicates that the performance advantage of rubberwood shavings was mainly expressed as more growth at a similar overall FCR. Accordingly, EPEF was higher in the rubberwood shavings group than in the rice hull group (381.25 vs. 322.90); p < 0.01, suggesting superior overall flock performance. (

Table 4. Effects of different types of bedding materials on productive performance from 0 to 42 days.

	Rice Hull	Rubberwood Shavings	SEM	p-Value
BW (g)	2604.17	2874.25	51.56	<0.01
BWG (g)	2583.04	2836.13	50.62	<0.01
FI (g)	4301.67	4650.47	64.17	<0.01
FCR	1.69	1.64	0.02	0.13
Mortality (%)	12.39	8.70	1.86	0.21
EPEF	322.90	381.25	11.41	<0.01

Note: EPEF: European Production Efficiency Factor. Data are presented as means ± SEM. Each treatment had 12 replicate pens (n = 12), and the pen was the experimental unit for statistical analysis.

)

For the economic analysis, technical results were integrated with current market prices. Live broilers, feed, rice hulls, and rubberwood shavings were valued at 1.40, 0.455, 0.053, and 0.064 USD/kg, respectively. At an application rate of 7.5 kg/m² and a stocking density of 11.5 birds/m², litter cost was estimated at 0.034 and 0.040 USD/bird for rice hulls and rubberwood shavings, respectively. Chicken feet were priced at 5.12 USD/kg for Grade A and 4.10 USD/kg for downgraded feet. Based on an average foot weight of 0.07 kg, downgrading resulted in an estimated loss of 0.072 USD/bird.

Economic results are presented in

Table 5. Economic evaluation from 0 to 42 Days.

Scenario	Variable	Rice Hull	Rubberwood Shavings	SEM	p-Value
Without footpad downgrade loss	Feed cost	61.08 (1.96)	66.04 (2.11)	0.91	<0.01
	Litter cost	1.08 (0.03)	1.30 (0.04)	0.02	<0.01
	Total cost	62.16 (1.99)	67.34 (2.16)	0.92	<0.01
	Revenue (without downgrade loss)	113.93 (3.65)	125.75 (4.02)	2.26	<0.01
	Profit	51.77 (1.66)	58.41 (1.87)	1.55	<0.01
	ROI (%)	82.96	86.94	1.97	0.14
With footpad downgrade loss	Feed cost	61.08 (1.96)	66.04 (2.11)	0.91	<0.01
	Litter cost	1.08 (0.03)	1.30 (0.04)	0.02	<0.01
	Total cost	62.16 (1.99)	67.34 (2.16)	0.92	<0.01
	Revenue (with downgrade loss)	113.04 (3.62)	125.74 (4.02)	2.30	<0.01
	Profit	50.88 (1.63)	58.29 (1.87)	1.59	<0.01
	ROI (%)	81.52	86.75	2.00	0.10

Note: All economic variables are expressed on a per-bird basis, except ROI, which is expressed as a percentage. Values are reported in THB; USD equivalents (in parentheses) were calculated using 1 USD = 31.24290 THB (OANDA, 22 January 2026). Revenue was calculated either without downgrade loss or with deduction of footpad downgrade loss. ROI was calculated as (Profit/Total cost) × 100. ROI: Return on investment. Data are presented as means ± SEM. All economic variables are expressed on a per-bird basis, but values were calculated from pen-level performance data and analyzed using pen means. Each treatment had 12 replicate pens (n = 12), and the pen was the experimental unit for statistical analysis.

. Without accounting for footpad downgrade loss, broilers reared on rubberwood shavings showed higher profit than those reared on rice hulls (1.870 vs. 1.657 USD/bird; p < 0.01). Return on investment (ROI) was numerically higher in the rubberwood shavings group (86.94% vs. 82.96%), although the difference was not significant (p = 0.14). When footpad downgrade loss was included, profit remained higher for rubberwood shavings (1.866 vs. 1.629 USD/bird; p < 0.01), with a smaller reduction compared to rice hulls. The numerical difference in ROI also increased (86.75% vs. 81.52%), although it remained non-significant (p = 0.10).

3.2. Footpad Dermatitis

At 14 days of age, footpad health was good in both treatments, with low scores and minimal lesions. By day 35, as body weight increased and litter moisture accumulated, clear differences emerged: rice hull pens showed more erosion, discoloration, and scab formation, whereas rubberwood shavings maintained a higher proportion of birds with score 0 and fewer severe lesions. This pattern persisted at day 42, with significantly lower mean scores and fewer severe lesions in the rubberwood shavings group (p < 0.01) (

Table 6. Effects of different types of bedding material on score of footpad dermatitis.

Day	Footpad Score	Rice Hull (%)	Rubberwood Shavings (%)	X2 (Significance)
Day 14	Score 0	137 (100%)	137 (100%)	NS
	Score 1	0 (0%)	0 (0%)	NS
	Score 2	0 (0%)	0 (0%)	NS
Day 35	Score 0	69 (51%)	133 (99%)	<0.05
	Score 1	61 (46%)	1 (1%)	<0.05
	Score 2	4 (3%)	0 (0%)	<0.05
Day 42	Score 0	71 (60%)	120 (94%)	<0.05
	Score 1	42 (36%)	6 (5%)	<0.05
	Score 2	5 (4%)	1 (1%)	<0.05

Note: Footpad scores are presented as the number of birds, with corresponding percentages in parentheses. Six pens per treatment were evaluated. Differences in score distribution between treatments were analyzed using the chi-square test (df = 2). NS = not significant.

).

3.3. Litter Quality and Chemical Composition

Litter moisture rose with age for both treatments. At 14 days, moisture was similar for rice hulls and rubberwood shavings (22.78% vs. 23.09%; p = 0.26). By 35 days, moisture increased more in rubberwood shavings (29.69%) than rice hulls (26.42%; p = 0.01). At 42 days, rubberwood shavings still had higher moisture (34.37% vs. 25.61%; p = 0.08). The wettest spots were mostly near drinkers due to water spillage (

Table 7. The moisture in the bedding materials.

	Rice Hull	Rubberwood Shavings	SEM	p-Value
Moisture Content (%)
Day 14	22.78	23.09	0.66	0.26
Day 35	26.42	29.69	1.57	<0.01
Day 42	25.61	34.37	2.94	0.08

Note: Data are presented as means ± SEM. Values represent pen averages (n = 6 pens per treatment), and the pen was considered the experimental unit for statistical analysis.

).

Litter samples for chemical analysis were pooled within treatment at each sampling age, yielding one composite sample per treatment; therefore, results are presented descriptively without statistical analysis. Despite this limitation, clear trends were observed over the production cycle. From placement to 42 days, reductions in fiber fractions were greater in rubberwood shavings than in rice hulls, including crude fiber (−60.7 vs. −45.6%), neutral detergent fiber (−54.0 vs. −49.1%), acid detergent fiber (−67.0 vs. −49.2%), and acid detergent lignin (−65.3 vs. −55.6%) (

Table 8. The fiber content, ash and non-protein nitrogen in the bedding materials at day 0 and day 42 (descriptive data from pooled samples).

	Day 0 of Age		Day 42 of Age
	Rice Hull	Rubberwood Shavings	Rice Hull	Rubberwood Shavings
CF (%)	43.19	46.74	23.50	18.38
Ash (%)	17.23	15.43	17.45	13.73
NDF (%)	78.25	67.26	39.87	30.94
ADF (%)	67.40	65.99	34.24	21.80
ADL (%)	18.07	14.27	8.03	4.95
NPN (%)	0.01	0.01	0.27	0.48

Note: CF: crude fiber, NDF: neutral detergent fiber, ADF: acid detergent fiber, ADL: acid detergent lignin, NPN: non-protein nitrogen. These chemical analyses were performed on pooled samples (one composite sample per treatment) and are therefore descriptive only, with no statistical analysis possible.

).

3.4. Bulk Density

The bulk density at placement varied significantly between rubberwood shavings and rice hulls (see

Table 9. Bulk density of bedding materials.

	Rice Hull	Rubberwood Shavings	SEM	p-Value
Bulk density (kg/m3)	102.63	227.13	16.08	<0.01

Note: Data are presented as means ± SEM (n = 5 samples per bedding material). Bulk density was analyzed by one-way ANOVA under a completely randomized design (CRD).

). Rubberwood shavings had a bulk density of 227.13 kg/m³, which was more than double that of rice hulls, measured at 102.63 kg/m³ (p < 0.01). When applied by weight at the same rate, rubberwood shavings created a litter layer that was thinner but denser compared to rice hulls.

3.5. IB Antibody Titer and Complete Blood Cell Count

IB antibody titers at 14 and 35 days did not differ between bedding types, indicating comparable humoral responses to vaccination (

Table 10. Infectious bronchitis antibody titer.

	Rice Hull	Rubberwood Shavings	SEM	p-Value
IB Antibody Titer
Titer at day 14	703.89	575.5	49.30	0.13
Titer at day 35	996.75	779.33	85.63	0.27

Note: In each treatment, six pens were selected from a total of 12 pens (two with below-average BW, two near the mean, and two with above-average BW). From each selected pen, three birds representing small, medium, and large body weights were sampled (n = 18 birds per treatment). Blood samples were collected from these birds, and values were averaged at the pen level prior to statistical analysis. Data are presented as means ± SEM.

). Complete blood counts remained within normal ranges at all ages. At day 14, broilers reared on rubberwood shavings showed a higher eosinophil percentage (p = 0.05), with trends toward higher heterophils, lower lymphocytes, and a slightly elevated heterophil-to-lymphocyte ratio. At day 35, red blood cell counts were lower in the rubberwood shavings group (p < 0.05) (

Table 11. Complete blood count at 14, 35, and 42 days of age.

	Rice Hull	Wood Shavings	SEM	p-Value
14 days of age
RBC (×106 cells/mm3)	1.88	1.92	0.04	0.97
WBC (cells/mm3)	7317	8674	1131	0.58
Eosinophils (%)	0.45	1.43	0.17	<0.05
Lymphocytes (%)	53.45	45.50	1.88	0.11
Monocytes (%)	1.91	2.43	0.24	0.55
Heterophil (%)	42.09	49.21	1.69	0.12
Basophil (%)	2.09	1.36	0.18	0.35
H/L ratio (%)	0.87	1.18	0.08	0.23
35 days of age
RBC (×106 cells/mm3)	2.53	2.35	0.04	<0.01
WBC (cells/mm3)	8023	8086	538	0.33
Eosinophils (%)	1.06	1.44	0.19	0.69
Lymphocytes (%)	56.59	48.72	2.06	0.11
Monocytes (%)	2.65	1.94	0.21	0.14
Heterophil (%)	38.47	46.28	2.04	0.09
Basophil (%)	1.18	1.56	0.17	0.36
H/L ratio (%)	0.78	1.06	0.09	0.20
42 days of age
RBC (×106 cells/mm3)	2.58	2.43	0.05	0.40
WBC (cells/mm3)	13,771	9064	1844	0.49
Eosinophils (%)	1.13	0.87	0.16	0.41
Lymphocytes (%)	49.00	50.33	1.64	0.53
Monocytes (%)	3.38	2.93	0.24	0.75
Heterophil (%)	41.19	44.00	1.60	0.44
Basophil (%)	2.31	1.87	0.28	0.78
H/L ratio (%)	0.96	0.93	0.08	0.74

Note: In each treatment, six pens were selected from a total of 12 pens (two with below-average BW, two near the mean, and two with above-average BW). From each selected pen, three birds representing small, medium, and large body weights were sampled (n = 18 birds per treatment). Blood samples were collected from these birds, and values were averaged at the pen level prior to statistical analysis. Data are presented as means ± SEM.

).

4. Discussion

4.1. Productive Performance, FPD and Economic Returns

Broilers reared on rubberwood shavings achieved higher final body weight and feed intake than those on rice hulls, while overall FCR remained unchanged. This pattern aligns with previous studies showing that litter type can enhance growth performance without consistently affecting feed efficiency [11,12,13,14]. Similar responses have been reported with wood-based materials, including hardwood sawdust and wood shavings [14,20]. The modest improvement in FCR during the finisher phase suggests enhanced feed utilization under high metabolic demand, consistent with improved housing conditions in late production [41,42]. This response is likely linked to a more favorable litter microenvironment, where reduced caking and a softer surface minimize subclinical stress and support voluntary feed intake [2]. Given the continuous contact between broilers and litter, including incidental ingestion, litter type may also influence microbial exposure and gut health [43]. Although such effects have been reported through alterations in cecal microbiota [14,43], these mechanisms remain speculative in the present study.

Broilers reared on rubberwood shavings exhibited lower FPD scores at 35 and 42 days, supporting previous findings that wood-based litters outperform more compacting or abrasive materials [10,23,24,44]. Although both materials were applied at the same rate (7.5 kg/m²), differences in resulting depth may have influenced insulation and surface contact [2,4,7,45,46]. Notably, in the present study, lower FPD occurred despite higher moisture content in rubberwood shavings at 42 days, indicating that the physical properties of the litter matrix such as friability, elasticity, and surface structure are more critical than total moisture alone [9,10]. Rice hulls tend to compact under wet conditions, increasing abrasion and mechanical damage [9,40,47], whereas rubberwood shavings maintain a softer, more resilient surface. Differences in ash dynamics (−11.0% vs. +1.3%) in this study further suggest contrasting mineral accumulation and moisture-buffering capacity [48]. Together, these results indicate that litter functionality depends on moisture distribution within the matrix rather than absolute moisture content [49].

From a management perspective, high litter moisture promotes ammonia generation, which impairs growth, feed efficiency, and respiratory health [5,6,50,51]. Although ammonia was not measured, the improved performance and lower FPD observed with rubberwood shavings suggest a more favorable litter–air interface at bird level [6]. Mortality during 36–42 days was numerically higher in the rice hull group (p = 0.43) and may partly reflect heat stress under elevated temperatures (30.06 ± 1.30 °C), indicating that environmental factors likely interacted with bedding effects.

The higher EPEF observed in broilers reared on rubberwood shavings translated directly into improved economic returns. Despite slightly higher litter costs, increased revenue and profit per bird more than compensated for this difference. Importantly, the economic advantage was amplified when footpad downgrade losses were considered, confirming that FPD is a major driver of profitability [16,18,19]. Profit reduction due to downgrading was minimal in the wood shavings group but substantially greater in the rice hull group, highlighting the economic value of improved footpad condition.

This study was conducted in a single commercial house using male Ross 308 broilers over one production cycle; therefore, extrapolation to other conditions should be made cautiously. Future studies should incorporate direct ammonia measurements and multiple flocks. Integrating suitable bedding materials with additional strategies such as litter acidification or optimized drinker management may further improve litter quality and bird health [5,50].

4.2. Blood Profiles and Immune Response

Bedding material had minimal impact on hematological parameters and IBV antibody titers [52]. Transient differences were observed at 14 and 35 days, including higher eosinophils and shifts in leukocyte profiles in broilers reared on rubberwood shavings; however, these differences did not persist to 42 days, and all values remained within normal physiological ranges [35,53]. Low eosinophil counts in the rice hull group are consistent with well-managed flocks under low parasite exposure [54] and should not be interpreted as pathological in isolation [35,36]. Overall, the absence of sustained changes in leukocyte profiles suggests that bedding-related effects on physiological stress were minimal, with only short-term adaptation to the litter environment [30,31,36,37,54]. Therefore, both bedding materials supported normal systemic health. Rubberwood shavings induced slightly greater immune activation between 14 and 35 days; however, treatment effects were more pronounced in performance and footpad condition than in blood profiles or IB antibody titers.

5. Conclusions

In this study, rubberwood shavings applied at 7.5 kg/m² provided a superior litter environment for male broilers compared with rice hulls in an evaporative-cooled, tunnel-ventilated system. Birds reared on rubberwood shavings achieved higher final body weight and European Production Efficiency Factor, with no change in overall feed conversion. The reduction in footpad dermatitis further indicates improvements in both animal welfare and paw quality, while stable hematological parameters and IBV antibody titers confirm the absence of adverse systemic effects. Although rubberwood shavings slightly increased litter cost, this was offset by improved growth performance, reduced downgrading losses, and higher profit per bird. The economic advantage became more pronounced when footpad-related losses were considered, with consistently higher ROI compared with rice hulls.