©2009 Poultry Science Association, Inc.
Effect of bedding types and different nutrient densities on growth performance, visceral organ weight, and blood characteristics in broiler chickens Y. Huang, J. S. Yoo, H. J. Kim, Y. Wang, Y. J. Chen, J. H. Cho, and I. H. Kim1 Department of Animal Resource & Science, Dankook University, Cheonan, Choongnam, 330-714, Korea Primary Audience: Poultry Producers, Nutritionists, Researchers SUMMARY The principal objective of this study was to assess whether bedding types could influence the growth performance of broiler chickens fed on high and low nutrient density diets. The broilers were bedded with clean hulls or shavings. Four hundred eighty male broiler chickens (Ross) were divided into 6 treatment groups, including 1) a high-density diet with rice hulls, 2) a highdensity diet with wood shavings, 3) a high-density diet with coconut hulls, 4) a low-density diet with rice hulls, 5) a low-density diet with wood shavings, and 6) a low-density diet with coconut hulls. Weight gain, feed intake, G:F, visceral organ relative weight, red blood cells, white blood cells, and lymphocyte concentrations were evaluated. The bursa of Fabricius, liver, and abdominal fat relative weight, white blood cells, and lymphocyte concentrations were not altered consistently by any of the treatments. For the overall period, weight gain and feed intake were greater in the coconut hull treatment groups as compared with the wood shavings treatments (P < 0.05). Feed intake was also greater in the low-density diet than in the high-density diet treatment groups (P < 0.05). The concentration of red blood cells in blood was reduced significantly by wood shavings bedding compared with the rice hull treatments (P < 0.05). Key words: broiler, bedding, rice hull, wood shaving, coconut hull 2009 J. Appl. Poult. Res. 18:1–7 doi:10.3382/japr.2007-00069
DESCRIPTION OF PROBLEM
Wood shavings have been the standard choice for poultry litter for many years. Recently, some research has focused on alternatives for broiler litter sources because of escalated costs and the short supply of wood shavings owing to their use in other value-added products [1]. According to Chamblee and Yeatman [2], a variety of paper products, gypsum, hardwood bark, kenaf, peanut hulls, sand, rice hulls, softwood chipping fines, wood chips, and leaves have all been com1
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pared with pine shavings with regard to their use as poultry litter. All of these litter materials have proven equal or superior to pine shavings as a litter material. Rice hulls appear to be a favorable alternative to wood shavings [3]. Rice hulls are a class A insulating material because they are difficult to burn and less likely to allow moisture to permit the propagation of mold or fungi [4]. The hull components include opaline silica and lignin. This provides the excellent thermal insulation
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2 of the hulls. In addition, the cost of using rice hulls rather than wood shavings is dependent on geographical location. Deforestation for pasture, agricultural, and other uses is a primary environmental threat throughout tropical regions [5]. Hence, the use of rice hulls to replace wood shavings is feasible. Coconut hulls contain mainly brown coir fiber [6]. The coir fiber is relatively waterproof and is one of the few natural fibers resistant to salt water damage. Coir is harvested from ripened coconuts. It is thick and strong and evidences profound abrasion resistance. Coir is typically used in mats, brushes, and sacking. Mature brown coir fibers contain more lignin and less cellulose than fibers of flax and cotton and thus are stronger but less flexible. They are made up of small threads, each approximately 1 mm long and 10 to 20 µm in diameter. Moreover, coir has been reported to be used to bind to NH3 and NH4+ in poultry litter as an amendment to poultry manure during composting [7]. Based on the NRC [8], “broiler chickens do not have a requirement for crude protein per se.” Broiler diets with CP content lower than the values suggested by the NRC (23.0%) can support performance results similar to those diets with greater concentrations of CP [9]. Lower CP diets can also reduce N losses, thereby decreasing environmental pollution. Ferguson et al. [10] observed a 7% reduction in N concentrations of broiler litter for each 1% reduction in dietary protein. Jacob et al. [11] found that N concentration in the poultry manure could be lowered by up to 21% by reducing dietary CP by 2.5%. Therefore, there is a trend in practice to use lower dietary CP concentrations than those recommended by the NRC. The principal objective of this research was to compare the effects of coconut hulls and rice hulls across low and high nutrient density diets on growth performance, visceral organ weight, and blood characteristics in broiler chickens.
MATERIALS AND METHODS The study was conducted under the approval and guidelines of the Dankook University Agricultural Animal Care and Use Committee and followed the principles and specific guidelines for agricultural animals [12].
Four hundred eighty 1-d-old male broiler chickens (Ross) obtained from a commercial hatchery [13] were weighed and allotted to 6 treatment groups, each of which included 4 replicates of 20 birds per pen (pen size: 1.2 × 1.2 m), in a temperature-controlled room. The total experiment period was 35 d. An artificial lighting program (24L:0D, 0 to 1 d; 23L:1D, 2 to 35 d) was instituted. Room temperature began at 33°C from d 1 to 3 and was reduced gradually in accordance with normal management practices (2 to 3°C/wk; electrical heaters were used to maintain the temperature) and was maintained constantly thereafter via the reduction of supplemental heat and the adjustment of thermostatically regulated ventilation fans. Broiler chickens received diets and water ad libitum. Each pen had a pan feeder with a 35-cm diameter. Water was provided by evenly spaced nipple drinkers (5 nipples per pen) positioned along the side wall of the pen. Stocking density allowed for 0.067 m2/bird (15 birds/m2). Adjoining walls of each pen were lined with 0.6 m of wire netting. Birds were treated in a 2 × 3 factorial arrangement and were randomly allotted, in accordance with initial BW, to 6 treatments in a randomized complete block design. The 6 dietary treatments involved the combination of 2 concentrations of nutrient density diets, with beddings of rice hulls, wood shavings, or coconut hulls. The 6 treatments were as follows: 1) a high-density diet with rice hulls, 2) a high-density diet with wood shavings, 3) a high-density diet with coconut hulls, 4) a low-density diet with rice hulls, 5) a low-density diet with wood shavings, and 6) a low-density diet with coconut hulls. Each of the pens was filled to a depth of 5 cm with rice hulls, wood shavings, or coconut hulls. Caked litter was not removed from the pens over the entirety of the experimental period. The highdensity concentrations of the diet were predicated on the NRC-recommended nutrient requirements for broiler chickens (Table 1), except for CP concentration. These plans were designed to evaluate the effects of varying nutrient concentrations in the diet and broiler litter types. Birds were group-weighed by pen at 1, 7, 21, and 35 d of age. Feed intake was monitored by pen at 7, 21, and 35 d of age. The pen was established as the experimental unit for performance. At the end of the experiment, 3 birds per pen
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Table 1. Composition of experimental diets High-density diet Item Ingredient, % Corn Soybean meal Wheat Corn gluten meal Rapeseed meal Tallow Dicalcium phosphate Limestone l-Lysine Salt Sodium bicarbonate dl-Methionine Choline liquid Mineral premix2 Vitamin premix3 Salinomycin Clinacox4 Avilamycin Chemical composition5 ME, kcal/kg CP, % Lysine, % Methionine, % Methionine + cysteine, % Ca, % Total P, %
Low-density diet
Starter1
Finisher1
Starter1
Finisher1
50.255 22.100 15.000 5.000 2.000 1.800 1.550 0.990 0.303 0.200 0.200 0.187 0.150 0.120 0.070 — 0.050 0.025
50.686 18.100 18.000 5.000 3.000 1.600 1.290 1.020 0.332 0.200 0.200 0.147 0.120 0.120 0.060 0.100 — 0.025
55.501 19.800 15.000 2.750 2.000 1.000 1.570 0.990 0.331 0.200 0.200 0.243 0.150 0.120 0.070 — 0.050 0.025
55.365 16.500 18.000 2.370 3.000 1.000 1.320 1.010 0.345 0.260 0.200 0.205 0.120 0.120 0.060 0.100 — 0.025
3,082 (3,440) 20.51 (19.4) 1.00 (0.79) 0.46 (0.44) 0.80 0.90 (0.88) 0.60 (0.85)
3,099 (3,434) 19.51 (18.4) 0.95 (0.71) 0.44 (0.39) 0.74 0.85 (0.82) 0.55 (0.80)
3,050 (3,360) 18.49 (17.5) 0.95 (0.74) 0.49 (0.49) 0.78 0.90 (0.87) 0.60 (0.74)
3,069 (3,357) 17.51 (16.5) 0.90 (0.68) 0.47 (0.45) 0.72 0.85 (0.82) 0.55 (0.68)
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Starter diet, provided for 0 to 3 wk; finisher diet, provided for 4 to 5 wk. Provided per kilogram of diet: 37.5 mg of ZnSO4·H2O, 37.5 mg of MnO, 37.5 mg of FeSO4·7H2O, 3.75 mg of CuSO4·5H2O, 0.83 mg of KI, and 0.23 mg of NaSeO3. 3 Provided per kilogram of diet: 15,000 IU of vitamin A, 3,750 IU of vitamin D3, 37.5 mg of vitamin E, 2.55 mg of vitamin K3, 3 mg of vitamin B1, 7.5 mg of vitamin B2, 4.5 mg of vitamin B6, 24 mg of vitamin B12, 51 mg of niacin, 1.5 mg of folic acid, 126 mg of biotin, and 13.5 mg of pantothenic acid. 4 Clinacox, a prophylactic anticoccidial feed additive active against coccidiosis in broiler, containing Diclazuril 2 g/1 kg (Woogene Production, Seoul, Korea). 5 Calculated values (analyzed values). 2
were selected randomly for blood collection. The blood samples were collected from the wing vein and placed in K3EDTA vacuum tubes [14] and stored in a refrigerator (4°C) until red blood cell (RBC), white blood cell, and lymphocyte analysis, in accordance with the method described by Puvadolpirod and Thaxton [15]. At the end of the feeding trial, 10 birds per treatment were selected randomly and killed via cervical dislocation. The bursa of Fabricius, liver, and abdominal fat, including the adipose tissues lining the proventriculus and gizzard, were obtained in accordance with the description of Romboli et al. [16]. The visceral organs were
evaluated as a percentage of live BW. To avoid variation in the cutting procedures, the same operator was used. All data were analyzed using the GLM procedure of SAS [17]. The experiment was analyzed as a 2-factor randomized complete block (fixed model) with 2-way interactions included in the model. For the comparison of bedding types and dietary density concentrations, the pen was considered as the experimental unit and the model included the effects of bedding types, nutrient concentrations, bedding type × nutrient concentration interactions, pen, and trial. Statements of statistical significance were based on P < 0.05.
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RESULTS AND DISCUSSION Growth Performance For the overall period, the interaction of diet × bedding for growth performance was not observed (Table 2). The G:F ratios were not affected by bedding treatments for the overall period of the experiment. In the first week, different bedding types affected weight gain in the broiler chicks. Weight gain was greater with rice hull bedding than with coconut hulls (12.9%, P < 0.05). During wk 1 to 3, weight gain was affected neither by diets nor by bedding types. However, from wk 3 to the end of this trial, weight gain was greater (12.0%, P < 0.05) in coconut hull treatments than in wood shavings treatments. This was similar over the whole period of our study: weight gain was increased in coconut hull treatments, whereas wood shavings treatments caused a negative effect on weight gain (coconut hull treatments were 4.9% greater than wood shavings, P < 0.05). Over the first 3 wk, feed intake was unaffected by treatments. However, from wk 3 to the end of the experiment, feed intake in chicks fed low-density diets was greater as compared with high-density treatments (5.0%, P < 0.05), which resulted an increased G:F ratio in low-density treatments (2.16 vs. 1.96, P < 0.05). Moreover, through-
out the entirety of the experimental period, the nutrient density concentrations of diets also significantly affected feed intake (low-density treatments were 3.3% greater than high-density treatments, P < 0.05). Other researchers [18–21] have reported that growth performance was unaffected by litter types, including recycled paper, pine shavings, refined gypsum, and hardwood bark. The G:F was unaltered by any of the litter treatments of pine shavings and rice hull ash in the experiment of Chamblee and Yeatman [2], which had results similar to those reported in our study. We determined that the rice hulls and wood shavings litter allowed for much easier caking than was the case with the coconut hulls, and the wood shavings were easily thrown into the feeder by broiler chickens following wk 3 of the trial. This phenomenon may explain why the feed intake of the wood shavings treatments was reduced in this period. Moreover, the previous work of Grimes et al. [22] showed that growth performance might be negatively affected by quick caking over of the litter, which was consistent with the results of the present experiment, and the wood shavings treatment group evidenced a lower (4.7%, P < 0.05) level of weight gain compared with the coconut hull treatments. On the other hand, the birds might have eaten the
Table 2. Effect of bedding types and different nutrient densities on growth performance in broiler chickens Bedding types1 Item 0~1 wk Weight gain, g Feed intake, g G:F 1~3 wk Weight gain, g Feed intake, g G:F 3~5 wk Weight gain, g Feed intake, g G:F Overall Weight gain, g Feed intake, g G:F a,b
Diet nutrient concentrations SEM2
High density
Low density
WS
CH
114a 131 1.15
109ab 133 1.22
101b 117 1.16
2.8 2.8 0.031
107 127 1.19
109 127 1.17
2.2 2.2 0.022
601 915 1.52
608 932 1.53
604 943 1.56
4.8 9.6 0.019
608 924 1.52
601 936 1.56
3.1 5.9 0.015
717ab 1,478a 2.06
669b 1,420b 2.12
749a 1,496a 2.00
20.2 16.6 0.064
728 1,429b 1.96b
695 1,500a 2.16a
19.3 17.4 0.065
1,432ab 2,524ab 1.76
1,386b 2,485b 1.79
1,454a 2,556a 1.76
22.8 18.2 0.029
1,443 2,480b 1.72
1,405 2,563a 1.82
22.8 13.2 0.027
Means within a row within bedding type or diet density with different superscripts differ significantly (P < 0.05). RH = rice hulls; WS = wood shavings, CH = coconut hulls. 2 Pooled SEM. 1
SEM2
RH
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Table 3. Effect of bedding types and different nutrient densities on visceral organ weight in broiler chickens at 5 wk Bedding types1
Diet nutrient concentrations
Item
RH
WS
CH
SEM2
High density
Low density
SEM2
Bursa of Fabricius, % of BW Liver, % of BW Abdominal fat, % of BW
0.311 2.80 1.53
0.294 2.68 1.23
0.313 2.82 1.51
0.0325 0.269 0.160
0.306 2.67 1.47
0.304 2.85 1.37
0.0223 0.234 0.158
1
RH = rice hulls; WS = wood shavings, CH = coconut hulls. Pooled SEM.
2
wood shavings. That may explain why the lower feed intake and weight gain in wood shavings treatments were observed during the experiment, especially in the last 2 wk. Feed intake was affected by diet nutrient concentrations in the last 3 wk and for the overall period. Broiler chickens fed high-fat diets with a very high energy:protein ratio had a lower heat production despite greater ME intake [23, 24], which can explain, in this study, the higher energy:protein ratio in the low nutrient density diet resulting in a greater feed intake. In a previous experiment, Ferguson et al. [10] observed similar trends, thereby confirming that a limitation in CP during the starter period (1 to 21 d) may not affect feed intake adversely. Some authors have observed equal weight gain and FE when comparing high-CP vs. low-CP diets supplemented with amino acids over the 1- to 3-wk period [25–27]. Similar results were observed in the present study. However, during the last 3 wk of this trial, feed intake in the low-CP treatments was detected to be greater than in the high-CP treatments (P < 0.05). This result is similar to the observation of previous studies [28, 29], which indicated that a marginally reduced dietary CP concentration can induce hyperphagia. Buyse et al. [30] found that broilers reared on a low-CP concentration (15% protein) diet increased their feed intake in an attempt to meet the requirements for protein and amino acids. Generally speaking, if energy density is decreased, feed intake will increase because feed consumption by animals is related to the energy requirement [31, 32]. Similarly, in the current study, the lower-CP diets had greater supplementation of Met and lower ME than the high-CP diets, whereas greater feed intake in lower-CP treatments was observed. However, Bartov and Plavnik [33] claimed that the high-energy diets did not af-
fect feed intake in a 42-d experiment that used Cobb broiler male chicks. That may suggest that the effect of energy is not as important as CP on feed intake, especially when tallow, a fat resource lacking of n-3 polyunsaturated fatty acids, is supplied in diet. The BW of chickens in wk 5 were quite a bit lower than what was reported in the Ross Breeder Management Guide (500 to 700 g). Based on previous studies [34, 35], the growth performance of Ross broilers in Korea was lower than the Ross Breeder Management Guide suggestion. The reported BW of Ross broilers in wk 5 was similar to the present study. This decline of growth performance might be caused by the breeding environment in Korea and the Korea nutrient standard of poultry. Moreover, the decreased growth performance could be explained by the lower diet CP. In some previous studies [10, 11, 36, 37], feeding broilers low-CP diets resulted in slightly inferior growth performance (vs. high-CP control diets), despite supplementation of the lowCP diets with concentrations of essential amino acids to meet NRC requirements. The low-CP diet is effective in decreasing N excretion and ammonia emissions in poultry production facilities [10, 11]; thus, the dietary CP concentration (17.51 to 20.51%) used in the present study was lower than the NRC recommendation. Visceral Organ Relative Weight Table 3 shows the relative weight of the visceral organs at the end of the current experiment. The relative weight of the bursa of Fabricius, liver, and abdominal fat remained unaffected by different concentrations of nutrient density in diets and by different bedding types. The interaction of different concentrations of diet × bedding for organ weight was not observed (P > 0.05).
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Table 4. Effect of bedding types and different nutrient densities on blood characteristics in broiler chickens at 5 wk Bedding types1 Item RBC,3 ×106/mm3 WBC,3 ×104/mm3 Lymphocyte, %
Diet nutrient concentrations
RH
WS
CH
SEM2
High density
Low density
SEM2
2.43a 48.2 81.3
2.09b 40.6 77.7
2.26ab 45.2 79.5
0.143 4.77 3.64
2.25 44.8 77.9
2.30 44.5 81.3
0.121 4.50 3.17
a,b
Means within a row within bedding type or diet density with different superscripts differ significantly (P < 0.05). RH = rice hulls; WS = wood shavings, CH = coconut hulls. 2 Pooled SEM. 3 RBC = red blood cells; WBC = white blood cells. 1
Hermes et al. [1] reported that histopathological examination of liver tissues showed no gross or microscopic abnormalities induced by different beddings. This result was consistent with the results of Atapattu and Wickramasinghe [38], who also indicated that liver weight was not influenced by different litter types. Vieira and Moran [39] reported that the relative weight of abdominal fat was unaffected by treatments with new and used pine shavings. Physiological stress may be one reason for a reduction in the weight of the bursa of Fabricius [15]; however, the broilers in our experiment were well taken care of, and thus this influence did not exist. Animal welfare is generally considered controversial because it is commonly assumed that any improvements in the area of animal welfare will have a negative effect on farm profitability [40]. Heckert et al. [41] reported a significant reduction in bursa weights and bursa:BW ratios with increasing densities (ranging from 0.10 to 0.05 m2 per bird), suggesting a greater degree of stress, particularly for birds at densities above 0.067 m2/bird (15 birds/m2). The relative weight of the bursa of Fabricius in our study was not affected by treatments, which showed that the different bedding types or reduced nutrient density concentration diets did not affect the immune response when broiler chicks were reared at a density of 0.067 m2/bird. Blood Characteristics White blood cells and lymphocyte concentrations remained unaffected by either treatment; however, the concentration of RBC was affected by bedding type (Table 4). No bedding × diet interaction for blood characteristics proved significant. The RBC concentration was greater in
the rice hull bedding treatments in comparison with the wood shavings treatments (P < 0.05). The mechanism of unexpected change in RBC concentration in the present trial must be studied further.
CONCLUSIONS AND APPLICATIONS
1. Coconut hull bedding can increase feed intake and improve weight gain, as compared with wood shavings. 2. Lower density concentration diets increase feed intake and result in poorer feed conversion, especially in the finisher period.
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