Effect of Broccoli Residues Fermented with Probiotics on the Growth Performance and Health Status of Broilers Challenged with Clostridium Perfringens

ABSTRACT

This study aimed at investigating the effects of broccoli residues fermented with probiotics (BF) on the growth performance, immunity, and gut health in broilers challenged with Clostridium perfringens (C. perfringens). A total of 600 broilers (one day old) were randomly allotted into five treatments with six replicates of 20 birds each and were reared until 42 days of age. The treatments included a positive control (PC, fed a basal diet and reared on uncontaminated litter), a negative control (NC, birds reared on litter contaminated with C. perfringens and fed a basal diet), and NC plus BF at 25, 50 or 75 g/kg of diet. The BF contained yeast 3.1 × 10⁷cfu/g, lactic acid bacteria 9.5 × 10⁶cfu/g and Bacillus subtilis 3.5 × 10⁶cfu/g. Birds in the NC group showed lower (p<0.05) feed intake and body weight gain, whereas BF supplementation recovered (p<0.05) the growth performance to the levels of PC group. Dietary BF at 50and 75 g/kg reduced (p<0.05) broiler mortality. Similarly, compared to the NC group, BF increased (p<0.05) immune organ weights and serum immunoglobulins A, G, and M to the levels of PC group. The ileal populations of Escherichia coli and Gram-negative bacteria were decreased (p<0.05) by BF to the levels of PC, and C. perfringens was also decreased (p<0.05) by BF. The serum profiles of mono- and di-amine oxidase were decreased (p<0.05) by BF. BF at 75 g/kg reduced (p<0.05) monoamine oxidase compared with the other BF doses. The results suggest that broccoli residues fermented with probiotics can be a novel biological feed additive to protect the performance and health of broilers against C. perfringens infection.

Keywords:
Broilers; broccoli residues fermented with probiotics; growth performance; gut health; immunity

INTRODUCTION

Broccoli as an excellent source of essential nutrients and it is a popular vegetable food item in Eastern and Western cultures (Mahn & Reyes, 2012; Williamson, 2017). However, its residues (stems and leaves), which account for a major section of its total yield, are seldom used. Studies have shown that dried broccoli floret residues improved the growth performance and meat quality of broilers, providing more intense skin pigmentation and lower breast meat drip loss (Hu et al., 2012; Mustafa & Baurhoo, 2016). In addition of being a protein source, broccoli residues fermented with probiotics (BF) present high contents of probiotics, organic acids, and small molecular proteins (Parvez et al., 2006).

Due to the recent ban of antibiotics, enteric diseases induced by Clostridium perfringens (C. perfringens) are the leading cause of death and economic losses in the broiler industry, and probiotics and organic acids have been increasingly used as antibacterial growth promoters and immune enhancers in farm animals (Lee et al., 2015; Ragaa & Korany, 2016).

Based on the knowledge of the use of unfermented broccoli by-products in animals, coupled with its probiotic and organic acid contents after fermentation, the present study investigated the effects of BF as a biological additive on the growth performance, immune organs, immunoglobulins, gut harmful bacteria and endotoxins of broilers reared on litter contaminated with C. perfringens.

MATERIALS AND METHODS

Animal ethics statement

All animal procedures were approved by the Animal Care Committee of the College of Animal Science of Henan University of Science and Technology (Luoyang, China).

Broccoli residues fermented with pro-biotics and experimental diets

The BF additive was produced using broccoli stem and leaves, according to the following steps: a) green broccoli stems and leaves were ground, squeezed, and the residues were filtered (mesh size of 1.98 mm); b) the collected filter residues were mixed with wheat bran, corn flour and a probiotic product at a ratio of 75:15:9:1; and c) the mixture was placed in asealed container and anaerobically fermented for 7d to obtain the BF additive. The probiotic product was composed of lactic acid bacteria, Saccharomyces cerevisiae, Bacillus subtilis (B. subtilis), and brown sugar at 2 × 10¹⁰, 4 × 10¹⁰, 2 × 10¹⁰cfu/kg and 50 g/kg, respectively. The components of BF are listed in Table 1.

Table 1
Composition of broccoli residues fermented with probiotics.

Ingredients	Contents	Ingredients	Contents	Ingredients	Contents
Microbiota, cfu/g		Chemical composition, g/100g			Minerals, mg/kg
Molds	<10	Dry matter	62.7	Ca	1.6×103
Yeasts	3.1×107	Crude protein	20.0	Total P	9.7×103
LAB	9.5×106	Mesonin	5.4	Available P	4.3×103
B. subtilis	3.5×106	Crude fat	2.0	Mg	4.5×103
Bioactive materials, mg/100g		NFE	28.1	K	1.3×104
Vitamin C	12.7	Crude ash	5.2	Na	826.0
DL-α-tocopherol	7.3	Crude fiber	7.4	Cu	5.1
Vitamin A	0.3	NDF	36.5	Fe	148.0
β-carotene	18.7	ADF	7.7	Mn	78.7
Flavonoids	3.0	ADL	0.7	Zn	41.7
Organic acids, mg/kg				Pb	-
Acetic acid	5.5×103			As	-
Propanoic acid	33.0			Cd	-
Butyric acid	8.0
pH	4.5

• ADF, acid detergent fiber; ADL, acid detergent lignin; B. subtilis, Bacillus subtilis; LAB, lactic acid bacteria; NDF, neutral detergent fiber; NFE, nitrogen-free extract.
• -, not detectable.

The basal diet was formulated according to the nutritional recommendations of the Arbor Acres Broiler Management Handbook in China. The diets were stored in a cool, dry, dark and well-ventilated place and fed as mash on air-dry basis. No antibiotics were offered to broilers via either feed or water throughout the trial. The formulation of the basal diet is shown in Table 2.For the convenience of customers, the BF additive is recommended to be supplemented on top of a complete diet. Therefore, in the present study, the BF was added at 25, 50 or 75 g/kg of basal diet.

Table 2
Ingredients and nutritional levels of the basal diet^* (air-dried basis).

	Contents, g/kg				Contents, g/kg
Ingredients	d 1 to 21	d 22 to 42		Nutrients	d 1 to 21	d 22 to 42
Corn	502.5	553.0		CP	219.2	198.6
Soybean meal	250.0	220.0		ME, MJ/kg	12.24	12.51
Corn gluten meal	70.0	55.0		Crude fiber	30.0	28.9
Corn germ meal	100.0	100.0		Ca	10.3	9.3
Soybean oil	25.0	30.0		Available P	5.0	4.4
Lysine	3.0	1.5		Lysine	12.4	10.0
Methionine	1.5	1.0		Methionine	5.0	4.2
Salt	3.0	3.0		Threonine	7.9	7.2
Limestone	12.0	11.0		Tryptophan	2.2	2.0
Dicalcium phosphate	21.5	20.0
Choline chloride	1.5	1.5
Premix**	10.0	5.0

• ^*
  Calculated by Chinese Feed Database (25th ed, 2014); The broccoli residues fermented with probiotics contained crude protein, yeasts, lactic acid bacteria and Bacillus subtilis at 200 g/kg, 3.1×10⁷, 9.5×10⁶ and 3.5×10⁶cfu/g, respectively, and was supplemented at 25, 50 or 75 g/kg of diet based on the basal diet.
• ^*
  ^*Provided per kg diet: vitamin A (retinyl acetate), 9,000 IU; cholecalciferol, 4,000 IU; vitamin E (DL-tocopheryl acetate), 50 IU; vitamin K, 2 mg; thiamin, 2 mg; riboflavin, 5 mg; d-pantothenic acid, 15 mg; niacin, 40 mg; pyridoxine, 2 mg; biotin, 0.1 mg; folic acid, 0.55 mg; vitamin B₁₂, 0.01 mg; manganese, 120 mg; iodine, 1.2 mg; iron, 40 mg; copper, 16 mg; zinc, 100 mg; and selenium, 0.3 mg.
• CP, crude protein; ME, metabolizable energy.

Birds, litter contaminated with C. perfringens , and sample collection

In total, 600 one-day-old male Arbor Acres broilers were randomly distributed into five treatment groups with six pens of 20 chicks each. All chicks were reared on floor pens (1.2 m × 2.0 m) in an environmentally-controlled facility at the Research Center of the Henan University of Science and Technology and given ad libitum access to feed and water throughout the trial. Birds were housed in an environmentally controlled room under a 20L:4D lighting cycle. A standard temperature regimen was followed: the house temperature was gradually decreased from 32 to 22ºC by 21 d of age, which was maintained for the remainder of trial.

All birds were vaccinated against Newcastle disease, avian influenza and infectious bursal disease vaccine (inactivated; No. 006) at 7 and 25 d of age, according to the directions of manufacturer (Luoyang Huizhong Biotechnology Co., Ltd, Luoyang, China). The broilers were monitored twice a day throughout the experiment.

The treatments consisted of a positive control group (PC), which was reared on uncontaminated, new litter and fed the basal diet; a negative control group (NC), which was reared on litter contaminated with C. perfringens from 1 d old and fed the basal diet), and three groups reared on litter contaminated with C. perfringens from 1 d old and fed the basal diet with the inclusion of BF at 25, 50 or 75 g/kg of diet.

Birds in the NC and BF groups were placed on litter previously used by a flock of broilers challenged via feed with C. perfringens type A CVCC52 cultures (China Veterinary Culture Collection Center, China Institute of Veterinary Drug Control, Beijing, China). Approximately 1 mL of the stock of C. perfringens was cultured in 250 mL of thioglycolate broth for 18 h at 39 °C, and then the C. perfringens cultures were produced according to the method by China National Food Safety Standard (GB 4789.13-2012). The suspension of C. perfringens cultures were then adjusted with thioglycolate broth to approximately 1.5 × 10⁵colony forming units (cfu)/mL. The bacterial suspension was evenly spread on the top of the feed. Approximately 10⁹ cfu/broiler of C. perfringens were administrated in the feed when broilers were 14 and 18 d old. The litters of the challenged birds were used for the present study.

Birds were weighed on d 1, 21 and 42, and feed intake, body weight gain, and feed efficiency were adjusted for mortality on a pen basis.

At 42 d of the trial, six birds per pen were randomly selected, weighed, euthanized by CO₂, and dissected. Blood was immediately collected from the heart with a syringe and aliquoted into sterile vials for the preparation of the serum according to the method by Liu et al. (2008). Thymus, spleen and bursa were collected and weighed. Ileal digesta was collected and stored at −40 ºC for microbiota enumeration.

Chemical and biological analysis

The chemical analysis of nutrients, minerals and volatile fatty acids in BF was carried out according to the method by Zhang (2016). Mesonin content was detected according to China National Standard (GB/T 22492-2008). Bioactive ingredients were detected according to China National Food Safety for vitamin A and D (GB 5009.82-2016), vitamin C (GB 14754-2010), b-carotene (GB 8821-2011), and flavonoids (GB/T 20574-2006).

Serum parameters were measured using commercial kits (Nanjing Jiancheng Bioengineering Institute, Jiangsu, China), and included endotoxin (H178), diamine oxidase (DAO, A088-3), monoamine oxidase (MAO, A034), IgA (H107), IgG (H106), and IgM (H109).

Enumeration of the microbiota

The microbiota in BF and ileal digesta were enumerated according to the methodsof the China National Food Safety Standard, and included molds and yeasts (GB 4789.15-2016), lactic acid bacteria (GB4789.35-2016), B. subtilis (GB/T 26428-2010), Escherichia coli (E. coli, GB 4789.38-2012), and C. perfringens (GB 4789.13-2012).Total Gram-negative bacteria (Gram^-)were enumerated using Gram^- Selective Medium (HB8643) and incubated at 37ºC for 24 h. The media were purchased from Qingdao Hopebio Co., Ltd. (Qingdao, China). All microbiological analyses were performed in triplicate, and the average values were used in statistical analysis. After the incubation periods, colonies of the respective bacteria were counted. The count of cfu was expressed as a logarithmic (log₁₀) transformation per gram of intestinal digesta.

Statistics

Data were analyzed using one-way analysis of variance (IBM SPSS, Armonk, NY, USA). Pen was used as the experimental unit for growth performance parameters, and the average of six birds per pen was the statistical unit for immune organ weights, serum parameters, and ileal bacteria populations. Means were compared using Tukey’s honest significant difference test at p<0.05 level of significance, and the Tamhane T2 test was used in case of equal variances not assumed.

RESULTS

Growth performance and mortality

As shown in Table 3, from 1 to 21 d of age, NC birds showed lower (p<0.05) average daily feed intake (ADFI) and average daily body weight gain (ADG), and higher (p<0.05) mortality, compared with the PC birds. The inclusion of BF at 25, 50 or 75 g/kg in the basal diet of the NC group recovered (p<0.05) ADFI and ADG to the levels of PC group but did not affect mortality. There were no ADFI or ADG differences among birds fed the three doses of BF.

Table 3
Effect of broccoli residues fermented with probiotics (BF) on the growth performance and mortality of broilers.

			BF*, g/kg of diet
Items	PC	NC	25	50	75	SEM
		Birds reared on litter contaminated with C. perfringens
1 to 21 d of age
ADFI, g/bird	52.84a	50.52b	52.82a	52.86a	53.07a	0.238
ADG, g/bird	40.90a	37.77b	41.04a	41.03a	41.03a	0.272
FCR, g:g	1.293ab	1.338a	1.287c	1.288bc	1.294ab	0.006
Mortality, %	3.33b	8.33a	4.17ab	5.83ab	5.83ab	0.555
1 to 42 d of age
ADFI, g/bird	110.79b	105.49c	112.83a	112.94a	113.68a	0.578
ADG, g/bird	53.19c	49.12d	54.69b	56.26a	55.52ab	0.483
FCR, g:g	2.093ab	2.145a	2.063b	2.007c	2.048bc	0.010
Mortality, %	5.83b	11.67a	9.17ab	7.50b	7.50b	0.554

• ^a
  ^-d Means within a row not sharing a superscript are significantly different (p<0.05).
• ^*
  The BF contained crude protein, yeasts, lactic acid bacteria and Bacillus subtilis at 200 g/kg, 3.1×10⁷, 9.5×10⁶ and 3.5×10⁶cfu/g, respectively.
• ADFI, average daily feed intake; ADG, average daily body weight gain; C. perfringens, Clostridium perfringens; FCR, feed:gain; NC, negative control; PC, positive control; SEM, standard error of mean.

From 1 to 42 d of age, the inclusion of BF increased (p<0.05) ADFI and ADG and exceeded (p<0.05) the values obtained in the PC group. The FCR of birds fed BF at 50 g/kg was lower (p<0.05) than those fed 25 g BF/kg. The mortality of the birds fed BF at 50 or 75 g/kg was lower than that of the NC group. These findings indicated that the addition of BF at 50 g/kg diet improved broiler ADFI and ADG and reduced their FCR and mortality.

Immune organ weights and serum immunoglobulins

The relative weights of thymus, spleen and bursa were lower (p<0.05) in the NC group (Table 4) and higher (p<0.05) in the groups fed BF at 25, 50 or 75 g/kg. The BF groups had the same immune organ weights as the PC group. There were no dose advantages in terms of immune organ weights.

Table 4
Effect of broccoli residues fermented with probiotics (BF) on the immune organ weights and serum immunoglobulins of broilers at 42 d of age.

			BF*, g/kg of diet
Items	PC	NC	25	50	75	SEM
		Birds reared on litter contaminated with C. perfringens
Organ weight/body weight, g/kg
Thymus	2.40a	1.70b	2.27a	2.20a	2.31a	0.051
Spleen	1.41a	1.10b	1.44a	1.38a	1.44a	0.030
Bursa	0.52a	0.40b	0.51a	0.50a	0.52a	0.011
Serum immunoglobulins, mg/dL
IgA	55.43a	44.00b	55.47a	53.03a	54.19a	0.938
IgG	27.65a	20.82b	27.20a	25.33a	24.51ab	0.598
IgM	286.96a	172.14b	266.12a	278.47a	291.93a	8.698

• ^a
  ^-b Means within a row not sharing a superscript are significantly different (p<0.05).
• ^*
  The BF contained crude protein, yeasts, lactic acid bacteria and Bacillus subtilis at 200 g/kg, 3.1×10⁷, 9.5×10⁶ and 3.5×10⁶cfu/g, respectively.
• C. perfringens, Clostridium perfringens; NC, negative control; PC, positive control; SEM, standard error of mean.

The NC group showed lower (p<0.05) serum IgA, IgG and IgM compared with PC group. The dietary inclusion of BF increased (p<0.05) these levels of these immunoglobulins, except for the birds fed BF at 75 g/kg, compared with the NC group. No immunoglobulin differences were detected between the PC and BF groups or among BF doses.

Ileal toxigenic bacteria and endotoxins

The NC group presented larger (p<0.05) populations of E. coli, C. perfringens, and Gram^- bacteria, whereas the dietary inclusion of BF decreased (p<0.05) the populations of E. coli and Gram^-bacteria to the levels of PC group. However, although the populations of C. perfringens determined in broilers fed BF at all doses were reduced compared with the NC group, they did not reach to the level of the PC group. The modulating effect of BF on the microbiota did not change as BF doses increased.

Relative to the serum profiles of enterotoxic markers, the NC group presented higher (p<0.05) endotoxin, DAO, and MAO levels when compared with the PC group. The dietary inclusion of BF at 25, 50 or 75 g/kg decreased (p<0.05) DAO and MAO levels compared with the NC group, and the doses at 50 or 75 g/kg showed stronger (p<0.05) effects than 25 g/kg of BF. The NC group presented higher (p<0.05) endotoxin level compared with the PC group, whereas the groups fed BF at all doses presented intermediate and not statistically different endotoxin levels compared with NC and BC. The decreased DAO and MAO levels indicate that BF may prevent intestine and liver damage induced by C. perfringens, but the lack of effect on endotoxins implies that BF has no effect on toxic stress in the serum.

Table 5
Effect of broccoli residues fermented with probiotics (BF) on the intestinal harmful bacteria and toxins of broilers at 42 d of age.

			BF*, g/kg of diet
Items	PC	NC	25	50	75	SEM
		Birds reared on litter contaminated with C. perfringens
Intestinal bacteria, Log10cfu/g of ileal digesta
E. coli	6.06b	6.93a	6.11b	6.08b	6.13b	0.067
C. perfringens	1.69c	4.25a	3.62b	3.80b	3.59b	0.168
Gram-	5.43b	6.78a	5.16b	4.96b	5.32b	0.132
Serum levels toxic markers, U/mL
Endotoxin	0.24b	0.30a	0.27ab	0.25ab	0.27ab	0.031
DAO	0.89c	1.37a	1.05b	1.02bc	1.02bc	0.178
MAO	3.36bc	3.97a	3.41b	3.21bc	3.11c	0.062

• ^a
  ^-c Means within a row not sharing a superscript are significantly different (p<0.05).
• ^*
  The BF contained crude protein, yeasts, lactic acid bacteria and Bacillus subtilis at 200 g/kg, 3.1×10⁷, 9.5×10⁶ and 3.5×10⁶cfu/g, respectively.
• C. perfringens, Clostridium perfringens; E. coli, Escherichia coli; DAO, diamine oxidase; Gram^-, Gram-negative bacteria; MAO, monoamine oxidase; NC, negative control; PC, positive control; SEM, standard error of mean.

DISCUSSION

In the present study, the dietary inclusion of BF at 25, 50 or 75 g/kg improved the ADFI and ADG of broilers, but there were no significant dose effects. Notably, lower mortality was observed in the groups fed BF at 50 or 75than at 25 g/kg from 1 to 42 d of age. These findings support the wide use of fermentation by the food and feed industries to improve nutritional values, and to produce bioactive ingredients, probiotics and organic acids (Wang et al., 2011; Li et al., 2014; Akinola et al., 2015). Additionally, studies showed that dried broccoli floret residues improved broiler growth performance and meat quality (Hu et al., 2012; Mustafa & Baurhoo, 2016).

In the present study, dietary BF inclusion increased the relative weights of immune organs and serum immunoglobulin levels of broilers reared on litter contaminated with C. perfringens, although no differences were found among the evaluated BF doses. These findings indicate that BF enhances humoral and cellular immunity. The effect of BF on the immune function may be attributed to the beneficial functions of components, which include yeasts, lactic acid bacteria, bacilli, organic acids, and flavonoids. The immunomodulation effects of probiotics and organic acids have already been demonstrated in broilers (Lee et al., 2015; Ragaa & Korany, 2016). In addition, broccoli, as a cruciferous vegetable, is also rich in secondary metabolites that are beneficial to health, such as glucosinolates and S-methylcysteine sulfoxide, flavonoids, anthocyanins, coumarins, carotenoids, antioxidant enzymes, terpenes and other minor compounds (Manchali et al., 2012).

There are several controversial findings about broccoli residues on gut flora. Hubbard et al. (2017) reported that consumption of broccoli heightened intestinal aryl hydrocarbon receptor activity, decreased microbial abundance of the family Erysipelotrichaceae and attenuated colitis in mice. Pezeshkpour et al. (2018) observed that broccoli extract inhibited the growth of standard and clinical Pseudomonas aeruginosa strains. On the other hand, Mustafa & Baurhoo (2016) reported that broccoli floret residues did not affect presumptive bacterial populations in the cecal digesta of broilers.

Studies have shown that fermented feeds were able to prevent dysbiosis of gut microbiota. Ashayerizadeh et al. (2017) found that fermented rapeseed meal was effective in controlling Salmonella enterica serovar Typhimurium infection and improving the growth performance of broilers. Consuming fermented distillers’ dried grains with solubles feed revealed a shift in the fecal microbiota of pigs (Wang et al., 2017). In the present study, the populations of E. coli, C. perfringens and total Gram- were decreased in the diets containing BF, and the lower harmful bacteria population may be caused by the competition of probiotics and bacteriostasis of broccoli bioactive components. However, how the BF impacts specific bacteria of Gram^- needs further study.

In the present study, the lowered serum profiles of endotoxin, MAO and DAO indicated that the BF can decrease toxic stress of broilers. Endotoxin and DAO are the markers of intestinal toxic damage, and MAO is an indicator of necrotic status of liver. As known, the broccoli contains bioactive ingredients, and its fermented by-products contain probiotics and organic acids, all of which also possess antioxidant activity. Hu et al. (2012) found that broilers fed dried broccoli stem and leaf meal presented better total antioxidant capacity, lower malondialdehyde concentration, and dietary 80 and 120 g/kg broccoli stem and leaf increased the activities of superoxide dismutase and catalase of breast muscle compared with the controls. Tomofuji et al. (2012) reported that the supplementation of broccoli or Bifidobacterium longum-fermented broccoli suppressed serum lipid peroxidation and osteoclast differentiation on the alveolar bone surface in rats fed a high-cholesterol diet. In the jejunum, broccoli extract increased the expression of xenobiotic enzymes and of the antioxidant enzyme heme-oxygenase regulated by an antioxidant response element (Muller et al., 2012).

In summary, the broilers reared on litter conta-minated with C. perfringens presented poor growth performance, whereas BF added at 25, 50 or 75 g/kg to the basal diet recovered these losses to the levels of birds in the PC group. The doses of BF at 50 and 75 g/kg reduced the mortality of birds between 1 and 42 d of age. The immune organ weights and serum immunoglobulins were increased by dietary BF inclusion, but there were no differences among doses. The harmful ileal bacterial population and their toxicity to the intestine and liver were also decreased by BF feeding, and the effects of BF doses of 50 or 75 g/kg on the intestinal toxic marker DAO reached to the levels of PC group. The results suggest that broccoli residues fermented with probioticsis a novel biological protein feed supplement that added at 25, 50 and 75 g/kg improves the growth performance, immunity, and intestinal microbiota f broilers.

ACKNOWLEDGEMENTS

This research was supported by China Agricultural Research System (CARS-41) and National Natural Science Foundation of China (31272466).

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Publication Dates

• Publication in this collection
  Oct-Dec 2018

History

• Received
  20 Jan 2018
• Accepted
  12 Mar 2018