Effects of prebiotic supplementation on growth performance, slaughter performance, growth of internal organs and small intestine and serum biochemical parameters of broilers

Abstract

The objective of this study was to investigate the effects of prebiotic supplementation on growth performance, slaughter performance, growth of internal organs and small intestine and serum biochemical indices of broilers. A total of 360 1-day-old Ross 308 broilers were randomly divided into 4 groups with 3 replicates and 30 broilers per replicate (15 male and 15 female). The treatments were fed with basal diet supplemented with 0, 0.07, 0.10 and 0.13% prebiotic. The broilers of all replicates were weighted at the weekends. The results showed that prebiotic increased the daily gain and final weight and decreased the feed conversion ratio (P < 0.05) at the 42 days of age. When the addition of the prebiotic was 0.13%, the eviscerated carcass ratio of broilers was the lowest, the live weight and the contents of albumin (ALB) and total protein (TP) were lower than other group broilers (P < 0.05). Prebiotic improved the weight and length of duodenum, jejunum and ileum (P < 0.05). It had no significant effect on the weight of cecum and rectum (P > 0.05). According to the above analysis, the feasible supplementation of prebiotic in broiler dietary was 0.10%.

Keywords:

• prebiotic
• performance
• internal organs
• small intestine
• serum biochemical parameters

1. Introduction

Antibiotics, as one of feed additive, cause many problems such as drug residue, drug resistance of bacteria, and so on, which have attracted people's attention (Neu 1992; Timothy et al. 1998; Hume 2011). It is a hotspot to find out a substitute for antibiotics in current researches, and prebiotic is one important direction. Prebiotic is defined as a kind of growth material of microbial secretion to stimulate another microbial for the first time by Lilly and Stillwell in 1965. Fuller (1989) enriches the definition of prebiotic as the additive of live microorganisms to promote the microecological balance of intestinal and have beneficial effects on host. Now, the prebiotic is defined as the microorganisms of either live or killed and their metabolic products and they can maintain the microecological balance of intestinal. Research has showed that prebiotic can change the intestinal microecological structure after the livestock and poultry eating it. In addition, prebiotic can restrain the growth of pathogenic microorganism, regulate the structure of gut flora, enhance the immune function, regulate the metabolic activity, improves the feed conversion ratio and production of livestock and poultry (Fuller 1989; Ouwehand et al. 2002; Zhou et al. 2008).

This study was conducted to evaluate the effects of prebiotic supplementation on growth performance, slaughter performance, growth of internal organs and small intestine and serum biochemical parameters of Ross 308, then determined the feasible addition of prebiotic in the diets of broilers for optimising the feed formula and reducing the production cost.

2. Material and methods

2.1. Materials and the site of experiment

Prebiotic was a commercial product contained of 3×10¹⁰ cfu of Bacillus subtilis and Bacillus licheniformis. There is not prebiotic in the vitamin-mineral premix. The experiment was conducted at the pasture of Yangzhou University, Yangzhou, China.

2.2. Experiment design and the diet of broilers

The treatments were fed with basal diet supplemented with 0, 0.07, 0.10 and 0.13% prebiotic and were set to group A, B, C and D, respectively. A total of 360 1-day-old Ross 308 broilers were randomly divided into 4 groups with 3 replicates and 30 broilers per replication (15 male and 15 female). Chicks were given a free choice access to diets and tap water for 42 days. The chicks were fed the experimental diets throughout the experimental period. There were three phases, starter phase (1–10 days), grower period (11–24 days) and finisher period (25–42 days). All the broilers were weighted by pen at 0, 7, 14, 21, 28, 35 and 42 days of age. Weight gain was determined by difference between initial weight and final weight. Feed intake was estimated by the difference between feed and leftovers. Feed conversion ratio was the relationship between feed intake and weight gain of birds in each experimental unit. The gross composition and mineral composition of the experimental diets are shown in Table 1.

Table 1. Composition of the control experimental diet to test broilers.

Ingredients	0–10 days	11–24 days	25–42 days
Corn	60.7	65.4	69.3
Soybean meal	28.9	24.3	20.3
Corn protein meal	7	5	5
Vitamin-mineral premix^a	1	1	1
Calcium phosphate secondary	0.4	0.4	0.4
Limestone	2	1.9	1.8
Soybean oil		2	2.2
Total	100	100	100
Calculated value
ME (MJ/Kg)	12.59	13.14	13.31
Crude protein (%)	22.98	19.98	18.46
Ca (%)	0.91	0.86	0.81
P (%)	0.45	0.42	0.41

^a Containing by kg of diets: manganese – 10,000 mg; zinc – 7500 mg; copper – 800 mg; iron – 10,000 mg; iodine – 45 mg; selenium – 44.7 mg; vitamin A – 1,100,000 IU; vitamin D – 3,360,000 IU; vitamin E – 3600 IU; vitamin K – 3260 mg; thiamine hydrochloride – 260 mg; riboflavin – 960 mg; DL – calcium pantothenate – 1300 mg; nicotinic acid – 8000 mg; sinkaline – 66,000 mg; vitamin B1 – 22.7 mg; folic acid – 120 mg; pyridoxine hydrochloride – 530 mg; biotin – 24 mg.

2.3. Analysis of biochemical indicator

At the 42 days of age, 6 chickens (3 male and 3 female) randomly were taken out from every replicate to draw blood from wing venous. The blood was centrifuged 10 min at 4500 r/min and got serum for measuring the serum biochemical index. Serum levels of alkaline phosphatase (ALP), albumin (ALB), total protein (TP), alanine aminotransferase (ALT) and urea nitrogen (BUN) were measured by using the automatic biochemical analyzer of beckman coulter of unicel DxC 800 and serum level of growth hormone (GH) was measured by using the radiation immune instrument of γ-911.

2.4. Mensuration of slaughter performance, internal organs and small intestine

At the 42 days of age, 6 chickens (3 male and 3 female) were killed by cervical dislocation, which were taken out randomly from each cage and starved overnight. Then, the weight of birds and their organs were harvested. Organs analyses included heart, liver, spleen, duodenum, jejunum, ileum, cecum and rectum weights and duodenum, jejunum and ileum lengths. The ileum was defined as the region from Meckel's diverticulum to a point 40 mm proximal to the ileocecal junction. The jejunum was defined as the portion of intestine extending from the bile duct enterance to Meckel's diverticulum.

2.5. Data analyses

All data were recorded on a weekly basis, and statistically, analyses were performed using SPSS 17.0 for windows. The data was analysed by analysis of variance (ANOVA). The differences between group means were separated by least significant difference (LSD) multiple range test. In all instances, differences were reported as significant at P < 0.05.

3. Results

3.1. Effects of prebiotic addition on growth performance of broilers

The results of growth performance of broilers are presented in Tables 2 and 3. The prebiotic supplementation could affect the weight of broilers. The weight of experimental broilers increased along with the raise of prebiotic supplementation, and they were all lower than that of control group broilers at 1 week. At 2 weeks, the weight of group A broiler was higher than that of group B broilers (P < 0.05) and lower than that of group C and D broilers (P > 0.05). At 3, 4 and 5 weeks, the weight of group B broilers was lower than that of group A broilers (P > 0.05), and there was no significant difference among group A, C and D broilers (P > 0.05). The weight of experimental group broilers was higher than that of group A broilers (P < 0.05).

Table 2. Effects of prebiotic supplementation on weight of broilers (g).

Stage	Group A	Group B	Group C	Group D
0 week	43.33 ± 4.35	43.04 ± 4.11	43.38 ± 4.30	43.14 ± 5.15
1 week	133.13 ± 6.47^a	123.53 ± 4.07^b	127.28 ± 4.60^bc	132.02 ± 6.83^ac
2 weeks	314.39 ± 4.67^a	295.17 ± 7.94^b	324.10 ± 6.24^a	326.67 ± 17.01^a
3 weeks	618.67 ± 16.92^ab	597.00 ± 13.33^a	605.90 ± 28.47^ab	640.49 ± 23.04^b
4 weeks	1011.67 ± 41.20^ab	993.33 ± 11.02^a	1001.67 ± 20.26^ab	1052.00 ± 33.72^b
5 weeks	1434.88 ± 52.17	1416.22 ± 23.00	1446.00 ± 65.05	1439.80 ± 31.91
6 weeks	1767.33 ± 41.00^a	1916.97 ± 42.37^b	1922.50 ± 66.71^b	1970.52 ± 58.06^b

Note: Values in the same row without a common superscript letter are significantly different (P < 0.05).

Table 3. Effects of prebiotic supplementation on growth performance of broilers.

Stage	Group A	Group B	Group C	Group D
Initial weight (g)	43.33 ± 4.35	43.04 ± 4.11	43.38 ± 4.30	43.14 ± 5.15
Final weight (g)	1767.33 ± 41.00^a	1916.97 ± 42.37^b	1922.50 ± 66.71^b	1970.52 ± 58.06^b
Daily feed intake (g)	82.46 ± 1.42	83.44 ± 1.13	82.22 ± 4.65	83.48 ± 0.21
Daily gain (g)	41.05 ± 0.98^a	44.61 ± 1.01^b	44.75 ± 1.59^b	45.89 ± 1.38^b
Feed conversion ratio	2.01 ± 0.03^a	1.87 ± 0.06^b	1.84 ± 0.06^b	1.82 ± 0.05^b

Note: Values in the same row without a common superscript letter are significantly different (P < 0.05).

Table 3 shows the order of final weight, and daily gain were both D > C > B > A. The final weight and daily gain of group A broilers were both lower than that of experimental group broilers (P < 0.05). There was no significant difference among experimental group broilers (P > 0.05). The order of feed conversion ratio was A > B > C > D. The feed conversion ratio of group A broilers was higher than that of experimental group broilers (P < 0.05), and there was no significant difference among experimental group broilers (P > 0.05). The daily feed intake of group C broilers was lower than that of group A, B and D (P > 0.05).

3.2. Effects of prebiotic addition on slaughter performance of broilers

The results of slaughter performance of broilers are presented in Table 4. The eviscerated carcass ratio of group D broilers was lower than that of group A, B and C broilers (P < 0.05). There was no significant difference among treatment group broilers in breast muscle ratio, leg muscle ratio and abdominal fat ratio (P > 0.05). Compared with group B broilers, the breast muscle ratio and leg muscle ratio of group C broilers were higher and the abdominal ratio was lower (P > 0.05).

Table 4. Effects of prebiotic supplementation on slaughter performance of broilers (%).

Stage	Group A	Group B	Group C	Group D
Eviscerated carcass ratio	71.31 ± 1.81^a	71.67 ± 1.41^a	71.17 ± 1.69^a	69.76 ± 1.60^b
Breast muscle ratio	22.66 ± 4.75	22.19 ± 2.10	22.32 ± 1.85	21.81 ± 1.58
Leg muscle ratio	21.15 ± 6.03	18.59 ± 2.76	18.98 ± 2.01	20.12 ± 3.70
Abdominal fat ratio	2.75 ± 1.67	2.35 ± 0.93	2.24 ± 0.59	2.68 ± 1.52

Note: Values in the same row without a common superscript letter are significantly different (P < 0.05).

3.3. Effects of prebiotic addition on growth of internal organs of broilers

The results of the growth of internal organs of broilers are showed in Table 5. The liver weight of group D was higher than that of group A and D broilers (P < 0.05), and there was no significant difference between group C and D broilers (P = 0.089). What's more, there was no significant difference in heart weight and spleen weight among treatments group broilers (P > 0.05).

Table 5. Effects of prebiotic supplementation on internal organs of broilers (g).

Stage	Group A	Group B	Group C	Group D
Heart weight	9.72 ± 1.48	10.36 ± 1.53	10.48 ± 1.86	10.25 ± 2.34
Liver weight	35.85 ± 4.01^a	38.15 ± 5.44^a	38.86 ± 6.05^ab	42.20 ± 7.22^b
Spleen weight	2.25 ± 0.74	2.32 ± 0.60	2.64 ± 0.74	2.55 ± 0.83

Note: Values in the same row without a common superscript letter are significantly different (P < 0.05).

3.4. Effects of prebiotic addition on growth of small intestine of broilers

The results of the growth of small intestine of broilers intestine are shown in Table 6. The duodenum length of group A and D broilers were higher than that of group B and C broilers (P < 0.05). What's more, the jejunum length and ileum length of group D broilers were both higher than that of group A, B and C broilers (P < 0.05). The duodenum weight of group C and D broilers was higher than that of group A and B broilers (P < 0.05). And the jejunum weight and ileum weight of group D broilers were higher than that of group A, B and D broilers (P < 0.05). There was no significant difference among treatments group broilers about cecum weight and rectum weight (P > 0.05).

Table 6. Effects of prebiotic supplementation on small intestine of broilers.

Stage	Group A	Group B	Group C	Group D
Duodenum length (cm)	26.83 ± 3.48^ab	25.42 ± 1.72^a	25.85 ± 1.98^a	27.64 ± 2.59^b
Jejunum length (cm)	63.83 ± 5.30^a	64.39 ± 7.07^a	64.97 ± 6.34^a	70.44 ± 6.91^b
Ileum length (cm)	65.25 ± 5.63^a	66.12 ± 6.37^a	65.71 ± 6.39^a	73.25 ± 7.07^b
Duodenum weight (g)	7.62 ± 1.27^a	7.60 ± 1.51^a	8.38 ± 1.52^b	8.87 ± 1.24^b
Jejunum weight (g)	63.83 ± 5.30^a	64.39 ± 7.07^a	64.97 ± 6.34^a	70.44 ± 6.91^b
Ileum weight (g)	12.76 ± 2.66^a	12.12 ± 3.10^a	13.70 ± 2.11^a	15.26 ± 2.62^b
Cecum weight (g)	4.99 ± 0.82	5.27 ± 1.27	5.09 ± 0.84	5.18 ± 0.94
Rectum weight (g)	2.18 ± 0.47	2.18 ± 0.66	2.30 ± 0.49	2.53 ± 0.58

Note: Values in the same row without a common superscript letter are significantly different (P < 0.05).

3.5. Effects of prebiotic addition on serum biochemical parameters of broilers

Assay of biochemical indicator from blood serum is shown in Table 7. The ALB and total protein of group D broilers were both lower than that of group A, B and D broilers (P < 0.05). There was no significant difference among treatments group broilers on ALP, ALT, urea nitrogen and GH (P < 0.05). According to these results, prebiotic could affect the immune function of broilers.

Table 7. Effects of prebiotic supplementation on serum biochemical parameters of broilers.

Stage	Group A	Group B	Group C	Group D
ALB (g/L)	20.01 ± 1.99^a	20.08 ± 1.68^a	19.72 ± 1.40^a	17.86 ± 2.14^b
TP (g/L)	37.67 ± 6.31^a	36.96 ± 5.37^a	36.10 ± 4.60^a	30.52 ± 6.60^b
ALP (U/L)	6743.67 ± 3914.14	5229.17 ± 3324.08	7307.59 ± 4426.24	5498.56 ± 3346.53
ALT (IU/L)	17.60 ± 5.26	19.61 ± 4.95	18.53 ± 4.93	19.13 ± 4.00
BUN (mg/L)	0.43 ± 0.09	0.44 ± 0.11	0.41 ± 0.11	0.42 ± 0.08
GH (ng/ml)	0.33 ± 0.24	0.37 ± 0.21	0.24 ± 0.16	0.38 ± 0.22

Note: Values in the same row without a common superscript letter are significantly different (P < 0.05).

4. Discussion

4.1. Effects of prebiotic addition on growth performance of broilers

As we all know, there are many microbes in the intestine of animals. The microbes include beneficial and harmful ones, and they can maintain moving balance in the host body. And at this time, physiologic function such as nutrition, immune and digestion of host can keep normal. It will cause the body lesions when the ecological balance of broilers disorder (Guarner & Malagelada 2003; Eckburg et al. 2005). As a new kind of feed additive, prebiotic can change the microecological structure of intestine, increase the quantity of beneficial germ and inhibit the growth of pathogenic microorganism, then get the purpose of adjusting the structure of intestinal flora, enhancing the immune function, improving the feed conversion ratio, and so on.

A large number of experiments were carried out to investigate the effects of prebiotic supplementation on growth performance. Some researchers reported that the prebiotic supplementation had no effect on growth performance (Lima et al. 2003; Li & Zhang 2007; Houshmand et al. 2012), however, some other researchers held opposite views (Yeo & Kim 1997; Mateova et al. 2008; Wang & Gu 2010), which were similar to the current experiment. Many researches show that prebiotic in the intestine of animals can grow and reproduce and produce a variety of nutrients such as vitamins, amino acid, some factors of promoting growth, and so on. These matters participate in the metabolism of body and promote the growth of animals. What's more, prebiotic, containing a variety of microbes especially bacillus, can produce many kinds of digestive enzymes and enhance the activity of protease, lipase and amylase. Then prebiotic promotes the digestion and absorption of nutrients and improves the feed conversion ratio. The experiment results show that the daily weight gain and final weight of broilers of diets supplemented prebiotic were higher than that of control group broilers, and the feed conversion ratio was improved. Salianeh et al. (2011) got same results by supplementing with 3 g/kg prebiotic to feed chicks for 42 days. However, there was no significant difference among experimental group broilers.

The prebiotic can improve the growth performance of broilers. Lutfullah et al. (2011) reported that they must interfere with the intestinal cell morphology and absorption. Prebiotic supplementation can disturb the flora balance of intestine and affect the metabolism of body. This might be the reason that the weight of experimental groups broilers declined. Intestinal microbes would form a new balance after a period of time. But the length of the time was concerned with the amount of prebiotic supplementation. The more prebiotic supplemented the shorter the time. Khaksefidi and Ghoorchi (2006) got the similar results under the same conditions.

4.2. Effects of prebiotic addition on slaughter performance of broilers

The experiments about prebiotic supplementation on slaughter performance were seldom and the results of experiments were not quite similar. Song et al. (2006) reported that prebiotic could reduce abdominal fat and the heavy of dogmeat. Li and Zhang (2007) found that prebiotic could improve the breast muscle ratio of broilers and had no effect on eviscerated carcass ratio, leg muscle ratio and abdominal fat ratio. The experiment showed that the eviscerated carcass ratio of group D broilers was higher than that of group A, B and D broilers. Compared with group A broilers, the eviscerated carcass ratio of group D broilers was reduced by 2.17%. That may be because much of nutrients such as amino acid in the intestine of body were used by prebiotic, on the contrary, the amount of nutrients used for animals were decreased and reduced the eviscerated carcass ratio. The prebiotic had no effect on breast muscle ratio, leg muscle ratio and abdominal fat ratio in the current experiment.

4.3. Effects of prebiotic addition on growth of small intestine of broilers

There are a great number of microorganisms in the intestine of broilers, and they can keep in a state of equilibrium under normal circumstances. But some extreme cases, such as all kinds of physiological stress, feed changed suddenly, and the improper use of antibiotics will cause flora disorder of intestine and metabolise disorder of organism. Prebiotic supplementation can compete with harmful bacteria and form new flora being better than the original beneficial microbes. At the same time, prebiotic will produce acids material, broad-spectrum antibacterial material in the process of metabolic to inhibit the growth of pathogenicbacteria (Cavazzoni et al. 1998; Besselink et al. 2008). Lutfullah et al. (2011) reported that prebiotic supplementation increased in crypt cell proliferation, but no effect was observed on the intestinal weight and length. However, prebiotic had a great influence on duodenal length and weight in current experiment. When the addition was 0.13%, prebiotic influenced the length and weight of jejunum and ileum.

4.4. Effects of prebiotic addition on growth of internal organs and serum biochemical parameters of broilers

Awad et al. (2009) reported that prebiotic supplementation had no effect on the weight of live, heart and spleen when the basal diets were supplemented with prebiotic (1 kg/tonne of feed). Bozkurt et al. (2009) found that the prebiotic supplementation decreased the live weight of male broilers and had no effect on the live weight of female broiler at 42 days of age. In current experimentation, the live weight was the highest when the addition of prebiotic was 0.13%. Prebiotic supplementation did not affect the contents of ALP, ALT, urea nitrogen and GH. However, compared with other experiments, the contents of ALB and total protein were the lowest. It was not well if the live weight was too large. It could reduce the immunity of broilers and might result in broilers' sudden death. It might be well if only the economic efficiency was considered. But, that was not well to consider the animal welfare. It is not clear about the reason of liver weight too big, and it needs the efforts of other animal researchers.

5. Conclusion

According to the above analysis, the results of group C broilers were the optimal. Consequently, the optimum adding levels of dietary prebiotic was 0.10% which was made up by nutrient standard of flesh chicks.

Funding

This research was financially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Support Project of Science and Technology of Jiangsu Province [NO. BE2011408], P. R. China.

Additional information

Funding

Funding: This research was financially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Support Project of Science and Technology of Jiangsu Province [NO. BE2011408], P. R. China.