Citation of this paper

The use of Fermented purple sweet potato flour in broiler chicken feed: Effect on production performance

Dhita Febrianti, Hanny Indrat Wahyuni, Turrini Yudiarti, Endang Widiastuti, Ikania Agusetyaningsih, Tri Agus Sartono and Sugiharto Sugiharto

Department of Animal Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro, Semarang, Central Java, Indonesia
sgh_undip@yahoo.co.id

Abstract

The aim of this present study was to investigate the effect of feeding Fermented purple sweet potato flour in comparison to the unfermented purple sweet potato flour in terms of growth performance of broiler chickens. A total of 189-day-old broiler chicks were distributed to 3 groups of 7 replicates, including cont (chicks were provided with corn-soybean meal-based diet), unferm (chicks were provided with diet containing 15% unfermen purple sweet potato flour) and ferm (chicks were provided with diet containing 15% yeast fermented purple sweet potato flour). Body weight and cumulative feed consumption were recorded weekly. On day 35, the internal organ weight and carcass yield were determined. Throughout the study, chickens in the fermen group had higher weight gain (p<0.05) and lower FCR (p<0.05) compared to the unferm chicken group. However, there were no differences between treated and control chickens in terms of weight gain, feed intake and FCR during rearing. Dietary treatments had no impact (p>0.05) on eviscerated carcass and commercial cuts of broiler chickens. In conclusion, feeding fermented purple sweet potato flour to broilers resulted in better growth performance as compared to the unfermented purple sweet potato flour.

Keywords: broiler, energy source, fermentation, growth, purple sweet potato

Introduction

Broiler chickens are meat-producing livestock that have a short rearing period because of their fast growth. One factor that greatly influences the productivity and growth of broiler chickens is feed. In general, feed costs reach 70-80% of the total production costs of broiler chickens (Sulfani et al 2018), and hence reducing feed costs will have a huge impact on the broiler production efficiency. One effort that can be made to reduce feed costs is by using alternative feed ingredients. However, the use of non-conventional ingredients as alternative feed ingredients in rations is often hampered by low nutritional quality and the presence of antinutritional factors (Helda et al 2021). Fermentation is a simple method that can improve nutritional value and minimize the content of antinutritional substances contained in feed ingredients (Sugiharto and Ranjitkar 2019). Indeed, the increase in nutritional value and reduction in antinutritional components in Fermented feed ingredients greatly depend on the type of starter used and conditions during fermentation (Wea et al 2020). Among the types of starter that are often used for the Fermentation process of feed ingredients is the yeast Saccharomyces cerevisiae (Elghandour et al 2020). S. cerevisiae can produce enzymes such as amylase and proteolytic peptidase (Akamine et al 2023), which can hydrolyze complex carbohydrates such as cellulose, hemicellulose and lignin into simpler compounds (Otu et al 2020). Beside that, S. cerevisiae is also a probiotic microorganism that can have a positive effect on the health and productivity of broiler chickens (Sugiharto 2016; Vohra et al 2018).

Apart from having a positive impact on improving nutrition, fermentation is also reported to increase the bioactive components in feed ingredients (Palupi et al 2023). In line with this, Sugiharto et al (2018) reported that Fermentation can be used to produce functional feed ingredients which can have a positive influence not only from a nutritional aspect on broiler chickens, but also have a positive impact on health. Purple sweet potato flour is one stuff that provides broiler chickens with energy (due to its high carbohydrate content [75-90%]) and can be used as a functional feed ingredient (Murtiningsih and Suyanti 2011; Seran et al 2019). There are plenty of anthocyanin compounds in purple sweet potato flour, which have the potential to act as antioxidants and provide health benefits (Artadana et al 2016). Due to their antibacterial properties, anthocyanins can also reduce the growth of harmful bacteria and enhance the digestive system’s health (Edi et al 2018). Apart from its benefits, purple sweet potato flour contains antinutritional ingredients like a trypsin inhibitor, which can inhibit the trypsin activity (Luju et al 2021). Likewise, the content of crude protein in purple sweet potato flour is relatively low, at about 3.2% (Hartadi et al 2005). These circumstances may limit the amount of purple sweet potato flour used in the diets of broiler chickens.

Based on the description above, it is necessary to carry outfermentation to maximize the use of purple sweet potato flour in broiler feed and improve its functional characteristics so that it has more benefits for broiler chickens. In this study, purple sweet potato flour was fermented using S. cerevisiae before being offered to the broiler chickens. The aim of this present study was to investigate the effect of feeding fermented purple sweet potato flour in comparison to the unfermented purple sweet potato flour in terms of growth performance of broiler chickens.

Materials and methods

Preparation of the Fermented purple sweet potato flour

The purple sweet potato was purchased from local market around Semarang city, Central Java, Indonesia. The purple sweet potato was cleaned, and its decaying portions were discarded. After being chopped into small pieces, the purple sweet potatoes were sun-dried. The dried purple sweet potatoes were ground in a disk mill and then sieved to produce purple sweet potato flour. The flour was then sterilized in an autoclave for 15 minutes at 121°C. Subsequently, the sterilized flour was mixed throughly with water (2:1, g:mL), and added with baker’s yeast (0.5 mg/g) containing of 6.6 × 10 ⁸ cfu/g. Fermentation was carried out aerobically for 2 hours. The Fermented purple sweet potato flour was sun-dried, and stored until used for in vivo trial.

Broiler trials

A total of 189-day-old broiler chicks (strain Cobb) were employed in the present study. They were raised in open-sided broiler house throughout the rearing period using rice husk as a litter. The birds were provided with the commercial pre-starter feed for 7 days upon the arrival (body weight 45.85 ± 3.04 g). From day 8 and onward, the birds (body weight 142.17 ± 0.34 g) were distributed randomly according to the experimental treatment groups. The birds were fed formulated starter feed (Table 1) from day 8 to day 21, and finisher feed (Table 2) from day 22 to day 35. Feed and drinking water were provided ad libitum for the entire rearing period. The dietary treatments were arranged according to a completely randomized design with 3 groups of treatments and 7 replicates (consisted in 9 chicks in each). The treatments were applied started from day 8 until 35, including cont (chicks were provided with corn-soybean meal-based diet), unferm (chicks were provided with diet containing 15% unfermented purple sweet potato flour) and Fermen (chicks were provided with diet containing 15% Fermented purple sweet potato flour). Vaccinations were given in accordance with the Cobb broiler strain rearing guidelines. Body weight and cumulative feed consumption were recorded. The ratio of accumulative feed intake (g) to total body weight gain (g) was calculated to obtain the FCR value of broiler chickens.

One chick from each replicate was randomly taken, slaughtered, and de-feathered on day 35. The selected organs were taken out, emptied and weighed following evisceration. Commercial proportions and carcass percentages of broiler chickens were also recorded at the end of study.

Analysis of variance (ANOVA; SPSS Statistics 22.0) was used to analyze the data. Following the observation of a significant (p<0.05) variation among the dietary groups, the Duncan’s multiple-range test was employed.

Table 1. Feed ingredients and nutritional compositions of broilers (day 8-21)
Ingredients (%)	Cont	Unferm	Fermen

Yellow corn	53.5	36.2	36.4
Palm oil	2.32	2.39	2.55
Soybean meal	40.13	42.36	42.0
DL-methionine	0.19	0.19	0.19
Bentonite	0.75	0.75	0.75
Limestone	1.00	1.00	1.00
Monocalcium phosphate	1.30	1.30	1.30
Premix ¹	0.34	0.34	0.34
Chlorine chloride	0.07	0.07	0.07
Salt	0.40	0.40	0.40
Purple sweet potato flour	-	15.0	-
Fermented purple sweet potato flour	-	-	15.0
Nutritional compositions:
ME ² (kcal/kg)	2,900	2,900	2,900
Crude protein	22.0	22.0	22.0
Crude fibre	5.47	4.56	4.75
Ca	1.14	1.09	1.09
P (available)	0.57	0.50	0.50
¹The following nutrients are provided per kilogram of feed: 1,100 mg Zn, 1,000 mg Mn, 75 mg Cu, 850 mg Fe, 4 mg Se, 19 mg I, 6 mg Co, 1,225 mg K, 1,225 mg Mg, 1,250,000 IU vitamin A, 250,000 IU vitamin D₃, 1,350 g pantothenic acid, 1,875 g vitamin E, 250 g vitamin K₃, 250 g vitamin B₁, 750 g vitamin B₂, 500 g vitamin B₆, 2,500 mg vitamin B₁₂, 5,000 g niacin, 125 g folic acid and 2,500 mg biotin ² ME (metabolizable energy) was calculated according to formula: 40.81 {0.87 (crude protein + 2.25 crude fat + nitrogen ‐ free extract) + 2.5} cont: chicks were provided with corn-soybean meal-based diet, Unfermented: chicks were provided with diet containing 15% Unfermeted purple sweet potato flour , Fermented: chicks were provided with diet containing 15% Fermented purple sweet potato flour

Table 2. Feed ingredients and nutritional compositions of broilers (day 22-35)
Ingredients (%)	Cont	Unferm	Fermen

Yellow corn	61.74	44.49	44.6
Palm oil	2.41	2.46	2.63
Soybean meal	31.8	34.0	33.72
DL-methionine	0.19	0.19	0.19
Bentonite	0.75	0.75	0.75
Limestone	1.00	1.00	1.00
Monocalcium phosphate	1.30	1.30	1.30
Premix ¹	0.34	0.34	0.34
Chlorine chloride	0.07	0.07	0.07
Salt	0.40	0.40	0.40
Purple sweet potato flour	-	15.0	-
Fermented purple sweet potato flour	-	-	15.0
Nutritional compositions:
ME ² (kcal/kg)	3,000	3,000	3,000
Crude protein	19.0	19.0	19.0
Crude fibre	5.57	4.67	4.85
Ca	1.12	1.07	1.07
P (available)	0.59	0.51	0.51
¹The following nutrients are provided per kilogram of feed: 1,100 mg Zn, 1,000 mg Mn, 75 mg Cu, 850 mg Fe, 4 mg Se, 19 mg I, 6 mg Co, 1,225 mg K, 1,225 mg Mg, 1,250,000 IU vitamin A, 250,000 IU vitamin D₃, 1,350 g pantothenic acid, 1,875 g vitamin E, 250 g vitamin K₃, 250 g vitamin B₁, 750 g vitamin B₂, 500 g vitamin B₆, 2,500 mg vitamin B₁₂, 5,000 g niacin, 125 g folic acid and 2,500 mg biotin ² ME (metabolizable energy) was calculated according to formula: 40.81 {0.87 (crude protein + 2.25 crude fat + nitrogen ‐ free extract) + 2.5} cont: chicks were provided with corn-soybean meal-based diet, unfermented: chicks were provided with diet containing 15% unfermented purple sweet potato flour , Fermen: chicks were provided with diet containing 15% fermented purple sweet potato flour

Results and discussion

Currently, the price of yellow corn as the main ingredient for broiler chicken feed is quite high, thus encouraging farmers to look for alternative ingredient for broiler feed as energy sources. In tropical areas, purple sweet potatoes can grow well. This type of tuber has a high energy content so it has great potential as an alternative energy source to reduce the proportion of yellow corn in broiler feed. In addition to that, purple sweet potato is also rich in active ingredients which can have a functional impact on improving broiler health. In this present study, purple sweet potato flour, either fermented or not, was included in the broiler rations to reduce the proportion of yellow corn as an alternative energy source for broilers.

Data regarding production performance of broilers are presented in Table 3. On days 8-21 of rearing, chickens fed diets containing 15% purple sweet potato flour showed lower feed consumption (p<0.05) compared to chickens fed control diet. However, the difference in feed intake was not accompanied by the differences in weight gain and FCR of broilers. During days 22-35, weight gain and feed intake were not significantly different (p>0.05) among groups. However, when compared with chickens in the unferm group, chickens in the fermen group showed lower FCR values (p<0.05). Overall (day 8-35), chickens in the Fermen group had higher weight gain (p<0.05) and lower FCR (p<0.05) compared to the unferm chicken group. However, there were no significant differences between treated and control chickens in terms of weight gain, feed intake and FCR during rearing (day 8-35). Based on the results of this study, it can be inferred that purple sweet potato flour can be used as an alternative energy source to replace corn in broiler chicken feed without having a negative impact on broiler chicken production performance. Similar data have also been reported by Maphosa et al (2003) as well as Ayuk and Essien (2009). They reported that sweet potato flour was safe to be used as an alternative energy source to reduce the proportion of yellow corn in broiler chicken feed. However, these authors noticed that the higher proportion of sweet potato flour in the feed may result in a decrease in broiler weight gain.

In this current study, purple sweet potato flour was fermented using S. cerevisiae before being given to chickens. Compared to the group of chickens given unfermented purple sweet potato flour, chickens given fermented purple sweet potato flour had higher weight gain and better FCR (p<0.05). Several reasons may explain the beneficial effect of Fermentation as compared to the unfermented purple sweet potato flour, including the better nutritional content of the stuffs following Fermentation (Sugiharto and Ranjitkar 2019). In this study, the crude protein increased from 2.55% to 3.43%, crude fiber from 0.60% to 1.89%, crude fat from 1.20% to 1.39% and ash from 3.89% to 4.98%. The improvement in nutritional content may therefore enhance nutrient availability and growth performance of the chickens. Apart from the nutritional improvement, fermentation of the purple sweet potato flour using S. cerevisiae may be associated with the feeding of probiotics, which results in improvement in intestinal health and functions of the chickens (Sugiharto 2016). Indeed, S. cerevisiae is one of the most prominent probiotics that has been widely used by broiler farmers.

Table 3. Production traits of broiler chicks fed treatment diets
Items	Cont	Unferm	Fermen	SE	p value

Days 8-21
Weight gain (g)	578	551	566	7.65	0.37
Feed intake (g)	669 ^a	631 ^b	655 ^ab	6.29	0.04
FCR	1.16	1.15	1.15	0.02	0.98
Days 22-35
Weight gain (g)	967	957	1,018	12.7	0.11
Feed intake (g)	1,768	1,789	1,757	14.1	0.66
FCR	1.83 ^ab	1.87 ^a	1.72 ^b	0.02	0.03
Days 8-35
Weight gain (g)	1,545 ^ab	1,508 ^b	1,584 ^a	13.9	0.07
Feed intake (g)	2,437	2,421	2,412	17.1	0.84
FCR	1.57 ^ab	1.61 ^a	1.52 ^b	0.01	0.02
^a,b Means with various letters within the similar row indicate substantial difference. cont : chicks were provided with corn-soybean meal-based diet, unferm: chicks were provided with diet containing 15% unfermented purple sweet potato flour, fermen: chicks were provided with diet containing 15% fermented purple sweet potato flour, SE: standard error

Data regarding the relative weight of internal organs of broiler chickens are presented in Table 4. In general, the relative weight of internal organs of chickens were not affected (p>0.05) by dietary treatments. However, the relative weight of the proventriculus was higher (p<0.05) in chickens given purple sweet potato flour compared to cont chickens. It was not known for certain why the relative weight of the proventriculus was higher in the unferm compared to cont chicken group. A study by Zaefarian et al (2016) showed that fine particles can adversely affect the development of foregut (i.e., proventriculus and gizzard). However, this condition seemed not to occur in this study, as the corn particle size in the cont group was greater than the purple sweet potato flour in the unferm group which was in the form of fine powder. In this study it was very possible that the relatively lower final body weight in unferm (as the denominator in the calculation) resulted in higher values of the relative proventriculus weight in the respective chicken group.

Table 4. Organs weight of broiler chicks fed treatment diets
Items (% live weight)	Cont	Unferm	Fermen	SE	p value

Heart	0.47	0.44	0.46	0.01	0.78
Liver	2.73	2.23	2.48	0.11	0.21
Proventriculus	0.42 ^b	0.50 ^a	0.48 ^ab	0.01	0.04
Gizzard	1.62	1.50	1.52	0.04	0.40
Pancreas	0.26	0.29	0.30	0.01	0.22
Abdominal fat	0.79	1.04	0.75	0.09	0.39
Duodenum	0.48	0.55	0.52	0.02	0.47
Jejenum	1.01	0.99	1.04	0.05	0.96
Ileum	1.01	0.75	0.82	0.07	0.32
Caecum	0.41	0.48	0.43	0.02	0.34
Spleen	0.20	0.18	0.23	0.02	0.71
Thymus	0.22	0.23	0.25	0.02	0.89
Bursa fabricius	0.11	0.09	0.12	0.01	0.65
^a,b Means with various letters within the similar row indicate substantial difference cont: chicks were provided with corn-soybean meal-based diet unferm: chicks were provided with diet containing 15% unfermented purple sweet potato flour, fermen: chicks were provided with diet containing 15% Fermented purple sweet potato flour, SE: standard error

In this study it was found that dietary treatments had no impact (p>0.05) on eviscerated carcass and commercial cuts of broiler chickens (Table 5). Based on these facts, it can be explained that the use of purple sweet potato flour (fermented or unfermented) did not have a negative effect on the edible portion of broiler chickens. In line with this study, Maphosa et al (2003) also did not report a negative impact of giving sweet potato tuber on carcass and commercial cuts of broiler chickens.

Table 5. Carcass traits of broiler chicks fed treatment diets
Items	Cont	Unferm	Fermen	SE	p value

	(% live weight)
Eviscerated carcass	66.92	64.89	64.97	0.59	0.29
	(% eviscerated carcass)
Breast	35.63	35.87	36.09	0.59	0.95
Wings	10.60	11.06	11.52	0.17	0.09
Thighs	16.30	16.45	17.34	0.34	0.44
Drumsticks	15.55	15.61	15.09	0.32	0.78
Back	21.92	20.13	20.84	0.59	0.49
cont: chicks were provided with corn-soybean meal-based diet, Unferm: chicks were provided with diet containing 15% unfermented purple sweet potato flour, fermen: chicks were provided with diet containing 15% fermented purple sweet potato flour, SE: standard error

Conclusion

Feeding fermented purple sweet potato flour to broilers resulted in better growth performance as compared to the unfermented purple sweet potato flour.

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