Using banana leaf and pseudo-stem (Musa spp) silage substituted rice bran in the diet of growing wild crossbred boar

Nguyen Thiet, Phan Van Binh, Nguyen Thi Hong Nhan¹ and Nguyen Trong Ngu

College of Rural Development, Can Tho University, Can Tho City, Vietnam
nthiet@ctu.edu.vn
¹ College of Agriculture, Can Tho University, Can Tho City, Vietnam

Abstract

This experiment aimed to determine the effect of additive sources on banana leaf and pseudo-stem (BLS) silage and evaluate the effect of using BLS silage in the diet of growing wild crossbred boar. First experiment was arranged with a completely randomized design with 04 treatments and 04 replicates. The ratio of materials was calculated as a dry matter ratio and the treatments were control (BS): 99.5% wilting BLS + 0.5% salt; treatment 1 (BSC): 94.5% wilting BLS + 5% corn meal + 0.5% salt; treatment 2 (BSB): 94.5% wilting BLS + 5% rice bran + 0.5% salt; treatment 3 (BSM): 94.5% wilting BLS + 5% sugar cane molasses + 0.5% salt. The second experiment was arranged into a completely randomized design, consisting of three treatments and four replicates. The treatments were control group (BSM0): 70% rice bran + 30% water spinach (based on DM); treatment 1 (BSM10): 10% BSM silage + 60% rice bran + 30% water spinach; treatment 3 (BSM20): 20% BSM silage + 50% rice bran + 30% water spinach. The results from the first experiment showed that BLS mixed with 5% sugar cane molasses could improve the silage quality by decreasing pH after 7 days of ensiling and NH ₃-N content within the acceptable range for feed silage quality. In addition, wild crossbred boar can consume BSM up to 10% without negative impacts on feed intake and weight gain. But, 20% BSM in the diet decreased weight gain and remained unchanged in feed intake throughout the study. It was found that 5% sugar cane molasses can effectively ensile with BSL, and that BSM may substitute 10% rice bran in the diet of growing wild crossbred boars.

Key words: banana leaf and pseudo-stem, goat, silage, weight gain

Introduction

In Vietnam, the banana tree is regarded as one of the most important fruit trees, occupying a high position in planted area and total annual output. The natural conditions of Vietnam are very suitable for banana tree development. However, after harvesting fruit, the leaves and pseudo-stems have not been used in the appropriate ways for animal feed. Banana leaves have relatively high CP with 11.18% (Van 2012), whereas pseudo-stems were low CP with 2.79% (Wang et al 2016). Additionally, banana pseudo-stems are also limited to use in livestock diets, especially monogastric, due to high water content and low digestibility. Therefore, it is necessary to develop appropriate methods to preserve this feed resource to make full use of its potential. The ensiling technique is a suitable approach for the preservation of animal feed resources, and the method is extensively used worldwide (McDonald et al 1991). Silage quality depends on several factors, of which moisture content and feed composition are the most important (McDonald et al 1991). To improve the silage quality, cereal grains or sugar cane molasses can be added to provide conditions for an efficient fermentation process and reduce effluent production (Sibanda et al 1997; Jaurena and Pichard, 2001). Previous studies suggested that banana pseudo-stems could be improved by making silage together with taro foliage or yeast to improve protein content, feed intake, and live weight gain in growing pigs (Ty et al 2012; Manivanh and Preston 2015). In Vietnam, wild crossbred boars are popular recently, particularly in small farmers and remote areas due to good quality meat and low feed cost compared to commercial pigs. In addition, the farmers traditionally fed their wild crossbred boars with fresh banana pseudo-stem or green vegetable (sweet potato leaf and water spinach), rice bran, or cereal grains, and mineral. However, there is little information on the use of BLS silage in the diets of wild crossbred boar. Thus, the present experiment aimed to determine the effect of additive sources on BLS silage and evaluate the impacts of using BLS silage in the diet of growing wild crossbred boar. The results from this study would contribute to the sustainable exploitation of local resources for livestock development and environmental protection.

Materials and methods

Experiment 1: Effects of additives supplementation on the quality of banana leaf and pseudo-stems silage

Banana leaf and pseudo-stem preparation for silage:

After harvesting fruit, leaf and stem were chopped into 2 to 4 cm length and then sundried a half day before processing the silage (Photo 1).

Photo 1. Banana leaf and pseudo-stem preparation for silage

Experimental design and analysis

This experiment was arranged with a completely randomized design with 04 treatments and 04 replicates. The ratio of materials was calculated as a dry matter ratio and the treatments were control (BS): 99.5% wilting BLS + 0.5% salt; treatment 1 (BSC): 94.5% wilting BLS + 5% corn meal + 0.5% salt; treatment 2 (BSB): 94.5% wilting BLS + 5% rice bran + 0.5% salt; treatment 3 (BSM): 94.5% wilting BLS + 5% molasses + 0.5% salt. The level of salt from these treatments was followed by Hung L T et al. (2020) for Taro leaf and petiole silage. The mixtures were packed into polyethylene bags of 10 kg capacity with air removed from the bags. During storage, the bags were checked regularly and would be re-opened, made compact and re-tied if found to be loose.

The silage samples (500 g each bag) were collected on days 7, 14, 21, and 28 after ensiling. All samples were divided into two parts; the first part (100 g) was immediately measured for pH by using pH meter (pH221, Lutron, Taipei, Taiwan), ammonia nitrogen (NH₃-N) was determined by Kjeldahl method (AOAC, 1990); the second part (400 g) was dried in an oven at 65^oC until the weight was stabilized (12 hours) and then analyzed for crude protein (CP), ash, and crude fiber (CF) contents according to AOAC (1990).

Experiment 2: Effects of BLS silage substituted rice bran in diets on dry matter intake and weight gain of wild crossbred boar

Experiment 1 showed that BLS mixed with 5% sugar cane molasses (BSM) is a good choice for making the silage. Therefore, the experiment used this formula (BSM) to substitute the rice bran in the diets of wild crossbred boar. BLS from this study was ensiled with 5% sugar cane molasses within 14 days before feeding for the wild crossbred boar

Experimental design and data collection

Twelve male wild crossbred boars with average body weight (BW) of 18.63 ± 0.69 kg were arranged into a completely randomized design, consisting of three treatments and four replicates. The study lasted for 70 days, with 10 days for adaptation and 60 days for data collection. The treatments were control group (BSM0): 70% rice bran + 30% water spinach (based on DM); treatment 1 (BSM10): 10% BSM silage + 60% rice bran + 30% water spinach (based on DM); treatment 3 (BSM20): 20% BSM silage + 50% rice bran + 30% water spinach (based on DM). The ingredients and chemical compositions of experimental rations are presented in Table 1. The animals were fed twice daily at 08:00 and 14:00 h and had free access to water. All animals were weighed before morning feeding at the beginning and the end of the experiment.

Feed offered and refusals (10%) were recorded daily in the morning starting from day 1^st to 60^th of the experiment. Feed and refusal samples were collected daily from day 1^st to 60 ^th and were divided into two parts: one half was immediately dried in the oven at 105°C until its weight remained constant to determine dry matter, and the remaining samples were kept frozen at -20°C until chemical analysis. At the end of the experiment, all feed samples were thawed and mixed thoroughly, and subsamples were dried at 65°C for approximately 12 hours for CP, CF, and ash analysis according to AOAC (1990).

Statistical analysis

The data are presented as the mean ± SEM. All data were analyzed with one-way ANOVA. The significance of pairwise comparisons was determined by Tukey posttest. Significance was declared at p<0.05.

Results and discussion

Effects of additives supplementation on the quality of banana leaf and pseudo-stems silage

The effects of additive sources on the pH, DM, and NH3-N contents of ensiled banana leaf and pseudo-stem, as well as the changes over the days of ensiling, were found (Table 2, 3, and 5; p<0.05). However, additive sources did not affect the CP content of ensiled BLS. (Table 4;p>0.05).

Generally, the pH from BSC and BSM groups ranged from 4.45 to 4.84 and was lower than those from BS (pH from 5.47 on day 7 decreased to 5.28 on day 28) and BSB (pH from 6.5 on day 7 decreased to 5.5 at day 28) groups throughout the days of ensiling. Additionally, pH from BSM decreased rapidly and lowered to 4.5 during the first week and then remained unchanged until 4 weeks. In contrast, pH from BS or BSM groups slowly decreased during the days of ensiling, and pH was higher than 5. Higher pH from BS and BSB groups may be due to either greater NH₃-N level (Table 5; p<0.05) or low water-soluble carbohydrates to provide the conditions for the fermentation process. In comparison, sugar cane molasses and corn meal are readily available feedstuffs in Vietnam and are high in readily available carbohydrates in the form of sugar or starch, which can promote the growth of lactic acid bacteria (McDonal et al 1991), resulting in a rapid pH decrease at day 7 in the BSC and BSM groups. Wang et al  (2016) reported that pH on day 20 and 30 from banana pseudo-stem silage was 5.09 and 4.43, respectively and differed from the present experiment. Liu et al. (2013) suggested that BLS can be directly ensiled for 60 days. However, pH value indicated that wilting BLS or addition with 5% rice bran moderately preserved as silage within 4 weeks.

The results from the present study show that wilting BLS before ensiling can be achieved an adequate DM level (more than 20%) for the fermentable process (McDonal et al 1991). DM content from additive groups was higher than in control groups (Table 3, p<0.05). The increase in DM content from BSC, BSB, and BSM groups can be explained by the added DM from corn meal, rice bran, and sugar cane molasses. An and Lindberg (2004) reported that sweet potato leaves added with cassava root meal and sugar cane molasses also increased the DM level and similar findings from this study. In this study, DM content decreased all treatments after ensiling (day 7 to day 28). Accordingly, McDonal et al (1991) suggested that DM losses during fermentation should not exceed 40 g/kg DM (4%). However, DM losses between days 7 and 28 from this study arranged from 11.99% (BS group) to 22.85% (BSC group) and were much higher than the recommendation from McDonal et al (1991). DM losses from this study were also greater than the result reported by Wang et al (2016) in banana pseudo-stem silage. The result from DM content suggested that BS, BSB, and BSM were the same DM losses, while BSC was high two times compared to other treatments (Table 3, p=0.054).

There were no effects of additive sources in ensiled BLS on CP content, even though corn meal, rice bran, and molasses were added to BSC, BSB, and BSM groups (Table 4, p>0.05). The CP content from additives did not differ in CP level from the BSL mixture in this study. The CP content of silage decreased as the time of ensiling. During the ensiling, the decline in CP content may be due to the nitrogen loss from protein decomposition by bacteria in the silage (An and Lindberg 2004). Therefore, NH₃-N level from this study increased by the time of ensiling, particularly in BSB and BS group (Table 5); as a result the pH from BSB and BS also slowly decreased over time (Table 2). Moreover, NH₃-N level from BSB was significantly higher than those of other treatments in this study and increased from 19.05 to 29.55 g/100g of the total N (Table 5, p=0.001). In addition, after 28 days of ensiling NH₃ -N level did not differ in BS, BSC and BSM groups. Similar finding was reported by Lima et al (2010) that addition of molasses to forage resulted in silage with lower pH and ammonia content. Álvarez et al (2015) found that combination of molasses and beet pulp to banana by-products (green banana and bunch) was also lower ammonia compared to without the additives. Silage is considered excellent when the NH3-N/N content is below 7 g/100 g of the total N and considered good when the NH3–N/N content is between 7 g and 10 g/100 g of the total N (Lima et al 2010). Therefore, NH₃ -N content from BSM group arranged in acceptable level for feed silage quality (McDonal et al 1991; Lima et al 2010).

Effects of BLS silage replaced rice bran in diets on dry matter intake and weight gain of wild crossbred boar

There was no difference in the daily intakes of DM and CP, body weight among treatments (Table 6, p>0.05), although the crude fiber content increased as the inclusion of BSM increased in the diet (Table 2). Some studies found that increasing the fiber content in diet decreased the feed intake and nutrient digestibility (Ngoc et al 2013 and Lindberg 2014). A similar finding was reported by Sivilai et al (2016) when Moo Lath pigs fed ensiled banana pseudo-stem and ensiled taro foliage with daily DMI from 23.3 to 26.3 g/kg BW/day. But, Arjin et al (2021) reported that local Thai pigs consumed fresh or fermented banana pseudo-stem was about 40 g DMI/head/day and higher than the DMI from the present study. The difference in DMI between this study and previous studies may be due to differences in breeds, ingredients, and fiber levels in the diet. The higher fiber in the diet may decrease palatability, thereby reducing daily weight gain and FCR, as reported by Avelar et al (2010) and Ngoc et al (2013). But the results from current study show that the increasing level of BSM in diet did not affect body weight and FCR (Table 6, p <0.05), but daily weight gain decreased as the inclusion of BSM increased. Reduced daily weight gain with BSM20 may be owing to increased fiber levels in the diet as a result of BSM inclusion (Table 2), which decreased nutrient digestibility. (Ngoc et al 2013 and Lindberg  2014). The inclusion level of BSM was negatively correlated with daily weight gain (p=0.03, R²=0.927, Table 6 and Figure 1).

Figure 1. The relationship between total weight gain (kg/head) and the level of BSM in diet

Conclusions

• Banana leaf and pseudo-stem mixture ensiled with 5% sugar cane molasses which decreased pH to 4.5 within 7 days, and NH₃-N content arranged acceptable level for feed silage quality.
• BSM can be substituted for rice bran up to 10% in the diet of wild crossbred boar without affecting daily intakes of DM, CP, and weight gain.
• There is a limitation in this experiment that we did not measure the tannin and NaCl levels in the silage mixture. Therefore, it is nessessary to analyze these parameters for further experiment and need to pay attention in the salt level in the diets to provide for local pig.

Acknowledgments

The author would like to thank the manager of the Experimental farm at College of Rural Development, Can Tho university for supplying all the experiment materials and sincere gratitude thanks to Mr. Khang and Ms. Tram for taking care of the experiment.

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