Use of cashew apple fruit silage in the cattle fattening diet

Vu Anh Tai¹, Bui Quang Tuan, Tran Thi Thuy Van¹ and Nguyen Xuan Trach

Vietnam National University of Agriculture, Hanoi, Vietnam
nxtrach@vnua.edu.vn
¹ Institute of Geography, Vietnam Academy of Science and Technology, Hanoi, Vietnam

Abstract

A lab experiment and an on-farm feeding trial were conducted to test the possibility of making silage from fresh cashew apple fruit (CAF) as feed for cattle. CAF was made silage in combination with the other ingredients according to 3 different formulae, viz. CSL1 (only CAF), CSL2 (75% CAF + 25% maize cobs), and CSL3 (75% CAF + 12.5% maize cobs + 12.5% rice bran). The CAF based silages (CSL) were made in 10-litre plastic vases with 3 replicates per formula for each ensiling period of 30 or 60 days. Samples of the silages were collected at the end of each ensiling period for quality evaluation based on colour, smell, mould, pH and chemical composition. The results showed that it was possible to make acceptable quality silage from CAF with CSL3 being the best, followed by CSL2 and then CSL1. Therefore, a follow-up on-farm feeding trial was carried out to test the response of fattening cattle to CSL2 and CSL3 in comparison with whole crop maize silage (MSL) as roughage in the ration. A total of 15 Lai Sind male cattle 18-19 months of age were allocated to 3 groups of 5 each according to a completely randomized design to be fed 3 different rations: (1) Control ration (MSL) in which MSL was used as normally applied by the local farms, (2) Experimental ration 1 (CSL2) in which MSL in the control ration was replaced with CSL2, and (3) Experimental ration 2 (CSL3) in which MSL in the control ration was replaced with CSL3. Except for the silages, which accounted for 35% dry matter (DM) of the rations, all the other ingredients were the same for all groups. The results showed that the CSL3 can replace MSL in rations for fattening cattle without any losses in body weight gain, potentially reducing feeding costs as well as environmental pollution.

Keywords: byproduct, ensiling, maize cobs, rice bran

Introduction

Cashew (Anacardium occidentale L) is a perennial evergreen tree that is cultivated primarily for cashew nut production. Cashew apple fruits (CAF) as a by-product is rich in carbohydrates, minerals, vitamins, amino acids, carotenoids, phenolics, organic acids, and antioxidants (Antony 2020). Therefore, CAF can be considered to be a potential feed for livestock (Sreekutty 2017). It has been concluded from experiments by Bhamare et al (2016) that CAF could be included in the broiler ration in all phases without compromising performance. However, in most of the cases of cashew nut production, CAF is still left as waste after nut separation, causing environmental concerns.

In Vietnam, cashew trees are grown in large areas in the Central Highlands. Only in Dak Lak, one of the cashew growing provinces, in 2019, there was 23,187 hectares of cashew trees with a yield of 20,394 tons of nuts/year (Dak Lak Statistical Office, 2020). When harvesting, the nuts are collected, leaving the fruits in the garden as a waste. The weight of cashew apple fruit as waste is usually about 10 times of the nut weight (Tuan, 2007), so the volume of CAF in Dak Lak is estimated at 203,940 tons/year. Cashew nut harvesting season is from March to April, coinciding with a severe shortage of roughage for the province's large cattle herds during the dry season. Therefore, processing and preserving of CAF for safe use to feed cattle would contribute to addressing the shortage of feed for cattle in the last months of the dry season while saving the environment.

However, it is still of a concern that because of the high content of sugar, CAF is quickly fermented after harvesting of the nuts. It may then cause poisoning for cattle if fed fresh due to ethanol produced in the rumen from the fermentation of cashew carbohydrates, resulting in alcoholic toxification. Also, CAF also contains some antinutritive substances such as cyano-genetic glycosides and oxalic acid (Senthil Murugan et al 2015). It is possible that making silage of fresh CAF can help solve the problems. Nevertheless, the too high water content of the byproduct can easily make it difficult to produce good silage if it is ensiled alone. Therefore, the purpose of this study was to examine if it is possible to make silage for cattle feeding using CAP in combination with other locally available byproducts which had high dry matter contents.

Materials and methods

Ensiling cashew apple fruits

Study site and time

This study was carried out in the Central Lab of the Faculty of Animal Science, Vietnam University of Agriculture from March to June 2018.

CAF was ensiled together with other ingredients according to 3 different combination formulae, viz. CSL1: only CAF; CSL2: 75% CAF + 25% maize cobs; CSL3: 75% CAF + 12.5% maize cobs + 12.5% rice bran. All the mentioned percentages were based on the weight of the ingredients as they were at the time of making silage. The CAF was chopped into 1-2cm in length. The dry maize cobs were ground through a 0.5cm sieve. All the ingredients were well mixed together according to the silage formulae and then compacted layer by layer in 6 plastic vases per formula of 10 litres each to make 3 replicates per formula for each ensiling period of 30 or 60 days. Samples of the silages were collected at the end of each ensiling period for quality evaluation based on colour, smell, mould, pH, and chemical composition.

All the material samples collected were subjected to pre-drying at 60ºC for 72 hours and ground in knife mill with 1mm pore diameter, for subsequent analysis of DM, crude protein (CP), crude fibre (CF), ether extract (EE), and total ash according to the respective methods of the AOAC (1990).

Samples of silage were tested for pH according to Hartley and Jones (1978). The organic acids were analyzed with HPLC (high-performance liquid chromatography). NH3-N was analyzed with the Kjeldahl method using MgO to distill the NH3 out of the sample solution.

On-farm feeding trial

Study site and time

An on-farm feeding trial was carried out at Ea Wer commune, Buon Don district, Dak Lak province, Central Highlands of Vietnam from March to July 2019.

Materials

The feeding trial was conducted on Lai Sind male cattle to test if it was possible to replace MSL with CSL in their diets. Most of the feedstuffs used in the feeding trial (Table 1) were those normally used by the farm, except for CSL2 and CSL3. Maize and elephant grass were grown by the farm. Whole crop maize was made silage. Elephant grass was fed fresh after cutting. Ground soybean cake, maize meal and mineral-vitamin premix were bought from a local feed agency.

Fresh CAF collected from farms nearby. It was made silage according to the 2 formulae selected from the above mentioned lab experiment, viz. CSL2 and CSL3. CAF was chopped with a chopping machine into 1-2cm in length. The dry maize cobs were ground with a grinding machine through a 0.5cm sieve. All the ingredients were well mixed together and then compacted layer by layer in nylon bags with a diameter of 1.5m, length of 2.5m, which were then sealed airtight. After 30 days of ensiling the silages were used as an ingredient of the rations in the feeding trial (Table 2).

Experimental design

A total of 15 Lai Sind male cattle 18-19 months of age with an average bodyweight of 206kg ± 1.29kg were allocated to 3 groups of 5 each according to a completely randomized design to be fed 3 different rations (Table 2). One group was fed the control ration (CTL) with MSL as normally used by the local farms (MSL). The second group was fed experimental ration 1 (CSL2), in which MSL in CTL was replaced with CSL2. The third group was fed experimental ration 2 (CSL3), in which MSL in CTL was replaced with CSL3. Except for the silages, which accounted for 35% dry matter (DM) of the rations, all the other ingredients (elephant grass, ground soybean cake, maize meal, mineral-vitamin premix) were the same for all groups.

The main period of experiment was 3 months after 15 days of adaptation. The animals were kept in individual stalls and fed twice daily at 8 am and 4 pm. Before each feeding, elephant grass was chopped into 1-2cm in length and mixed thoroughly with all the other diet ingredients. The supplied amounts were adjusted to maintain the individual leftovers at around 10% of the total supplied. Water was supplied freely at all times.

Feed intake

Total feed offered and refusal were measured every day for each cattle during the whole feeding trial to determine intake. Samples of feed offered and refusal were taken before the last morning feeding of each week. After homogenization, an amount of about 0.5kg of feed offered was taken for each cattle and put into a plastic bag. Feed refusals were mixed well together, then an amount of around 10% was taken into a plastic bag for each cattle. All the feed and refusal samples were stored at -18°C in freezers immediately after collection until the end of the experimental period. After thawing, the composite samples were made and then dried in a forced-ventilation oven at 60°C for 72h. Subsequently, they were processed in a knife mill with 1mm sieve and stored in glass bottles at room temperature for later chemical analyses of DM, CP, CF, and EE according to the respective proximate methods of the AOAC (1990). Dry matter intake (DMI) and CP intake (CPI) were calculated by the difference between the amount offered and the amount left in refusals.

Bodyweight gain

The fattening cattle were weighed before the morning feedings on the first two days and the last two days of the trial using an electronic balance (RudWeight, Australia) to determine weight gain, which was calculated as the difference between the two average weights for each cattle. In addition, intermediary weightings were performed in one-month intervals throughout the experimental period to monitor the animal performance and identify any possible anomalies.

Statistical analysis

Data were statistically analyzed using Proc GLM in MINITAB software. The sources of variation were ration and error term. Tukey’s pairwise comparison was used to find significant differences between means at p<0.05.

Results and discussion

Quality of cashew apple fruit silage

Visible parameters

After 30 days of ensiling, all the silages had a slight yellow colour with a soft texture, a slightly sour smell, without any mould, except SL1 with some mould on one-third of the surface (Table 3). After 60 days, the silages became darker with some mould on one-third of the surface. Especially, the silage made from fresh CAF only (CSL1) became sour, very soft and slightly smashed, indicating low quality. The silages made from fresh CAF in combination with 25% dry maize cobs or 12.5% dry maize cobs and 12.5% rice bran showed better results with longer times of ensiling.

The moisture content of materials in the range of 65-75% is normally considered appropriate for making silage. A higher moisture content would facilitate mould development on the silage. In the present experiment, of the 3 silage formulae, 2 formulae, viz. CSL2 and CSL3 had moisture contents within this range (Table 4), so after 30 days of preservation, there was almost no surface mould, and after 60 days only mild mouldy surface appeared. Meanwhile, due to too high moisture content (87.2%), CSL1 showed mouldy surface after 30 days of preservation, and after 60 days, the mould was spread almost on all over the surface.

Changes in pH and chemical composition of silages

Figure 1 shows that after 30 days the pH value of all the silages dropped below 4.40 and maintained stable until 60 days of ensiling, indicating good fermentation during the first two months of ensiling. However, the silage made from CAF only (CSL1) showed its pH values (4.36 and 4.27) higher than those of the other two silages. The lowest pH values belonged to CSL3, which was made from 75% CAF + 12.5% maize cobs + 12.5% rice bran. It was also of interest that CSL2, which was made from 75% CAF and 25% maize cobs with no easily fermentable supplement added, also showed good pH values (<4.2). That should indicate a high level of easily fermentable carbohydrates available in fresh CAF.

NB. CSL1: Only CAF; CSL2: 75% CAF + 25% maize cobs; CSL3: 75% CAF + 12.5% maize cobs + 12.5% rice bran

Figure 1. Changes in pH of silages after different ensiling times

From the chemical composition of the silages (Table 4), it can be seen that the DM contents of CSL1 was too low (12.8%), which should have resulted in lower quality of silage (Muck 1988). Adding dry maize cobs and/or rice bran increased the DM content in CSL2 and CSL3 up to a level better for anaerobic fermentation. As a result, CSL2 and CSL3 had better organic acid profiles with higher proportions of lactic acid compared to CSL1. Low DM would have also allowed bacteria to produce butyric acid, resulting in higher levels of butyric acid in CSL1. It could, therefore, be said that fresh CAF in combination with 25% dry maize cobs, or 12.5% dry maize cobs and 12.5% rice bran can be made into good silage based on the evaluation of the pH values and chemical composition.

La Van Kinh et al (1997) examine the possibility of using whole cashew apple (WCA) and cashew apple waste (CAW) after fruit processing as feed for dairy cows by ensiling them with poultry litter (PL) to increase the DM of the ensiling materials according to four treatments as follows: (1) 100% CAW or WCA, (2) 90% CAW or WCA +10% PL, (3) 80% CAW or WCA + 20% PL, and (4) 70% CAW r WCA) + 30% PL based on fresh weight. Their results show that CAW or WCA can be preserved for long term use by anaerobic ensiling. The best ratio is 90% CAW or WCA and 10% PL on a fresh weight basis. Higher ratios of PL result in poor quality silages which are not suitable as animal feed. As soluble sugars are present in high concentrations in WCA and CAW, irrespective of the presence of PL, the sugars are fermented to organic acids and alcohol, which may have negative effects on nutritive value.

Passion fruit peel (PFP), which is a fruit processing byproduct with high moisture content as CAF, has also been recently made silage in combination with dry maize cobs and molasses b Tran Hiep et al (2020). Their results show that the formulae of 75% passion fruit peel + 20% dry maize cobs + 5% molasses give good quality silage for a long time without spoilage.

The present results look in line with those of the two above mentioned studies. Based on the above results, formulae CSL2 and CSL3 were kept for a further on-farm investigation to examine responses from cattle.

Responses of fattening cattle to cashew apple fruit silage in the diet

Changes in body weight

After 3 months of fattening, the bodyweight changes of cattle fed the control ration (MSL) were almost the same compared with those fed CSL2 and CSL2 as can be seen in Table 5. That is, a good CAF based silage can substitute maize silage in the diet of fattening cattle.

The results may be explained because the two experimental rations using CSL2 and CSL3 had almost similar nutritional values as the control diet using MSL. However, on the average, the average daily gain of cattle fed CSL2 was a little lower than that of cattle fed CSL3. That may be because CSL3 used rice bran which had higher ME and crude protein contents than dry maize cobs in CSL2. Anyway, both CSL2 and CSL3 can be used to replace MSL in the ration for the fattening cattle.

Feed intake and feed conversion ratio

CPI of cattle fed CSL2 was the lowest among the rations. This is due mainly to the lower protein content of dry maize cobs compared to whole crop maize and rice bran used in the silages. Although the use of dry maize cobs together with CAF (CSL2) can ensure good quality of the silage, the nutritive values of the silage were not as high as that of the silage using a combination of rice bran with the dry maize cobs (CSL3).

From the present results, it can be said that the two CSLs were almost the same as MSL as feed for the fattening cattle. That may be because the CSLs had similar chemical composition compared with those of MSL as shown in Table 1. This confirms that it is possible to use CSL instead of MSL in cattle fattening diets without reducing the efficiency of cattle fattening. Therefore, CAF can and should be utilized to substitute whole crop maize in making silage as feed wherever it is available to reduce feeding costs and minimize environmental pollution at the same time. The two formulae for CSL making would also pay the way for better utilization of maize cobs as a locally available byproduct for cattle feeding.

Conclusions

• Fresh cashew apple fruits can be made silage if it is ensiled in combination with dry materials such as maize cobs and rice bran. Two recommended combinations of materials for silage making should be: (1) 75% CAF + 25% maize cobs, and (2) 75% CAF + 12.5% maize cobs + 12.5% rice bran based on as used weight.
  
  
• The cashew apple fruit silages can replace whole crop maize silage in rations for fattening cattle without any losses in body weight gain, potentially reducing feeding costs as well as environmental pollution.

Acknowledgements

The present research was sponsored by Project coded TN17/T05 under financial support of the National Program “Science and Technology Support for Economic and Social Development in the Central Highlands of Vietnam in the period 2016-2020” coded KHCN-TN/16-20. We would also like to thank the support of the staff of the Central Highlands Program Office for their assistance during the study.

References

Antony A P, Kunhiraman S and Abdulhameed S 2020 Bioprocessing with cashew apple and its by-products. In Book: Valorisation of Agro-Industrial Residues – Volume II: Non-Biological Approaches, Pp.83-106.

AOAC 1990 Official methods of analysis, 15th Edition. Association of Official Analytical Chemists, Washington DC.

Bhamare K S, Dildeep V, Senthil Murugan S and Chavan S J 2016 Nutritive evaluation of cashew apple waste in broilers, International Journal of Science and Nature, 7 (3), 629-632.

Dak Lak Statistical Office 2020 Dak Lak Statistical Year Book.

Harley R D and Jones E 1978 Effect of aqueous ammonia and other alkalis on the in-vitro digestibility of barley straw. Journal of Science of Food and Agriculture, 29(2), 92-98.

Hiep T, Tuan B Q, Phuong L V, Son N H, Ha L V and Trach N X 2020 Passion fruit (Passiflora edulis) peel as feed for ruminants in Vietnam: Quantification, chemical composition and possibility to make silage. Livestock Research for Rural Development. Volume 32, Article #35. Retrieved March 24, 2020, from http://www.lrrd.org/lrrd32/2/trach32035.html

Kinh L V, Do V V and Phuong D D 1997 Chemical composition of cashew apple and cashew apple waste ensiled with poultry litter. Livestock Research for Rural Development. Volume 9, Article #6. Retrieved March 24, 2020, from http://www.lrrd.org/lrrd9/1/kinh91.htm

Muck R E 1988 Factors influencing silage quality and their implications for management. Journal of Dairy Science, 71(11), 2992-3002.

Senthil Murugan S, Fiji E, Sudish Kumar, Justus K Rajan, Ann Nisa Thomas, Varshney L and Virendra Kumar 2015 New perspectives on the use of cashew apple waste as futuristic animal feed resources. https://www.researchgate.net/publication/307509336_New_perspectives_on_the_use_of_cashew_apple_waste_as_futuristic_animal_feed_resources_Senthil_Murugan_S_Fiji_E_Sudish_Kumar_Justus_K_Rajan_Ann_Nisa_Thomas_L_Varshney_Virendra_Kumar

Sreekutty P S, Senthil Murugan S, Dildeep V, Biju Chacko and Balusamy C 2017 Chemical composition of cashew apple waste, Shanlax International Journal of Veterinary Science, 5 (1), 1-3.

Tuan B Q 2007 Investigation on the utilization of agricultural and industrial by-products as feedtuffs, Final Project Report, Ministry of Agriculture and Rural Development, Hanoi, Vietnam.

Received 5 April 2020; Accepted 5 April 2020; Published 1 May 2020

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