Supplements of water spinach (Ipomoea aquatica) and biochar improved feed intake, digestibility, N retention and growth performance of goats fed foliage of Bauhinia acuminata as the basal diet

Phonevilay Silivong and T R Preston¹

Animal Science Department, Faculty of Agriculture and Forest Resource, Souphanouvong University, Lao PDR
silivongpvl@yahoo.com
¹ Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV), Carrera 25 No 6-62 Cali, Colombia

Abstract

The objective of the study was to determine the effect of water spinach and biochar on feed intake, digestibility, N retention and growth performance of local goats fed Bauhinia acuminata  as basal diet. Ground sun-dried cassava root was included at 5% (as DM) of all the diets to serve as a carrier for the biochar The experiment was arranged as a 2*2 factorial with 3 replications using twelve goats in individual pens (initial body live-weight 12.5kg and 5-6 months of age).

Daily live weight gain and feed conversion, apparent digestibility of DM, OM, crude protein, and N retention, were improved by supplements of water spinach and biochar. The higher values of rumen ammonia in goats fed water spinach reflected the greater solubility of the crude protein (CP) in the water spinach compared with that in the basal diet of Bauhinia) This could be the explanation for the better animal response with this supplement.

Key words: N-balance, protein solubility, rumen ammonia

Introduction

Livestock are the most important source of protein food and family cash income of farmers in Laos, and also give manure for cropping in the rural areas. Most of the production from livestock such as goats, cattle, pigs and poultry comes from smallholders using traditional management systems.

The goat population in Laos is estimated to be about 268,900 heads (DLF 2007). Farmers tend to restrict their herds in order to avoid excessive damage to crops, for which the owner is held responsible. The great challenge is to make the goats become environmentally friendly through the changing of the free range farming system to stall feeding system.

A principal characteristic of the goat is its dietary selectivity, which enables it to survive in apparently harsh environments.

The conventional feeding system in goats in Lao PDR is based mainly on the use of natural grasses. However, the dry season is difficult for forage production, as natural pasture becomes dry and improved grasses cannot grow. Therefore, it is important to find an alternative feeding system because purchased supplements are so expensive for poor farmers. On the other hand, there are many trees and shrubs available. Preston and Leng (1987, web version 2009) and Leng (1997) have emphasized that in tropical countries one of the most appropriate ways to improve feed supplies for ruminants is through utilization of tree and shrub foliages.

The legume tree Bauhinia acuminata is widely distributed in the Luang Prabang Province and it has been observed that the foliage is readily consumed by goats. As is the case with most foliage from legume trees, it contains many secondary plant compounds including tannins (Queiroz Siqueira et al 2012). The low solubility of the crude protein in Bauhinia is indicative of the binding action of tannins on this nutrient source.

Kongmanila et al (2007) reported that water spinach supplementation of low quality tree foliage (from Fig [ Latin names] , Jujube and Mango trees) increased the DM and crude protein intake of goats, and improved the apparent digestibility and N retention. It was therefore hypothesized that the growth performance of goats fed Bauhinia foliage as the basal diet would be improved by supplementing it with water spinach. According to Thu Hong et al (2011), the live weight gain of goats fed Mimosa foliage was increased by supplementing with fresh water spinach at 27% of the total DM intake. Goats fed a sole diet of cassava foliage also responded with increased DM digestibility and N retention when fresh water spinach was provided as a supplement (Pathoummalangsy and Preston 2006).

Biochar, through its capacity to act as a support mechanism for biofilms that adsorb consortia of micro-organisms and nutrients (Leng 2014), has also been shown to have positive effects on ruminant performance (Leng et al 2012)

In the research reported here, it was hypothesized that: the performance of growing goats fed Bauhinia acuminata as the basal diet would be improved by supplementation with both water spinach and biochar. A dietary level of 5% of cassava root chips was proposed as the carrier of the biochar.  The research is a follow-up to a previous experiment with the same forages (Silivong and Preston 2015) in which the biochar was suspended in molasses; however, through an oversight the amount of molasses offered in that experiment accounted for 40% of the diet DM a level inappropriately high in a diet based on forages.

Materials and methods

Location of the study area

The experiment was conducted in the Animal Science Farm and Laboratory of the Faculty of Agriculture and Forest Resource, Souphanouvong University, Luang Prabang Province, Lao PDR. The site is located 7.5 km from Luang Prabang Town to the South-west, at an altitude of 385m above sea level. The experiment was conducted from August to December 2015.

Treatments and experimental design

The experimental design was a 2*2 factorial arrangement in a Randomized Completely Block

Design (RCBD) with 4 treatments and four replications.

The factors applied to a basal diet of fresh Bauhinia foliage were: · With or without water spinach (WS and NWS) · With or without biochar (BC and NBC) Individual treatments were:

- BA = Bauhinia acuminata ad libitum

- BABC = Bauhinia acuminata ad libitum + 1% biochar in diet DM

- BAWS = 70% Bauhinia acuminata and 30% water spinach on DM basis

- BAWSBC = 70% Bauhinia acuminata and 30% water spinach + 1% biochar

Sun-dried cassava root chips were used as the carrier for the biochar. The biochar was mixed with finely-chopped, sun-dried cassava root chips (20% biochar: 80% sun-dried cassava root chips) which were fed at 5% of the diet (DM basis) once daily at 7.00am.

Animals and management

Twelve weaned goats (local breed) with initial average body weight of 12.5kg and 5-6 months of age were used. They included 8 males (non-castrated) and 4 females. These animals were purchased from Chomphet District, Laung Prabang Province. They were housed in individual pens made from local material (dimensions of width 1 m, length 1 m and height 0.9 m), designed to collect separately feces and urine (Photo 1).They were vaccinated against Pasteurellosis, foot and mouth disease and treated with Ivermectin (1ml/20 kg live weight) to control internal and external parasites. They were adapted to the pens and the feeds for 10 days before starting the experiment. The experiment lasted 100 days, including the adaptation period.

Feed and management

Cassava root was purchased from farmers in Luang Prabang District, chopped

into small pieces and exposed to sunlight for 48 hours to reduce the moisture to about 15%, Foliages of Bauhinia acuminata and water spinach were collected daily from natural stands in the University campus. The foliages were offered twice daily at 07:30 and 16:00h by hanging in bunches above the feed trough (Photo 1).

Photo 1. Bauhinia acuminata foliage as presented to the goats

Data collection

Live weight was recorded in the morning before feeding at the beginning and at the end of the experiment and at intervals of 10 days during the experiment. Quantities of feed offered and refused were recorded daily. Every 10 days, samples were taken for analysis of DM and N. Samples of Bauhinia acuminata foliage offered and residues were separated into stem and leaves (containing attached petioles). Representative samples of each component were analyzed for DM, N and ash. Samples of rumen fluid were taken by stomach tube 2h after morning feeding on the last day of the experiment. The pH value was measured immediately with a portable digital pH meter. A drop of concentrated sulphuric acid was added prior to determination of ammonia by steam distillation. Digestibility and N retention were recorded three times, over 5 day periods at 30 day intervals (after 30, 60 and 90 days). In each collection period, samples of feeds offered and refused were taken daily and bulked for the 5 days of each period. Urine was collected in buckets containing 20ml of a solution of sulphuric acid (10% sulphuric acid concentrate + 90% distilled water). Feces were collected daily and stored in the refrigerator at 4-8ºC and at the end of each period, when sub-samples were mixed together and ground with a coffee grinder.

Chemical analyses

The sub-samples of feces and of feeds offered and refused were analysed for DM, N and ash according to AOAC (1990) methods. Urine was analysed for nitrogen (AOAC 1990).

Statistical analyses

Data for feed intake, N intake, N retention, live weight and pH, NH₃-N were analysed with the General Linear Model option of the ANOVA program in the MINITAB software (Minitab 2000). Source of variation were: animals, periods, water spinach, biochar, interaction water spinach*biochar and error.

Results and discussion

Chemical composition

The concentrations of crude protein and ash and the solubility of the protein were lower, and of DM were higher, in Bauhinia than in water spinach (Table 1).

Feed intake, growth rate and feed conversion

DM intake was increased 38% by supplementation with water spinach and by 5% from feeding of biochar (Table 2).

Daily live weight gain was improved 120% by supplementation with water spinach and by 27% due to biochar (Table 3; Figure 1). Water spinach improved DM feed conversion by 27%. There was a close relationship between live weight gain and feed conversion (Figure 3).

Figure 1. Supplements of water spinach and biochar increased the live weight gain of goats fed Bauhinia acuminate and cassava root chips

Figure 2. Supplements of water spinach and biochar improved the DM feed conversion of goats fed Bauhinia acuminate and cassava root chips

Figure 3. Relationship between live weight gain and feed conversion in goats fed Bauhinia foliage and cassava root chips supplemented or not with water spinach and biochar

Apparent digestibility and N retention

Apparent digestibility coefficients were increased by water spinach supplement for DM, OM and crude protein and by biochar for DM and OM (Table 4). Daily N retention and N retention as percent of N intake and N digested were all improved by supplementation with water spinach and biochar (Figures 4-6).

Figure 4. Supplements of water spinach and biochar increased the N retention by goats fed Bauhinia acuminata and cassava root chips

Figure 5. Supplements of water spinach and biochar improved the N retention as % of N intake by goats fed Bauhinia acuminata and cassava root chips

Figure 6. Supplements of water spinach and biochar improved the N retention as % of N digested by goats fed Bauhinia acuminata and cassava root chips

pH and Rumen ammonia

The rumen pH was not affected by supplements of water spinach and biochar (Table 5). Rumen ammonia was high for all diets and was increased by supplementation with water spinach, but was not affected by biochar (Figure 7). There was a close relationship between live weight gain and rumen ammonia concentration (Figure 8).

Figure 7. A supplement of water spinach increased rumen ammonia in goats fed Bauhinia acuminata

Figure 8. Relationship between live weight gain and rumen ammonia in goats fed Bauhinia foliage and cassava root chips supplemented or not with water spinach and biochar

The results of this experiment agree with the finding from: (i) Kongmanila et al (2011) that supplementation with water spinach increased the digestibility of mango foliage for growing goats, and (ii) Silivong and Preston (2015) that water spinach supplementation increased the apparent digestibility of DM, OM, crude protein, and N retention and the growth rate of goats fed Bauhinia acuminata foliage and molasses. Presumably the high content of soluble protein in water spinach furnished amino acids and peptides, required by micro-organisms for efficient rumen digestion, and which were in short supply in the basal diet of Bauhinia the protein of which is of low solubility.

Conclusions

• Goats fed a basal diet of Bauhinia acuminata and cassava root chips supplemented with water spinach and biochar grew faster and had better DM feed conversion and higher apparent digestibility of DM, OM and crude protein and higher N retention than goats fed only Bauhinia and cassava root chips.
  
  
• The greater concentration of rumen ammonia in the goats fed Bauhinia supplemented with water spinach, probably reflected the greater solubility of the crude protein in water spinach, which in turn led to faster growth rates.

Acknowledgements

This research was done by the senior author as part of the requirements for the PhD degree in Animal Production "Improving Livelihood and Food Security of the people in Lower Mekong Basin through Climate Change Mitigation", in Nong Lam University, Vietnam. The authors acknowledge support for this research from the MEKARN II project financed by Sida. Special thanks are given to Mr Phonesavath, Mr Sonepeth and Mr Khamlek who provided valuable help in the farm and laboratory.They also thank the Faculty of Agriculture and Forest Resource, Souphanouvong University for providing the facilities to carry out this research.

References

AOAC 1990 Official Methods of Analysis.Association of Official Analytical Chemists.15th Edition (K Helrick editor).Arlington pp 1230.

Daovy Kongmanila, Preston T R and Ledin Inger 2007 Chemical composition, digestibility and intake of some tropical foliage species used for goats. MSc Thesis, MEKARN-SLU http://www.mekarn.org/MSC2005-07/theses07/daov1.htm

DLF 2007 Department of Livestock and FisheriesMinistry of Agriculture and Forestry Vientiane Laos http://www.nsc.gov.la/Statistics/Selected%20Statistics/Agriculture/Lifestock.htm

Kongmanila D, Phommachanh K and Preston T R 2011 Effect on growth rate and digestibility in goats of supplementing a basal diet of mango foliage with fresh water spinach (Ipomoea aquatica). Livestock Research for Rural Development.Volume 23, Article #203.Retrieved December 16, 2014, from http://www.lrrd.org/lrrd23/10/daovy23203.htm

Lehmann J and Joseph S (Editors) 2009 Biochar for Environmental Management; Science and Technology.Earthscan, London, EC1N 8XA, UK, Sterling,VA 20166-2012, USA

Leng R A 1997 Tree foliage in ruminant nutrition.FAO, Animal Production and Health Paper. 139 http://www.fao.org/docrep/003/w7448e/w7448e00.htm

Leng R A 2014 Interactions between microbial consortia in biofilms: a paradigm shift in rumen microbial ecology and enteric methane mitigation. Animal Production Science.http://dx.doi.org/10.1071/AN133881

Leng R A, Preston T R and Inthapanya S 2012 : Biochar reduces enteric methane and improves growth and feed conversion in local “Yellow” cattle fed cassava root chips and fresh cassava foliage. Livestock Research for Rural Development. Volume 24, Article #199. http://www.lrrd.org/lrrd24/11/leng24199.htm

Minitab 2000 Minitab Software Release 16.0

Preston T R and Leng R A 2009 Matching ruminant production systems with available resources in the tropics and sub- tropics. Penambul Press: Armidale, Australia http://www.utafoundation.org/P&L/preston&leng.htm

Pathoummalangsy Khamparn and Preston T R 2006 Effect of a supplement of fresh water spinach (Ipomoea aquatica) on feed intake and digestibility in goats fed a basal diet of cassava foliage.Livestock Research for Rural Development.Volume 18, Article #35.Retrieved April 24, 2007, from http://www.cipav.org.co/lrrd/lrrd18/3/kham18035.htm

Preston T R, Do H Q, Khoa T D, Hao T P and Leng R A 2013 Protein solubility of fish meal and groundnut meal and methane production in an in vitro incubation. Livestock Research for Rural Development.Volume 25, Article #16.http://www.lrrd.org/lrrd25/1/hqdo25016.htm

Silivong P and Preston T R 2015 Growth performance of goats was improved when a basal diet of foliage of Bauhinia acuminata was supplemented with water spinach and biochar.Livestock Research for Rural Development.Volume 27, Article #58.Retrieved March 20, 2015, from http://www.lrrd.org/lrrd27/3/sili27058.html

Queiroz Siqueira C F de Vasconcelos Cabral D L, da Silva PeixotoSobrinho T J, Cavalcanti de Amorim E L, de MeloJ G, de Sousa Araújo T A and de Albuquerque U P 2012 Levels of tannins and flavonoids in medicinal plants: evaluating bioprospecting strategies. Evidence-Based Complementary and Alternative Medicine. Volume 2012, Article ID 434782 pp 7

Thu Hong N T and Lam N T 2011 Effect of Mimosa pigra and water spinach (Ipomoea aquatica) on intake, digestibility and growth of goats in the Mekong delta, Vietnam.Livestock Research for Rural Development.Volume 23, Article #150.Retrieved December 16, 2014, from http://www.lrrd.org/lrrd23/7/hong23150.htm

Received 21 January 2016; Accepted 27 April 2016; Published 1 May 2016

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