ACUMINATA AND MOLASSES OR CASSAVA ROOT CHIPS AS THE BASAL DIET
ABSTRACT
This chapter was combined two experiments (experiments 2 and 3) in order to study effects of water spinach and biochar on enteric methane emissions and growth performance of local goats fed Bauhinia acuminata and molasses or cassava root chip as the basal diet. Experiment 2: The aim of the experiment was to determine the effect of water spinach and biochar on enteric methane emissions, feed intake, digestibility, nitrogen retention and growth performance in local goats fed Bauhinia acuminata and molasses as basal diet. The experiment was arranged as a 2×2 factorial with 4
11.65±3.95kg and 5-6 months of age). They included 4 males (non-castrated) and 12 females. Factor 1 were: with or without water spinach; Factor 2 were: with or without biochar. The result shown that daily live weight gain, feed conversion, DM digestibility and N retention were improved by feeding water spinach and biochar. The higher value of rumen ammonia in goats fed water spinach reflected the greater solubility of the crude protein in the water spinach. Supplementation with water spinach led to a reduction in the methane/carbon dioxide ratio in the eructed breath of the goats but this criterion was not affected by biochar. Experiment 3: The aim of this experiments was to determine the effect of water spinach and biochar on feed intake, digestibility, N retention and growth performance in local goats fed Bauhinia acuminata and cassava root chips as basal diet. The experiment was arranged as a 2×2 factorial with 3 replications using twelve goats in individual pens (initial body live-weight 12.1±3.7kg and 5-6 months of age). They included 8 males (non-castrated) and 4 females. The result shown: Daily live weight gain, feed conversion, apparent digestibility of DM, OM, crude protein, and N retention were improved by supplements of water spinach and biochar. The higher value of rumen ammonia in goats fed water spinach reflected the greater solubility of the crude protein in the water spinach.
Key words: carbon dioxide, climate change, methane, 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 main feed resources for ruminants are native grasses, legumes and tree leaves that are available in the natural grassland and forests (Phengsavanh, 2003). The conventional feeding system for goats in Lao PDR is based mainly on the use of natural grasses. However, in the dry season, natural pasture decreases in nutritive value and improved grasses cannot grow.
Therefore, it is important to find an alternative feeding system because purchased supplements are too expensive for poor farmers. On the other hand, there are many trees and shrubs available. Preston and Leng, 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 negative feature of livestock is that they contribute some 18% of the greenhouse gases that are causing global warming (Steinfeld et al., 2006). Enteric methane from fermentative digestion is the main source of these emissions. Thus when new or modified feeding systems are being researched the effects of these changes on enteric methane emissions should be
monitored, in view of the need to reduce methane emissions so as to meet future targets for mitigating global warming.
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. The leaves of Bauhinia acuminata have 14.5% of protein of low solubility (22%). 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 acuminata is indicative of the binding action of tannins on this nutrient source (Silivong and Preston, 2015).
Daovy et al., 2007 reported that water spinach (Ipomoea aquatica) supplementation of low quality tree foliage (from Fig, Jujube and Mango trees) increased the DM and crude protein intake of goats, and improved the apparent digestibility and N retention. 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 ith increased DM digestibility and N retention when fresh water spinach was provided as a supplement (Pathoummalangsy and Preston, 2006).
Molasses is a source of highly fermentable carbohydrate (contains > 50% soluble sugars) and is very low in crude protein “<0.5% in DM” (Ffoulkes and Preston, 1978).
Cassava roots have high levels of energy (75 to 85% of soluble carbohydrate) and minimal levels of crude protein (2 to 3% CP); they have been used as a source of readily- fermentable energy (Kang et al., 2015; Polyorach et al., 2013; Wanapat et al., 2013a,b)
A positive approach to the problem of how to reduce methane emissions from live stock has been to incorporate a low level (1%) of biochar in the diet (Sangkhom et al., 2012; Leng et al., 2012a,b,c). Biochar is the product of incomplete carbonization of fibrous biomass at high temperatures (Lehmann and Joseph, 2009). It is a highly porous material which gives it valuable properties as a support mechanism for biofilms that may facilitate the adsorption of consortia of micro-organisms and nutrients (Leng, 2014).
In the research reported here, it was hypothesized that: (i) the performance of growing goats fed Bauhinia acuminata and molasses or cassava root chip as the basal diet would be improved by supplementation with water spinach as a rapidly fermentable protein source; and (ii) that incorporation of a low level of biochar in the diet might reduce enteric methane emissions.
MATERIALS AND METHODS Location
Two experiments were conducted in the Animal Science Farm and Laboratory of the Faculty of Agriculture and Forest Resource, Souphanouvong University, LuangPrabang Province, Lao PDR. The site is located 7.5 km from Luangprabang Town to the South-west, at an altitude of 385m above sea level.
Treatments and experimental design
The experimental plan was a 2×2 factorial arrangement in a Randomized Completely Block Design (RCBD) with 4 treatments and there were 4 replications of the experiment 2 and 3 replications of the experiment 3.
The factors applied to a basal diet of fresh Bauhinia acuminata foliage were:
- With or without water spinach (WS and No-WS) - With or without biochar (BC and No-BC)
Individual treatments were:
- BA = Bauhinia acuminata ad libitum
- BABC = Bauhinia acuminata ad libitum + 1% biochar on DM intake - BAWS = 70% Bauhinia acuminata and 30% water spinach on DM basis - BAWSBC = 70% Bauhinia acuminata and 30% water spinach + 1% biochar Biochar was given 1% on DM intake
+ In the experiment 2: Molasses diluted with fresh water by ratio of 1:9 (1 kg of molasses and 9 litters of fresh water) and was used as the carrier for the biochar and was given ad libitum on all diets.
+ In the experiment 3: 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 7:00 am.
Animals and housing
- Experiment 2: Sixteen local weaned goats with initial average body weight of 11.65±3.95kg and 5-6 months of age were used. They included 4 males (non-castrated) and 12 females.
- Experiment 3: Twelve weaned goats (local breed) with initial average body weight of 12.1±3.7kg and 5-6 months of age were used. They included 8 males (non-
castrated) and 4 females. These animals were purchased from Chomphet District Laungprabang Province.
In both experiments, goats were housed individual pens and made from local material such as: bamboo (dimensions of width 1 m, length 1 m and height 0.9 m) and 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.
Photo 1. Goats confined in the metabolism pens
Feed and management
Molases were purchased from Vientiane Province, cassava root was purchased from farmers around the Luangprabang 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 biochar was produced by burning rice husks in a top lit updraft (TLUD) gasifier stove (Olivier, 2010). It was ground to a particle size that passes through a 1 mm sieve. The foliages were offered twice daily at 07:30 and 16:00h by hanging in bunches above the feed trough (Photo 2)
Photo 2. Bauhinia acuminata foliage as presented to the goats
Data collection and measurements - Experiment 2:
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 four times, over 5 days periods at 20 day intervals (after 20, 40, 60 and 80 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, sub-samples were mixed together and ground with a coffee grinder. Samples of eructed gases were measured on the last day of the experiment, in the morning 2h after feeding. The goats were placed in a plastic-covered cage (Photo 3) and after a period of 10 minutes for equilibration with the surrounding air, the concentrations of methane and carbon dioxide were recorded over a 10 minute period, using a GASMET 4030 meter (Gasmet Technologies Oy, Pulttitie 8A, FI-00880 Helsinki, Finland).
Photo 3. Goats were confined in a plastic-lined cage for the measurement of the eructed gases with the Gasmet meter
Photo 4. Taking rumen fluid by stomach tube
- Experiment 3:
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, 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). Solubility of the protein in the leaves was determined by shaking 3g of dry leaf meal in 100 ml of M NaCl for 3h then filtering through Whatman No.4 filter paper, and determining the N content of the filtrate (Whitelaw et al., 1963).
Statistical analyses
The data were analysed statistically as a Randomize Complete Block Design
procedure of Minitab software version 16.0 (Minitab, 2014). The treatment least square means showing significant at difference at the probability level of P<0.05 were compared Turkey’s pair wise comparison procedure.
The statistical model used in the experiments 2 and 3:
- Growth study was:
Yijk = μ + Bk+ Pi + Aj + Pi*Aj+ eijk
Where:
Yijk is dependent variables μ is overall mean
Bk is the effect of live weight Pi is the effect of protein source Aj is the effect of biochar source
(P*A) ij is the interaction between source of protein and source of biochar eijk is random error
- Digestibility study was:
Yijk = μ + Ti + Pj + Ak + eijk
In where, Yijk = Dependent variables μ = Overall mean
Ti = Treatment effect (i=1-4) Pj = Column effect (j=1-4) Ak = Row effect (k=1-4) eijk = Random error
The relationship between N intake and N retention was developed by regression analyses. The best model was selected based on adjusted R2.
The methane to carbon dioxide ratios were used to calculate the reduction of methane production according to the formula proposed by Madsen et al., 2010:
Ratio CH4/CO2 = (a-b)/(c-d)
Where "a" is methane concentration in mixed eructed gas plus air
"c" is carbon dioxide concentration in mixed eructed gas plus air
"b" is methane in the air in the goat shed
"d" the carbon dioxide in goat shed air
The relationship between N intake and N retention was developed by regression analyses. The best model was selected based on adjusted R2.
RESULTS
Chemical composition
The concentrations of crude protein and ash and the solubility of the protein were lower, and of DM were higher, in Bauhinia acuminata than in water spinach (Table 1).
Table 1. Chemical composition of dietary ingredients (% in DM, except DM which is on fresh basis)
DM N*6.25 Ash Protein solubility Tannin NDF ADF
Bauhinia leaves 40.0 15.0 21.2 23.7 1.1 43.7 32.4
Bauhinia stem 38.1 12.3 4.29 - 42.7 31.5
Water spinach 8.16 18.3 9.74 69.4 42.3 33.3
Molasses 80.4 5.4 10.5
Cassava root chips 82.4 2.81 2.23 - - -
Biochar - - 38.3 - - -
- Experiment 2:
Feed intake, growth rate and feed conversion
DM intake expressed as a percentage of live weight was not affected by supplementation with biochar or water spinach (Table 2).
Table 2. Mean values of feed intake by goats fed Bauhinia acuminata supplemented with water spinach (WS) or biochar (BC) or not supplemented
PS p BCS
P SEM Interaction
WS No-WS BC No-BC SEM p
DM intake, g/d
Bauhinia 149 229 <0.001 164 214 <0.001 3.07 35.69 0.719 Water spinach 161 0 <0.001 82.0 79.2 0.025 0.87 6.25 0.683 Biochar 2.47 2.85 <0.001 5.31 0 <0.001 0.03 0.4 1 0.371 Total 526 455 <0.001 469 512 <0.001 3.77 47.67 0.558 Per kg LW 32.9 33.1 0.21 32.8 33.2 0.016 0.13 0.6 0.923 N*6.25, % in DM 12.5 10.3 11.5 11.5
BC: Biochar, BCS: Biochar source, d: day, g gram, Kg: Kilogram, LW: live weight, P: Probability value, PS: Protein source, SEM: Standard error of the mean with dferror: 9, WS: Water spinach.
Daily live weight gain and feed conversion were improved by feeding water spinach and by supplementation with biochar (Table 3; Figures 1 and 2). There was a close relationship between live weight gain and feed conversion ratio (Figure 4).
Table 3. Mean values for live weight, live weight change, feed DM intake and DM feed conversion for goats fed a basal diet of Bauhinia acuminata foliage and molasses
PS p BCS
p SEM Interaction
WS No-WS BC No-BC SEM p
Live weight, kg
In wt, kg 12.9 12.2 0.598 11.8 13.3 0.263 0.87 1.22 0.571
Fin wt, kg 18.6 15.3 0.019 16.5 17.4 0.495 0.87 1.22 0.382
LWG, g/d 51.4 28.7 <0.001 43.7 36.5 0.047 2.32 3.28 0.543 DMI, g/d 526 455 <0.001 469 512 <0.001 3.77 47.67 0.558
FCR, g/g 10.7 16.2 0.014 11.4 15.5 0.055 1.34 1.90 0.580
BC: Biochar, BCS: Biochar source, DMI: DM intake, FCR: DM feed conversion, Fin wt: Final weight, In wt: Initial weight, Kg: Kilogram, LWG: Live weight gain, P: Probability value, PS: Protein source, SEM: Standard error of the mean with dferror: 9, WS: Water spinach.
Object 20
Object 23
Figure 1. Effect of biochar on live weight gain of goats fed Bauhinia acuminate and molasses with and without water spinach
Figure 2. Effect of supplementation with water spinach and biochar, separately or together, on the growth rate of goats fed a basal diet of foliage from Bauhinia acuminata and molasses
Object 25
Object 27
Figure 3. Effect of biochar compared with water spinach on feed conversion of goats fed Bauhinia acuminata and molasses as
basal diet
Figure 4. Relationship between live weight gain and feed conversion in goats fed Bauhinia acuminata foliage and molasses supplemented or not with water spinach and biochar
Apparent digestibility and n retention
Supplementing the basal diet of Bauhinia acuminata and molasses with water spinach increased the apparent digestibility of DM, OM and crude protein, but there were no differences due to biochar (Table 4). Daily N retention, N retention as percent of N intake and of N digested were all improved by supplementation with water spinach. There was a tendency for biochar to improve daily N retention (p=0.082) and this effect was significant when N retention was expressed as a percent of N intake or of N digested (Figures 5 and 6).
Table 4. Mean values of apparent digestibility and N balance in goats fed Bauhinia acuminata and molasses supplemented with water spinach (WS) and biochar (BC) or not supplemented (No-WS; No-BC)
PS
p
BCS
p SEM
Interaction
WS No-
WS BC No-
BC SEM p
Apparent digestibility, %
DM 72.0 64.5 <0.001 69.1 67.5 0.100 0.68 1.68 0843
OM 75.0 67.4 <0.001 71.5 70.9 0.579 0.74 2.10 0.591
N*6.25 69.2 43.8 <0.001 55.0 57.9 0.294 1.98 6.48 0.502 N balance, g/day
Intake 11.1 7.0 <0.001 8.8 9.3 0.296 0.32 1.04 0.502
Feces 3.2 2.3 <0.001 2.5 3.0 0.021 0.16 0.53 0.583
Urine 1.8 1.4 <0.001 1.4 1.8 0.007 0.09 0.29 0.371
Retention 6.1 3.4 <0.001 4.9 4.5 0.082 0.16 0.41 0.719
N retention as:
% N intake 55.0 50.0 0.008 56.2 48.8 <0.001 1.32 3.73 0.324
% N digested 76.8 72.1 0.009 77.1 71.7 0.003 1.25 3.76 0.440
BC: Biochar, BCS: Biochar source, DM: Dry matter, Kg: Kilogram, N:
Nitrogen, OM: Organic matter, P: Probability value, PS: Protein source, SEM:
Standard error of the mean with dferror: 9, WS: Water spinach
Object 30 Object 32
Figure 5. Effect of biochar on N retention as % N intake of goats fed Bauhinia acuminata and molasses as basal diet with or without water spinach
Figure 6. Effect of biochar on N retention as % N digested of goats fed Bauhinia acuminata and molasses as basal diet with or without water spinach
Rumen ammonia, pH and methane to carbon dioxide ratio
Rumen pH did not differ among the diets (Table 5). Rumen ammonia, which was high on all diets, was increased by supplementation with water spinach but was not affected by biochar.
Table 5. Mean values of rumen pH and ammonia, and ratio of methane to carbon dioxide in eructed breath of goats fed Bauhinia acuminata and molasses supplemented with water spinach (WS) and biochar (BC) or not supplemented (No- WS; No-BC)
PS
p
BCS p SEM Interaction
WS No-WS BC No-BC SEM p
Rumen pH 7.08 7.03 0.465 7.04 7.06 0.756 0.05 0.063 0.727
NH3, mg/liter 397 298 <0.001 347 347 0.999 9.70 13.71 0.935 CH4:CO2 0.0211 0.0292 0.043 0.0243 0.0260 0.641 0.003 0.0036 0.800
BC: Biochar, BCS: Biochar source, CH4: Methane, CO2: Carbon dioxide, NH3: Ammonia, pH: Percentage of hydrogen ion, P: Probability value, PS: Protein source, SEM: Standard error of the mean with dferror: 9, WS: Water spinach.
Object 34
Figure 7. Effect of supplementation with water spinach and biochar, separately or together, on rumen ammonia of goats fed a basal diet of foliage from Bauhinia acuminate and molasses
The ratio of methane to carbon dioxide in eructed breath of the goats was lower in the eructed breath of the goats supplemented with water spinach and not affected by supplementation with biochar (Figures 8 and 9).
Object 36 Object 38
Figure 8. Effect of water spinach on ratio of methane to carbon dioxide in eructed gas from goats fed either Bauhinia acuminata and molasses as basal diet
Figure 9. Effect of biochar on ratio of methane to carbon dioxide in eructed gas from goats fed either Bauhinia acuminata and molasses as basal diet
Experiment 3: