AND GROWTH PERFORMANCE IN GOAT FED BAUHINIA ACUMINATA PLUS CASSAVA ROOT CHIPS AS THE BASAL DIET
ABSTRACT
The aim of the study was to determine the effect of different protein sources (cassava foliage or water spinach, with or without of brewers’ grains (5% of diet DM)) on feed intake, digestibility, N balance and growth performance of local goats. In the digestibility study the design was a 4×4 Latin Square with 4 female goats and 4 periods each of 12 days: 7 days for adaptation and 5 days for collection of feed refusals, feces and urine. In the growth study the design was a random block with 4 replications of the two factors in a 2×2 factorial design, with sixteen goats (balanced males and females) with initial body weight of 14.4 ± 1.45 kg and 5-6 months of age.
goats by 44% and the DM feed conversion by 25% when the protein supplement was cassava foliage. Comparable data when water spinach was the protein supplement were 11 and 5%. It is suggested that brewers’ grains, a fermented by-product from brewing “beer”, act as a prebiotic when added to a diet containing potentially toxic elements such as the cyanogenic glucosides present in cassava foliage.
Key words: biochar, bauhinia acuminata, prebiotics, protein solubility, synergism INTRODUCTION
Research by Silivong and Preston (2015) showed that the growth rate of goats fed foliage of the legume tree Bauhinia acuminata was increased by supplementation with fresh water spinach and biochar. The protein in water spinach is very soluble (Silivong and Preston, 2015) and it is thought that its role in improving the utilization of foliages of low digestibility, such as Bauhinia acuminata, is because the water spinach acts as a source of readily available nitrogenous compounds for rumen micro- organisms (Silivong and Preston 2015, 2016).
The positive role of biochar as a supplement in ruminant diets is thought to reflect another feature of ruminant nutrition, namely as a support mechanism for biofilms that host consortia of micro-organisms facilitating the utilization of nutrients with major benefits for the process of rumen fermentation (Leng, 2014). In this role, it appears that biochar is acting as a “prebiotic”, by promoting synergism between nutrients and micro-organisms in the animal’s digestive system.
A similar synergism appears to be the explanation for the beneficial effects on growth rates of cattle (Binh et al., 2017) and goats (Sina et al., 2017) of small proportions in the diet of brewers’ grains, a byproduct derived from the industrial brewing of beer. The research with goats (Sina et al., 2017) highlighted a major interaction between the effect of the supplementary brewers’ grains and the nature of the basal diet. The improvement in growth rate due to addition of brewers’ grains was 130% when the basal diet was fresh cassava foliage but only 30% when the basal diet was water spinach (Sina et al., 2017).
The hypothesis that was tested in the present experiment was that goats fed foliage of the legume tree Bauhinia acuminata would respond positively in growth rate and feed conversion to a supplement of brewers’ grains, and that the degree of response would be greater when cassava foliage, rather than water spinach, was the complementary source of protein.
MATERIALS AND METHODS LOCATION
The experiments were conducted in the Department of Animal Science Farm, Souphanouvong University, Luang Prang Province, Lao PDR.
TREATMENTS AND EXPERIMENTAL DESIGN
The basal diet was fresh foliage from the legume tree Bauhinia acuminata fed ad libitum, supplemented with biochar (1% of diet DM) and cassava root chips (4% of diet DM).
The treatments in a 2×2 factorial arrangement were:
Source of protein-rich foliage:
- 30% of DM feed intake (Water spinach: WS) - 30% of DM feed intake (Cassava foliage: CF) Supplementary brewers’ grains:
- 4% of DM feed intake (Brewer’s grains: BG) - No supplement (No-BG)
In the digestibility study (Table 1) the design was a 4×4 Latin Square with 4 male goats and 4 periods each of 12 days: 7 days for adaptation and 5 days for collection of feed refusals, feces and urine. The goats (local breed) weighed 15.5±0.65 kg and were 5-6 months of age. They were purchased from farmers around Luangprabang city. They were housed individually in metabolism cages made from bamboo (dimensions of width 0.8 m, length 0.9 m and height 1 m), designed to collect separately feces and urine.
Table 1. Layout of the digestibility/N retention study
Period Goat 1 Goat 2 Goat 3 Goat 4
1 BAWSBG BAWS BACFBG BACF
2 BACF BAWSBG BAWS BACFBG
3 BACFBG BACF BAWSBG BAWS
4 BAWS BACFBG BACF BAWSBG
BA: Bauhinia acuminata
In the growth study the design was a Randomized Completely Block Design (RCBD) with 4 replications of the two factors in a 2×2 factorial design, with sixteen goats (balanced males and females) with initial body weight of 14.4 ± 1.45 kg and 5-6 months of age. They were housed in individual pens made from wood and bamboo.
In both studies, the goats were vaccinated against Pasteurellosis and Foot and Mouth disease and were de-wormed before the start of the experiment.
FEEDING AND MANAGEMENT
In both studies: Foliages of Bauhinia acuminata and water spinach (Ipomoea aquatica) were collected daily from natural stands in and around the University campus. Cassava (Manihot esculenta Crantz) foliage was collected daily from a demonstration plot in the Department of Animal Science Farm. Cassava root was harvested from the demonstration plot in the department of Animal Science Farm. It was chopped into small pieces and exposed to sunlight for 48h to reduce the moisture to about 15%. Brewers’ grains were purchased from a brewery in Vientiane city.
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 biochar was mixed with the cassava root chips and fed from a plastic bucket. Bauhinia acuminata foliage, water spinach and cassava foliage were hung in bunches above the feed trough (Photos 1-3). Fresh feeds were offered twice daily at 07:30 and 16:00h. Water was freely available.
Photo 1. Cassava foliage
hanging above the feed trough
Photo 2. Water spinach
hanging above the feed trough
Photo 3.
Bauhinia
acuminata hanging
above the feed trough
MEASUREMENTS
Metabolism study: Live weight was recorded in the morning before feeding at the beginning and at the end of each period. Feeds offered, and refusals were collected daily during the 5 days of the collection period. Urine was collected in buckets with 20 ml of a solution of sulphuric acid to ensure a pH of less than 4 (10% sulphuric acid concentrate + 90% distilled water). Feces and urine were collected daily and stored in the refrigerator (4-8ºC) until the end of each period, when sub-samples were mixed together.
Photo 4. Goats were presented in the metabolism pen
Growth study
Live weight was recorded in the morning before feeding at the beginning and at 10-day intervals until the end of the 90-day experiment. Live weight gain was calculated from the linear regression of live weight (Y) on days from the start of the experiment (X). Feed consumption was recorded daily. Refusals were collected from individual animals every morning before offering new feed. Samples of Bauhinia acuminata, water spinach and cassava foliage (offered and residues) were separated into stems and leaves (containing attached petioles). Representative samples of each component were stored at -18°C until they were analysed. Samples of rumen fluid were taken on the last day of the experiment, using a stomach tube.
CHEMICAL ANALYSES
The samples of feeds offered and refused were analysed for DM, NDF, ADF, N and ash according to AOAC (1990) methods. The pH of rumen fluid was measured with a digital pH meter, prior to addition of sulphuric acid for subsequent analysis of ammonia by steam distillation (AOAC, 1990) and VFA by high pressure liquid chromatography (Water model 484 UV detector; column novapak C18; column size 3.9 mm x 300 mm; mobile phase 10 mM H2 PO4 [pH 2.5]) (Samuel et al., 1997).
Solubility of the protein in the diet components was determined by extraction with M NaCl (Whitelaw et al., 1961).
STATISTICAL ANALYSES Metabolism study
The data were analyzed by the general linear model (GLM) in the ANOVA program of the Minitab software (Minitab, 2014).
The statistical model used in the 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 Growth study
The statistical model was:
Yijk = μ + Bk + Pi + Aj + P i*Aj+ eijk
Where:
Yijk is dependent variables μ is overall mean
Bk is the effect of live weight
Pi is the effect of foliages source (water spinach and cassava foliage) Aj is the effect of brewers’ grains source
(P*A) ij is the interaction between source of foliages and source of brewers’ grains eijk is random error
RESULTS
Cheminal composition of diet components
The low values for solubility of the protein in the leaves of Bauhinia acuminata and cassava, and the high values for the leaves of water spinach (Table 2), are in agreement with previous observations (Silivong and Preston, 2016) and are assumed to reflect different levels of tannin-rich compounds in the leaves of all three species.
Table 2. Chemical composition of dietary ingredients (% in DM, except DM which
is on fresh basis)
DM N*6.25 Ash Protein solubility, % NDF ADF
Bauhinia leaves 40.0 15.0 21.2 23.7 43.7 32.4
Bauhinia stem 38.1 12.3 4.29 - 42.7 31.5
Cassava leaves 32.1 22.2 4.48 31.4 48.7 34.4
Cassava petiole 16.8 16.7 6.39 - 48.3 38.6
Cassava root chips 82.4 2.81 2.23 - - -
Water spinach 8.16 18.3 9.74 69.4 42.3 33.3
Brewers’ grains 28.7 27.2 38.1 - 40.7 29.5
Biochar - - 38.3 - - -
Metabolism study
The two factors had contrasting effects on digestibility of DM and on daily N retention (Table 3). Supplementation with brewers’ grains increased the digestibility of DM but the effect was more pronounced when cassava foliage was the source of additional protein as compared with water spinach. Daily N retention was similar for both foliages in the absence of brewers’ grains but, when brewers’ grains were added, N retention was greater with cassava than with water spinach (Figure 1).
Table 3. Mean values of apparent digestibility and N balance in goats fed Bauhinia acuminata supplemented with water spinach or cassava foliage, with (BG) and without (No-BG) brewers’ grains
Items
CF WS SEM p
No-BG BG No-BG BG SEM SEM Foliage*BG P Foliage P BG P Foliage*BG
Apparent digestibility, %
DM 68.4 74.9 69.9 72.3 0.60 0.86 0.558 <0.001 0.035
N balance, g/day
Intake 14.0 14.8 13.8 14.1 0.45 0.63 0.474 0.414 0.619
Feces 4.8 3.8 4.7 4.5 0.34 0.48 0.545 0.199 0.393
Urine 2.9 2.3 2.5 2.2 0.28 0.40 0.47 0.245 0.715
N retention as:
% N intake 44.8 59.5 48.2 53.0 1.80 2.54 0.555 0.002 0.073
% N digested 68.6 79.2 73.0 78.1 2.12 2.99 0.585 0.022 0.368
BG: Brewer’s grain, CF: Cassava foliage, d: day, g: Gram, No-BG: Non- Brewer’s grain, P: Probability value, SEM: Standard error of the mean with dferror: 0, WS: Water spinach
Object 56 Object 58
Figure 1. Effect of brewer’s grain on N retention in goats fed water spinach or cassava foliage as supplementary protein source
Figure 2. Effect of brewer’s grain on N retention as % of digested N in goats fed Bauhinia acuminata and water spinach or cassava foliage as supplementary protein source
Growth study
The Bauhinia acuminata foliage accounted for two thirds of the total DM consumed (Table 4; Figure 3). Other components were in similar proportions in each of the diets, except for the brewers’ grains which was slightly higher (5% of diet DM) compared with the planned level of 4% of diet DM. Addition of the brewers’ grains resulted in a small increase in diet crude protein content from 13.6 to 14.2% and from 13.8 to 14.5%, for the cassava foliage and water spinach treatments, respectively.
Table 4. Mean values of feed intake by goats fed Bauhinia acuminata plus cassava root
chip supplemented with water spinach or cassava foliage and/or brewer’s grain
Items CF WS SEM p
No-BG BG No-BG BG SEM SEM Foliage*BG P Foliage P BG P Foliage*BG
DM intake, g/d
Bauhinia 395 403 380 384 1.94 2.74 <0.001 0.026 0.483
Water spinach - - 171 171 0.39 0.55 - 0.988 0.988
Cassava foliage 49 54 - - 0.43 0.60 - - -
Brewer’s grain - 0.8 - 1.5 0.12 0.16 0.045 - 0.045
Cassava root chip 1.6 2.5 2.2 2.3 0.10 0.14 0.130 <0.001 0.009 Biochar 7.9 8.1 8.0 8.1 0.02 0.03 0.130 <0.001 0.009 Total, g/day 583 628 591 627 2.55 3.61 0.375 <0.001 0.221 DM intake g/kg LW 34.4 35.2 34.0 35.6 0.10 0.15 0.911 <0.001 0.010
BG: Brewer’s grain, CF: Cassava foliage, d: day, g: Gram, Kg: Kilogram, LW:
Live weight, No-BG: Non-Brewer’s grain, P: Probability value, SEM: Standard error of the mean with dferror: 9, WS: Water spinach
Object 60
Figure 3. Proportions of dietary components in each treatment
There was an interaction between the effects of the two dietary factors on DM intake, growth rate and DM feed conversion (Table 5). When the protein-rich foliage was from cassava, the supplement of brewers’ grains increased the DM intake and the growth rate and improved the feed conversion but did not affect these criteria when the supplementary protein source was water spinach (Figures 3 and 4). This result is in line with the findings of Sina et al., 2017 who supplemented brewers’ grains (5% of diet DM) to goats fed fresh cassava foliage or water spinach, as the sole diet. In that study there was a 129% increase in live weight gain when brewers’ grains were added to cassava foliage, compared with only 25% improvement on the water spinach diet.
Table 5. Mean values for live weight, live weight change, DM intake and DM feed conversion for goats fed Bauhinia acuminata supplemented with cassava or water spinach foliage, with or without brewers’ grains (interaction effects)
Items CF WS SEM p
BG BG M Foliage*BG Foliage Foliage*BG
Live weight, kg
Initial 14.4 14.
5 14.5 14.
4 0.39 0.54 0.893 0.822 0.964
Final 20.7 20.
9 20.1 21.
4 0.59 0.83 0.826 0.134 0.378
Daily gain, g/day 58 83 68 75 2.61 3.69 0.858 0.001 0.032
DM intake, g/kg
LW 34.4 35.
2 34.0 35.
6 0.10 0.15 0.911 <0.00
1 0.010
DM feed
conversion 10.1 7.6 8.8 8.4 0.19 0.27 0.397 <0.00
1 0.002
BG: Brewer’s grain, CF: Cassava foliage, d: day, g: Gram, Kg: Kilogram, LW:
Live weight, No-BG: Non-Brewer’s grain, P: Probability value, SEM: Standard error of the mean with dferror: 9, WS: Water spinach
Object 62
Object 64
Figure 4. Effect of a supplement of brewers’ grains on live weight gain of goats fed Bauhinia acuminata in combination with cassava foliage (CF) or water spinach (WS).
Figure 5. Effect of a supplement of brewers’ grains on DM feed conversion of goats fed Bauhinia acuminata in combination with cassava foliage or water spinach.
The higher values for rumen ammonia on the diets with water spinach (Table 6) were to be expected in view of the greater solubility of the protein in water spinach compared with cassava foliage (Table 2). However, on all diets, ammonia levels were sufficiently high to support normal rumen function. On each foliage source, rumen ammonia values were higher when brewers’ grains were included in the diet.
There were minor differences in molar proportions of the VFA, and the Ac:Pr ratio, apparently related to the treatments; however, the small order of magnitude of the differences means they are unlikely to be of importance in relation to animal performance.
Table 6. Molar VFA proportions in rumen fluid from goats fed Bauhinia acuminata supplemented with water spinach or cassava foliage, with and without brewers’ grains
Items CF WS SEM p
No-BG BG No-BG BG SEM SEM
Foliage*BG P Foliage P BG P Foliage*BG
Molar %
Acetic 65.55 64.93 66.28 64.85 0.20 0.28 0.263 0.003 0.174 Propionic 24.83 23.50 24.08 24.60 0.21 0.29 0.56 0.196 0.008 Butyric 9.63 11.58 9.65 10.80 0.05 0.07 <0.001 <0.001 <0.001 Ac:Pr ratio 2.64 2.76 2.75 2.64 0.03 0.04 0.862 0.949 0.017
Rumen pH 7.06 7.05 6.99 6.90 0.02 0.03 0.01 0.166 0.233
NH3, mg/liter 186 194 215 232 1.31 1.85 <0.001 <0.001 0.003
BG: Brewer’s grain, CF: Cassava foliage, NH3: Ammonia, No-BG: Non-Brewer’s grain, P: Probability value, pH: Percentage of Hydrogen Ion, SEM: Standard error of the mean with dferror: 9, VFA: Volatile Fatty Acids, WS: Water spinach
DISCUSSION
We propose that the interaction in the degree of improved animal performance, according to whether the brewers’ grains were added to the diet with cassava foliage, compared with the diet containing water spinach, was because the brewers’ grains act as a prebiotic when included in diets containing potentially toxic elements such as the cyanogenic glucosides present in cassava foliage. A similar explanation can be applied to the effects of “Kilao” (the byproduct from the fermentation/distillation of “rice wine”) in increasing growth and feed conversion of cattle fed ensiled cassava root and cassava foliage (Sengsouly and Preston, 2016).
The improved performance appears to be manifested by increased diet digestibility and improved biological value of the digested protein. The greater response to brewers’ grains when cassava foliage was fed, compared with water spinach, could be because of enhanced capacity to detoxify the cyanogenic glucosides present in cassava foliage as reported by Binh et al., 2017.
CONCLUSIONS
- Supplementing growing goats with brewers’ grains (5% of diet DM) increased diet digestibility and the biological value of the absorbed protein, resulting in improvement of live weight gain of 44% and in DM feed conversion of 25% when the basal diet was a legume tree foliage (Bauhinia acuminata) and the protein supplement was cassava foliage. Comparable data when water spinach was the protein supplement were relative improvements of 11 and 5%.
- It is proposed that brewers’ grains, a fermented byproduct from brewing
“beer”, act as a prebiotic when added to a diet containing potentially toxic elements such as the cyanogenic glucosides present in cassava foliage.
REFERENCES
AOAC., 1990. Official Methods of Analysis. Association of Official Analytical Chemists. 15th Edition (K Helrick editor). Arlington pp 1230.
Binh, P.L.T., Preston, T.R., Duong, K.N. and Leng, R.A., 2017. A low concentration (4% in diet dry matter) of brewers’ grains improves the growth rate and reduces thiocyanate excretion of cattle fed cassava pulp-urea and “bitter” cassava foliage. Livestock Research for Rural Development. Volume 29, Article #104.
http://www.lrrd.org/lrrd29/5/phuo29104.html
Leng, R.A., 2014. Interactions between microbial consortia in biofilms: a paradigm shift in rumen microbial ecology and enteric methane mitigation. Animal Production Science.54 (5) 519-543 http://dx.doi.org/10.1071/AN13381Animal Biosciences
Minitab., 2014. Minitab Software Release 16.0
Olivier, P., 2010. The Small-Scale Production of Food, Fuel, Feed and Fertilizer; a Strategy for the Sustainable Management of Waste.
http://www.mekarn.org/workshops/pakse/html/olivier.docx
Samuel, M., Sagathewan, S., Thomus, J. and Mathen, G., 1997. An HPLC method for estimation of volatile fatty acids of rumen fluid. Indian Journal of Animal Science 67:805-807.
Silivong, P. and Preston, T.R., 2015. Growth performance of goats was improved when a basal diet of foliage of Bauhinia accuminata 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
Silivong, P. and Preston, T.R., 2016. Supplements of water spinach (Ipomoea aquatica) and biochar improved feed intake, digestibility, N retention and growth performance of goats fed foliage of Bauhinia accuminata as the basal diet. Livestock Research for Rural Development. Volume 28, Article #98. Retrieved June 9, 2016, from
http://www.lrrd.org/lrrd28/5/sili28098.html
Sengsouly, P. and Preston, T.R., 2016. Effect of rice-wine distillers’ byproduct and biochar on growth performance and methane emissions in local “Yellow” cattle fed ensiled cassava root, urea, cassava foliage and rice straw.Livestock Research for Rural Development. Volume 28, Article #178. Retrieved June 1, 2017, from
http://www.lrrd.org/lrrd28/10/seng28178.html
Sina, V., Preston, T.R. and Tham, T.H., 2017. Brewers’ grains have a synergistic effect on growth rate of goats fed fresh cassava foliage (Manihot esculenta Crantz) as basal diet. Livestock Research for Rural Development. Volume 29, Article
#137. Retrieved July 3, 2017, from http://www.lrrd.org/lrrd29/7/sina29137.html
Whitelaw, F.G., Preston, T.R. and Dawson, G.S., 1961. The nutrition of the early weaned calf, 2: A comparison of commercial groundnut meal, heat-treated groundnut meal and fish meal as the major protein source in the diet, Animal Production 3:127.
CHARPTER 5
EFFECT OF SWEET OR BITTER CASSAVA LEAVES AND BIOCHAR ON METHANE PRODUCTION IN AN IN VITRO INCUBATION WITH SUBSTRATES OF BAUHINIA ACUMINATA AND WATER SPINACH
(IPOMOEA AQUATICA)
ABSTRACT
The aim of this study was to determine the effect of biochar, leaf meal from sweet and bitter cassava leaves on methane production in an in vitro incubation of Bauhinia acuminata and water spinach as basal substrate. The experimental design was a 2×2 factorial arrangement of 4 treatments (leaf meal of sweet or bitter cassava;
with and without biochar) with 4 replications. Measurements were made of gas production, percent methane in the gas and DM digested after incubation periods of 6, 12, 18 and 24h. The result shown that increasing the length of the incubation increased methane concentration in the gas and methane produced per unit substrate digested.
The methane content of the gas was reduced when leaves of bitter cassava replaced leaves of sweet cassava as protein source and when 1% of biochar was added to the substrate. The magnitude of the differences was relatively small but consistent for all incubation times. The proportion of the substrate DM that was digested during the incubation was increased when biochar was included in the substrate and reduced when the protein supplement was leaf meal from bitter compared with sweet cassava.
It is concluded that the higher levels of cyanogenic glucosides (precursors of hydrocyanic acid HCN) in the leaves from bitter compared with sweet cassava were the reasons for the reduction in digestibility of the substrate and in the production of methane during the in vitro incubations.
Key words: biochar, cyanogenic glucosides, fermentation, greenhouse gas, HCN, incubation
INTRODUCTION
Reducing GHG emissions from agriculture, especially from livestock, is a priority in order to reduce global warming (Sejian et al., 2010). Ruminants - cattle, buffalo, sheep and goats - are the major contributors of methane emissions from the agriculture sector (Lassey, 2007). There is therefore a need to develop feeding systems for ruminants that will result in reduced emissions of methane gas from the enteric fermentation in these animals. Promising ways to do this are: (i) by the feeding of biochar (Leng et al., 2012) derived from the carbonization of fibrous wastes (Orosco et al., 2018); and (ii) using as protein supplement the foliage from bitter as opposed to sweet cassava (Phuong et al., 2012).