anti-The varieties used for industrial starch production are known as “bitter” varieties due tothe high content of cyanogenic glucosides that are converted into the highly toxic hydrocya
Trang 1HUE UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY
PHANTHAVONG VONGSAMPHANH
CASSAVA BY-PRODUCT AS POTENTIAL FEED SOURCE
FOR YELLOW CATTLE IN LAO PDR
DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES
HUE, 2019
Trang 2HUE UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY
PHANTHAVONG VONGSAMPHANH
CASSAVA BY-PRODUCT AS POTENTIAL FEED SOURCE
FOR YELLOW CATTLE IN LAO PDR
SPECIALIZATION: ANIMAL SCIENCES
CODE: 9620105 DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES
SUPERVISOR 1: ASSOCIATE PROFESSOR DR NGUYEN XUAN BA SUPERVISOR 2: DR DINH VAN DUNG
HUE, 2019
Trang 31 PROBLEM STATEMENT
According to the MAF (2017), there are 1.98 million cattle in Lao PDR mostly dominated
by indigenous "Yellow" cattle (Bos indicus) 95% of the total cattle population is owned by
smallholders 297,000 of farm households or 38% of the total farm household have cattle The majority of the cattle production is based on low input integrated with various types of crop production systems at the household level Many rural households with cattle are currently best considered to be “livestock keepers” rather than “livestock producers"
It is estimated that the five cassava starch factories have a yearly production of 55,000 tons of pulp and more than 200.000 tone of cassava pulp is stored in open pits (resulting in local pollution problems) Cassava foliage by-product from cassava plantation which annually is left
in the field after root harvesting (around 1,250 tons from 63,260 ha of harvested area) (MAF 2017), in addition the availability of rice straw is 3 million tons per year and brewers’ grains the residue of beer processing are around 150,000 tons per year from four brewery factories over the whole country All these all resources would be sufficient to fatten some 200,000 beef cattle per year with an added value to the Lao economy of USD $36 million
In view of the decrease of natural resources and limitations in access to conventional feeds
is timely to introduce cassava byproduct which is cheap and less competitive - cattle can convert
it to a higher production yield and end product quality It has shown that cassava pulp composes 15.8-23.4% dry matter (DM) with 1.2-2.8% crude protein (CP), 55.0-74.4% nitrogen-free
extract, 0.1-2.4% fat, 17.9-24.0% crude fiber and 1.7-2.8% ash, on DM basis (Yimmongkol, 2009; Pilajun and Wanapat, 2018), and according to Sriroth et al (2000)cassava pulp is rich in starch with 69% in DM, Keaokliang O et al (2018) reported the total digestible nutrients,
digestible energy and ME contents of cassava pulp were 74.4%, 12.9 MJ/kg DM and 11.3 MJ/kg
DM respectively, it suitable as the energy component of an intensive feeding system for fatteningcattle it would need to be supplemented only with urea, a source of roughage and bypass protein and minerals, as has been demonstrated for other low-protein, carbohydrate-rich tropical feeds such as molasses(Preston 1971) and sugar cane (Preston et al., 1976; Ffoulkes and Preston 1978)
Cassava foliage can be harvested from 4 months old without any effect on average totalbiomass and storage root yields, with non-significant effects on both height and stem diameter(Munyahali et al 2017) For every tonne of roots that are harvested there are an additional 600 kg
of stems and leaves which also have a high potential feeding value for cattle (Ffoulkes andPreston 1978; Wanapat et al., 1997), and goats (Ho Quang Do et al., 2002) The protein content
in cassava leaves is around 22-25% in dry matter (DM), Cassava foliage also contains nutritional factors (ANF’s) such as cyanogenic glucosides and tannins Cyanogenic glucosidescan give rise to toxic hydroxyanic (HCN) by the action of either enzymatic activity in damagedplant tissue or within the digestive tract of the animal (Van Soest, 1994)
anti-The varieties used for industrial starch production are known as “bitter” varieties due tothe high content of cyanogenic glucosides that are converted into the highly toxic hydrocyanicacid (HCN >50mg/kg as fresh), The cassava varieties that are planted for human consumptionare known as “sweet” varieties as they have a lower content of (HCN < 50mg/kg as as fresh).Much research on evaluating the use of cassava for livestock feeding has thus concentrated onmethods to reduce the HCN content, such as sun-drying and ensiling (Phuc et al 1995).Development of cassava by-product to cattle feed sources has been negligible and not beenstudied previously under Lao conditions especially cassava pulp storage in open pit
Trang 42 THE OBJECTIVES OF THE STUDY
1 To evaluate the potential of feeding value of the storage cassava pulp in an open pit
2 To measure the response of cattle performance on bitter cassava foliage or/and brewers’ grains as a source of bypass protein and fiber supplements to cassava pulp-urea basal diet for feeding local yellow cattle
3 To evaluate the effect of different varieties of cassava leaves and supplementation with
brewers' grains (0 or 4%) on methane production in an in vitro production of cassava pulp –
urea as the main substrate
4 To find out the most efficient/economic methodology for incorporating bitter cassava foliage
as the protein-fiber source in the cassava pulp for a cattle fattening system
3 SIGNIFICANCE / INNOVATION OF THE DISSERTATION
- Cassava pulp about 100.000 tones in open pit at cassava starch factory can be high potential feed in term of nutrition value and production for fattening cattle in Lao condition and could
be used as basal diet
- The bypass protein and fiber source can be provided in the form of either: (i) brewers’ grains or: (ii) bitter cassava foliage combines with brewers’ grains (50:50) will give good
performance
- In vitro rumen incubations of a substrate of cassava pulp showed that: methane production
was decreased by: supplementation with cassava leaves of bitter rather than sweet varieties; and by the addition of low levels of brewers’ grains (4%)
- Cassava pulp through various methodologies such as separate, fermented and ensilage feed was shown to have potential for developing intensive fattening of cattle in feedlot and also in small holders in Lao PDR
CHAPTER 1: LITERATURE REVIEW
In this chapter, there are main points following (i) cattle production system in Lao PDR; (ii)
cattle feed management; (iii) Challenge and opportunities for cattle production in Lao PDR; (iv)
rumen microbial ecosystem; (v) manipulated feeding practices and (vi) cassava by-product forcattle feeding The literature review shows a potential to use cassava by-product as local feedresources for cattle production in Lao PDR for the purposes of increasing animal performance
CHAPTER 2: CASSAVA PULP IN OPEN PIT AS POTENTIAL FEED FOR FATTENING CATTLE IN LAO PDR
INTRODUCTION
The Lao-Indochina Cassava Factory at Vientiane Capital, processes up to 100.000 tons per year of cassava roots into starch for export During the 6-7 month harvest season from October toMarch-April this amounts to 480 tons of roots daily The byproduct remaining after starch
extraction, known as cassava pulp, represents from 10 to 15% of the original weight of fresh roots (Sriroth et al 2000) Over the past 4 years, very little of the cassava pulp was bought by farmers and almost all of it had been stored in a pit adjacent to the factory, which had not been covered or protected in any way
The cassava pulp is composed almost completely of non-structural carbohydrate, 65% of which is starch according to Sriroth et al (2000), and is very low in crude protein (less than 3% in
Trang 5the dry matter) and in minerals To take advantage of the high carbohydrate content of cassava pulp it should be supplemented with:
Fermentable nitrogen that will produce the ammonia needed to optimize the growth of the microbes in the rumen
Protein that will by-pass the rumen to complement that produced by the rumen microbes
A source of fiber that will act as the support structure for the formation of biofilms (Leng,2014) which is where rumen microbes and their required nutrients come together to optimize the digestive process in the rumen
The cheapest source of ammonia for rumen microbes is urea, which is produced and used as fertilizer One of the best sources of "bypass" protein is brewers’ grains (Promkot and Wanapat 2003), a by-product from the beer factory An excellent source of fiber is rice straw, most of which is presently burned, adding carbon dioxide to the atmosphere and thus contributing to global warming Minerals are required only in small quantities (1-2% of the feed), and are available locally or can be imported Sulfur is important as a component of the process of
detoxification of HCN to thiocyanate
MATERIALS AND METHODS
Testing the pH, dry matter and nutritive value content
The cassava pulp sampling was collected at the cassava factory from Lao-Indochina Group Public Company at Nashaw village, Vientiane Capital, taken over the pit was at a depth of0.5 to 7.0 m Further tests were done on 16th of July 2014 taking consecutive samples as far as tothe bottom of the pit using a 10cm diameter PVC tube 8m long, collected in 5 points of open pit
Figure.1 cassava pulp sampling points were taken 5 points, 4 for the corner and 1 for middle
In vitro gas and methane production
A sample of the cassava pulp was taken at 2.5m depth to determine in vitro gas
production according to the method developed The sample had a pH of 3.5 In the in vitro test it
was compared with fresh whole cassava root Urea and cassava leaf meal were added to bothsubstrates (Table 1) There were two replicates of each of the treatments (cassava root andcassava pulp) Fresh cassava root was chopped into small pieces 1-2 cm of length, then ground (1mm sieve) by machine The cassava leaf was collected in the farm of SouphanouvongUniversity; Luang Prabang and chopped into small pieces around 1-2 cm, then dried in an oven
at 60°C for 24h and ground (1mm sieve) by machine
Table 1 Proportions of the substrates in the in vitro incubation
Trang 6Total 100 100
Representative samples of the substrates (12 g DM) were put in each incubation bottle, after which were added 960 ml of buffer solution (Table 2) and 240 ml of rumen fluid (obtained from a recently slaughtered buffalo in the local abattoir), prior to filling each bottle with carbon dioxide The bottles were incubated at 38ºC in a water bath for 24h
Table 2 Ingredients of the buffer solution
Ingredients CaCl 2 NaHPO 4 12H 2 O NaCl KCl MgSO 4 7H 2 O NaHCO 3 Cysteine
Tilly and Terry (1963)
The gas volume was recorded over intervals of 0-6hours, 6-12hours and12-24hours after incubation The methane concentration in the gas collected over each interval was measured with
a Crowcon infra-red analyser (Crowcon Instruments Ltd, UK) At the end of the incubation, the remaining substrate was filtered through cloth and the solid residue dried at 100C to determine the DM digested
Feeding trail
Eight local "Yellow" cattle (range 78 to 108 kg) were allocated according to live weight
to two groups each of four animals They were fed a basal diet of ad libitum cassava pulp
enriched with urea at the rate of 3% (DM basis) The experiment was done in the dry season (February -June 2015), 121 days Fresh Brewer’s grains were used as an alternative source of
"bypass" protein (Promkot and Wanapat 2003) Rice straw was given as a source of “roughage”
to stimulate rumen function A sulphur-rich mineral mixture (50% common salt, 25% dicalium phosphate,20% clacium carbonate, 5% sulphur) was provided ad libitum The urea was dissolved
in water and sprayed on the cassava pulp Brewers’ grains and rice straw were offered separately
Table 3 Composition of the diet fed to the Yellow cattle
These quantities were provided on the basis of 100 kg live weight They were increased
proportionately as the animals increased in weight
#50% common salt, 25% dicalium phosphate, 20% clacium carbonate, 5% sulphur
Animal test
The cattle were weighed before morning feeding at the beginning of the trial and every
14 days Feeds offered and refused were recorded daily Feed was sampled daily during thecollection period and was composition prior to analyses Feed samples were collected weeklyand divided into two parts, the first part be analyzed for DM, while the second part was kept andpooled at the end of each period for chemical analysis Samples were dried 60°C and ground(1mm screen) and then analyzed for DM, ash, EE and CP content (AOAC, 2002), NDF, ADF(Van Soest et al., 1991)
Statistical analysis
Trang 7Data for gas production was analyzed by the GLM option in the ANOVA program of the Minitab (2010) software Sources of variation were treatments, replicates and error Regression equations were derived using Microsoft Excel software The feeding data were analyzed by the general linear model option of the ANOVA program in the Minitab (2000) software (version 16.0).Live weight gain was determined by the linear regression of live weight (Y) on days in the experiment (X).
RESULTS AND DISCUSSION
pH and chemical composition of cassava pulp
All samples taken from the pit had a consistent pH below 3.5 and appeared to be
perfectly stable as silage (Figures 1 and 2) Due to compression of the pulp inside the tube, as this was forced to the bottom of the pit, the recovered samples most probably represented
material over the whole range of depth of 0.5 to 7.0m The chemical compositions of cassava pulp, DM content is between 20.00 and 31.41 %, CP 2.28%, NDF 35% and ADF 28.4%
Figure 2 Changes in dry matter content of the
pulp at increasing depth in the pit
Figure 3 Changes in pH of the pulp at
increasing depth in the pit
The chemical composition
Table 4 The chemical composition of cassava pulp in difference collected point
In vitro gas and methane production
There were no differed for total gas production, methane in the gas and DM mineralizedamong the treatments, but there was higher for cassava root as basal substrate supplemented withurea and cassava leaf meal compared with cassava pulp (Table 5)
Table 5 Mean values for gas production, methane in the gas and DM mineralized in the in
vitro incubation of cassava pulp and cassava root supplemented with urea and cassava leaf
meal
Trang 8Figure 4 Gas production from cassava pulp and cassava root supplemented with urea and cassava leaf meal
Total gas production over 24 h tended (p <0.18) to be less with the pulp than with the
whole cassava root (Table 4; Figure 3), however, the overall difference was only 9% ; there were
no differences in DM mineralized which were less than 1% during this period Thus it can be expected that the energy feed value of the ensiled pulp will be only slightly less than that of the whole fresh root The methane content of the gas produced between 12 and 24h did not differ between the pulp and root samples
The crude protein in cassava pulp is very low Reported values are 1.55 to 2.6% in DM (Sriroth et al., 2000; Suksombat et al., 2007) However, it is rich in starch with 69% of DM (Sriroth et al 2000) This makes it suitable as the energy component of an intensive feeding system for fattening cattle It would need to be supplemented only with urea, a source of
roughage and bypass protein and minerals, as has been demonstrated for other low-protein, carbohydrate-rich tropical feeds such as molasses (Preston 1971; Ffoulkes and Preston 1978)
Feed intake and live weight gain of cattle
The data on growth rate, feed intake and feed conversion over the 4 months of the
fattening period (Table 5) confirmed that ensiled cassava pulp could be the basis of a successful diet for the intensive fattening of cattle The excellent conformation, after 90 days of fattening onthe cassava pulp diet, was confirmed by the high carcass yield of the first animal to be
slaughtered which was 49% (carcass yields of local cattle in Lao PDR are of the order of 35%)
The initial live weight of both group were 101 and 84 kg, after 120 days the weight gain were 185 and 158 kg, the average daily gain were 0.7 and 0.62
Trang 9 The pH was changed with the level of pit depth the pH was high when collected sample
in surface and pH decreased when collected deeper and DM was between 20 to 25%
Gas production and DM mineralization values after 24h fermentation in an in vitro
incubationshowed cassava pulp was slightly inferior (<10%) to fresh cassava root as an energy feed resource for ruminants
Local "Yellow" cattle fed ad libitum ensiled cassava pulp, urea, brewers' grains and rice straw was gain averaged 0.66 kg/day (both 2 groups) after 4 months of fattening, with a
DM feed conversion of 6.67, confirming that ensiled cassava pulp could be the basal diet for intensive fattening of cattle in Lao PDR
CHAPTER 3: CASSAVA FOLIAGE (MANIHOT ESCULENTA CRANZ) AND
BREWERS' GRAINS AS PROTEIN SOURCES FOR LOCAL “YELLOW” CATTLE FED CASSAVA PULP AS BASAL DIET
INTRODUCTION
Promoting beef production from the local “Yellow” cattle is one of the development activities ear-marked by the Ministry of Agriculture and Forestry (MAF 2015) in Lao PDR Emphasis is on technological upgrading and innovation to develop intensive fattening systems using the locally available feed resources, especially the by-products from agro-industry
It is estimated that the five cassava starch factories in Lao PDR have a yearly production
of 200,000 tons of pulp (MAF 2015) The four breweries produce between 200 and 300 tons of brewers’ grains daily (about 150,000 tons per year).The availability of rice straw is of the order
of 3 million tons per year These resources would be sufficient to fatten some 200,000 cattle per year with an added value of USD 36 million
In an introductory experiment, an investigation was made of the potential nutritive value
of the cassava pulp produced in the Lao-Indochina cassava starch factory in Vientiane Capital, where it had accumulated in an open pit over a period of 5 years (Phanthavong et al., 2014) Microbiological studies on cassava residues also revealed abundant lactobacilli in the fresh pulp (Napasirth et al., 2015) The initial evaluation of the ensiled pulp showed that it had a potential nutritive value only slightly inferior to that of fresh cassava roots (Phanthavong et al., 2014).The
Table 6 Mean values for the feed intake, growth rate and feed conversion over the 120 days of the fattening period
Trang 10potential of the ensiled pulp as the basis of an intensive fattening system was demonstrated in an experiment in which the pulp, supplemented with urea, fresh brewers’ grains and rice straw, supported growth rates of over 600 g/day in local "Yellow" catte (Phanthavong et al., 2016).
The availability of fresh brewers’ grains is limited, as a major proportion is exported and the cost of transport restricts the economic use of this product to a radius of some 50-100 km around the factories An attractive alternative to brewers’ grains is the fresh foliage of cassava which has been shown to be an effective source both of protein and fiber in intensive cattle fattening diets based on molasses-urea in the Dominican Republic (Ffoulkes and Preston 1978) The cassava foliage used by these researchers was of the “sweet” variety as the cassava in the Dominican Republic is grown mainly for human consumption However, the cassava used for starch production in Lao PDR is produced from “bitter” varieties as these are higher-yielding The difference between the sweet and bitter varieties is in the level of cyanogenic glucosides which are in higher concentration in the bitter varieties (Phuong et al 2016)
The hypothesis tested in this experiment was that foliage from a bitter variety of cassava could be used as the source of bypass protein and fiber for fattening local “Yellow” cattle on a basal diet of cassava pulp-urea
MATERIALS AND METHODS
Location and duration
The experiment was carried out in Soukanya Farm, Xaythany District, situated some 19
km from Vientiane Capital, from 1 June to 29 September 2015
T2: Foliage of bitter cassava variety (CF)
T3: 50:50 bitter cassava foliage: brewers’ grains (CF-BG)
Animals and housing
Eighteen “Yellow” cattle, average age 2 years and initial weight of 80-120 kg the cattle were housed in individual pens They were treated for internal and external parasites with
Ivomec-F intramuscularly, and vaccinated against Foot and Mouth Disease (FMD)
Table 1 Approximate amounts of the diet ingredients (DM, kg/day)*
* These quantities were provided on the basis of 100 kg live weight They were
increased proportionately as the animals increased in weight
** 50% common salt, 25% dicalcium phosphate, 20% calcium carbonate, 5% sulphur
Feeding system
The fresh cassava foliage was harvested daily from farmers’ plots near the research farm
It comprised tender stems, leaves and petioles from the top 30-40 cm of the plant It was chopped
Trang 11by machine into lengths of 2-3cm The fresh cassava pulp and fresh brewers’ grains were
transported to the farm every 1-2 weeks from the factory/brewery in the Vientiane area The ingredients were given a separated at the same time in the trough
Measurements
The cattle were weighed before morning feeding at the beginning of the trial and every
14 days Feeds offered and refused were recorded daily DM and crude protein in ingredient feeds were analysed using the methods of AOAC (1990) Protein solubility was determined by the method described in Whitelaw et al (1961) Live weight of cattle was measured at begin and finish experiment The live weight gain (kg/day) of each cattle was calculated by final LW (kg) and initial LW (kg)
Chemical analysis
Feed was sampled daily during the collection period and was composition prior to
analyses Feed samples were collected weekly and divided into two parts, the first part be
analyzed for DM, while the second part was kept and pooled at the end of each period for
chemical analysis Samples were dried 60°C and ground (1mm screen) and then analyzed for
DM, ash, EE and CP content (AOAC, 2002), NDF, ADF (Van Soest et al., 1991)
RESULTS AND DISSCUSION
Chemical composition of the experimental diet
Proximate analysis was done to determine chemical composition of the experimental diet (ingredients) (Table 2) Found the percentage of dry matter of cassava pulp, brewers’ grain, cassava foliage and rice straw were 23.6, 24.3, 26.6 and 90.1 and crude protein was 2.6, 24.8, 16.4 and 3.1, respectively
Table 2 Chemical composition of diet ingredients
Cassava pulp Brewers' grain Cassava foliage Rice straw
Feed intake, live weight gain and feed conversion
There was a tendency (p=0.076) for DM intake to be lower on the diet with cassava
foliage and rice straw (Tables 3 and 4; Figures 1-3) Responses in live weight gain and feed conversion were similar for the diets in which all the protein came from brewers’ grains (BG) or when the source of protein was divided equally between brewers’ grains and bitter cassava foliage (CF-BG) (Figure 5) Animal performance was very poor when bitter cassava foliage was
Trang 12the only source of protein Effects of treatments were similar for intact male and female cattle (considered as replicates in the statistical analysis).
Table 3 Mean values for feed intake according to dietary treatments
Table 4 Mean values for DM intake, live weight gain and feed conversion for “Yellow”
cattle fed a basal diet
Figures 1-3 DM intake, live weight gain and DM feed conversion of cattle fed.
Trang 130 14 28 42 56 70 84 98 112 126 0
50 100 150 200
Table 5 Economic analysis of value of live weight gain over costs of feed
of initiating the first experiment led to the decision to use brewers’ grains as the source of bypassprotein and rice straw as the source of fiber (Phanthavong et al., 2016) The present experiment was the first attempt to introduce the use of cassava foliage as the protein-fiber source in a diet based on cassava pulp-urea The cassava foliage was from a "bitter" variety which has higher
Trang 14root yield than "sweet" varieties and is exclusively planted by farmers when the roots are
destined for starch manufacture Bitter varieties (hence the use of the description "bitter") have much higher concentrations of HCN precursors (Phuong et al., 2016)
The first observations, when bitter cassava foliage was the only source of protein-fiber to balance the cassava pulp-urea, indicated low feed intakes due to reluctance of the cattle to consume the bitter cassava foliage However, it was observed that when some brewers’ grains were also offered then the intake of the bitter cassava foliage was increased Based on these observations the present experiment was designed
The better LW gain with BG is because BG is acting as a prebiotic probably providing habitat (eg: beta-glucan derived from the cell wall of yeasts and probably of rice; due to in biofilms supporting consortia of microorganisms that detoxify the HCN formed in the rumen from the cyanogenic glucoside linamarin present in cassava foliage Binh et al (2017) showed that adding BG to diets of cattle fed cassava foliage helped to reduce the toxicity from HCN (improved the health of the cattle), as shown by increased excretion in the urine of thiocyanate (the end-product of the detoxification of HCN) (HCN is formed in the rumen from linamarin the cyanogenic glucoside present in cassava) Further confirmation for the role of brewers’ grains as a prebiotic was the research of Binh et al (2017), which demonstrated a direct
relationship between feeding brewers’ grains, growth enhancement of cattle and reduced
excretion in the urine of thiocyanate -the product of the detoxification of HCN
The results of the experiment show clearly that combining small amounts (15% of the diet DM) of brewers’ grains with the bitter cassava foliage supported the same growth as on diets
in which the brewers ‘grains provided all the bypass protein (29% of the diet) with rice straw (Phanthavong et al., 2016) Based on these findings, experiments were subsequently carried out
in which the brewers’ grains were reduced to even lower levels (4% of the diet DM) as the supplement to fattening diets for cattle based on cassava pulp-urea and sweet cassava foliage (Inthapanya et al., 2016) or cassava pulp-urea and bitter cassava foliage (Le Binh Phuong
CHAPTER 4 : EFFECT OF CASSAVA LEAVES FROM DIFFERENT
VARIETIES AND BREWERS’ GRAINS ON METHANE PRODUCTION IN
AN IN VITRO RUMEN INCUBATION OF CASSAVA PULP
INTRODUCTION
Cassava in Lao PDR is mainly planted as an industrial tuber crop for starch production It
is the third most important food crop after rice and maize, the planting area having increased from 6,765 ha in 2005 to 63,260 ha in 2017 (MAF 2017) In the processing of the roots some 15% remains in the form of cassava pulp (Sriroth et al 2000) The pulp is high in fermentable