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Increasing the level of cassava chips or cassava pulp in leucaena based diets increases feed intake and live weight gain of Bali bulls

Luh Ade Kariyani, Dahlanuddin1, Tanda Panjaitan2, Ryan Aryadin Putra1, Karen Harper3 and Dennis Poppi3

Postgraduate Study Program, University of Mataram, Lombok, NTB, Indonesia
1 Faculty of Animal Science the University of Mataram, Lombok, Indonesia
dahlan.unram@gmail.com
2 The West Nusa Tenggara Assessment Institute for Agriculture Technology, Lombok, Indonesia
3 School of Agriculture and Food Sciences. The University of Queensland, Queensland, Australia

Abstract

The live weight gain response of Bali bulls (Bos javanicus) fed increasing levels of cassava chip or cassava pulp mixed with a leucaena based diet was measured. Forty Bali bulls with initial live weight (LW) of 112±7.1 kg and around 18 months of age were assigned into 10 treatment groups. Each treatment group was offered ad libitum leucaena mixed with either cassava chips or cassava pulp included at levels of 0, 15, 30, 45, 60% on an approximate dry matter basis. All diets included rice straw provided at 0.5% live weight/day and urea at 2% of cassava chip or cassava pulp on a dry matter basis. Including cassava chip up to 30% of the ration increased total daily dry matter intake from 24.1 g/kg LW to 29.3 g/kg LW. The dry matter intake with cassava pulp was lower than with cassava chip at all levels of inclusion. Consequently, the live weight gain was generally higher with cassava chip. The equations for the response of the live weight gain (kg/d) in relation to level of cassava chip or cassava pulp inclusion were quadratic with values higher for cassava chip inclusion. The inclusion of cassava chip resulted in a higher live weight gain response most likely due to the higher starch content. The maximum live weight gain was achieved at a level of inclusion of 47.5% for the cassava chip and 28% for cassava pulp. Feeding higher amounts than these optimal levels significantly decreased feed intake and live weight gain. Dry matter digestibility was higher with cassava chip inclusion compared with cassava pulp inclusion. Generally, the digestibility increased with increasing levels of both cassava chip and cassava pulp inclusion. Rumen ammonia concentrations declined with the increasing levels of cassava chip and cassava pulp inclusions as the crude protein levels declined. The VFA concentrations were within the normal range (82-137 mM) but there were no particular patterns of molar % related to the levels of cassava chip and cassava pulp inclusions.

Keyword: energy, growth rate, protein, tree legumes


Introduction

Feeding legumes to growing Bali bulls (Bos javanicus) improves live weight gain from around 0.2 kg/day with grass-based diets (Dahlanuddin et al 2012) to 0.34-0.37 kg/day (Dahlanuddin et al 2014) in solely legume based diets. Improving the liveweight to this extent, reduces the time required to reach the slaughter weight of 250 kg from almost 4 years to 2 – 2.5 years. Leucaena (Leucaena leucocephala) is a tree legume that contains 20 – 30% crude protein (Shelton and Brewbaker 1998; Hartadi et al 2005). Since its introduction to the West Nusa Tenggara region (eastern Indonesia), the variety Tarramba Leucaena has been widely used for cattle fattening all year round in the dryland areas of the region. It is fed as the sole diet in the wet season, while during the dry season it is fed at 60-80% of the diets. Panjaitan et al (2014) reported cattle live weight gains of 0.4-0.6 kg/day under these systems.

Leucaena with its high protein content could be combined with high metabolizable energy ingredients to improve the use of the protein and also extend limited amounts of leucaena in a production system (Harper et al 2019). There are limited sources and amounts of high metabolizable energy ingredients in Indonesia with corn grain and high quality rice bran used largely by poultry. Cassava (Manihot escullenta, Crantz) is widely grown in Indonesia and used mainly for starch production and as a food source. Both ground cassava chip and cassava pulp, the product after starch extraction, are widely available in Indonesia and it is one of the few plants which can be grown in low soil fertility and dryland areas. It has potential to grow in association with leucaena and be combined in rations to fatten bulls (Panjaitan et al 2014). Cassava chip and cassava pulp have been combined with protein by-products to devise fattening rations and there has been an upper level of inclusion of approximately 40-50% beyond which intake and live weight gain is compromised (Ba et al 2008; Thang et al 2010; Wanapat and Kang 2015; Cowley et al 2021; Retnaningrum et al 2021). No studies combining these cassava products with leucaena and using Bali bulls appear to have been done.


Materials and methods

This experiment was carried out for 19 weeks, from March to July 2019 in the Teaching Farm of University of Mataram, Lingsar, West Lombok, Indonesia (8o31’48’’S, 116o11’41’’ E), according to the University of Queensland Animal Ethic Committee Approval number SAFS/517/17/INDONESIA. Forty Bali bulls around 18 months of age with initial weight of 112±7.1 kg were allocated into 10 treatment groups. Each treatment group was offered ad libitum leucaena mixed with either cassava chips or cassava pulp included at levels of 0, 15, 30, 45, 60% on an approximate dry matter basis. Rice straw was fed to all animals at 0.5% of live weight (LW) on a dry matter basis. Urea was added to cassava chips or cassava pulp at 2% of cassava chip or cassava pulp to ensure adequate rumen degradable N. Clean drinking water was freely available to all animals at all times.

Photo 1. Leucaena on farm

Photo 2A. Ground cassava chip; 2B Ground cassava pulp

Cassava chips were obtained from Trenggalek, East Java and were hammer milled prior to feeding. Cassava pulp was obtained from Lampung and ground using the same hammer mill prior to feeding. Leucaena was harvested fresh, dried and hammer milled before being mixed with other ingredients. Rations were mixed weekly to give the proportions of ingredients. Urea was added to the cassava chips or pulp at the rate of 2% urea to meet rumen degradable N (RDN) requirements. Rice straw was sun dried and fed in long chopped form at the rate of 0.5% LW/day to meet effective NDF requirements. Subsamples of each ingredient were taken weekly, dried, bulked and analysed for DM, OM, CP, lipid and NDF (Table 1).

Feed intake was measured daily over the 19 week period and feed digestibility was measured for seven consecutive days during week 12 of the experimental period. All animals were weighed at the same time each week before the morning feed to measure live weight gain and calculate allocation of rice straw. Rumen fluid samples from all animals were collected 3 hours after feeding at the end of week 19 to measure the concentrations of rumen ammonia (Chaney and Marbach 1962) and volatile fatty acids (VFA) (Filípek and Dvořák 2009). All data were analysed using Analysis of Variance and any significant differences between treatments were analysed by Tukey Test. All data analysis were conducted using SPSS version 20. The quadratic equations were generated using Microsoft excel.

Table 1. Nutrient composition of the diets

% cassava chip
or cassava
pulp inclusion

Dry
matter
(%)

Organic
matter
(%)

Crude
protein
(%)

Crude
fat
(%)

Neutral
Detergent
Fibre (%)

Cassava chip

0

87.5

91.8

18.2

2.2

52.7

15

87.6

85.7

16.8

1.2

56.3

30

87.0

91.6

14.9

1.2

31.6

45

87.0

92.2

11.8

1.0

34.4

60

87.2

92.3

7.8

0.7

31.6

Cassava pulp

0

87.5

91.8

18.2

2.2

52.7

15

87.3

89.4

18.4

2.2

53.0

30

89.7

93.8

16.4

1.9

48.7

45

89.8

92.1

14.2

1.3

50.8

60

90.3

91.7

9.9

1.5

48.0

Feed stuff

Leucaena

88.8

92.8

18.2

2.2

50.8

Cassava chip

89.0

95.1

3.8

0.8

23.1

Cassava pulp

89.5

96.1

2.7

0.1

44.9

Rice straw

90.1

80.2

6.0

1.1

70.2


Result

Live weight gain (LWG, kg/day) increased in response to both cassava chips and cassava pulp level of inclusion (Table 2). The response was greater to cassava chip inclusion than to cassava pulp inclusion. There was a quadratic response of live weight gain to level of inclusion of cassava chip or pulp. The equations were:

y = -0.0002x2 + 0.019x + 0.1648 (R2 = 0.697) for cassava chip and

y = -0.0002x2 + 0.0112x + 0.1576 (R2 = 0.924) for cassava pulp

where y is LWG (kg/day) and x is % level of inclusion of cassava chip or cassava pulp.

The quadratic relationship is expressed in Figure 1. Maximum LWG was achieved at 47.5% inclusion of cassava chip and 28% inclusion of cassava pulp.

Figure 1. The live weight gain (LWG, kg/day) response of Bali bulls to level of
inclusion % of cassava chip or cassava pulp with leucaena

Photo 3. Bali cattle fed cassava chip and leucaena

Table 2. Live weight gain of Bali bulls fed leucaena with increasing levels of cassava chip or cassava pulp mixed with leucaena and fed ad libitum with rice straw offered at 0.5%LW/d DM basis

% cassava chip or
cassava pulp inclusion

Initial
weight (kg)

Live weight gain (LWG)

Cumulative LWG (kg)

LWG (kg/day)

Cassava chip

0

115±13.4

23.1±7.0

0.20 ±0.06c

15

120±3.8

30.0±5.4

0.26 ±0.04bc

30

121±14.1

73.6±12.0

0.65 ±0.11a

45

121±5.5

54.5±18.7

0.48 ±0.17a

60

115±6.0

50.8±6.7

0.45 ±0.06b

Cassava pulp

0

115±8.9

15.34±4.2

0.14 ±0.03bc

15

121±7.0

36.2±3.9

0.32 ±0.03a

30

120±8.0

29.8±12.7

0.26 ±0.11ab

45

116±7.2

21.5±6.6

0.19 ±0.05b

60

111±5.4

3.9±6.3

0.03 ±0.05c

abc values with different superscripts within the LWG (kg/day) column differ significantly (P<0.05)

For all levels of inclusion, Balli bulls had higher intakes and live weight gain when supplemented with cassava chip compared to cassava pulp. Feed intakes between supplement types were greatest at 30% inclusion with bulls consuming the 30% inclusion mix at 29.3 g/kg LW (Table 3). As with LWG there was a quadratic relationship between intake and inclusion. The equations were:

y = -0.0049x2 + 0.2951x + 24.233 (R2 = 0.940) for cassava chip and y = -0.0022x2 + 0.0803x + 24.303 (R2 = 0.697) for cassava pulp

where y is DM intake (g/kg LW/day) and x is % level of inclusion of cassava chip or cassava pulp.

From the quadratic relationship, maximum feed intake was reached at 30.10% for cassava chip inclusion and 18.25% for cassava pulp inclusion, mirroring the LWG results. Digestibility of DM and OM increased with increasing level of cassava chip or cassava pulp inclusion and cassava chip increased digestibility to a greater extent than cassava pulp (Table 3).

Table 3. Dry matter intake, organic matter intake and organic matter digestibility by Bali bulls fed leucaena with increasing levels of cassava chip or cassava pulp inclusion

% Cassava chip
or Cassava
pulp in diet

Dry matter intake (g/kg LW/day)

Organic
matter intake
(g/kg LW/day)

Organic matter
digestibility
(%)

Rice straw

Mixed feed

Total

Cassava Chip

0

5.2±0.24a

18.9±1.65b

24.1±1.66b

21.6±1.48b

49.8±3.56c

15

4.1±1.13a

23.4±0.93a

27.5±1.29ab

23.6±1.04b

50.8±3.96c

30

4.8±0.21a

24.5±1.88a

29.3±1.77a

26.3±1.60a

58.1±2.01b

45

4.6±0.66a

22.2±2.49ab

26.8±2.18ab

24.3±2.04ab

65.9±2.32a

60

5.0±0.63a

19.6±0.84b

24.0±0.79b

22.1±0.72b

70.2±4.66a

Cassava pulp

0

5.1±0.46a

18.6±1.18ab

23.8±1.10ab

21.4±0.83a

51.6±2.27c

15

4.7±1.40a

21.8±1.47a

26.5±0.58a

23.2±0.50a

53.6±3.45bc

30

5.2±0.27a

18.3±1.47ab

23.4±3.67ab

21.3±3.52a

57.8±1.84ab

45

5.4±0.15a

18.3±0.85ab

23.7±0.76ab

21.5±0.69a

61.8±1.56a

60

5.5±0.11a

15.9±1.19b

21.3±1.31b

19.1±0.88a

61.9±1.32a

ab values with different superscripts within columns and cassava chip or cassava pulp differ significantly (P<0.05)



Table 4. Imbibed water, total water intake and water to feed intake ratio of Bali bulls fed Leucaena with increasing levels of cassava chip or cassava pulp

% cassava chip or
cassava pulp in the diet

Imbibed water
(kg/day)

Total water
intake (kg/day)

Water to feed intake ratio
(g water/ g feed DM)

Cassava chip

0

12.3±2.9b

12.7±2.9b

4.20±0.60a

15

14.3±2.1ab

14.8±2.1ab

3.98±0.40a

30

18.7±3.9a

19.3±4.0a

4.25±0.36a

45

14.2±2.4ab

14.8±2.5ab

3.73±0.28a

60

11.8±1.8b

12.3±1.9b

3.46±0.38a

Cassava pulp

0

12.9±2.2a

13.3±2.2a

4.70±0.85a

15

13.6±2.1a

14.1±2.2a

3.79±0.45b

30

11.4±3.0ab

11.8±3.1ab

3.72±0.23b

45

10.7±0.9ab

11.0±0.9ab

3.64±0.21b

60

8.3±0.7b

8.9±0.7b

3.53±0.17b

abvalues with different superscripts within columns and cassava chip or cassava pulp differ significantly (P<0.05)

Total water intake in Balli bulls fed the various mixtures generally mirrored the total dry matter intake. The total water to feed intake ratio tended to decline with the cassava chip or cassava pulp supplementation. However, a significant difference occurred only between the control group (no cassava pulp) with the diets supplemented with cassava pulp. Total water intake was as high as 18.7 L/day.

Rumen ammonia was high and there was no relationship to level of inclusion of cassava chip or pulp. There were significant differences between some treatments and the lower the level of cassava inclusion or higher the proportion of leucaena in the ration then the higher the rumen ammonia levels (Table 5). There was no relationship in the total concentration of VFA and level of inclusion of cassava chip or pulp and the only significant differences were small biologically (Table 5). Similarly, there were only small differences in the molar % of individual VFA.

Table 5. Ammonia (NH3-N) and volatile fatty acid (VFA) concentration of rumen fluid of Bali bulls fed Leucaena with increasing levels of cassava chip or cassava pulp

% cassava
product in the diet

NH3-N
(mgN/l)

Total
VFA (mM)

Proportion of VFA acids

Acetate (%)

Propionate (%)

Butyrate (%)

Cassava chip

0

213±25.7a

102±15.7a

76.6±1.1a

17.7±1.0bc

5.7±0.1ab

15

205±13.3a

97±5.2a

77.5±1.0a

16.2±1.0c

6.2±0.4ab

30

192±28.2a

91±9.6a

76.1±1.6a

18.4±1.9bc

5.6±0.3b

45

142±12.0b

110±13.4a

67.9±2.4c

26.2±2.5a

5.8±0.1ab

60

139±44.5b

104±9.1a

72.8±2.0b

20.4±1.2b

6.8±1.0a

Cassava pulp

0

204±14.0a

137±42.8a

75.2±4.0ab

18.8±3.1a

6.1±1.0a

15

166±27.3b

82.7±12.8b

77.8±1.0a

16.1±1.1a

6.1±1.0a

30

208±9.7a

127±7.0ab

72.8±2.8ab

21.2±4.0a

6.0±1.2a

45

182±2.6ab

105±10.1 ab

75.0±2.2ab

18.3±2.1a

6.7±1.0a

60

164±16.1b

119±21.8ab

69.0±3.9b

24.1±5.8a

6.9±1.8a

abvalues with different superscripts within columns and cassava chip or cassava pulp differ significantly (P<0.05)


Discussion

Cassava chips and cassava pulp can be successfully mixed with leucaena to achieve high live weight gains at a maximum level of inclusion (47.5% for cassava chip and 28% for cassava pulp respectively). This suggests that production systems can be devised to fatten bulls in these dry regions of eastern Indonesia using these two ingredients with whole tubers harvested on farm at low cost compared to buying more expensive by-products. The use of cassava in this manner can extend the use of limited amounts of leucaena and also meet feed requirements at various times of the year. It is estimated at current prices that the cost of home grown cassava tuber is IDR1600/kg DM and leucaena is IDR 2,500/kg DM much lower than commercial sources of alternative feeds most of which exceed IDR 3500/kg DM.

The quadratic nature of the response of live weight gain to level of inclusion of cassava chips or cassava pulp into leucaena based diets was similar to previous studies with different breeds of cattle but using protein meals instead of leucaena (Cowley et al 2020; Cowley et al 2021; Retnaningrum et al 2021) and the optimum level of inclusion from 30-40% (Devendra 1977; Ba et al 2008; Yimmongkol et al 2009; Thang et al 2010; Wanapat and Kang 2015). This strongly suggests that both cassava tuber chips and cassava pulp can be included at a maximum level of 40% of the final ration. The reason for this is not clear but it is related to intake with a decline in intake and sometimes digestibility (in other studies) as the level of inclusion increases beyond this level. It has previously been shown not to be related to HCN levels (Retnaningrum et al 2021), but HCN was not measured in this experiment. Both the cassava chips and pulp were dried and so HCN would have declined markedly (Retnaningrum et al 2021).

Phanthavong et al (2014) showed no difference the in vitro fermentability of fermented cassava pulp and fresh cassava root. In our in vivo experiment, however, the cassava pulp was not fermented and the overall cattle live weight gain was higher with cassava chip than with cassava pulp inclusion. The level of starch is higher in cassava chips (58.5%) and combined with the higher digestibility promotes a higher digestible organic matter intake and this would account for the higher live weight gain. Cassava chips would be a better product to use and practically the whole tuber could be used if home grown cassava chips were used. Starch level and its effect on rumen pH and digestibility would not appear to be the limiting factor to high inclusion of cassava pulp as the cassava pulp has little starch. The RDN levels are quantitatively adequate with the addition of urea and the high CP of leucaena and this is supported by the high level of rumen ammonia (Table 5) which was in excess of the minimum requirement of 50mg rumen ammonia N/L for all rations (Satter and Slyter 1974). The reason for the detrimental effect on intake and live weight gain at high levels of inclusion of both cassava chips and cassava pulp is not known but to be safe cassava tuber chips or cassava pulp are best included in rations to a maximum of 40%. The maximum live weight gain recorded here with cassava chips was 0.65 kg/d and this is similar to the maximum live weight gain recorded for growing Bali bulls fed very high quality rations (Moran 1985; Quigley et al 2014; Dahlanuddin et al 2018).

The digestibility values of the leucaena based diet without cassava product were comparable with the values reported previously (49 - 69%) in Bali cattle fed similar diets (Quigley et al 2009; Dahlanuddin et al 2014; Soares et al 2018) and reflected the leucaena and rice straw mix with a final level of leucaena in the mixed ration consumed of 78% (Table 3). Digestibility generally increased with higher inclusion levels of a cassava product but was much higher when cassava chip was used. In an in vitro study Putridinanti et al (2019) reported that cassava pulp treatments had lower DMD (10% units) than that of cassava chip due to its lower starch content. At high levels of inclusion the decline in intake for both cassava sources was greater than the maintenance of a higher OM digestibility and so digestible organic matter intake and live weight gain did not increase as expected.

The rumen parameters were as expected with high rumen ammonia N levels in response to the high CP as formulated and the maintenance of an adequate rumen ammonia level with urea despite the decrease in total CP%. The VFA patterns were as often observed and the molar % of propionate increased to higher levels under increasing cassava chip inclusion (18-26%) but lower than that observed by Retrananingrum et al (2021) of 33%. This was most likely related to the higher starch content of cassava chips.

Feeding a ration with a low water content means that more attention is needed to ensure adequate water is available to bulls. The values for water intake/kg DM intake (3.5 - 4.7 kg/kg DMI) are slightly lower than 5.2 kg/kg DMI derived by Dahlanuddin et al (2014) and farmers should be advised to have approximately 20L/day available for Bali bulls of this class.


Conclusion


Implication

Cassava is an excellent supplement for the leucaena based diet fed to cattle but it is currently not readily available for the smallholder cattle producers in West Nusa Tenggara region of eastern Indonesia. However, a vast area of dry land is available in the region and the planting and feeding of leucaena has been widely adopted. Cassava could be integrated with leucaena in an alley cropping arrangement. Using a mixture of leucaena and cassava tuber in rations would not only improve live weight gain in cattle but also more efficiently utilize leucaena throughout the year.


Acknowledgement

This experiment was part of the project “Profitable Feeding Strategies for Smallholder Cattle in Indonesia” (LPS/2013/021 funded by The Australian Centre for International Agricultural Research (ACIAR).


Conflict of interest

The authors declare that they have no conflict of interest


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