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Solutions to the practical problems of feeding cocoa-pods to ruminants

O.B. Smith
Department of Animal Science
Obafemi Awolowo University
Ile - Ife, Nigeria


Abstract
Introduction
Conclusion
References


Abstract

Data is presented showing that cocoa-pods, a by-product of cocoa processing could be used as a ruminant feed. The widespread nature of cocoa-processing sites which makes it difficult and expensive to collect and transport the cocoa-pods to sites of utilisation, and the need to grind the pods prior to feeding are identified as the main physical constraints while the high cell wall and low cell content of the material constitute the main nutritional constraints to its effective utilisation.

One way of overcoming part of the physical constraint is to develop technologies that would permit the use of the pods at the main sites of production. Chemical treatment using ash solutions of crop residues, ensiling the material with poultry manure or urea, and strategic supplementation with fermentable nitrogen and good quality forages are suggested as strategies to overcome the nutritional constraints to the utilisation of cocoa-pods as a ruminant feed.

Introduction

The competition between man and his animals for food such as cereals, pulses and oil seeds is partly responsible for the ever-increasing livestock feed costs. In developing countries, the production of these feed items is too low to meet demands, and as in all such situations, where demand exceeds supply, the cost of these items has continuously soared. Research efforts have therefore been directed towards finding alternative sources of nutrients for livestock, using materials that cannot be directly consumed by man. This approach may alleviate man-animal competition and reduce animal feed costs particularly for ruminants which can utilise fibrous crop residues and byproducts of cereals, pulses and oil seed processing.

Enormous quantities of these materials which are usually not eaten by man, are produced annually on the farm after crop harvesting and in the food processing industry (Table 1). Many of these materials are currently being evaluated on a worldwide basis in order to determine their suitability as livestock feeds. Cocoa-pod produced after the removal of the cocoa beans from the fruit, is one such crop residue being evaluated in Nigeria as a potential feed for ruminants. The pod forms about 75 - 80% of the weight of the fruit, and from estimates of cocoa production in Nigeria, about 1 million tonnes of dried pod could be available annually on Nigerian cocoa plantations for feeding ruminants.

Table 1. Available quantities of major crop residues in Africa.

Crop

Residue

Type

Quantity
('000 tonnes)

Maze

Stover

62,000

Sorghum

Stover

48,600

Rice

Straw

9,300

Sugar-cane

Tops

17,070

Groundnut

Haulms

8,200

Husk

1,250

Cocoa

Pods

9,710

Banana/plantain

Leaves

15,020

Pseudo stems

32,700

Cassava

Tops

45,000

According to published values, the dried pod may contain about 6-10% crude protein, 24-42% crude fibre, 49-61% nitrogen-free extracts, 9 - 16% ash, made up primarily of potassium salts (Owusu-Domfeh, 1972; Gohl, 1975; Devendra, 1977; Otchere et al, 1983; Smith and Adegobola, 1985). This nutrient profile is similar to that of many tropical grasses (Ademosun and Kolade, 1973). The material therefore has good potential as a feed ingredient particularly for ruminants.

This report presents results obtained to date, at the Obafemi Awolowo University, Ile-Ife, Nigeria, to develop a feeding strategy using cocoa-pod in ruminant diets, followed by a discussion of identified constraints and suggested solutions to its efficient utilisation.

Preliminary experimental studies

Three cattle growth trials and two digestion studies (cattle and sheep) constituted the first series of experiments. In the cattle growth trials, local cattle (Keteku, N'Dama and Muturu) found mainly in the cocoa-growing areas of Nigeria were used as experimental animals. Using standard experimental procedures, the animals were allocated into control and test groups, and fed their respective diets for periods of 98 to 112 days. The control and test diets as shown in Table 2 were maize or guinea-maize based, and were similar, except that the cereals were replaced in graded amounts with cocoa-pod at 20, 30, 40, 50 and 60%.

For the sheep digestion studies, the total collection method was used, while the indicator method, using acid-insoluble ash as an internal maker, was used for the cattle study. The digestibility of diets containing 0, 15, 30, 45, 60 and 75% pod (sheep) and 0, 20, 40% pod (cattle) were determined. Cocoa-pod digestibility in sheep where six levels of the material were used was determined by extrapolation.

Table 2. Composition of diets fed to growing cattle in two trials.





Diet

First trial

Second trial

Ingredients

Control

20%

40%

Control

30%

50%

60%

(% as fed)

1

pod

pod

2

pod

pod

pod

Maize

-

-

-

69.4

38.9

20.0

8.9

Sorghum vulgare

62.3

43.2

24.4

-

-

-

-

Cocoa pod

-

19.2

38.4

-

30.5

50.0

60.2

Dried brewers' grains

19.5

19.5

19.3

14.6

14.5

15.0

14.4

Wheat offals

-

-

-

10.5

10.5

8.0

10.5

Molasses

11.7

11.6

11.5

-

-

-

-

Groundnut cake

4.7

4.7

4.7

3.4

3.6

5.0

3.5

Dicalcium phosphate

0.4

0.7

0.9

-

-

0.8

-

Bone meal

-

-

-

1.0

15

10


Oystershells

0.9

0.6

0.3

0.6

-

0.5

-

Salt

0.3

0.3

0.3

0.3

0.3

0.5

0.3

Vitamin - trace mineral mix

0.2

0.2

0.2

0.2

0.2

0.2

0.2

Growing cattle consumed cocoa-pod diets as much as they did the control diets even at the highest level of inclusion (60%) (Table 3). Pod dry-matter intake averaged 2.4% of body weight, while total dry-matter intake was about 3 to 4% of body weight.

Table 3. Cattle response to grain substitution with cocoa-pod.


Diets



First trial

Second trial

Parameters

Control

20%

40%

Control

30%

50%

60%


1

pod

pod

2

pod

pod

pod

Dry-matter intake (kg/day)









- Cocoa-pod

-

1.4

3.2

-

1.7

2.3

3.3


- total feed

5.2

5.5

5.6

5.3

5.2

4.6

5.6

Growth rate(kg/day)

0.8

0.6

0.5

0.7

0.6

0.4

0.2

Feed/gain

6.5

9.2

11.2

7.6

8.7

11.5

28.0

There was a negative correlation between level of dietary pod and growth rate and efficiency of utilization parameters (Figure 1). Thus, growth rate declined and feed conversion became less efficient as dietary pod level increased. A regression of dietary pod level on growth rate gave the following equation, Y = 0.82 - 0.009%, with an r value of -0.97 where Y = growth rate and X = dietary pod level. A similar trend of decreasing dry-matter digestibility with increasing dietary pod level, mainly due to the low digestibility of pod dry-matter (23%) is indicated in Table 4.

Table 4: Digestibility of cocoa-pod based diets by ruminants (%).

% dietary cocoa-pod (cattle)

% dietary cocoa-pod (sheep)

Nutrients

0

20

40

0

15

30

45

60

75

100¹

Dry-matter

76.9

62.3

58.6

19.7

76.7

66.1

53.1

50.0

35.8

22.7

Organic matter

-

-

-

80.6

78.0

67.6

54.0

49.0

36.5

22.9

Crude protein

73.0

62.7

57.2

73.2

72.3

70.4

60.9

61.6

56.8

50.8

Acid-detergent fibre

53.8

38.7

35.2

-

-

-

-

-

-

-

¹ By extrapolation.

At the end of these first series of experiments, it was possible to identify a number of constraints that might reduce the effective utilisation of cocoa-pod as a feed ingredient, or make the adoption of feeding strategies built around cocoa-pod difficult. These constraints can be described as being physical or nutritional.

Strategies for eliminating physical constraints

As indicated earlier, about one million tonnes of cocoa-pods are generated annually on Nigerian cocoa plantations. It is difficult to assess what amount is available for animal feeding. Most of the available pod is annually wasted because cocoa-growing and processing is to a large extent carried out by individual smallholders scattered all over the cocoa-producing area. Many of the farms are not easily accessible, and when accessible may not produce enough pods to encourage setting up a collection service. The lack of easily accessible processing centres in areas where large amounts of pod can be collected is one of the major constraints to the utilization of pod as animal feed.

Smith (1984) indicated that transportation costs for collecting pods from sites of production to the site of utilisation accounted for 78% of the total cost of producing a tonne of dried pod for feeding. The farther apart the production sites are from each other and from the sites of utilisation, the higher the transportation costs, and the less attractive the use of pod will become.

If it were possible to centralise cocoa processing, a large part of the constraint of collection and transportation could be overcome. This, however, does not appear feasible. A more practical solution would be to use the pod at or near the site of production. The major target users would therefore have to be the cocoa farmer or his neighbour keeping a few goats and sheep. On the other hand feed manufacturers who may want to use the material in compounded ruminant diets or as an energy diluent in pellets or finishing swine feeds may contract cocoa farmers to supply dried pods once or twice a year, much as maize growers now supply maize to feed manufacturers.

Figure 1. Correlation between level of dietary pod and growth rate.

Cocoa-pod has to be processed before being fed to livestock. Processing requirements are minimal, but may still constitute a constraint in the rural setting. The material contains up to 75% moisture and may have to be dried before feeding. However, drying may not constitute any constraint, since the major cocoa harvesting period coincides with the dry season, and the pods can easily be sun-dried. After drying, it has to be reduced to appropriate particle sizes for livestock by grinding.

Three different types of hammermills have been used to reduce the particle size and these have proved suitable. Grinding where it requires electricity, may constitute another constraint in a village setting. Nevertheless, when properly dried, cocoa-pod is very brittle, and can be easily broken up into small particles by trampling. It is possible to reduce particles to sizes small enough to feed with other ingredients. On the farm, trials need to be carried out to evaluate this in terms of acceptability to both the farmer and the animal.

Strategies for eliminating nutritional constraints

The generally low nutritional value of cocoa-pod is a major constraint to its being used efficiently as animal feed. It is low in protein (6%) and high in cell wall components (57% ADF, 66% NDF and 24% lignin) (Smith et al, 1987). This poor nutrient profile accounts for its low rumen degradability (T1/2 = 288 hr) and overall poor digestibility, and may constitute a constraint to optimally utilising the material as a feed ingredient. Two proven strategies are suggested as remedies to this nutritional constraint - chemical treatment and supplementation.

Alkaline treatment of cocoa-pod

Chemical treatments of fibrous crop residues, similar in composition and nutritive value to cocoa-pods, have reportedly improved their utilisation to such an extent as to make their utilisation as feed ingredients feasible and profitable (Jackson, 1977; Doyle et al, 1986). None of the proven chemicals such as sodium hydroxide, calcium hydroxide, potassium hydroxide and ammonia are suitable for our target users because of the high cost and scarcity of the chemicals and hazards associated with their use. A suitable alternative which, under limited testing, appears as effective as sodium hydroxide is the caustic ash solution of some crop residues. Cocoa-pod ash, for example, contains about 44 mg of potassium per kg, and according to Adebowale (1985) the ash solution contains about 21 and 29% OH ions in the form of NaOH and KOH respectively.

This property was effectively exploited by Smith et al (1987) who used different concentrations of cocoa-pod ash solutions as a chemical to treat cocoa-pod in an attempt to improve its feed value. As shown on Table 5, a linear increase in the rumen degradability of cocoa-pod treated with its own ash solutions of increasing concentration was observed. More significantly, the improvement in rumen degradability obtained by cocoa-pod ash solution treatment was similar to that obtained by using NaOH solutions of equivalent alkalinity. The authors also reported that treated cocoa-pod-based diets were better digested by both goats and sheep than untreated pod-based diets (Table 6).

Table 5. Rumen degradability of treated cocoa-pod.

Nutrients


% NaOH solution

% pod ash solution

2

4

6

8

2

4

6

8

Dry matter

34.8

41.1

47.6

52.6

37.

46.3

54.8

55.4

Acid-detergent fibre

24.6

33.8

38.6

42.5

26.7

35.9

44.2

46.6

Neutral-detergent fibre

15.0

25.9

35.7

36.5

15.3

29.8

44.7

41.7

Table 6. Digestibility of treated cocoa-pod by goats and sheep (%).



Sheep

Goats

Control diet ¹

Test diet

Control diet

Test diet

Dry matter

45.2

54.5

46.3

59.8

Acid-detergent fibre

12.4

30.7

31.0

36.2

Neutral-detergent fibre

15.6

39.5

37.9

40.2

¹ Control diets contained 50% untreated cocoa-pod, while test diets contained 50% treated cocoa-pod. Other ingredients are as shown on Table 2. (50% cocoa-pod diet).

This treatment method has the potential to remove a major constraint to the efficient utilisation of cocoa-pod as a livestock feed. The technology should be attractive to cocoa-farmers who generate cocoa-pod on their farms. The technology involved is simple, and the farmers are used to handling the ash which is used locally as a base for soap manufacture.
Another treatment method which may improve the feed value of pod, is ensiling pod with poultry manure or urea. Both manure and urea would liberate ammonia which has been shown to effectively improve the utilisation of fibrous residues through ammoniation of cell walls (Doyle et al, 1986). We have, however, not evaluated this technique.

Forage supplementation

A second strategy suggested for eliminating the nutritional constraint associated with the feeding of cocoa-pod is that of supplementation with suitable forage to enhance rumen function. According to Preston and Leng (1981) supplementation of crop residue based diets with fermentable nitrogen and forages will ensure an adequate rumen ecosystem that will improve the utilisation of the residue.

Tables 7 and 8 show the results of two forage supplementation studies that were carried out in sheep and cattle.

Table 7. Effect of forage supplementation of cocoa-pod-based diet on nutrient digestibility by sheep.

Item

Control sheep¹

Test sheep

Feed intake (gDm/day)


Basal diet

735.0

645.0


Centrosema

-

19 0

Total

735.0 (80g/kg W 0.75)

664.0 (70g/kg W0.75)

Digestibility (%)


Dry matter

57.0

60.0


Organic matter

59.6

61.0


Crude fibre

34.0

37.0


T1/2 of dry matter (hrs)

288.0

182.0

¹ Both control and test sheep were fed a 50% cocoa-pod-based diet. Test sheep were offered freshly cut Centrosema daily.

Table 8. Response of cattle fed on cocoa pod-based diets to Gliricidia supplementation.

Item

Control cattle 1

Test cattle

Feed intake (kg DM/day)

Cocoa-pod

4.6

4.6

Gliricidia

-

0.2

Total

4.6

4.8

Daily gains (kg/day)

0.4

0.4

Feed/gain

11.5

12.0

1 Control and test cattle fed 50% cocoa-pod-based diet. Test cattle were offered freshly cut Gliricidia daily.

In the sheep study, some improvement in the utilisation of the pod-based diet due to forage supplementation was obtained, although poor-to-medium quality Centrosema was used, in order to simulate the quality likely to be available to target users. Better forage material may therefore further improve cocoa-pod utilisation. We could not confirm the above speculation with the cattle study because of poor intake of Gliricidia by the test cattle. We conclude, as suggested by Preston (1982) that for forage supplementation to enhance the utilisation of crop residues, the forage should be of good and digested. Although we have not experimented with fermentable nitrogen supplementation of cocoa-pod-based diets, theoretical considerations suggest that the strategy may enhance cocoa-pod utilisation.

Conclusion

All of the strategies suggested for alleviating the physical and nutritional constraints to the efficient utilisation of cocoa-pod in ruminant diets were carefully selected to ensure that they are within the reach of the target users - the small-scale farmer. Some of these strategies have been evaluated on an experimental basis, and results obtained showed that they have the potential to achieve the set objectives. These, as well as those yet to be evaluated need to be tested on farm in order to fully assess their value.

References

Adebowale, E.A. 1985. Organic waste ash as possible source of alkali for animal feed treatment. Anim. Feed Sci. Technol. 13: 237-248.

Ademosun, A.A. and Kolade, J.O.Y. 1973. Nutritive evaluation of Nigerian forages. III. A comparison of the chemical composition and nutritive value of two varieties of Cynodon. Niger. Agric. J. 10: 160-169.

Devendra, C. 1977. The utilisation of cocoa-pod husk by sheep. Mall Agric. J. 51: 179-186.

Doyle, P.T; Devendra, C. and Pearse, G.R. 1986. Rice straw as a feed for ruminant. Australian Government Printing Services, Canberra.

Jackson, M.G. 1977. Review article: The alkali treatment of straw. Anim. Feed Sci. Technol. 2: 105 - 130.

Otchere, E.O; Musah, I.A. and Bafi-Yeboah, M. 1983. The digestibility of cocoa husk based diet fed to sheep. Trop. Anim. Prod. 8: 33 - 38.

Owusu-Domfeh, K. 1972. The future of cocoa and its byproducts in feeding of livestock. Ghana J. Agric. Sci. 5: 57 64.

Preston, T.R. 1982. A strategy for the efficient utilisation of crop residues and agro-industrial byproducts in animal production based on their nutritional constraints. In: Crop residues and agro-industrial byproducts in animal feeding. Proceedings of the FAO/ILCA workshop held in Dakar, Senegal, 21-25 September 1982. FAO Animal Production and Health Paper No. 32. FAO, Rome. pp. 29-47.

Preston, T.R. and Leng, R.A. 1986. Matching livestock production systems to available resources. Pretesting edition. ILCA, Addis Ababa, Ethiopia.

Smith, O.B. 1984. Studies on the feeding value of agro-industrial by-products for livestock. IV: The economics and feasibility of feeding cocoa-pods to ruminants. World Rev. Anim. Prod. 20: 61-66.

Smith, O.B. and Adegbola, A.A. 1985. Studies on the feeding value of agro-industrial by-products for livestock. III. Digestibility of cocoa-pod and cocoa-pod-based diets by ruminants. Anim. Feed Sci. Technol. (The Netherlands) 13: 249 - 254.

Smith, O.B; Osafo, E.L.K. and Adegbola, A.A. 1988. Studies on the feeding value of agro-industrial byproducts: Strategies for improving the utilisation of cocoa-pod-based diets by ruminants. Anim. Feed Sci. Technol. (The Netherlands) 20(3): 189-201.


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