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Calliandra leaf meal in goat rations: Effects on protein degradability in the rumen and growth in goats

C. Ebong

Namulonge Agricultural and Animal Production Research Institute
P.O. Box 7084, Kampala, Uganda

Abstract
Introduction
Materials and methods
Results
Discussion
References

Abstract

A study was carried out to evaluate the value of Calliandra leaf meal as a soybean meal supplement for goats. Goats on 75 and 100% Calliandra meal diets consumed more dry matter and utilised the feed more efficiently (P<0.05) that goats on other diets. Compositing Calliandra leaf meal with soybean meal enhanced the uptake and utilisation of both supplements by providing a better amino acid profile. The results show that while Calliandra alone can provide the required nitrogen for growth and feed utilisation efficiency, its nutritive value is enhanced when fed together with soybean meal.

Introduction

Calliandra calothyrsus is one of the multi-purpose tree species that has been intensively evaluated in Uganda since 1989 under the agroforestry programme. The use of the crop for fodder is impeded by low production of forage biomass within smallholdings and its high tannins and related polyphenols content. These compounds make the leaves astringent and poorly digestible.

Preliminary investigation (Ebony et al 1992) indicated that astringency and adverse effects on digestibility can be negated by compositing the forage with soybean meal (SBM). The objective of the present study was to examine the effect of levels of substitution of Calliandra leaf meal (CLM) for SBM on animal performance, especially in relation to energy and nitrogen retention.

Materials and methods

Animals and treatment

Thirty-six young, intact male goats were used in a growth trail of 70 days. These were stratified according to body weight and randomly allocated to six dietary treatments: ad libitum elephant grass (diet 1); ad libitum elephant grass plus pure SBM (diet 2); 25:75 SBM:CLM (diet 3); 50:50 SBM:CLM (diet 4); 75:25 SBM:CLM (diet 5) pure CLM (diet 6). All composites were made isonitrogenous by addition of maize bran. The amounts of maize bran added was calculated using the Pearson Square method.

Daily feed offers and refusals were weighed and sampled for subsequent analysis. Live weight of each animal was measured at weekly intervals for 10 weeks. Thereafter four animals from each treatment group were selected randomly and fitted with faeces and urine collection harnesses. Total collection of faeces and urine was undertaken for four days following an adaptation period of five days. Samples of urine and faeces from each animal were taken and bulked across the days of collection for subsequent analysis.

Chemical analysis

Samples of feed and faeces were analysed for dry matter (DM), nitrogen (N) (AOAC 1980); neutral-detergent fibre (NDF), acid-detergent fibre (ADF), lignin and fibre bound nitrogen (Goering and Van Soest 1970).

Calculations

Intake components were calculated as difference between offers and refusals corrected for dry matter contents of the feeds. Digestibility was calculated as the proportion of dry matter intake (DMI) not recovered in the faeces. Growth rate was calculated as the regression coefficient of weekly body weights on days of feeding (ADG). Feed conversion efficiency (FCE) was calculated as the ratio of intake per gram of body weight gain. These parameters were examined by Least Square Analysis of Variance using the Statgraphics programme. Means were compared by Duncan's Multiple Range Tests (Gomez and Gomez 1984).

Results

The chemical composition of the feeds is shown in Table 1. The results indicate that the attempt to realise isonitrogenous feed treatments was not successful. This may have been due to improper mixing; mixing was undertaken by hand. It was not possible to carry out analysis before the feeding trial.

Average DM intake and average daily weight gain (ADO) during growth are shown in Table 2. Both parameters differed significantly (P<0.001) between diets. Goats fed on 75 and 100% CLM had the highest DM intakes. These values decreased progressively with increasing levels of SBM in the diet. With the exception of diet 2 (100% SMB) and diet 5 (75% SBM) all supplements increased DMI significantly (P<0.05) above the intake of control animals.

Table 1. Chemical composition (g/kg DM) of feed fed to goats in the growth trial.


Chemical composition

Diets

1

2

3

4

5

6

OMI

948.3

956.9

935.4

948.4

946.7

935.4

Nitrogen

15.7

56.7

34.9

39.2

43.7

33.3

NDF

707.2

182.7

224.3

202.1

191.1

242.5

ADF

425.2

173.6

174.3

175.3

168.8

164.0

Lignin

232.6

117.5

133.1

254.0

149.1

144.5

Ash

51.8

33.1

64.6

51.8

53.3

64.6

OMI = organic-matter intake;
NDF = neutral-detergent fibre;
ADF = acid-detergent five.

Table 2. Dry-matter intake (g/d; g/kg0.75), average daily gain (g/d) and feed conversion efficiency (FCE; g feed/g bodyweight gain) in goats fed elephant grass (Pennisetum purpureum) with or without supplements.


Parameters

Diets

1

2

3

4

5

6

SE

DMI (g/d)

456.8±23.0d

366.4±19.3e

595.3±18.5ab

529.6±19.0bc

473.0±19.0cd

658.9±87.4a

14.4

Kg0.75

67.2±3.1bc

54.5±2.8d

81.3±2.9a

71.9±2.5b

6.0±2.2c

79.4±2.9a

1.1

ADG (g/d)

27.1±4.0d

44.9±6.5c

83.9±7.8b

103.3±8.9a

67.0±12.9bc

58.6±9.8c

3.6

FCE (g/g gain)

17.6±2.6a

10.2±1.4b

6.7±0.5bc

4.8±0.4c

9.7±3.7b

10.0±1.5c

0.8

FCE = g feed/g weight gain; values in a row with the same superscript do not differ (P>0.05);
SE = standard error of the means.

Average daily gain also differed between diets (P<0.001). Supplementation increased average daily gain by 1.5- to fivefold. The highest daily gains were observed in animals supplemented with diet 4 (50:50 SBM:CLM). The differences in performance were also reflected in feed conversion efficiency (P<0.01).

Estimates of nutrient intakes, digestibility and N retention (NR) during the metabolic trial period are show in Table 3. DM (P<0.05) and N (P<0.001) intakes differed significantly between diets. The highest DM intake and OMI were observed in the control goats and those fed on diet 6 (100% CLM). The lowest DM intake and OMI values were observed in the animals fed on diet 4 (50:50 SBM:CLM). A strong quadratic trend was also evident.

The highest N intakes were observed in goats fed diets 2 and 6 (75 and 100% SBM, respectively). Values were observed in animals fed diets 3, 4 and 6 (25, 50 and 100% SBM, respectively) were similar to each other.

DM and OM digestibility and digestible organic matter intake (DOMI) did not differ between diets (P<0.05) (Table 3). All values were notably high (666 g/kg DM). However, apparent N digestibility differed between diets (P<0.01), but no consistent trend was established (Table 3). The lowest N retention values were obtained in animals fed the control diets 1 and 4 (no supplement and 50% SBM, respectively). Similar retention values were observed in diets 2, 3, 5 and 6; these were not different from one another.

Discussion

This experiment is a follow-up of the preliminary trial reported earlier (Ebony et al 1992). It has confirmed that compositing enhances intakes of both SBM and CLM. The mechanisms involved have not been adequately investigated. The experiment also confirmed that on its own, Calliandra can supply the N required to increase growth and possibly milk yields. However, the nutritional value can be improved by compositing with SBM.

However, the association of enhanced growth rate and feed efficiency with lower N retention values was not expected. Possible explanations include, improved amino acid balance, partition of energy between fat and protein deposition, or specific tissue metabolism and development, notably the gut, liver, skin and muscle. These tissues have variable contributions to total body pool of N and fractional synthesis rates. Indication of these required destructive sampling which was not done.

Table 3. Intake (g/d) and digestibility (g/kg DM) and nitrogen retention (g/d) in growing goats fed ad libitum elephant grass (Penniseteum purpureum) and supplements consisting of complementary proportions of soybean meal (SBM) and Calliandra calothyrsus leaf meal (CLM).



Diets

1

2

3

4

5

6

SE

Intake

Elephant grass

468.2±34.6a

616.6±27.8c

275.7±24.6de

217.8±34.4e

239.6±21.8e

398.2±33.3b

12.2

Supplements

-

268.9±34.2b

372.6±20.5a

368.2±39.2a

370.9±38.9a

284.9±33.5b

12.5

Total DM

684.2±34.6a

524.3±26.9bc

603.3±26.9ab

504.6±57.3c

545.1±47.2bc

667.6±35.2a

17.1

Total OM

611.2±27.1a

493.8±46.5bc

572.1±25.5ab

478.9±68.3ab

512.2±44.3bc

631.6±35.2a

16.6

Total N

10.2±0.5c

19.3±2.1a

16.7±0.7ab

16.5±2.2ab

19.0±1.7a

15.5±1.0b

0.6

Digestibility

DM

77.8±24.9

758.8±24.5

729.2±19.0

687.8±37.5

728.1±23.8

686.7±22.9

10.2

OM

739.9±26.6

771.2±23.1

784.2±19.0

720.1±32.1

789.7±27.7

711.1±21.0

10.1

App

846.9±13.7b

897.0±21.9a

794.4±15.5cd

766.1±32.4d

825.2±22.1bc

803.6±24.4cd

8.8

Dig. OMI

459.2±32.2

389.0±45.4

452.9±27.2

366.8±62.9

417.2±43.2

452.4±31.6

16.5

NR

7.3±1.8ab

11.1±8.9a

10.3±2.3a

5.3±9.4b

11.8±7.3a

11.5±3.2a

-

Values in a row with the same superscripts do not differ (P>0.05);
SE = standard error of the means.

Growth rates observed in goats fed supplements in this trial is rarely cited (Ebony 1990). It indicates that goats respond to improved nutrition. However, the economic justification of such interventions needs to be investigated further. The efficiency is likely to be enhanced in breed and nutritional improvement programmes.

Acknowledgements

The work was funded by the International Livestock Centre for Africa (ILCA) and co-ordinated by AFRNET. Samples collected in the study were analysed at the Faculty of Agriculture and Forestry, Makerere University, Kampala. The Calliandra feed was supplied by the AFRENA (ICRAF) project at Kalengere. We are grateful to Mr Robert Obonyo-Oker and John Kigongo who dutifully attended to the animals.

References

AOAC (Association of Official Analytical Chemists). 1980. Official Methods of Analysis. Thirteenth edition. AOAC, Inc., Arlington, Virgina, USA.

Goering H.K. and Van Soest P.J. 1970. Forage Fibre Analysis (Apparatus, Reagents, Procedures and some Applications). Agriculture Handbook 379. USDA (United States Department of Agriculture), Washington, DC, USA. 20 pp.

Gomez K.A. and Gomez A.A. 1984. Statistical Procedures for Agicultural Research. Second edition. John Wiley and Sons, Inc., New York, USA. 680 pp.


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