FEED SAMPLES FROM N W INDIA: REPORT ON INInAL EVALUATION

Project AO316Activity 1.5 Application of gas production method to the evaluation of feedsfrom India.

By C. D. Wood and R. W. Matthewrnan

Background

During a visit in March 1996 by Conroy and Matthewman (1996) to South Rajasthan(project AO506) some of the principal feeds for small ruminants were identified andselected samples taken by Dr. Matthewman for limited analyses and evaluation usingthe gas production method. This report has been prepared to report the findings andindicate possible implications for future work.

Sample collection

The samples were taken in Udaipur District in villages where Participatory RuralAppraisal (PRA) on goat keeping and feeding were being carried out. Two samples ofeach feed component were taken, either from a single location or from separatelocations, but in the same village or district. Samples were air dried in the sun andkept in airtight plastic bags.

Analytical work

The crude protein (CP) and acid detergent fibre (ADF) of the samples, together withtheir laboratory codes, are given in Table 1 below.

All the samples contained over 8% CP, and so would be expected to contain sufficientprotein to facilitate degradation by rumen microbes. Acacia leucophloea leaves andpods, Leucaena leucocephala leaves had CPs of about 20% indicating that they couldbe useful protein supplements. As is usual for leaves, fibre contents were modest(generally below 30%), although Caruga pinnata leaves with an ADF of about 30%could be of restricted digestibility.

However, the above conclusions are tentative as anti-nutritive factors and othercomponents can have major impacts on the availability of tree fodder nutrients.

Gas production evaluation

Seven fodder samples, representing some of the most important fodders in SouthRajasthan, were selected for a two stage evaluation using the gas production method.The samples selected are shown in bold in Table 1. Firstly the feeds were fermentedindividually in nitrogen-rich and nitrogen-free media to evaluate their relativedegradabilities and nitrogen sufficiency. Selected combinations were then fermented innitrogen-rich and nitrogen-free media to evaluate the ability of selected feeds to beused as protein (nitrogen) supplements.

The gas pro~uction curves for the seven samples fermented in nitrogen-rich mediumare shown in Figure 1. Acacia leucophloea leaves were considerably less fermentablethan the other samples. There were no indications as to why this was the case from thevery limited analyses done, but tannins are likely to be a factor with Acacia fodders.Leucaena leucocephala has been found in previous work (Wood et al., 1993) to be oneof the more readily fermentable tree fodders, so the other samples can be considered tobe relatively highly fermentable for tree fodders (which are generally less fermentablethan good quality pasture). Acacia leucophloea pods had a relatively high initialfermentation rate, possibly indicating a high content of readily fermentable solublecarbohydrates. Differences between fermentation properties in nitrogen-rich andnitrogen-free media were small for all the samples except Ziziphus mauritania leaves,where large differences were observed (Figure 2). This indicated that Ziziphusmauritania leaves were nitrogen deficient, again possibly due to tannins as the CPcontent of 12.66% was apparently more than sufficient. The other feeds were at leastsufficient in nitrogen.

In the second part of the evaluation, the ability of Acacia nilotica pods and leaves,Acacia leucophloea pods and leaves, and Leucaena leucocephala to supplementZiziphus mauritania leaves was assessed (the experimental plan was limited byinsufficient quantity of two of the feed samples). Table 2 indicates the extent ofnitrogen deficiency of the feed mixtures fermented, where the nitrogen deficiency index(at this stage experimental) was defined as:100 x (CG9~-rich -CG9~-fi'CC)/CG96N-richwhere CG96N-rich = cumulative gas production after 96 h fermentation (CG96) in the

feeds fermented in nitrogen-rich.CG96N-fi'CC = cumulative gas production after 96 h fermentation (CG96) in the feeds

fermented in nitrogen-free media.Unsupplemented Ziziphus mauritania leaves had a Nitrogen Defficiency of39, whichwas reduced to 12 by supplementation with 20% Acacia nilotica pods (i.e. 0.2gAcacia nilotica pods fermented with O.8g Ziziphus mauritania leaves), then to 5 with40% supplementation.

The pods of both Acacias were extremely effective protein supplements, 20%supplementation greatly reducing nitrogen deficiency, 40% supplementation largelyovercoming it (Figure 3 gives fermentation curves for Ziziphus mauritania leavessupplemented with Acacia nilotica pods). The leaves were considerably less effective,particularly Acacia leucophloea leaves. This was presumably a reflection of the lowfermentability of this sample, the protein apparently being similarly only poorlyavailable to rumen microbes.

Implications of findings

There would appear to be much to be gained by mixing feeds to aim for diets whichare more balanced in terms of protein and energy. The Acacia pods in particularappear to be good quality feeds better used as supplements to roughages than as solefeeds or as feeds given with protein sufficient tree leaves. The possible negative effectsofanti-nutntive factors (not fully evaluated here) may also be minimised by using these

feeds in limited quantities as supplements.

Settled village livestock owners in Rajasthan make rational judgements aboututilisation of feed resources for their livestock based on social, economic, labouravailability and animal production criteria. Different feeding strategies are adopted fordraught oxen, goats, sheep and milk cows/buffaloes. For example, crop residues suchas maize and wheat straw are usually fed to draught oxen, whereas tree loppings aremore often fed to goats and sheep than other livestock. The findings of the presentwork provide technical information about the nutritive value of local feeds and thismay be used to complement farmer knowledge in order to modify feeding strategiesfor livestock and to provide strategic supplements for diets at different times of the

year.

References

Conroy C. and Matthewman R. W. (1996) Agropastoralists' feeding systems for smallruminants in South Rajasthan, with particular reference to seasonal security. NRI

Report R2334(S).

Wood C. D., Johnson J. and Powell C. (1993) Evaluation of Bolivian tree leaves asfodders by an in vitro fennentation technique. Agroforestry Forum 4: 28 -34.

Table 1 Analytical data and description of feed samplesSamples shown in bold were selected for evaluation by gas production

Samplecode15051506150715081509151015111512151315141515151615171518151915201521152215231524

CP(% DM) (

14.0616.2714.5815.7012.3220.1221.7619.4818.4021.7620.9420.0416.0212.6615.9516.7412.8911.369.669.94

Sample typeAcacia nilotica podsAcacia nilotica podsAcacia nilotica podsAcacia nilotica leavesAcacia nilotica leavesAcacia leucophloea leavesAcacia leucophloea leavesAcacia leucophloea leavesAcacia leucophloea podsAcacia leucophloea podsLeucaena leucocephala leaves, pods, flowersLeucaena leucocephala leaves, pods, flowersZiziphus mauritania leavesZiziphus mauritania leavesZiziphus mauritania leavesZiziphus xylopyrus leavesZiziphus xylopyrus leavesZiziphus xylopyrus leavesCaruga pinnata leavesCaruga pinnata leaves

ADF

%DM)14.4718.2118.6812.5911.2819.7027.0422.7721.7721.5918.0318.3618.8324.9026.7918.8921.7723.2432.6328.83

Table 2 Nitrogen deficiency of supplemented Ziziphus mauritania leaves

Nitrogen deficiency index = 100 x (CG9~-rich -CG96N-frcc)/CG96N-richCG96 = cumulative gas production/g dry matter after 96h incubationN-rich = Nitrogen rich mediumN-free = Nitrogen free medium

Samplecode

Sample type Supple-ment

CG96 NitrogenDeficiency

Index(%) N-rich

medium178.7

N-freemedium108.70 39Ziziphus mauritania

leavesAcacia nilotica pods 20

40204020

187.1188.7184.4184.1182.6

164.1179.3134.9157.4134.6

125

271526

Acacia nilotica leaves

Acacia leucophloealeaves

40204040

168.0194.5193.3185.1

25135.

16

Acacia /eucoph/oea pods

Leucaena leucocephalaleaves, pods, flowers

126.4168.9183.9155.9

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