Effects of supplementing Jackfruit (Artocarpus heterophyllus L) wastes with urea or Gliricidia/cassava leaves on growth, rumen digestion and feed degradability of sheep fed on rice straw basal diet

Kusmartono

Department of Animal Nutrition, Faculty of Animal Husbandry,BrawijayaUniversity, Malang - Indonesia
Kusmartono_ub@yahoo.com

Abstract

Eighteen growing fat-tailed sheep (Experiment 1) with an average initial body weight of 25.5 kg (±3.36 kg) and three rumen fistulated sheep (Experiment 2) with an average initial body weight of 34.9 kg (± 4.79 kg) were used in a growth trial and metabolism study, respectively. They were placed in metabolism cages and subjected to the following treatments: JFW-MUB= Rice straw (ad lib)+Jackfruit wastes (ad lib)+Molasses-Urea-Block (ad lib); JFW-MUBG= JFW-MUB + gliricidia leaves hay (3% of body weight); JFW-MUBC= JFW-MUB + cassava leaves hay (3% of body weight). Parameters measured in Experiment 1. were feed intake and daily gain, whilst feed intake, digestibility, feed degradability, rumen pH, concentrations of volatile fatty acids and nitrogen retention were measured in Experiment 2. Data obtained were statistically analysed using a Randomized Block Design (Experiment 2).

The results showed that intake of JFW was dominant and ranged from 58 up to 70% of total dry matter intake. Crude protein intake (Experiment 1) and crude protein consumption and digestibility (Experiment 2) were increased significantly (P<0.05) by supplementating either gliricidia or cassava leaves hay. A similar value in crude protein digestibility was observed between sheep fed on JFW-MUBG (69.7%) and JFW-MUBC (73.0), but the amount of nitrogen retained was significantly higher in sheep fed on JFW-MUBC (22.2 g/day) than JFW-MUBG (19.22 g/day) and JFW-MUB (13.6 g/day). As a consequence, daily gain obtained was higher in sheep fed on JFW-MUBC (112.0 g/day) than JFW-MUBG (97.1 g/day) and JFW-MUB (95.6 g/day).

It is concluded that supplementing JFW as energy source together with cassava leaves hay at 3% of animal's body weight as protein sources improved digestibility value of the feeds. A higher crude protein consumed and nitrogen retained in the body of sheep receiving cassava leaves hay supplementation relative to the other nitrogen source has led to a higher daily gain achieved (112 g/day) than JFW-MUBG (97.1 g/day) and JFW-MUB (95.6 g/day). An-on farm trial to evaluate the economic benefits of integrating livestock in plantations of jackfruit and cassava trees needs to be done in further experiments.

Keywords: cassava leaves, gliricidia, jackfruit wastes, rice straw, soft molasses-urea block

Introduction

Rice straw has been the major source of feed for ruminants in many tropical countries as it is available abundantly, especially during the dry seasons. From nutritive value point of view many reports showed that it has low crude protein content and digestibility, but contains a high concentration of fibre (such as cellulose, hemicellulose and lignin; Jayasuriya 1979; Wanapat 1999). Previous studies showed that feeding rice straw as a sole diet to ruminants is not enough to supply nutrients required for production, but rather it only provides nutrients for a maintenance level of production (Wanapat 1985; Ibrahim and Schiere 1985). Therefore, some alternative ways aiming for improving its utilisation have been sought. Examples of these are ammoniation with urea or ammonia gas (Chenost and Kayouli 1997) or supplementing with protein-rich feeds like leaves from tree legumes or shrubs (Ho Quang Do et al 1999; Mom Seng et al 2001).

Jackfruit is a perennial trees which grows over a wide range of altitude and soil types in Indonesia (Nazaruddin and Muchlisah 1994) and the farmers have been using jackfruit leaves as animal feed, especially during the dry seasons. Keir et al (1997) and Phengvilaysouk and Kaensombath (2006) reported that fresh jackfruit leaves can be a valuable feed resource for ruminants when combined with nitrogen sources such as legume leaves. Other than the leaf part, the potential and nutritive value of jackfruit wastes (JFW) consisting of skin, aerial part, seed and heart parts for sheep and steer has been initially reported by Kusmartono (2001; 2002). It was shown that JFW contained low crude protein (CP; 8.6% of DM), but had a high value of organic matter digestibility (OMD;70-78%) as well as metabolisable energy (ME; 11-12 MJ/kg DM). When the materials were used to supplement rice straw together with nitrogen sources such as urea in the form of soft-cake molasses-urea block (MUB) and/or gliricidia leaves, feed intake of rice straw increased as well as its digestibility both in sheep and steers (Kusmartono 2002). The present study aims to investigate effects of supplementing JFW with urea and gliricidia or cassava hay on feed intake, rumen digestion, feed degradability and performance of sheep given rice straw straw as basal diet.

Materials and methods

Experiment 1 (Growth trial)

Animals and housing

The experiments were conducted in the Research Station of the Faculty of Animal Husbandry, Brawijaya University, Malang - East Java, Indonesia using 18 intact growing male fat-tailed sheep aging of  8-9 months old, with average initial body weight of 25.5 kg (±3.36 kg). They were put in metabolism cages to measure feed consumption and growth over a period of 84 days.

Treatments and design

The treatments were arranged in a randomized block design according to initial body weight as follows:

JFW-MUB: free access to RS + free access to JFW + free access to soft molasses urea block

JFW-MUBG: JFW-MUB + dried gliricidia leaves (3% of body weight as fresh basis)

JFW-MUBC: JFW-MUB + dried cassava leaves (3% of live weight as fresh basis).

Feed preparation

Rice straw obtained from paddy fields was transported to Brawijaya University Research Station (BURS) and they were directly scattered on the floor for a few days and then hung on bamboo racks to avoid becoming mouldy until they were used. Jackfruit wastes were taken from cracker factories every three to four days, chopped into pieces approximately 4-5 cm long and stored in plastic bags. Gliricidia leaves were harvested at vegetative stage from plantations surrounding the BURS, dried for 4-5 days and stored until they were used, whilst cassava leaves were harvested from rented land at least 7 months after plantation. They were then dried for 4-5 days and bulked before being given to the animals. The soft molasses-urea cake was prepared according to the procedure of Ho Quang Do et al (1999) using the following composition (%): molasses 35, rice bran 40, coconut cake meal 10, urea 10 and salt 5. The soft cake was made in a steel frame (8 cm wide x 15 cm long x 5 cm height) that produced a 1 kg cake.

Experiment 2 (Metabolism study)

Animals and housing

Three rumen fistulated sheep aging approximately 2.0-2.5 years old with average initial body weight of 34.9 kg (± 4.79 kg) were kept in individual cages throughout the study to measure feed consumption, digestibility, degradability of rice straw and JFW, rumen ammonia and VFA concentrations, protozoa population and nitrogen retention.

Treatments and design

The treatments in a 3*3 Latin square arrangement were:

JFW-MUB: free access to RS + free access to JFW + free access to soft molasses urea block

JFW-MUBG: JFW-MUB + dried gliricidia leaves (3% of body weight as fresh basis)

JFW-MUBC: JFW-MUB + dried cassava leaves (3% of live weight as fresh basis).

Feed preparation

The feeds given in Experiment 2. were prepared in the same manner as described previously in the Experiment 1.

Experimental protocol

Experiment 1 ( Growth trial)

The experiments were conducted following the procedure of Harris (1970) with two stages; adaptation and data collection. The adaptation period lasted for 12 up to 14 days for each treatment until the daily intake was constant. The data collection period lasted for 84 days during which daily feed intake, feed refusals were measured, whilst body weight changes were measured in every 14 days. Samples of feed offered, feed refusals were taken every day from each animal in each period. The samples were bulked for the same animal in each period. Sub-samples of feed offered, feed refusals were then oven dried, ground and stored until used for chemical analysis. Growth rate of sheep was determined by a linear regression of live weight over growing period.

The procedure of Harris (1970) as described in Experiment 1 was also applied in the Experiment 2. The data collection period lasted for 7 days for each period during which daily feed offered, refusals, feces and urine excreted were measured. For the purpose of urine collection, each cage was equipped with urine collecting bottle and concentrated sulphuric acid was added to each bottle to preserve the N in the urine. Samples of feed offered, feed refusals and faeces taken every day from each animal in each period were bulked for the same animal in each period and sub-samples of feed offered, feed refusals and faeces were oven dried, ground and then stored for chemical analysis. Urine samples taken daily were pooled for each animal every week and sub-samples were taken for N analysis.

At day 8 in each period, rumen liquid samples were aspirated at 0, 3, 6 and 12 hours after feeding for measurements of rumen pH, rumen ammonia and VFA concentrations and protozoa population. About 45 ml rumen fluid were aspirated from each animal through the rumen cannula on each occasion by inserting a probe attached to a syringe. Fifteen ml of rumen liquid was used for rumen pH measurement, 10 ml for counting protozoa and 20 ml was added to 5 ml of deproteinising reagent (1M H₂SO₄ saturated with magnesium sulphate; Domingue et al 1991), centrifuged at 2000 g for 15 minutes and then kept at -20^oC for ammonia and VFA analysis.

Degradability measurements of rice straw and jackfruit wastes were started at day 10 in each period in which the ground rice straw and jackfruit wastes were placed in nylon bags and incubated in the rumen at different times (0, 3, 6, 9, 12 and 24 hours) following the procedure of Ørskov and McDonald (1979). The observed values for losses of substrates were then fitted to the model

p = a + b (1-e^-ct) ,

where :

"p" is the degradability after time "t"

"a" is the intercept of the degradation curve at time zero

"b" is the fraction degraded over a period of time at a rate constant of "c"

"a+b" is potential degradability in the rumen given sufficient time

Laboratory analysis

Samples of feed offered, feed refusals and faeces (Experiments 1 and 2) were analysed for dry matter (DM), organic matter (OM) and crude protein (CP) according to procedures of AOAC (1984), whilst analysis of acid detergent fibre (ADF) and neutral detergent fibre (NDF) were done following the procedure of Goering and Van Soest (1970). Urine samples were used for N analysis using Kjeldahl method. .Rumen ammonia was analysed using the microdiffusion Conway method, whilst determination of VFA proportions followed the method described by Preston (1995). Protozoa counting was done in a deep chamber under x100 magnification according the procedure of Navas et al (1992).

Statistical analysis

The data in Experiment 1 were subjected to statistical analysis using a Randomized block design according to initial body weight, whilst a Latin square design was used in Experiment 2 following the procedure of Steel and Torrie (1980). Daily gain data in Experiment 1 was tested using analysis of covariance with initial body weight used as covariate. The mean values of each variable were compared when a significant effect of the treatments was observed.

Results and discussion

Chemical composition of feeds

Data of chemical composition of feeds offered for both Experiments 1 and 2 are presented in Table 1.

Dry matter, OM and CP contents of rice straw were in the range of values reported earlier by other authors (see Jayasuriya 1979; Chuzaemi 1994). The CP content of the JFW used in the current study (8.3%) was slightly higher than the 7.3% reported by Kusmartono (2001). The OM and CP contents of gliricidia hay (88.9 and 23.9 %, respectively) were similar to those reported by previous researchers (see Pathirana and Ørskov 1995; Keir et al 1997; Orden et al 2000). Likewise, NDF and ADF contents of the feeds used also were in the range of values reported by other authors (see Seijas et al 1994; Yuangklang et al 2001).

Experiment 1

Voluntary feed intake and daily gain

Data of feed consumption and average daily gain during the study are presented in Table 2.

In the present study the amount of gliricidia and cassava leaves hay offered was 3% of animals' body weight (fresh basis) as suggested by Preston (1995), but during the course of the study the animals did not consume the whole gliricidia hay offered, whilst none of the cassava hay was left in the trough. This evidence indicated a lower palatability of gliricidia than cassava hay which led to a slightly lower contribution of crude protein observed in sheep given JFW-MUBG compared to those given JFW-MUBC. The potential of gliricidia and cassava leaves as protein sources for ruminants to supplement fibrous-based diet has been reported earlier by other researchers (see Preston 2001; Ho Quang Do et al 2002).

Figure 1 shows that intake of JFW was dominant and ranged from 58 up to 70% of total DMI and this was in line to the result reported earlier by Kusmartono (2002). He concluded that there were marked differences between sheep and cattle in the relative intakes of rice straw and jackfruit waste when these were offered on a free choice basis where sheep ate a much greater proportion of the diet in the form of jackfruit waste (90% of DMI) than the cattle (50% of DMI).

Intake of gliricidia in the hay form recorded in the present study was higher than the value reported earlier when the gliricidia was given in the fresh form (14.6 v. 7.2 g DM/kg BW^0.75/d). This indicated the importance of wilting process before feeding, as Norton (1994) suggested that wilting or drying gliricidia leaves can eliminate the odour caused by the compound "coumarin" and also decrease HCN content that leads to the improvement of acceptance of this forage to the animals (Makkar 1993).

Growth rate of sheep determined by a linear regression of live weight over growing period showed that the degree of linearity among the treatments was different and the greatest response in growth was achieved by the animals receiving cassava hay supplementation followed by those receiving supplementation of gliricidia hay which was slightly faster compared to those receiving nitrogen source only through soft-cake MUB. Analysis of covariance using initial body weight as covariate showed that its effect on daily gain was not significant (P>0.05). However, as shown in Table 2, treatments significantly affected daily gain (P<0.05) with the sheep receiving JFW-MUBC being higher in daily gain (112.1 g/day) compared to the other two treatments (95.6 g/day for JFW-MUB and 97.1 g/day for JFW-MUBG). Intake of cassava leaves hay was twice as high as gliricidia hay, and this brought about the increase in total energy intake, microbial growth and N retention. Besides, the presence of condensed tannin in cassava hay may increase it's rumen protein by-pass properties, and hence increase animal growth (Wanapat et al 2000). Condensed tannin concentration was measured in this study using a butanol-HCl method (Porter et al 1979) and showed that gliricidia and cassava hay contained 5.32 and 3.26% of DM respectively. Barry (1989) suggested that condensed tannin level at 2-4% of DM in the diet will increase protein flow into duodenum which ultimately will improve he protein fraction absorbed, hence animals' growth is improved. A high level of condensed tannin as observed in gliricidia hay (5.32% of DM) might have led to the protein consumed by the animals receiving JFW-MUBG treatment being overprotected and this is indicated by a slightly lower amount of N retained in the body.

Experiment 2

Feed intake, digestibility and Nitrogen balance

Feed intake of the rumen fistulated sheep during the study are presented in Table 3.

Although the intake values were not exactly the same as those observed in Experiment 1 using growing sheep, a similar evidence showed that intake of JFW was very high (Figure 2). The sheep receiving cassava or gliricidia hay supplementation consistently had higher CPI values than the animals receiving JFW-MUB treatment. The mechanism described in the earlier section may also be applied to explain the phenomenon shown in Table 3.

Table 3 also showed that addition of either gliricidiaor cassava leaves hay improved digestibility value, but a significant improvement was only observed in CP digestibility (P<0.05) with the sheep receiving cassava hay supplementation tending to have a higher value (73.0%) than those receiving gliricidia hay supplementation (69.7%). The most obvious supporting evidence observed was rumen ammonia concentrations in all treatments which were adequate to support microbes to digest fibre (see Table 4).

However, a higher amount of N excreted in the urine of sheep fed on JFW-MUBG compared to those fed on JFW-MUBC can be interpreted that less amount of ammonia incorporated into microbial protein synthesis which may be due to less amount of energy supply in the form of ATP. A significantly higher N-retention in the animals fed on JFW-MUBC implied that cassava leaves hay had a higher potential in contributing N to the animals than gliricidia or urea. One of the reasons as explained earlier may be the presence of an appropriate condensed tannin content in cassava hay which led to a better protein protection and higher contribution of protein in the abomasum. Wanapat et al (2000) also reported that by supplementing cassava hay that had 3.21% of condensed tannin increased protein input in the duodenum which ultimately improved protein fraction absorbed, hence animals' growth is improved.

Data presented in Table 4 showed that treatment did not significantly affect rumen pH, protozoa population and protein degradability, but significantly affected ammonia concentration and total concentration of volatile fatty acids (P<0.05). Rumen ammonia concentration levels were above the level needed for optimum fibre digestion and feed intake (200 mg N/litre) according to Preston and Leng (1987) and Ørskov (1992) and this allowed the animals used in this study to have higher digestibility value compared to the value when jackfruit wastes alone was used to supplement rice straw as reported earlier by Kusmartono (2002).

Molar proportions of acetic, propionic and butyric acids increased as the intake of crude protein increased and these increases did not seem to be related to diet dry matter consumed as jackfruit wastes but rather it was related to the source nitrogen used to supplement the rice straw basal diet. As mentioned earlier that due to their palability, cassava leaves hay were much easier to be ingested by the sheep and hence capable of supporting more crude protein intake than the other nitrogen sources. However, the fact that sheep fed on JFW-MUBC tended to have a higher protozoa population than the others, it therefore needs a more judicious consideration in combining jackfruit wastes, which is high in fermentable carbohydrate (Kusmartono 2001), with nitrogen source if it is aimed to improve voluntary feed intake and digestibility of rice straw as basal diet because at least 58% of total dry matter intake as observed in the present study came from jackfruit wastes. Protozoa population increases along with the increase intake of fermentable carbohydrate and in most cases, it brings about the depression of digestible nutrients (Jouany 1989; Van Soest 1994).

Implications

Since rice straw is abundantly available during dry seasons in most tropical regions, its utilization should be maximized by implementing technologies which are technically easy to be adopted by farmers and economically feasible. Previous studies have shown that nutritive value of rice straw could be increased by implementing either physical, biological or chemical treatments prior to feeding (see Sundstol et al 1978; Ibrahim et al 1983). However, the level of farmers' adoption is considered low and varies among the regions in Indonesia due mainly to lack of technical skill and the fact that additional profits obtained by small farmers who own up to 5 sheep by implementing such technology is not significant.

Results of the present study showed that supplementing nitrogen sources (i.e urea, gliricidia or cassava leaves) together with jackfruit wastes as energy sources has given positive impacts to the nutritive value of rice straw as basal diet as well as animal performance with cassava leaves hay being the best protein supplement. Under tropical agricultural systems like in Indonesia, jackfruit trees are grown in the backyard and one farmer owns up to 5 jackfruit trees. Likewise, cassava is considered one of the most important staple foods and the use of cassava leaves for animal feed has been widely practised by farmers. Therefore, it may be easy for farmers to apply feeding systems in their ruminant production by integrating livestock with cassava and jackfruit plantations using rice straw as basal diet.
 

Conclusions

• Ruminant production systems practised in most tropical countries like in Indonesia largely depends on seasonal feed resources that are relatively low in quality. Therefore, supplementation strategy involving the utilization of feeds locally available, either as protein or energy source, has attracted much attention of ruminant nutritionists.

• Based on the results of the present study, it can be seen that supplementing JFW as energy source together with cassava leaves at 3% of animal's body weight as protein sources improved digestibility value of the feeds. A higher crude protein consumed and nitrogen retained in the body of sheep receiving cassava leaves hay supplementation relative to the other nitrogen sources might have been the reason of better animal performance expressed in a higher value of daily gain.

Acknowledgements

The author wishes to thank IFS-Sweden for financial support. Dr T R Preston and Prof E R Ørskov are acknowledged for their encouragement, advice and criticism during preparation of the experiment.

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Received 5 July 2006; Accepted 25 November 2006; Published 8 February 2007

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