Effect on intake and digestibility by goats given jackfruit (Artocarpus heterophyllus) leaves alone, the whole branch or free access to both

Ammaly Phengvilaysouk and Lampheuy Kaensombath

Livestock Research Centre, National Agriculture and Forestry Research Institute
Ministry of Agriculture and Forestry, PO Box 811, Vientiane Lao PDR
ammalyp@yahoo.com

Abstract

A study was made of different ways of offering Jackfruit  foliage [Artocarpus heterophyllus] to goats. The feeding methods were: fresh leaves in the feed trough (L), the whole branch hanging from the roof of the pen (B) or foliage hanging  plus leaves in the feed trough (BL).  The experimental design was a 3*3 Latin square arrangement with 3 goats and 3 periods each of 7 days.

DM and crude protein concentrations were higher in leaves than in the foliage (leaves plus stems). The goats ate more DM when they were offered the foliage hanging from the roof of the cage (486 g DM/d). Intake was lowest and eating time longest when only the leaves were offered in the feed trough (282 g DM/d). DM and OM digestibility and N retention followed the same pattern as DM intake, with highest values for hanging foliage and lowest for leaves fed separately.  There was no effect of feeding method on rumen pH and rumen ammonia levels which ranged from 130 to 310 mg/litre.

It is concluded that dry matter intake, digestibility and N retention of jackfruit by goats is higher when the leaves are attached to the stem and hung from the walls of the pen, compared with putting only the leaves in a feed trough.

Key words: feeding, digestibility, goats, Jackfruit, intake, N retention.

Introduction

Livestock are an important component of smallholder farms in the Lao PDR with sales of livestock accounting for more that 50% of cash income in many upland and highland areas. Over 95% of all livestock is produced by smallholders (Stur et al 2002). Goat production plays an important role in the agricultural sector in the rural areas, especially in the mountainous areas, supplying meat, milk and fertilizer. Goat production is not yet performed properly at the grass-roots level. Goats are generally left to graze freely all year in small groups in forest and fallow land. Farmers raise local breeds, which have a small body size and there is a lack of feed during the dry season resulting in low productivity and poor reproduction (Sopha Xaypha and Ledin 2005).

Farmers tend to restrict the number of goats they raise to avoid excessive damage to crops for which the owner is held responsible. There usually is good local market demand for goat meat which is one of the reasons for the relatively high rate of increase in the goat population (8% per annum) over the last 20 years (Stur et al 2002)

Tree leaves have been used traditionally by farmers as animal feed but relatively little is known about their potential to replace conventional protein-rich concentrates such as soya bean meal and fish meal (Keir et al 1997).  The method of offering tree foliages has been found to be important with higher intakes and digestibility when the foliage was offered hanging as a branch rather than as leaves fed alone (Theng Kouch et al 2003; Le Thi Thuy Hang 2003; Keopaseuht Toum et al 2005).

Hypothesis

• Goats will have higher feed intake when offered the hanging branch of jackfruit or mixture of the branch and leaves rather than just the leaves.
• The digestibility of the foliage from jackfruit by goats will be higher when hanging in the pen compared with  leaves offered in the feed trough.

Materials and methods

Location

The experiment was conducted at the Livestock Research Center, Nam Xuang about 44 km from Vientiane City, Lao PDR. The experiment started on 12 September 2005 and finished on 12 October 2005.

Experimental animals

Three growing male goats (local breed) of 9.6 to 12.9 kg live weight were confined in cages made from wood with plastic mesh and plastic sheet beneath the floor to collect separately the faeces and urine.

Experimental design

The experimental design was a 3*3 Latin Square arrangement with periods of 10 days, 5 for adaptation to the diet and 5 for collection of faeces and urine.. The treatments were:

• Jackfruit leaves alone [ L]
• Hanging the whole branch of jackfruit [B]
• Free access to hanging branch of jackfruit and the leaves in the trough [BL]

The layout of the experiment is shown in Table 1.

Feeds and feeding system

The jackfruit branches were harvested within the Livestock Research Center or in households near the center. For the treatment [L] the leaves were separated from the stem and put in the feed trough; for [B] the branch was hanging above the feed trough; [BL] was a combination of [B] and [L].  In all cases feeding was ad libitum with an offer level of about 20% above actual intake. The feeds were offered twice daily: about 7.00am and 16.30pm. Days 1 to 5 of each period were for adaptation to the new treatment; and days 6 to 10 for data collection. The feeding methods for "B" and "L" are shown in Figures 1 and 2.

Measurements

Leaf: stem ratio

Before preparing the feeds, the ratio of leaves plus petioles and stems was determined on samples (1 kg of foliage) taken 2 times per day.

Intake, digestibility and N retention

Feed offered and refused, and output of faeces and urine, were recorded daily during the last 5 days of each period. Samples of feed offered and refusals were taken daily and analyzed for DM, CP, CF, OM and N. Faeces were put in plastic bags in the freezer (-20 °C). Urine was collected in a bucket containing 25% H₂SO₄ solution (10 ml added per day) to maintain a pH of 4 or lower.

Rumen environment

Rumen fluid samples were collected by stomach tube two hours after feeding on day 10, at the end of each experimental period. About 15 ml of rumen fluid were collected from each goat to measure immediately rumen pH and ammonia nitrogen.

Chemical analysis

Feed and faecal samples were dried by microwave radiation to measure the DM content (Undersander et al 1993). Total N of feed, faeces and urine was measured by the Kjeldahl procedure as outlined by the AOAC (1990). The ash content of feed and faeces was determined by combustion in a furnace at 500°C, following the procedure of AOAC (1990). Organic matter was assumed to be the result of subtracting the percentage of ash from 100. The water extractable DM and N were determined according to Ly and Preston (1997, 2001).

Rumen pH was determined using a glass electrode and digital pH meter. NH₃ was estimated by steam distillation according to the procedure described by Nguyen Van Lai and Ly (1997).

Biometrical analysis

The data were analyzed using the general linear model (GLM) procedure in the ANOVA and Tukey test software in MINITAB (release 13.31).

Results and discussion

Feed composition

The ratio of leaves + petioles: stems was 64: 36. This ratio is similar to that reported by Theng Kouch et al (2003) (72: 28).

The values for DM and crude protein of the leaves + petioles (Table 2) were similar to those reported by Nguyen Thi Mui et al (1997) for Jackfruit leaves harvested in the dry season (38 and 18%, respectively). Lower values for DM (26.9%) and higher values for crude protein in DM (18%) were recorded by Nguyen Thi Duyen et al (1996).

Voluntary feed intake

There were major differences in intake of leaves and of total DM (Table 3; Figure 3), with lowest values when the leaves were offered alone compared with offering the leaves attached to the stems (hanging branch). There were no advantages from giving the goats access to both the hanging branch and the separated leaves. The intake of DM as proportion of live weight on the hanging branch treatment (42 g DM/kg LW) was similar to the value (48.7) reported by Theng Kouch et al (2003).  Foliage suspended in the cage most closely simulates the natural condition when goats browse trees and shrubs. It appears that the goats find it easier to bite the leaves when they are attached to stems offering some resistance to the action of eating, as is the case for hanging foliage compared with the leaves placed loosely in the feed trough.

Figure 3: Intakes of leaves and stems according to offer method (error bars relate to intake of leaves)

Digestibility and N retention

Apparent digestibility coefficients of DM and N were higher when the whole branch was fed compared with leaves only (Table 4). There were no advantages from giving additional leaves as well as the branch.  The same order of differences was observed for N retention.

The data for digestibility are similar to those reported by Theng Kouch et al (2003)  (48% for leaves alone and 63% for foliage). A higher value of 66% for DM digestibility of leaves was recorded by Keir et al (1997), but the leaves in this case were supplemented with a block of molasses-urea.

A retention of N of 2.8 g/day (Table 4) is equal to about 18 g/day of protein which, assuming the body contains 20% protein, would be reflected in a rate of live weight gain of the order of 100 g/day.

The feeding method did not affect rumen pH nor ammonia concentration (Table 5).

Conclusions

• The method of feeding by hanging the whole branches of jackfruit was the best way to improve feed intake of the goats.
• This method can be accepted easily by farmers, because of need for fewer inputs (feed troughs not required; no need to chop or process the foliage).
• The foliage of jackfruit can be fed as the sole component of the diet to goats and should support live weight gains close to 100 g/day

Acknowledgments

This paper formed part of the MSc mini-project (MEKARN-SLU, Uppsala, September 2005) of the senior author, who wishes to express his gratitude to the MEKARN project, supported by SIDA/SAREC of Sweden for financing this study.  The advice of Dr Preston and Mr Chhay Ty are gratefully acknowledged.

References

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Received 2 January 2006; Accepted 25 February 2006; Published 17 March 2006

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