Feed intake and growth performance of goats fed with Napier grass and oil palm frond supplemented with soya waste

Abstract

The effect of Napier grass and oil palm frond (OPF) supplemented with soya waste on the intake and growth performance of goats was evaluated. Twelve female cross-bred goats (Boer × local) were divided into three groups and randomly assigned to three experimental diets: (1) Napier grass ad libitum (NG), (2) OPF ad libitum (OPF) and (3) Napier grass ad libitum+ OPF ad libitum (NG-OPF). All goats in each group received soya waste at the rate of 1.3% of their body weight (BW). Dry matter intake per kg unit of BW was higher (P < 0.05) in the NG-OPF diet than in the NG or OPF diets. However, the crude protein intake per kg unit of BW was higher (P < 0.05) in the OPF or NG-OPF diet than in the NG diet. Animals on the OPF diet showed a lower (P < 0.05) daily BW gain followed by the animals on the NG and NG-OPF diets, but no variation (P > 0.05) was observed between the animals on the NG and NG-OPF diets. The results showed that the feeding of NG alone or NG-OPF combination to goats could lead to a better growth rate in these animals compared to feeding them with OPF alone.

Keywords:

• feed intake
• growth rate
• Napier grass
• oil palm frond
• soya waste

1. Introduction

In Southeast Asia, grass production or the availability of natural pastures is one of the main constraints in ruminant production. This is due to the shortage of land or land topography. Agricultural by-products or wastes are often considered as alternative feeds for ruminants to overcome feed problems. The utilization of these by-products or wastes can also reduce feed cost and environmental pollution. Oil palm frond (OPF) is a by-product. It is a residue from the harvesting and pruning management of oil palm fruit bunches. However, OPF contains low protein and it needs protein supplementation to enhance the growth rates of ruminants that are based on the OPF diet (Dahlan et al. 2000). Nasir et al. (1997) observes that OPF silage alone does not support the maintenance requirement of milking goats due to low intake. Dahlan et al. (2000) reports that OPF can efficiently be used as a roughage source when used together with concentrate supplement. However, additional studies need to be carried out to improve the intake of OPF using different techniques of processing and supplementation. Feed supplementation (e.g. with pistachio by-products, live Saccharomyces cerevisiae) improved nutrient utilization and productivity of the goats (Kamal et al. 2013; Ghaffari et al. 2014), which could be due to the balanced nutrients for optimum feed digestibility.

Soya waste is a by-product of the tofu, soymilk and soya juice manufacturing industry, and it is high in protein content (Dong et al. 2005). Inclusion of soya waste in the OPF-based diet of goats may lift protein content significantly. Research regarding the uses of these by-products (soya waste and OPF) for feeding goats is limited. Goats have more selective eating behaviour compared to other ruminants; therefore, the present study is being undertaken to investigate the feeding effect of Napier grass and OPF supplemented with soya waste on the feed intake and growth performance of goats and to promote these by-products as goat feed.

2. Materials and methods

2.1. Study site and experimental diets

This study was carried out at a goat farm in Rumpun Asia Sdn. Bhd. (3° 28′ N latitude and 101° 38′ E longitude), Selangor, Malaysia. The procedure on animal care was conducted according to the guidelines established by the Animal Care Committee of the University of Malaya. Napier grass (Pennisetum purpureum) was harvested daily from different plots in the goat farm by cutting at different periods (45–50 days interval) to obtain similar quality throughout the experimental period. Plots were fertilized with goat manure at 200 kg N ha⁻¹ annually. Fresh OPF was collected daily from the nearest goat farm. The harvested Napier grass and OPF were chopped in 5–7 cm lengths and fed to the animals on a fresh basis. Commercial pellet and soya waste were supplied by local suppliers once a week. Soya waste was stored in plastic containers and kept airtight (anaerobically).

2.2. Animals and management

Twelve female cross-bred goats (Boer × local) aged between seven and nine months, with an initial body weight (BW) of 16.3 ± 0.6 kg, were used in an 80-day experiment. Goats were adapted to the feeding management for 14 d before the start of data collection. During this time, the goats were fed with Napier grass (ad libitum) supplemented with commercial goat pellet at the rate of 1.0% of BW. At the end of the adaptation period, the goats were individually weighed and divided into three groups of equal number and weight as follows: (1) Napier grass + soya waste (NG), (2) OPF + soya waste (OPF) and (3) Napier grass + OPF + soya waste (NG-OPF). Napier grass or OPF was supplied ad libitum (about 130% of the fresh intake of previous day) twice daily (morning and afternoon) to respective goats, while soya waste was supplied once every morning meal to all goats at the rate of 1.3% dry matter (DM) of BW. All goats were dewormed for internal parasites with Bomectin as prescribed by the manufacturers of the product (Bomac Laboratories Ltd., Auckland, New Zealand). The goats were kept in individual pen with free access to water.

The dietary metabolizable energy (ME) and crude protein (CP) intakes of the goats should be 6.0 MJ/d and 97.0 g/d, respectively, to meet the requirements of a goat weighing 16.3 kg and growing at 100 g/d, according to NRC (2007). In all treatments, the approximate ME and CP from the daily offered soya waste were 2.52 MJ/h/d and 54 g/h/d, respectively. The ME contents (MJ/kg DM) of feeds were calculated from the equation [(15.2 × digestible CP + 34.2 × digestible crude fat + 12.8 × digestible crude fibre + 15.9 × digestible free extract)/1000] according to MAFF (1984). It was hypothesized that goats could take the rest of the ME and CP from the daily offered ad libitum Napier grass or OPF.

2.3. Measurement of feed intake and BW change

The BW changes of goats in response to the experimental treatments were measured by taking the BW of individual goats at the commencement of the trial. This was then followed by individual weighing on a bi-weekly basis until day 70. Final treatments of BWs were taken on day 80. The amount of daily offered feeds and morning refusal per goat were weighed and recorded to calculate the daily feed intake. The feeding trial was continued for 80 days after the initial 14 days adaptation period.

2.4. Sample preparation and analysis

Samples of feed and refusal were collected every two weeks. The DM content of the composite samples was determined by drying the samples at 70°C for 48 h. The dried samples were ground with Willey mill to pass through a 1 mm sieve. Ground composite samples were analyzed for DM, ash and nitrogen (N) according to the methods of the AOAC (1990). Organic matter (OM) was determined by subtracting percentage ash content from 100. CP content was calculated as N × 6.25. Neutral detergent fibre (NDF) was determined as described by Van Soest et al. (1991). The calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na) contents of the feeds were determined using the flame atomic spectroscopy method (Laboratory of Agricultural Chemistry, the University of Tokyo, 1978). Briefly, 1 g dry sample was digested through repeated additions of nitric acid and hydrogen peroxide until the solution was clear and without colour. The digested sample was diluted to a final volume of 100 mL (including 1 mL of 5% lanthanum chloride) for Ca and Mg determination. The Na, K, Ca and Mg contents in the samples as well as the calibration standards were estimated using flame atomic spectroscopy at wavelengths of 588.9, 766.4, 422.7 and 285.2 nm, respectively.

2.5. Statistical analysis

Data on feed intake and BW changes were analyzed using analysis of variance in completely randomized design. Mean values were tested for differences (P < 0.05) between treatments with least significant difference using SPSS (version 12.0, SPSS Inc., Chicago, IL, USA).

3. Results

3.1. Chemical composition

The DM contents of Napier grass and soya waste were almost similar, but OPF showed higher DM content than the others (Table 1). On the other hand, the CP, OM and NDF contents of Napier grass and OPF were similar, but the soya waste showed higher CP and OM contents and lower NDF content than the other feeds. Napier grass contained higher contents of Mg and K followed by soya waste and OPF, whereas OPF contained higher contents of Ca followed by Napier grass and soya waste. Napier grass and OPF contained similar contents of Na, while soya waste contained higher contents of Na compared to other feeds.

Table 1. Chemical composition (%, DM) of Napier grass, OPF, and soya waste.

Parameter	DM	CP	OM	NDF	Ca	Mg	K	Na	ME (MJ/kg DM)
Napier grass	24.0	9.5	88.9	55.7	0.34	0.47	3.38	0.01	7.5
OPF	59.2	10.5	87.5	53.5	0.43	0.19	1.22	0.01	6.5
Soya waste	22.5	21.9	96.6	27.8	0.16	0.36	1.29	0.08	11.2

DM, dry matter; CP, crude protein; OM, organic matter; NDF, neutral detergent fibre; Ca, calcium; Mg, magnesium; K, potassium; Na, sodium; ME, Metabolizable energy.

3.2. DM and nutrient intakes

In all the treatments, the soya waste offered was consumed readily by the goats. The total DM intake of the goats fed with the NG-OPF diet was higher compared to those fed with the NG or OPF diets (Table 2). The total OM intake of the goats was different among the treatments – the highest intake was on the NG-OPF diet and the lowest was on the OPF diet. The total CP intake per unit of the metabolic BW (BW^0.75) of goats fed with the NG diet was lower compared to those fed with the OPF or NG-OPF diets. ME intake was lower in the OPF diet group compared to the other groups, but no difference was observed between the NG and NG-OPF diet groups.

Table 2. Feed intake by goats fed with Napier grass and OPF supplemented with soya waste.

	Diets
Parameter	NG	OPF	NG-OPF	SEM
Soya waste DM intake (g/d)	206.3^a	214.0^a	208.0^a	2.26
Grass DM intake (g/d)	413.8^b	–	231.2^a	17.63
OPF DM intake (g/d)	–	382.4^b	229.2^a	16.49
Total DM intake (g/d)	620.1^a	596.4^a	668.4^b	8.43
Total DM intake (% BW)	3.5^a	3.4^a	3.7^b	0.03
Total DM intake (g/kg W^0.75/d)	71.6^a	69.3^a	76.1^b	0.62
Total CP intake (g/d)	85.1^a	89.2^ab	92.1^b	1.04
Total CP intake (g/kg W^0.75/d)	9.8^a	10.4^b	10.5^b	0.06
Total OM intake (g/d)	571.1^ab	549.8^a	601.3^b	7.13
Total OM intake (g/kg W^0.75/d)	65.9^b	63.8^a	68.4^c	0.45
Total ME intake (MJ/d)	5.4^a	4.9^b	5.6^a	0.06

DM, dry matter; CP, crude protein; OM, organic matter; ME, metabolizable energy; SEM, standard error of mean; NG, Napier grass; OPF, oil palm frond; NG-OPF, Napier grasss + oil palm frond.

^a,b,c Means in the same row having different superscripts are significantly different (P < 0.05).

3.3. BW gain

There was no difference in the initial BW among the three dietary treatment groups. However, the animals fed with the OPF diet resulted in lower final BW than when they were fed with the NG or NG-OPF diets (Table 3). Similarly, the animals fed with the OPF diet resulted in a lower average daily BW gain than when they were fed with the NG or NG-OPF diets. The gain efficiency was also higher for the NG and NG-OPF diet groups compared to the OPF diet group.

Table 3. BW change of goats fed with Napier grass and OPF supplemented with soya waste.

	Diets
Parameter	NG	OPF	NG-OPF	SEM
Initial BW (kg)	16.0^a	16.4^a	16.4^a	0.45
Final BW (kg)	19.5^a	18.8^b	19.8^a	0.47
BW gain (g/d)	43.5^a	30.8^b	43.0^a	2.32
G:F ratio	0.071^a	0.052^b	0.065^a	0.001

^a,b,c Means in the same row having different superscripts are significantly different (P < 0.05).

NG, Napier grass; OPF, oil palm frond; NG-OPF, Napier grasss + oil palm frond.

4. Discussion

The efficient use and management of natural resources are important factors for success in agricultural farming. Oil palm is one of the natural resources in Malaysia and Indonesia. OPF is a waste material from the harvesting and pruning management of oil palm fruit bunches. On the other hand, soya waste is an industrial waste and is a by-product of ground soybean processed for the production of tofu, soya milk and soya sauce. Huge quantities of soya waste are produced worldwide. The utilization of OPF and soya waste in ruminant feeding has been evaluated (Dahlan et al. 2000; Kim et al. 2012).The nutrient intake and digestibility of the feeds can be improved through the use of various techniques for processing and supplementation (Leng 1990). The present study was carried out to determine whether OPF and Napier grass supplemented with soya waste can be used efficiently to feed goats.

The CP contents ranged from 9.5% in Napier grass to 21.9% in soya waste. The CP, OM and NDF contents of Napier grass in this study were similar to the values reported by Rahman et al. (2013b). The CP, OM and NDF contents in the soya waste used in this experiment were also in line with the value reported by Dong et al. (2005) and were similar to those in our previous study (Rahman et al. 2013b). The Ca content of soya waste was lower compared to that reported by Dong et al. (2005). OPF in the present study has higher DM and CP contents than that reported by Dahlan et al. (2000), which might be due to the differences in age of plants, harvesting time and processing methods.

Goats are selective feeders and their food intake can be reduced under confinement; therefore, careful attention should be observed when determining ad libitum intake (Goetsch et al. 2010). Fedele et al. (2002) observed that the DM intake of free choice goats increased by 12% compared to those under control treatment. This observation corresponds with the present observation as animals on the NG-OPF diet can select either Napier grass or OPF based on palatability that resulted in higher cumulative intake. The authors assume that the Napier grass-OPF combination can improve the DM intake of goats due to their freedom of feed choice (Fedele et al. 2002) and high gas production (Joo et al. 2012). Consequently, animals on the NG-OPF group showed a significantly higher average daily BW gain compared to the animals on the OPF group. However, no difference was observed on the daily BW gain between the animals on the NG and NG-OPF groups in spite of lower DM intake in the NG group than in the NG-OPF group. It is believed that the feeding of Napier grass provided better growth response due to the higher DM digestibility of Napier grass compared to OPF. This premise was supported by Imsya et al. (2013) who reported that increasing OPF in the ration reduced nutrient digestibility. However, the Napier-OPF combination is more fermentable and represents higher in vitro DM digestibility than Napier grass or OPF alone (Joo et al. 2012).

On the other hand, animals on the OPF group showed a lower BW gain compared to the animals on the NG group even though the animals of both groups had similar intakes of DM, CP, OM and ME. These results indicate that OPF is low-quality roughage in terms of BW gain. This result is supported by Dahlan et al. (2000) who reported that OPF is low in voluntary intake and that it can only provide the required amount of energy and protein for maintenance. In this study, however, dietary soya waste improved the intake of OPF (3.4% of BW) in the OPF group, resulting to positive BW gain (30.8 g/d). Dahlan et al. (2000) reported that goats fed with freshly chopped OPF supplemented with 1% concentrate showed very low BW gain – only 10.33 g/d, which was lower compared to our present study. The increased BW gain obtained in goats fed with Napier grass or OPF or Napier grass-OPF combination may be attributed to the protein content of the soya waste, which would have influenced the available N for animal performance. The present results of the in vivo feeding is partially supported by the previous findings of the in vitro study of Joo et al. (2012) who suggested that the feeding of Napier grass-OPF combination to goats can represent better results in certain aspects compared to the feeding of Napier grass or OPF alone, which would reduce feed cost as well as environmental waste.

Although soya waste may be time-consuming and labour intensive when it comes to transportation, it is a relatively cheap feed resource considering its nutritive value. It is high in ME (11.2 MJ/kg) and CP (27.9%) as reported by Dong et al. (2005) and Rahman et al. (2013b), respectively. Kim et al. (2012) reported that the feeding of soya waste improved the growth rate of cattle, which might have been due to the improved utilization of nutrients in soybean, such as protein and energy. Harjanti et al. (2012) reported that soybean curd residue silage could be used to replace the concentrate in the diet of sheep. A previous study reported that goats lost BW when fed with Napier grass alone (Rahman et al. 2013a). Dahlan et al. (1993) reported that fresh OPF can only support the maintenance requirement of growing goats. Thus, the authors assume that feeding goats with soya waste in this study can contribute significantly to the improvement of the growth performance of goats by exploiting the use of locally available feed resources. In conclusion, the goats fed with Napier grass-OPF combination presented higher feed intake and BW gain than those fed with OPF alone. Feeding based on Napier grass alone, although associated with the lower feed intake of the goats, resulted in a similar BW gain compared to those fed with the Napier grass-OPF combination. These variations in intake and BW can be attributed to the OPF effect.

Acknowledgement

The authors would like to thank the Ministry of Science, Technology, and Innovation of Malaysia for funding this study under the TF006/2007A project.