Evaluation and utilization of mulberry for poultry production in Japan

Hiroaki Machii
National Institute of Sericultural and Entomological Science
Owashi, Tsukuba, Ibaraki, Japan

INTRODUCTION

Mulberry is an indispensable crop for silkworm production. In Japan, sericulture need to be such an important industry that mulberry was not used for other purposes. However, with the recent decline of sericultural industry, mulberry has been re-evaluated for other purposes, such as medicinal, fruit and animal production. This paper reviews its evaluation and utilization for animal production, with special reference to poultry production in Japan.

FOWLS RAISED IN MULBERRY GARDENS

If domestic and guinea fowls were to be raised in mulberry gardens, multiple useful effects could be expected such as weeding; pest control; extra fertilizer (from manure); high quality and natural egg and/or meat; and feed cost reduction (Watanabe, 1985). With these points in mind, several experiments were carried out in various regional sericulture experiment stations in Japan.

Weeding effect

Uchino et al. (1988) utilized guinea and domestic fowls (New Hampshire breed) for weed control. A small poultry house was built in the corner of a mulberry garden. Eleven domestic fowl were put in a mulberry garden of 0.025 ha and ten guinea fowl in one of 0.012 ha. Commercial feed was given, 140-150 g/dY for each domestic fowl and 70 g/day for each guinea fowl. The amount of weeds growing after seven months was measured. Table 1 shows that there were no weeds in the guinea fowl plot, and only a few weeds in the domestic fowl plot, whereas a large number of weeds, such as Polygonum longisetum De Bruyn, Digitaria adscendens Henr. (large crab-grass), Malachium aquaticum Fries (Mater mouse-ear chickweed), Senecio vulgaris L. (common groundsel) and Veronica persica Poir. (Byzantine speedwell) grew in the control plot. These results indicate that raising guinea and domestic fowls in mulberry gardens controls weeds that would otherwise cause serious damage to mulberry growth. Similar results were obtained in the Oita Prefecture (Urushima, Iguchi and Sato, 1984; 1987).

TABLE 1

Amount of weeds growing after seven months, fresh matter (g/m²) and percentage relative to control in parenthesis

Treatment	Amount of weeds	Weed species
Control	1 064 (100 %)	Polygonum longisetum, Digitaria adscendens, Malachium aquaticum, Senecio vulgaris, Veronica persica
Domestic fowl	11 (11 %)	Senecio vulgaris, Erigeron philadelphicus
Guinea fowl	0 (0 %)

Source: Uchino et al., 1988.

The daily excrement of domestic fowls is about 150 g, corresponding to 54.8 kg annually. It contains 1.6 percent of N, 1.7 percent P and 0.8 percent K (Maeda et al., 1978). Uchino et al. (1988) measured non-organic nitrogen in three places in a mulberry garden. They found 12-14 times more in the front of the fowl house and two to five times more in between rows than in the control garden (Table 2). However, the quantity between stumps was almost the same as in the control garden. This study shows that both guinea and domestic fowls hang around their shelter. Spreading manure would be necessary to get a uniform fertilizing effect.

TABLE 2

Non-organic soil nitrogen, mg/g of dry soil

Sampling site	Guinea fowl	Domestic fowl	Control
Front of fowl house	21.3	17.8	-
Between mulberry rows	7.3	3.7	1.5
Between mulberry stumps	1.3	1.9	-

Source: Uchino et al., 1988.

Pest control effect

Uchino et al. (1988) investigated the pest control effect of guinea fowls by dissecting two birds in June and examining the insects inside their crops. They found that guinea fowls had eaten Japyx japonicum Enderlein, Aphodium rectus Motschusky, Arge similis Vollenhoven (azalea sawfly) and others. Moreover, daily observation confirmed that guinea fowls consumed Scotinophara lurida Burmeister (black bug), Spilarctia imparilis Butler mulberry tiger moth), Apriona japonica Tomson (mulberry borer), grasshopper, cicada, fry and earthworms. Apriona japonica, for example, is an insect that causes serious damage to mulberry growth in Japan.

Quality of egg and meat produced

Yearly egg production was 170 for a domestic fowl and 90 for a guinea fowl. Guinea fowl do not lay in winter. As shown in Table 3, guinea fowl eggs are smaller compared with those of domestic fowls, but they have a thicker eggshell and better preservation. Moreover, guinea fowl eggs are higher in Haugh unit and yolk colour. New Hampshire hens raised in a mulberry garden produced eggs with a greater proportion of yolk and higher Haugh unit and yolk colour, compared with eggs from commercial White Leghorn hens. These results demonstrate that eggs produced by guinea and domestic fowls raised in mulberry gardens are superior to those commercially available.

TABLE 3

Egg quality of guinea and domestic fowl raised in a mulberry garden

Species	Egg (g)	Yolk (%)	Yolk white	Shell (%)	Haugh unit	Yolk colour
Guinea fowl	39.2	31.4	0.60	16.6	83.1	13
Domestic fowl:
New Hampshire	60.3	29.5	0.48	9.3	67.1	12
White Leghorn*	59.0	27.5	0.44	9.5	61.4	10

*Commercially purchased as a control. Source: Uchino et al., 1988.

Guinea fowl meat has an excellent taste good and is relished as a high-quality meat in France and Italy, where it represents 30 percent of poultry meat products (Uchino et al., 1988). On the contrary, guinea fowl meat is rarely eaten in Japan. However, since Japanese food customs are changing and there is a growing demand for high-quality meat, guinea fowl meat might be a welcome addition to the Japanese table.

MULBERRY LEAF FOR POULTRY FEEDING IN JAPAN

This section reviews the effects of mulberry on poultry production when leaves were fed to domestic fowls.

Quality of domestic fowl

Several reports on the utilization of mulberry leaves for poultry production have been published recently (Tateno, Yatabe and Iso, 1998, 1999; Suda, 1999; Sudo, Kuramoto and Iso, 2000). When feeds containing 3 percent, 6 percent and 9 percent of mulberry leaf were fed to the domestic fowls (White Leghorn), egg quality (e.g. egg weight and egg production ratio) was almost the same as the control with commercially available feed (Suda, 1999). However, when the feed contained 15 percent of mulberry leaves, egg quality was significantly lowered (Tateno, Yatabe and Iso, 1999). However, yolk was more yellow because of the mulberry leaves (Table 4).

TABLE 4

Egg yolk colour of domestic fowl with mulberry leaves in the feed

Feed	Yolk colour
	Beginning	After 3 weeks	After 7 weeks
Control	8.0	8.5*	9.2*
15 percent mulberry leaves	7.8	9.6*	10.1*

* shows significant difference in 1 percent level between two food plots.
Source: Tateno, Yatabe and Iso, 1999.

Mulberry leaf in the feed increased vitamin K1 in the yolk (Table 5) but did not have an effect on the content of gamma-aminobutyric acid (GABA), which has a role in reducing human blood pressure (Table 5) (Machii, 1990). There was no significant difference in the cholesterol content of egg yolk (Table 5). However, lipid peroxide content in the yolk significantly decreased after seven weeks of feeding mulberry leaves. It is known that lipid peroxide is closely related to active oxygen species, which have a role in causing diseases.

TABLE 5

Health-related compounds in the egg yolk of domestic fowl fed with mulberry leaves

Compound	Feed
	Control	15% mulberry leaf
GABA (ppm)	1	1
Vitamin K1	1*	54*
Vitamin K2	22	29
Cholesterol (mg/100 mL):
Before	15.1	15.1
After 3 weeks	13.9	15.6
After 7 weeks	12.9	14.3
Lipid peroxide (nmol/mL):
Before	52.6	40.8
After 3 weeks	49.5	44.6
After 7 weeks	57.9*	41.1*

*Significant differences between feeds at 1% level.
Source: Tateno, Yatabe and Iso, 1999.

Health-related compounds in blood serum of domestic fowl fed with mulberry leaves

Compound	Feed
	Control	15% mulberry leaf
Cholesterol (mg/100 mL):
Before	130.7	146.9
After 3 weeks	150.4*	117.7*
After 7 weeks	156.4	135.7
Lipid peroxide (nmol/mL):
Before	11.6	12.1
After 3 weeks	12.8	13.2
After 7 weeks	13.9	11.3

* Significant difference between feeds at 1 percent level.

Source: Tateno, Yatabe and Iso, 1999.

Mulberry leaves to reduce odour in manure

Odours emitted from poultry manure, especially in peri-urban farms, have become a social problem in Japan. Ammonium and hydrogen sulphate are major odours in manure. Sudo, Kuramoto and Iso, (2000) tested whether mulberry leaves had an inhibitory effect on ammonium and hydrogen sulphate emissions from manure. Ammonium emission was significantly reduced by feeding mulberry, but hydrogen sulphate was not affected (Table 7). Suda (1999) obtained similar results on the inhibitory effect of mulberry leaves on ammonium emission. Thus, it can be concluded that mulberry leaves included in poultry feed have an odour reduction effect in manure.

TABLE 7

Ammonium and hydrogen sulphate emitted from poultry manure

Feed	Odour compound (ppm)
	Ammonium	Hydrogen sulphate
Control	2.67*	9.14
10 percent mulberry leaf	0.29*	10.89

* Significant differences between treatments at 1 percent level.

It was found that raising domestic and guinea fowls in mulberry gardens benefits mulberry growth through their weeding, pest control and fertilizer effects. The egg Haugh unit was also higher. Moreover, when mulberry leaves were given as part of the feed to domestic fowls, vitamin K1 content was increased and odour from manure decreased. Therefore, it is relevant to evaluate and utilize mulberry as a feed for poultry as well as for the sericulture industry.

BIBLIOGRAPHY

Hachisu, N. 1989. Chemical components of soil and mulberry leaves in a mulberry garden where domestic fowls were raised. Abstracts of Kanto Branch Meeting of Japanese Sericulture Society, 40: 11.

Machii, H. 1990. On gamma-aminobutyric acid contained in mulberry leaves. J. Seric. Sci.Jpn., 59: 381-389. (in Japanese)

Maeda et al., 1976: Handbook of fertilizers. Nosan Gyoson Bunka Kyokai, p.223,Tokyo.(in Japanese)

Suda, T. 1999. Inhibitory effect of mulberry leaves on ammonium emission from poultry excrement. Abstracts of Gunma Agriculture-related Experiment Stations Meeting, 7-8 (in Japanese)

Sudo, M., Kuramoto, H & Iso, M. 2000. Studies on functional poultry eggs. Effects of mulberry leaves on quantity and quality of eggs. Bull. Ibaraki Prefectural Poultry Experiment Station, 35: (in Japanese)

Tateno, H., Yatabe, T. & Iso, M. 1999. Studies on foliage of unused resources. Effects of mulberry leaves on egg production as a poultry food. Bull. Ibaraki Prefectural Poultry Experiment Station, 33: 15-20, (in Japanese)

Tateno, H., Yatabe, T. & Iso, M. 1999. Studies on functional poultry eggs. Effects of mulberry leaves on egg production as a poultry food. Bull. Ibaraki Prefectural Poultry Experiment Station, 33: 21-34 (in Japanese).

Uchino, K., Watanabe, M. Ishida, H. & Sato, A. 1988. Effect of guinea fowls raised in a mulberry garden. Bulletin of Chiba Prefectural Sericulture Experiment Station, 6: 1-10 (in Japanese).

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Watanabe, M. 1985, Raising guinea fowls in a mulberry garden. Sanshi-no-Hikari, 38: 44-45. (in Japanese)