Bromatological composition and degradation rate of mulberry in goats

Anita Schmidek & R. Takahashi
Faculty of Agrarian and Veterinary Sciences
São Paulo State University, Jaboticabal Campus
São Paulo, Brazil
A. Nuñes de Medeiros
Depto. Agropecuária-CFT- UFPB-Campus IV
Bananeiras-PB, Brazil
K.T. de Resende
Faculty of Agrarian and Veterinary Sciences
São Paulo State University, Jaboticabal Campus
São Paulo, Brazil

INTRODUCTION

Mulberry, traditionally used as feed for silkworm, has been the subject of research at the Faculty of Agrarian and Veterinary Sciences, São Paulo State University (FCAV-UNESP), with the objective of feeding goats. Its favourable characteristics for a high intake by goats include: high protein content (similar to alfalfa), and good green biomass production (5-8 tonnes/ha/cut) throughout the year, including the dry season.

The in situ technique enables the degradation curve to be drawn and provides information for balancing diets, considering that, independently of the degradation potential of a feed, its efficiency of utilization by the animals is highly influenced by the matching or not of the degradation rates of protein and energy (Russel et al., 1991, cited by Sampaio et al., 1998).

The objective of this work was to analyse the nutritional value of mulberry clones by means of their bromatological composition and degradation rate in the goat rumen.

MATERIALS AND METHODS

The research was conducted in the Caprine Section using mulberry cultivated in the Sericulture Section at FCAV-UNESP, Jaboticabal Campus.

The bromatological composition of leaves of Miura, FM Shima-Miura and FM 86 clontes at 90 days of regrowth and of the incubation residue was determined following the recommendations by Silva (1981).

For the incubation, five Saanen male goats, of two years of age, were utilized with a ruminal cannula. Their diet was Tifton hay and mulberry hay ad libitum and 300 g of concentrate with 21 percent protein. After an adaptation period of 21 days, the incubations lasted 6, 12, 24, 48 and 96 hours.

The estimates of the degradation rate of DM, crude protein and neutral detergent fibre were obtained from disappearance percentage in the incubation periods.

The experimental design was randomized blocks, with split plots (mulberry clones) with five repetitions (animals) and five plots (incubation times). The different parameters studies were compared by the Tukey test at 5 percent probability.

RESULTS AND DISCUSSION

The bromatological composition of the five clones is presented in Table 1. The Miura clone showed the best values (P <0.05) in organic matter (OM), total digestible nutrients (TDN), digestible energy (DE), NDF, hemicellulose and ash and lower contents of acid detergent fibre. Brazão (1992), studying the same cultivars and the same cutting frequency, obtained similar values for DM and CP, and an even lower NDF. The high contents of CP (2.7 percent), TDN (80.1 percent) and DE (3.53 Mcal/kg DM) found in mulberry, indicate its high nutritive value. There are few forage plants comparable to mulberry, among them alfalfa with 22 percent CP. However, the estimated DE values indicate an energy: protein relation of 63.8 g of CP: 1 Mal of DE, which is higher than the NRC (1981) recommendation for goats, 32 g of CP: 1 Mcal of DE, suggest the need to conduct performance trials with mulberry in pure diets and/or like protein supplement in balanced diets.

From the degradation results, it can be observed that the maximum degradation potential was reached at 48 hours of incubation. There were no statistical differences (P > 0.05) in DM degradation among the clones (Table 2). All of them showed high degradation rates, which indicates the great potential of mulberry with a higher degradation rate within the first hours (6-12h), followed by a stabilizing phase, reaching, after 48 hours, a degradation of 93 percent. There were no differences either (P > 0.05) in CP degradation among clones, reaching a mean degradation of 96.8 percent after 48 hours. Only in NDF degradation there were statistical differences (P < 0.05) among clones, the clone Miura being superior which contains less NDF, inversely related to feed digestibility.

TABLE 1

Bromatological composition of clones on a dry matter (DM) basis

Parameters

Clones

Miura

FM Shima Miura

FM 86

DM

24.6^a

25.3^a

24.5^a

Organic matter

90.9^a

89.8^b

90.0^b

Crude Protein (CP)

23.6^a

22.7^a

21.7^a

Ether Extract

2.1^a

2.1^a

2.1^a

Total Digestible Nutrients¹

82.9^a

77.8^b

79.5^b

Digestible Energy²

3.6^a

3.5^b

3.5^b

Neutral Detergent Fibre (NDF)

39.3^b

36.6^b

30.2^a

Acid Detergent Fibre

17.2^a

21.7^b

20.2^b

Hemicellulose

22.0^a

14.9^b

11.0^c

NDF-nitrogen (percentCP)

18.8^a

19.6^a

17.7^b

ADF-nitrogen (percentPB)

5.8^a

5.1^a

4.6^a

Ash

9.1^b

10.2^a

10.0^a

Values in lines with the same letter do not differ by the Tukey test (P <0.05).
¹Calculated from TDN = 102.56 - (ADF percentage x 1.40), proposed by Raffler (1975), cited by NRC (1989)
²(Mcal/kg DM); calculated from 1 kg TDN = 4.409 percent Mcal DE.

The superior qualities of the Miura clone for the studied parameters does not mean that is the best clone. Other variables should be compared such as biomass yield per unit area.

TABLE 2

Degradation rates of DM, crude protein and neutral detergent fibre (NDF) of the clones

Parameter

Clone

Incubation times (hour)

6

12

24

48

96

Dry Matter

Miura

52.2

81.7

91.8

93.3

91.0

FM Shima Miura

54.8

78.8

89.1

93.2

92.1

FM 86

56.7

80.3

91.5

93.0

91.4

Crude protein

Miura

50.7

84.1

94.9

97.3

96.8

FM Shima Miura

49.8

80.0

90.0

97.0

96.0

FM 86

50.9

83.1

94.7

96.2

96.3

FDN

Miura

34.2

71.4

83.8

86.8

85.2

FM Shima Miura

27.0

61.6

76.8

84.9

82.6

FM 86

27.7

63.3

79.7

83.4

76.9

CONCLUSIONS

The mulberry clones studied showed a satisfactory bromatological composition and high degradation rate in the rumen of goats. The values for CP (22.7 percent), TDN (80.1 percent) and NDF (37.7 percent, of which 44.8 percent is hemicellulose) stand out. After an incubation of 48 hours, the material reached the maximum degradation. Other studies should be conducted to determine the best way of utilizing mulberry.

BIBLIOGRAPHY

Brazão, C. S. 1992. Estudo da curva de crescimento e composição bromatológica da amoreira (Morus alba L.). Jaboticabal. 42 pp. Trabalho apresentado à Faculdade de Ciências Agrárias e Veterinárias, UNESP, Campus de Jaboticabal, para graduação em Zootecnia. (thesis).

NRC (National Research Council). 1981. Nutrient requirement of goats. No.. 15. Washington, DC. National Academy of Sciences, 91pp.

Sampaio, A. M. S., Rossi Júnior, P. Brito, R. M. et al. 1998. Efeito de diferentes volumosos sobre a degradabilidade in situ de nutrientes e variáveis da fermentação ruminal, mediantea aplicação da somatotropina bovina. R. Bras. Zootec., 27(6): 1234-1240.

Silva, D. J. 1981. Análise de alimentos. Viçosa, Brazil, Imprensa Universitária, 166pp.

Parameters	Clones
Parameters	Miura	FM Shima Miura	FM 86
DM	24.6^a	25.3^a	24.5^a
Organic matter	90.9^a	89.8^b	90.0^b
Crude Protein (CP)	23.6^a	22.7^a	21.7^a
Ether Extract	2.1^a	2.1^a	2.1^a
Total Digestible Nutrients¹	82.9^a	77.8^b	79.5^b
Digestible Energy²	3.6^a	3.5^b	3.5^b
Neutral Detergent Fibre (NDF)	39.3^b	36.6^b	30.2^a
Acid Detergent Fibre	17.2^a	21.7^b	20.2^b
Hemicellulose	22.0^a	14.9^b	11.0^c
NDF-nitrogen (percentCP)	18.8^a	19.6^a	17.7^b
ADF-nitrogen (percentPB)	5.8^a	5.1^a	4.6^a
Ash	9.1^b	10.2^a	10.0^a

Parameter	Clone	Incubation times (hour)
Parameter	Clone	6	12	24	48	96
Dry Matter	Miura	52.2	81.7	91.8	93.3	91.0
	FM Shima Miura	54.8	78.8	89.1	93.2	92.1
	FM 86	56.7	80.3	91.5	93.0	91.4
Crude protein	Miura	50.7	84.1	94.9	97.3	96.8
	FM Shima Miura	49.8	80.0	90.0	97.0	96.0
	FM 86	50.9	83.1	94.7	96.2	96.3
FDN	Miura	34.2	71.4	83.8	86.8	85.2
	FM Shima Miura	27.0	61.6	76.8	84.9	82.6
	FM 86	27.7	63.3	79.7	83.4	76.9