Multi-nutrient blocks with fresh fruit of Pitaya (Stenocereus griseus) replacing sugar cane molasses

L Arias, R Soriano, H Losada, J Rivera and J Cortés

Área de Investigación en Desarrollo Agropecuario Sustentable. Universidad Autónoma Metropolitana-Iztapalapa.
División de Ciencias Biológicas y de la Salud. Departamento de Biología de la Reproducción.
Avenida San Rafael Atlixco No. 186. Colonia vicentina. México, D.F. C.P. 09340
ramon@xanum.uam.mx

Abstract

The objective of this research was to evaluate the hardness and chemical composition of multi-nutritional blocks in which fresh Pitaya fruit (Stenocereus griseus),  at levels of 10, 20, 30 and 40%, replaced 25, 50, 75 and 100% of sugar cane molasses. The other components of the blocks were: ground maize stover 28, urea 10, cement 7.5, lime 7.5, salt 5 and mineral mixture 2%.

Maximum hardness of between 3.75 and 4 kg/cm² was reached by day 50 in all the formulations. Crude fibre increased, NFE decreased, but in vitro dry matter digestibility increased with increasing level of Pitaya in the block.

It is concluded that  fresh Pitaya fruit can replace molasses in the preparation of multi-nutritional blocks without compromising the hardness of the blocks, but that further studies are needed to assess their potential nutritive value for ruminants.

Key words: Digestibility, hardness, molasses,multi-nutrient blocks, Pitaya fruit

Introduction

Field studies carried out by us in the community of Cosoltepec, located in the Lower Mixteca Region, reported the seasonal production of cactus fruits of gender Stenocereus (S. griseus and S. stellatus) as well as Scontria chiotilla that are produced in the months of April to September. An important portion of these fruits is dedicated to human consumption and sold in local markets. However, because these are highly perishable commodities, a great part of the production is wasted  post harvest, another part it is consumed by birds and in some cases by the animals that are grazed in the area (goats and bovines). The use of Pitaya fruit as a potential resource presents two restrictive factors: its high availability during a short period of production (45 days between April and May), as well as a high content of water. However, as the whole fruit has up to 68.6% of nitrogen free extract, 6.93% of crude protein and 8.61% of total reducing sugars (DM basis)  (Bravo y Sanchez1991; Mercado y Granados 1999), the fresh fruit of  Pitaya might represent an alternative resource to substitute for molasses as a source of readily fermentable carbohydrate in multi-nutrient blocks (Hadjipanayiotou et al 1993; Osuna et al 1996; Sansoucy 1986).

In view of the need to develop appropriate technologies based on the use of local resources, a study was carried out with the objective of evaluating the potential of using Pitaya fruit in substitution of molasses in multi-nutrient blocks. 

Methodology

Study area

The study was carried out in the municipality of Cosoltepec, Oaxaca that is located in the semi-arid region known as the Low Mixteca, at 18° 08´ north latitude and 97° 45´ of longitude west of the origin meridian. The climate is semi-warm, sub-humid with rains in summer. The  climate designation is A (C) Wo (w) , according to Köppen and the modifications proposed by García (1981). Annual average temperature is 27 ºC. The annual rainfall is 300 mm and the height above sea level 1825 m  (Martínez 1994) The rains are distributed in the months of July to October and the original vegetation of this area corresponds to the Low Deciduous Forest.

Treatments and experimental design

The blocks that were compared contained 40, 30, 20 and 10% Pitaya fruit (Stenocereus griseus) that substituted for 100, 75, 50 and 25% of molasses (Table 1).  The quantities of cement, lime, mineral salts, urea and maize stover were maintained constant.

Elaboration of the blocks

Pitaya fruits (Stenocereus griseus) and maize stover were gathered in the Municipality of Cosoltepec, Oaxaca. The molasses and the urea were obtained in Mexico City. The Pitaya, after prior removal of the spines, was refrigerated at 5 °C until required. The blocks were made using moulds of 30 cm per side with capacity to hold 20 kg of finished block.  The internal walls were covered with acrylic sheets to avoid the mixture adhering to the wooden walls.

The fresh Pitaya fruit without spines was milled in a semi-industrial blender while the maize stover was processed in a hammer mill to obtain a homogeneous particle size of approximately 4 mm. Urea was milled to a particle size of 2 mm and homogenised with the molasses and the Pitaya according to the respective treatments. Next was added the maize stover,  the mineral mixture, cement, salt and the lime. The moulds were filled manually with the final mixture and consolidated. The moulds  were then placed in a well ventilated  area, and seven days later the blocks were extracted. The period of storage to reach maximum hardness was approximately 50 days.

Measurements

Samples of the fresh Pitaya fruit were dried in a forced-air oven at a temperature of 40° to 60°C during 72 hours. The samples were then ground in a Willey hammer mill, with a mesh of 2 mm,  in order to carry out the proximal analysis according to AOAC (1990). Hardness of the blocks was measured weekly with a penetrometer. Samples of the hardened block were taken for analysis of proximal composition according to AOAC (1990). In vitro digestibility was carried out according to the procedure of Tilley and Terry (1963), with some modifications suggested by Ruiz (1995). The  results were processed by analysis of variance and the significance of differences among means was calculated following the Duncan T test (Reyes 1999).

Results and Discussion

Despite the much higher content of moisture in the Pitaya fruit than in the molasses (Table 2), by the time the blocks had hardened the DM contents were similar on all treatments (Table 3)..

The IVDMD values tended to reflect the content of Pityaya fruit in the blocks; however, this relationship could not be attributed to the nutritional components indicated by the proximal analysis, since the fibre content was higher and the NFE lower in the blocks with highest IVDMD, while differences in ether extract and crude protein were minimal. It is to be expected that content of vitamin A would be higher in the Pitaya fruit than in the molasses. But this is unlikely to be an explanation for the observed differences in IVDMD.

Surprisingly, the blocks with complete substitution of the molasses  by Pitaya fruit appeared to be harder than the blocks with less Pitaya fruit, throughout the period of storage (Table 4 and Figure 1).  There were no consistent differences among the blocks with from 10 to 30% Pitaya fruit.For all the treatments, the degree of hardness reachedl after 7 weeks was in accordance with recommendations by  Osuna et al (1996) for blocks to be used in ruminant nutrition.

Figure 1: Development of block hardness during the 7 weeks of storage

Conclusions

• Fresh Pitaya fruit can replace molasses in the preparation of multi-nutritional blocks without compromising the hardness of the blocks.

• The potential nutritional benefits from the slightly higher content of crude protein, and the higher IVDMD, in the blocks with Pitaya fruit merit an evaluation with the target animals in a long term feeding trial.

References

AOAC 1990 Official Methods of Analysis. Association of Official Analytical Chemists 15th edition. Washington DC USA

Bravo H y Sánchez H 1991 Las cactáceas de México UNAM 3ra Edicion Volúmenes I y II

Hadjipanayiotou M, Verhaeghe L, Allen M, El-Rahman A, Al-Wadi M, Amin M, Naigm T, El-Said H and Kader A 1993 Urea Blocks I. Methodology of block making and different formulae tested in Syria. Livestock Research for Rural Development, Volume 5, No 3 http://www.cipav.org.co/lrrd/lrrd5/3/syria1.htm

Martínez M 1994 Monografía de Cosoltepec. Breve Historia de mi pueblo. Colección Glifo Secretaria de Desarrollo Económico y Social. Dirección general de educación, cultura y bienestar social del gobierno del Estado de Oaxaca. México

Mercado B A y Granados S 1999 La Pitaya: biología, ecología, fisiología, sistemática y etnobotánica. Primera edición. Universidad Autónoma Chapingo.

Osuna D, Ventura M y Casanova A 1996 Alternativas de suplementación para mejorar la utilización de los forrajes conservados I. Efectos de diferentes concentraciones de cemento y cal sobre la calidad de bloques nutricionales. Revista de la Facultad de Agronomía 13: 95-102.

Reyes C 1999 Diseño de experimentos agrícolas. Editorial Trillas. Tercera reimpresión. México.

Ruíz B 1995 Digestibilidad in vitro de forrajes. Universidad de Reading. Inglaterra.

Sansoucy R 1986 The Sahel: manufacture of molasses-urea blocks. World Animal. Review. 57:40-48.

Tilley J M A and Terry R A 1963 A two stage technique for the in vitro digestion of forage crops Journal of the British Grassland Society 18:104-109.

Received 11 November 2004; Re-submitted 15 November 2004; Accepted 20 January 2005; Published 1 April 2005

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