Performance traits of finishing pigs fed graded levels of cassava roots and a mixed foliage meal of cassava and trichanthera leaves

R F Jiménez, C González, A Ojeda, H Vecchionacce and J Ly*

Institute of Animal Production, Faculty of Agronomy, Central University of Venezuela, PO Box 4579, Maracay, Venezuela
gonzalezc@agr.ucv.ve
*Swine Research Institute, PO Box 1, Punta Brava, Havana City, Cuba
jlyca@yahoo.com

Abstract

A total of 40 crossbred pigs of approximately 54 kg initial live weight were distributed at random into four treatments in groups of two animals (one castrate male and one female) per pen to study, during seven weeks, the effect of the introduction of graded levels of cassava root meal (CRM, 0, 20 and 40% of the diet) on performance and carcass traits.  The experimental diets contained 20% of  a mixed foliage meal made from leaves of cassava and Trichanthera gigantea (1:1 by weight) compared to a control diet with neither cassava roots nor foliage meal.

There were no significant differences for performance traits of the animals, between the control treatment and the others (mean daily gain, from 647 to 688 g; feed conversion ratio, from 3.94 to 3.62 kg DM/kg gain) containing the mixed foliage meal and up to 40% CRM.

It is concluded that pigs fed ad libitum diets formulated to contain 40% of CRM and 20% from mixed cassava and trichanthera leaf meal have similar performance and carcass traits as those fed a conventional diet.

Key words: carcass characteristics, cassava leaf meal, performance traits, pigs, trichanthera leaf meal

Introduction

Several experiments conducted to determine the use of cassava roots in the diet of pigs have indicated the potential of this product as animal feed (Maner et al 1978; Méndez and Zaragoza 1980; González et al 1997). However, the use of increasing levels of cassava roots for pigs creates a problem of diet formulation, since the roots are very poor in N (see Buitrago 1990; Ly 1998) and therefore, very little protein can be derived from this feed resource. 

Another characteristic of cassava roots is the relatively low content of cell walls (Buitrago 1990; Ly 1998). This opens up the possibility of including foliages rich in protein in diets containing high levels of cassava roots. The foliar protein source to be employed could be cassava foliage (Garbati et al 2001), since this material has been successfully used in pig feeding (Rajaguru et al 1979; Parra 1987; Trómpiz et al 2000. The foliage from Trichanthera gigantea (Rosales 1997) could be another interesting possibility to explore for feeding pigs, since acceptable performance parameters have been reported (Sarría et al 1991), with relatively high digestibility indices (Ly et al 2001; Seijas et al 2003), in pigs fed trichanthera foliage.

The objective of the present experiment was to record the  performance and carcass traits of finishing pigs fed graded levels of cassava root meal in diets containing a fixed amount of leaf meal derived from trichanthera and cassava foliage.

Materials and methods

A total of 40 crossbred pigs of mean initial live weight 54 ± 3 kg were distributed at random into four treatments in groups of two pigs, to study, during seven weeks, the effect of the introduction of graded levels of cassava root meal (CRM) on performance and carcass traits. Four experimental diets contained a fixed amount of foliage meal of cassava and trichanthera leaves (1:1 in dry weight) and graded levels of CRM were compared to a control diet with neither cassava roots nor foliage meal. The diets were formulated to contain approximately 13.60 KJ of digestible energy/g DM as recommended for finishing pigs fed ad libitum on conventional diets (NRC 1998). The cassava and trichanthera mixed foliage meal contained crude protein 18.4 and NDF 34.8% in dry basis respectively, as determined by analysis.

The cassava and trichanthera leaves were harvested in the Experimental Station of the Faculty of Agronomy, at Maracay, and were dried according to the method described by Seijas et al (2003). In brief, both cassava and trichanthera foliage meals were prepared by dehydration of leaves, petioles and tender tops harvested after approximately 120 days of plant cultivation, in a closed room at 50^oC during 48 hours. The dry foliage was ground through a 0.5 mm screen then mixed with the other ingredients of the diets. The cassava root meal was prepared from recently harvested roots as reported elsewhere (Garbati et al 2001).

The animals were housed in groups of two (one castrate male and one female), in pens of 2*1.8 m with sloping cement floor, in an open shed. Every pen was provided with drinking nipples and a feed trough. The animals were weighed at the start and end of the trial, and were fed ad libitum during seven weeks. Every day, feed refusals from each pen were recorded at 9:00 am after which new feed was offered to the pigs. At the end of the growth trial, the animals were weighed after 24 hours of fasting and then sacrificed. After evisceration, the hot carcass was weighed and expressed as percentage of slaughter weight. Back fat thickness was measured at the level of the last lumbar vertebra in carcasses refrigerated at 4^oC during 24 hours.

Duplicate samples of feed were analyzed for DM, ash, crude fibre, ether extract and N content as outlined by AOAC (1990). The gross energy content of the samples was determined in an adiabatic bomb calorimeter, using benzoic acid as calorimetric standard.

Contrasts amongst means were made by the analysis of variance technique (Steel and Torrie 1980). The SAS (1992) computing package was used in all cases.

Results and discussion

There were no significant (P>0.05) differences for DM intake, live weight gain and feed conversion performance between the control treatment and those containing the mixed foliage meal and up to 40% CRM (Table 2). Carcass traits were similarly not affected by inclusion in the diet of the foliage meal and the CRM  (Table 3). 

Earlier studies in our laboratory have shown that up to 30% of leaf meal of either cassava or trichanthera can be included in pig diets with no depression in performance (Rangel et al 2001). This level  of cassava leaf meal has also given good results in studies carried out in Vietnam (Bui Huy Nhu Phuc 2001).  By contrast, this level of fresh leaves gave poor results in studies reported by Mahendranathan (1971) and Sarwat et al (1988).

Conclusions

• It is concluded that pigs fed ad libitum with diets formulated to contain 40% of cassava root meal and 20% from mixed foliage of cassava and trichanthera leaves have similar performance and carcass traits as compared to those fed a conventional diet.

Acknowledgements

The present article is an output from a collaborative investigation conducted by the Faculty of Agronomy, Central University of Venezuela at Maracay, and the Swine Research Institute at Havana City. Thanks are given to all the staff members of the Swine Unit at the Faculty, and to the librarians of the Swine Research Institute for their assistance.

References
 

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Received 21 June 2004; Accepted 6 December 2004

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