RESEARCH WORK
Utilization of fruit and leaf meals from breadfruit tree (Artocarpus altilis) for fattening New Zealand White rabbits
Coralia S. Leyva1, M. Valdivié2 y A. Ortiz1
1 Centro de Estudio de Especies Menores, Facultad Agroforestal de Montaña, Universidad de Guantánamo (UG)
Carretera a El Salvador, km 6½, El Salvador, Guantánamo, Cuba
E-mail: coralia@fam.cug.co.cu
2Instituto de Ciencia Animal (ICA), Mayabeque, Cuba
ABSTRACT
Thirty-six New Zealand White rabbits, 35 days old and with 506 g of live weight were used, in order to evaluate the effects of three diets on the productive and economic indicators of the animals during fattening. The diets consisted in: 1) commercial concentrate feed plus fresh forage of perennial soybean (Neonotonia wightií), as control; 2) breadfruit (Artocarpus altilis) meal plus perennial soybean and 3) integral concentrate feed composed by a mixture of fruit and leaf meal from the breadfruit tree, plus vitamins and minerals. A variance analysis was used according to a completely randomized design with three treatments and four repetitions. After 90 days of fattening, the live weight at slaughter was 2 347, 2 223 and 2 127 g/rabbit, respectively, the average gain was 20, 19 and 18 g/day and viability was 100% in all treatments. Economically, the concentrate feed balanced with fruit and leaf meal from the breadfruit tree had a profit of US $1,05/fattened rabbit, the feeding system with breadfruit meal plus perennial soybean foliage earned US $0,89/fattened rabbit, while the control system generated economic losses, due to the high costs of raw materials that composed the conventional concentrate feed. It is concluded that alternative feeding systems which use fruit and leaf meal from the breadfruit tree are economically and biologically suitable for fattening rabbits.
Key words: feeding, Artocarpus altilis, rabbit, Neonotonia wightii.
INTRODUCTION
Rabbit rearing in tropical countries constitutes an interesting choice to produce meat of high nutritional value for the human diet (Herrera, 2003). For the Cuban farmer sector, and even for the industrial sector, the use of commercial concentrates in rabbit feeding is an infeasible choice, due to the high costs of these feedstuffs (Lopez and Montejo, 2005).
In Cuba more than 70% of the rabbit meat production is generated in the private sector, with alternative feeding systems that allow them to obtain live weight gains from 10 to 25 g/rabbit/day, with a national average of 16 g/rabbit/day, together with low mortality rate and a suitable economic viability (La O, 2007).
In the state rabbit production sector, the high cost of conventional feedstuffs does not allow a sustainable development; moderate-quality pelleted feeds are used, besides forages that originate modest live weight gains (14 to 20 g/rabbit/day) and high mortality rate (García, 2005). Therefore, initiatives should be generated to exclude these feeding forms, and also to make a better use of local and alternative feedstuffs.
In this sense, the breadfruit tree (Artocarpus altilis) offers a sustainable alternative, due to its high availability, especially in the Guantanamo and Santiago de Cuba provinces, where 50 000 t of fruits are annually lost and the leaves are not used as feed, in spite of being a plant of perennial leaves and abundant biomass (Leyva, 2010). Based on this information, the objective of this work was to evaluate the effect of three diets on the productive and economic performance of fattening rabbits.
MATERIALS AND METHODS
The study lasted 90 days and was conducted at the new-type state farm «Lorenzo Boicet», which is located in the Guantánamo municipality, Guantánamo province, Cuba.
Thirty-six newly-weaned New Zealand White bucks, 35 days old and with an average live weight of 506 g/animal, were used, which were placed in twelve typical wire cages for fattening animals (three rabbits per cage). The design was completely randomized, with three treatments and four repetitions. Each animal was considered a repetition for the variables: initial live weight, final live weight and daily average gain, just like the cages for the variables: feed intake and feed conversion.
Three diets were compared: 1) commercial concentrate feed plus perennial soybean (Neonotonia wightii), as control; 2) breadfruit (A. altilis) meal plus perennial soybean; and 3) integral concentrate feed composed by fruit and leaf meal from the breadfruit tree (concentrate feed from breadfruit tree). Table 1 shows the raw materials of the concentrate feed from breadfruit tree and table 2 shows the chemical composition of the commercial concentrate feed and the perennial soybean forage.
The concentrate feed and the fruit and leaf meal from the breadfruit tree were provided with a particle size that fluctuated between 1 and 3 mm. The fruit and leaf meal from breadfruit tree was obtained through the methodology described by Leyva and Valdivié (2007). The fresh perennial soybean foliage was offered in the troughs for forage located between one cage and the other. The feedstuffs that integrated each diet were supplied ad libitum, which allowed their selection by the animals. Water was provided at will in nipple-drinkers and the concentrate feed was provided in two earthenware feeding troughs per cage, which were daily refilled at 8:30 a.m. and 4:30 p.m., to warrant the required feedstuff amounts for 24 hours per day.
The evaluated indicators were: viability, live weight, feed intake, feed conversion, carcass weight, weight of the edible viscera and yield in edible portions. A variance analysis was applied to the data and Duncan's (1955) multiple range test was used to find the differences between means.
At the end of the experiment 30 bucks were slaughtered, 10 for each treatment, to determine yield in carcass, neck and edible portions; the animals were deboned and the clean meat yield was determined. To process the evaluated indicators, a variance analysis was made according to a completely randomized design with three treatments and ten repetitions; each slaughtered rabbit was considered a repetition.
The longissimus dorsi muscle of each slaughtered rabbit was used to determine the meat chemical composition (dry matter, crude protein, fat and ash) in each feeding variant. Also, through this muscle, the scent, taste and meat toughness of each treatment were evaluated, for which a board of twelve official tasters from the meat industry in the Guantanamo province was hired, according to the methodology described by Díaz, Álvarez and Elías (1981).
The economic analysis was made from the intake data of each feedstuff that composed the diets and its price in USD and the following expenditure indicators were determined: diet cost per rabbit, diet cost per live weight ton and diet cost per carcass ton.
RESULTS AND DISCUSSION
The animals' viability in the three evaluated treatments was 100% (table 3), this proves the innocuousness of these new feeding systems, which were elaborated with fruits and leaves from the breadfruit tree.
The live weight at sacrifice exceeded 2 kg in all treatments, established in Cuba and internationally for the marketing of fattening rabbits, and it was higher (P<0,05) in the control (2 347g/rabbit) when it was compared with the two new variants, which did not differ between themselves (2 223 and 2 127 g/rabbit, respectively). The third treatment resulted to be the variant in which the animals decreased feed intake, which determined the best values of feed conversion. These results coincide with the ones obtained by Hurtado and Romero (1999), who also found significant differences by evaluating the use of commercial concentrate feed and alternative feedstuffs.
The average daily gain was 20, 19 and 18 g/rabbit/day, that is, around 14 to 20 g/rabbit/day that are obtained in Cuba with meal concentrate feed or with concentrate feed plus foliage, according to García (2005). Lukefahr and Cheeke (1991) considered these as satisfactory gains for tropical or arid climates with alternative feeding systems. La O (2007) also obtained a rate of live weight gain of 17 to 23 g/rabbit/day and according to Nieves et al .(2002b) these gains are typical of fattening rabbits with alternative and sustainable feeding systems in tropical zones.
The total yield (carcass plus edible viscera plus neck) fluctuated between 55,5 and 57,4% (table 4) and did not differ among treatments, like the yield in carcass, that varied between 48,7 and 49,9%. Significant differences were found only between the control treatment and the concentrate feed from the breadfruit tree for the yield in neck. These values of total yield and carcass coincide with the ones indicated by Nieves et al. (2002a), Ponce de León et al. (2002) and García (2005) for rabbits of 2 kg average live weight with non conventional diets.
The carcass yield responds to the characteristics of basic feedstuffs of the feeding variants, which provide a higher development of the digestive system; in addition to a high volume of feedstuffs in the stomach and caecum. These results are equivalent, if it is considered that the three groups were slaughtered at the same age and with similar maturity state. In this sense, Butterfield (1988) pointed out that when some animal groups coincide in maturity state, the carcass composition shows little variability.
García (2006) and La O (2007) obtained carcass yields from 47 to 51%, when evaluating tropical foliages such as Teramnus labialis, Ipomea batata and Hibiscus rosasinensis, in diets for rabbits in the growing-fattening stage; they stated that such results are in correspondence with the species and feeding systems, which coincide with the results shown in table 4.
The yields in total meat (37,3-38,1%) and bone (13,5-13,8%) were similar in the treatments, which indicates that with these new feeding variants the same amount of clean meat is obtained as the one achieved with fattening based on concentrate feeds, proportionally to the animal's weight. Rico (2002) reported similar yields in meat and bone when using non conventional feeding, such as palm (Roystonea regia) fruit meal, in New Zealand White rabbits.
The chemical composition of the longissimus dorsi muscle and the organoleptic analysis are shown in tables 5 and 6; the results allow inferring that there were not significant changes; therefore, the evaluated feedstuffs did not have negative effects.
Bonacic (2004) reported the chemical composition of meat in slaughtered rabbits at 90 days of age (dry matter 26,5%, crude protein 19,6% and lipids 3,6%) and added that these characteristics turn rabbit meat into a required foodstuff worldwide for high-income consumers, because this meat is suitable in diets aimed at preventing cardiovascular diseases and it is also suggested for children and elders. Viera and de Obschatko (2003) and Maggi (2007) also supported this criterion.
The diet based on concentrate feed from breadfruit tree as the only feedstuff was the most economical (table 7), because it allowed to obtain profits of US $1,05/fattened rabbit compared to the control treatment, which represents a saving of US $433,99/t of live weight and US $885,87/t of carcass.
On the other hand, the diet that included breadfruit meal plus perennial soybean brought about profits of US $0,89/fattened rabbit which is considered excellent, if the current grain, cereal and forage prices are taken into account. Magii (2007) reported that the principal input of rabbit meat production in Argentina is balanced feed, which represents between 60 and 70% of the production costs.
Nieves, Santana and Benaventa (1997) and La O (2007) reported considerable economic savings by using alternative feeding systems in rabbits, which substituted part of the conventional feedstuffs. They also said that the consumption, conversion and daily weight gain indicators were within the permissible range for this animal species.
CONCLUSIONS
The results allow concluding that the diets for fattening rabbits which include fruit meal or fruit meal plus leaf meal from the breadfruit tree do not compromise the chemical composition and acceptability of meats, and at the same time they allow obtaining satisfactory productive results, in agreement with the technological instructions for tropical climates with alternative feeding systems.
