Animal Science
Received: 02 April 2023
Accepted: 01 June 2023
Abstract: At present, the conventional raw matters for the elaboration of balanced (concentration) pig diets have been notably increase, so it is necessary to use resources of alternative feeding to achieve sustainable productions. Considering the reality, the chemical characteristics of the ripe guava fruit silage as alternative food for pigs are evaluated in this study. In eight days silage samples was determined the dry matter, crude protein, crude fiber, ether extract, ashes, nitrogen free extracts and gross energy. In the days 0, 1, 4, 8, 15 and 30 the pH was determined. In the nutritional composition (dry matter, crude protein, crude fiber, ether extract, ashes, nitrogen free extracts and gross energy) the average value, standard deviation and variation coefficient was checked. The pH data were processed through a completely random design, where the treatments were the fermentation days (0, 1, 4, 8, 15 and 30 d).At day eight of evaluation; the silage has considerable contents of dry matter (22.61 %), crude protein (13.51 %), crude fiber (9.90 %), ether extract (6.08 %), ash (10.24 %), nitrogen free extract (72.49 %) and gross energy (18.54 kJ g DM-1). With respect to the pH, the highest values (p < 0.05) were showed in the day 0 (4.75) and one (4.01), and between the days 4 and 30 was stabilized (3.74-3.76). The ripe guava fruit silage showed good nutritional composition and constitutes an alternative food with favorable nutritive characteristics for their use in pig diets under the Ecuadorian Amazonia conditions.
Key words: Alternative food, pigs, fermentation, tropical fruit.
Resumen: En la actualidad, las materias primas convencionales para la elaboración de dietas balanceadas (concentración) destinadas a cerdos se han encarecido notablemente, por lo que es necesario utilizar recursos de alimentación alternativa para lograr producciones sostenibles. Ante esta realidad, en este estudio se evalúan las características químicas del ensilado de fruta de guayaba madura como fuente de alimento alternativo para cerdos. En muestras de ensilado de ocho días se determinó la materia seca, proteína bruta, fibra bruta, extracto etéreo, cenizas, extractos libres de nitrógeno y energía bruta. En los días 0, 1, 4, 8, 15 y 30 se determinó el pH. En la composición nutricional (materia seca, proteína bruta, fibra bruta, extracto etéreo, cenizas, extractos libres de nitrógeno y energía bruta) se comprobó el valor promedio, la desviación estándar y el coeficiente de variación. Los datos del pH se procesaron mediante un diseño completamente aleatorizado, donde los tratamientos fueron los días de fermentación (0, 1, 4, 8, 15 y 30 d). Al día ocho de evaluación, el ensilado presentó apreciables contenidos de materia seca (22.61 %), proteína bruta (13.51 %), fibra bruta (9.90 %), extracto etéreo (6.08 %), ceniza (10.24 %), extracto libre de nitrógeno (72.49 %) y energía bruta (18.54 kJ g MS-1). Con respecto al pH, los mayores valores (p < 0.05) se evidenciaron en el día cero (4.75) y uno (4.01), y entre los días cuatro y 30 se estabilizó (3.74-3.76). El ensilado de fruta de guayaba madura presentó buena composición nutricional y constituye un alimento alternativo con características nutritivas favorables para su uso en dietas destinadas a cerdos en condiciones de la Amazonía ecuatoriana.
Palabras clave: Alimento alternativo, cerdos, fermentación, fruta tropical.
The alternative resources constitute a viable option to mitigate the costs of pigs feeding in extensive and semi-extensive rearing houses (Lezcano et al. 2014). Ecuador have an excellent potential, as to the alternative foods production for their use in this animal category, among which is the guava fruit (Psidium guajaba L.). In tropical and subtropical areas, this crop is cultivated and harvest twice a year in February-May and August -November. The regions of higher cultivation are the provinces Orellana, Pastaza, Pichincha, Esmeraldas, Azuay, Zamora Chinchipe and Tungurahua, but the main production line is in the cantons of Baños, Mera, Pastaza, Santa Clara, Palora and Joya de los Sachas. In Pataza canton, this crop is established in the most part of the farms from agricultural farmers (Morocho 2017).
The commercial production of guava fruit begins in Ecuador from a third year, with an average of 3 t/ha/year, which reaches 26 t/ha/year in the eighth. In selected crops a production of 35 t/ha/year is achieved. The greatest part of the fruit is use for the production of jellies, yogurt, wines and jams. However, there is a surplus which not fulfill with the parameters for commercialization and it is not assess for animal feeding due to its high humidity content the changeable characteristics of the fruit (Marquina et al. 2008), and, after harvested suffers the attack of microorganisms that causes the decomposition of this raw matter (MAGAP 2023).
For the preserving of these resources for a long time and for their use in pigs feeding (Caicedo et al. 2019) fermentative process can be used (silage). The traditional fermentative technique is performed with the use of lactic bacteria culture on the raw matter slightly chopped, under anaerobic conditions. However, in the fermentation of agricultural byproducts, today are applying inclusion variants of the draying material to improve the dry matter content and the nutrients concentration of the fermented food (Borrás-Sandoval et al. 2017 and Caicedo et al. 2019).The objective of this study was to evaluate the chemical characteristics of the ripe guava fruit (Psidium guajaba L.) silage for their use in pigs.
Materials and Methods
Location. The research was performed in the Microbiology and Bromatology laboratories from the Universidad Estatal Amazónica. The study was carried out in Pastaza canton, Pastaza province, Ecuador. This region has a subtropical humid climate, with high rainfalls (4000 to 4500 mm annuals), relative humidity of 87 % and altitude of 900 m o.s.l. The temperatures vary between 20 and 28 ºC (INAMHI 2014).
Preparation of the ripe guava fruit silage. For the silage preparation ripe and fresh guava fruit was used, from Caicedo Agricultural Farm. After the harvest, the fruits were washed with drinking water for human consumption and they leave drained for 10 min. They were immediately milled in a hammer mill with 2cm sieve. Later the milled raw matter was taken to the Microbiology laboratory from Universidad Estatal Amazónica. To formulate the silage, there were combined chopped ripe fruit, wheat dust, sugar cane molasses, vitamin and mineral premixture, calcium carbonate and natural yogurt (table 1). All the raw matter was weighed in a CAMRY digital scales, model Ek9150k, from China, with 5000 g capacity and ± 1 g precision. The mixture was placed in 24 plastic micro-silos with 1kg capacity, whose content was analyzed in different conservation times (0, 1, 4, 8, 15 and 30 d). A total of four micro-silos per conservation time were evaluated, throwing out every time the respective measurements were performed.

Determination of the chemical components of guava fruit silage. The chemical components of the silage were determined in the Bromatology Laboratory from Universidad Estatal Amazónica. For that three random samples of 1kg of the silage were taken, from the micro-silos of eight days post-elaboration. The time of the chemical characterization was established in function of Rodríguez (2008) and Lezcano et al. (2014) suggestions. In the fermented food was determined the dry matter (DM), crude fiber (CF), ash, crude protein (CP), ether extract (EE) and nitrogen free extract (NFE), according to the AOAC (2005) recommendations . The gross energy (GE) was determined in an adiabatic calorimetric pump, Parr brand, model 1241, from United States. All the analyses were made in triplicate.
Checking of the pH in the guava fruit silage. The determination of the pH was performed with a standard portable meter, Milwaukee brand, model MW102, American production. The checking was made in 24 micro-silos at 0, 1, 4, 8, 15 and 30 d of conservation (four micro-silos in each study). The pH measurement was made by the Cherney and Cherney (2003) procedure.
Experimental design and statistical analysis. For the analysis of the chemical components of the silage descriptive statistical was used and the mean, standard deviation and variation coefficient were determined. To analyze the pH data of the food a completely random design was applied. The treatments were the fermentation days 0, 1, 4, 8, 15 and 30 and Duncan (1955) test with (p ≤ 0.05) to contrast means was applied. All the analyses were carried out with the statistical program InfoStat (Di Rienzo et al. 2020).
Results and Discussion
The use of different raw matters and additives in a combination with the ripe guava fruit make a silage food of an appreciable nutritive quality for pigs feeding (table 2).

The inclusion of the wheat powder as drying material improves the DM content of the silage, from 12 to 13 %, with respect to the fruit in natural state (Torres 2010), which is beneficial to keep the food for a long time and avoid loses due to decomposing microorganisms. Nkosi et al (2016) state that the high DM content in the silage limits the developing of putrefactive microorganisms. The increase in the protein value is due to the colony forming units (CFU) of lactic acid bacteria and yeasts which are develop during the fermentative process (Gunawan et al. 2015, Caicedo et al. 2020 and García et al. 2020). The increase in the concentrations of ash, ether extract, nitrogen free extracts and energy is due to the inclusion of different raw matters and additives which was made the silage (Borrás-Sandoval et al. 2017 and Fonseca-López et al. 2018).
The nutritional composition of the ripe guava fruit silage is similar to some types of silages from agricultural byproducts used in pigs: cassava root (Reina-Rivas et al. 2022), sweet potato tubers (Lezcano et al. 2015) and banana (García et al. 2020).
The highest pH value was showed in the moment of the micro-silos elaboration (day zero) and was slightly decreased in 0.74 units towards the first day the fermentation process have been start. Among the 4 and 30 evaluation days, the pH was established in values lower to 4, without significant differences among the mentioned days. The results of the pH analysis in the ripe guava fruit silage are shown in table 3.

The highest pH values were showed in the 0 and 1 evaluation days. This is due to at the beginning of the fermentation process the lactic acid concentrations in the micro-silos are low or null because of the limited activity of the lactic acid bacteria (LAB).The changes in the pH are related with the amount of inoculum and soluble carbohydrates which are used in the silage formulation for the benefic microbial population reduce the pH efficiently, when increasing in the media the concentration of lactate and acetate (Ogiy et al. 2015 and Ogunade et al. 2018).
However to the previous, the pH was established between the 4 and 30 measurement days. This is satisfactory to achieve a good conservation of the product. Nkosi and Meeske (2010) show that the pH should stabilized in the first 96h of started the fermentation to reduce the concentrations of butyric acid and ammoniac nitrogen, as to achieve a good aerobic stability and restrict the developing of proteolytic enzymes, enterobacteria and clostridiums that damage the silage (Álvarez et al. 2015 and Da Silva et al. 2018).
The rapid pH stabilization is due to the lactic acid production because of the presence of Lactobacillus (Lopes et al. 2013).The inclusion of a carbon source (sugarcane molasses) of easily assimilation and the natural yogurt as inoculum source in the raw matter favors the growing of lactic bacteria and with this, the faster acidification of the medium (García et al. 2020 and Kim et al. 2021).This allow to reduce and stabilize the silage pH (Ossa et al. 2010 and Cárdenas et al. 2018) and keep the nutrients in the food. It is important to highlight that the faster stabilization inhibits the development of decomposing microorganisms that causes undesirable fermentations, deterioration of nutrients and silage quality (Borreani et al. 2017 and Ávila and Carvalho 2020).
Conclusions
The ripe guava fruit silage had good nutritional composition, so it constitutes an alternative food with appreciable nutritive characteristics for their use in pig diets under the Ecuadorian Amazonia conditions. The silage pH was showed constant in the first 96h of started the fermentation process, which is beneficial to avoid undesirable fermentations and achieve good aerobic stability and food conservation for a long time.
Acknowledgments
Thanks to the owners of Caicedo Agricultural Farm and to the technical staff of Microbiology and Bromatology laboratories from Universidad Estatal Amazónica by the support provided for this research.
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Author notes
*Email: orlando.caicedo@yahoo.es
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