RESEARCH WORK

Productive performance of ewes in a silvopastoral system

Y. López¹, J. Arece¹, E. León² y N. Aróstica¹

¹Estación Experimental de Pastos y Forrajes "Indio Hatuey" Central España Republicana CP 44280, Matanzas, Cuba

²Universidad de Granma, Granma, Cuba

E-mail: yoel.lopez@indio.atenas.inf.cu

ABSTRACT

In order to study the performance of productive indicators of Pelibuey ewes in a silvopastoral system, a study was conducted with 44 ewes at the Experimental Station «Indio Hatuey». The animals received Guinea grass and leucaena forage throughout the period, with a supply of 1 and 2 kg/animal/day, respectively; in the mating stage they received citrus pulp at a rate of 0,350 kg/animal/day and during the last third of pregnancy and the first 30 days postpartum concentrate was supplied (0,04 kg/animal/day). The body condition and live weight of the ewes were determined during the mating stage, parturition and 30 days postpartum. In addition, the influence of parturition type (single and double) on the weight of the lambs at birth and 30 days after being born, and on the mean daily gain, was analyzed. Significant differences were found (p<0,05) in live weight (31,4; 32,9 and 30,5 kg) and body condition (3,7; 3,5 and 3,0); while in the indicator hematocrit no significant differences were found. The parturition type had effect on the weight at birth, mdg and weight 30 days postpartum, with significant differences (p<0,05). The weight at birth was 3,23 and 2,66 kg and after 30 days it was 7,82 and 5,47 kg; while the mdg was 150 and 94 g for single and double parturitions, respectively. Sheep management in the silvopastoral system was concluded to allow favorable indicators in lamb growth and ewes during the stages of mating, parturition and 30 days postpartum.

Key words: Reproduction, sheep, silvopastoral systems.

INTRODUCTION

One way to increase food production in Cuba is the development of sustainable livestock production systems, which depend on the available local resources.

Sheep production constitutes at present an alternative to generate protein of animal origin for human consumption, especially in those zones where food availability becomes critical as a consequence of their agroecological characteristics.

Most sheep production in the country is developed in areas with natural pastures, marginal zones or in agricultural lands with low production of edible biomass for animals (Fonseca, 2003); these areas represent very fragile climatic regions, from the point of view of natural resource conservation. Under such conditions, the productive, reproductive and health indicators are affected.

In that sense, trees have been proven efficient in the utilization of solar energy and its conversion into biomass; that is why silvopastoral systems offer a diversified market opportunity which can stimulate rural economic development. In this system high quality wood and forage are produced, allowing an efficient livestock production (Bradshaw et al., 2003).

When a sustainable system is designed to produce milk and meat, in which pasture is used as main feedstuff, it is necessary to take into consideration the presence of legumes (Figueredo and Rosales, 2007), because in addition to improving the nutritional value of the diet, they are capable of establishing a symbiotic relationship with microorganisms that fix atmospheric nitrogen and transform it into assimilable forms for plants (Francisco et al., 2009); this characteristic benefits not only the legumes that have it, but also grasses and other families which grow in association with them.

With the use of leucaena for sheep feeding, the weight at birth and weight at weaning of the lambs has increased and the ewes have shown a better body condition for facing the next pregnancy, with which the stocking rate per hectare and meat production are increased and savings in protein supplements are achieved (López et al., 2004).

The objective of this work was to characterize the performance of the productive indicators of Pelibuey ewes in a silvopastoral system, at the Experimental Station «Indio Hatuey».

MATERIALS AND METHODS

Location. The study was conducted in May-December, in the production areas of the small livestock facility at the Experimental Station «Indio Hatuey», Matanzas province, Cuba.

Climate and soil. Average annual temperature is 23ºC, with a mean of 21ºC and 27ºC in the winter and summer, respectively, and high relative humidity (60-70%). Annual rainfall is 1 300 mm, varying from 1 000-1 200 mm in the rainy season to 200-400 mm in the dry season. The soil on which the trial was conducted has plain topography and it is classified as lixiviated Ferralitic Red (type Humic nodular ferruginous hydrated) of fast desiccation. The natural fertility is considered good, with slightly acid (6,4) to neutral (7,3) pH and it shows a low to moderate organic matter content (Hernández et al., 1999).

Animals. In a system of two matings per year, 44 Pelibuey ewes were used, being between three and four years old and having good health status. Before the study they were selected regarding their general condition. An only herd was randomly formed, assigned to a grazing area, and each animal was considered an experimental unit; for their identification chains with individually numbered plates were placed on them. The lambs were kept in the sheds and did not graze during their first month; afterwards, they were incorporated to grazing once or twice a week as part of the management.

Grazing system. The silvopastoral system was composed by the tree species Gliricidia sepium (2 400 plants), Leucaena leucocephala (2 200 plants) and Albizia lebbeck (1 800 plants) with more than 10 years of exploitation. The herbaceous stratum was represented by the pastures Dichanthium annulatum plus Panicum maximum and the latter was favored. The area (2,25 ha) was divided into nine paddocks which were grazed from 8:00 a.m. to 3:00 p.m., with average resting times of 24 and 40 days for the rainy and dry season, respectively. No mineral fertilization was used.

Feedstuffs. For the feeding balance the values of the chemical composition of feedstuffs were considered (DM, CP and ME for Guinea grass: 25,6%; 5,7% and 1,81 Mcal/kg DM; pasture: 31,7%; 4,8% and 1,83 Mcal/kg DM; leucaena: 31,0%; 20,5% and 2,25 Mcal/kg DM; citrus pulp: 16,3%, 7,7% and 2,83 Mcal/kg DM and concentrate: 86,7%; 12,4% and 2,82 Mcal/kg DM) reported by Cáceres et al. (2002).

Guinea grass forage was supplied throughout the period (1 kg/animal/day) and the leucaena pruning was utilized, provided directly in the field from 9:00 to 10:00 a.m. For that purpose 30 plants higher than 2 m and an approximate green biomass availability of 3,5 kg/plant were pruned, which guaranteed 2 kg/animal/day. The other feedstuffs were distributed in the three evaluated stages of the productive cycle; in the mating stage the animals received citrus pulp at a rate of 0,350 kg/animal/day; while during the last third of pregnancy and the first 30 days postpartum concentrate was supplied (0,04 kg/animal/day).

Measurements. The body condition, as well as live weight of the ewes, was determined during the mating, parturition and 30 days postpartum. The body condition of the ewes was obtained through the methodology proposed by Russel et al. (1969), where the minimum value of the scale (1) corresponds to weak animals and the highest (5) to those with the best body condition. The increase was based on mean score. The influence of the parturition type (single and double) on the weight of lambs at birth and 30 days later, and on the mean daily gain (mdg) was analyzed. The animals were weighed with a scale of 50 kg ± 0,2 and a dynamometer of 10 kg ± 0,02 for ewes and lambs, respectively. With a monthly frequency the agglomerate cell volume by microhematocrit was determined (Hansen and Perry, 1994).

Statistical analysis. The data were processed through the program SPSS® version 15.0 for Windows®. The effect of the evaluated periods (mating, parturition and 30 days postpartum) on the microhematocrit performance, body condition and weight of the ewes was determined, as well as the effect of parturition type on the variables, for which a variance analysis (ANOVA) was used; the differences among the means was determined through Duncan's multiple range comparison test (1955).

RESULTS AND DISCUSSION

Table 1 shows the live weight, body condition and agglomerate cell volume of the ewes during mating, parturition and first 30 days postpartum. Significant differences (p<0,05) were found in the live weight and body condition. The highest live weight values were found at parturition.

The live weight of the ewes (30 kg) is within the range proposed by León et al. (2006) under tropical conditions with the reports by López
et al. (2004) in supplementation studies with leucaena foliage and molasses-urea for ewes, in a system with natural pastures.

In works conducted by López et al. (2008) under silvopastoral system conditions similar values were reported, which suggests that feeding is a determining factor in the productive success of the herd (León et al., 2006).

In the 30 days after parturition a negative energy balance occurred, due to the increase of milk production and the decrease of voluntary intake, which caused a mobilization of body reserves and this was the reason for the remarkable live weight decrease (Yzaguirre and Combellas, 2002; López et al., 2008).

On the other hand, the body condition (3,7; 3,5 and 3,0 for the mating, parturition and 30 days postpartum, respectively) showed variations that were due to the physiological status of the ewes. This indicator has a direct relationship to the nutritional status of the herd and in this study the ewes maintained values of three units, which is ascribable to the feeding within the system, in which the leguminous component of the silvopastoral system and the concentrate considerably favored the improvement of the nutritional value of the diet based on natural pastures (considered as having very low nutritional quality for tropical conditions, according to Hernández et al., 1998; López et al., 2008) and, thus, the productive response of ewes.

The hematocrit did not show significant differences, indicating that the animals had good feeding conditions in the association. In this sense, the variation of live weight and body condition are important within the evaluated stages, because nutrition is one of the factors that affect the most these indicators (Fonseca, 2003).

On the other hand, the parturition type had a remarkable action on body condition in the first weeks after parturition (table 2). There were significant differences (p<0,05) for this indicator 30 days postpartum; while in the other moments the results did not differ significantly; the live weight of ewes had the same performance, which neither differed for the studied moments nor was affected by parturition type.

This is explained by the fact that since the first weeks after parturition, the animals are forced to make a mobilization of body reserves to guarantee lamb feeding, especially in the case of double parturitions, because the ewes must make a higher usage of the reserves for suckling two lambs (Zambrano et al., 1999).

The live weight of ewes did not show significant differences for single and double parturitions, which could have influenced the weight of lambs at birth.

Fonseca (2003) and Herrera and Pulgarón (2005) stated that the live weight of ewes at parturition has a significant effect on the weight of lambs at birth. This effect can be negative, making it possible that low-weight lambs die (Fonseca, 2003); although there are other factors that can influence mortality, such as nutritional deficiencies, bad zootechnical management and the environment (Diskin and Niswender, 1989).

Significant differences (p<0,05) were found for parturition type with regards to the evaluated indicators; single parturition lambs showed a better performance, with weight values of 3,23 and 7,82 kg at birth and after 30 days, respectively (table 3).

Fonseca (2003) found similar results in evaluations of the effect of parturition type, stage and feeding of the ewes on lamb weight at birth. Hence feeding management is vital to obtain a productive improvement in the herd (El-Hag et al., 1998; Fonseca et al., 2001; Herrera and Pulgarón, 2005; Waghorn, 2008).

The values obtained in this work in the weights of lambs at birth, are higher than the ones found by López et al. (2004) and León et al. (2006) under silvopastoral system conditions and supplemented with leucaena and molasses-urea; nevertheless, they are similar to the ones reported by López et al. (2008) when using good-quality mixed silage, in a system with natural pasture plus leucaena. In these works the parturition type was not taken into consideration.

The mean daily gain values were 150 and 94 g/day for single and double parturitions, respectively (table 3). In this indicator single-parturition ewes had a better performance, because they suffered less in the first days of lactation as compared to those with double parturitions under equal feeding and management conditions.

Sheep management in the silvopastoral system was concluded to allow favorable indicators in lamb growth and ewes during the stages of mating, parturition and 30 days postpartum.