Development and evaluation of an integrated pear trees-sheep production system

Hugo Vladimir Sánchez Moreno

ABSTRACT
The land use in an efficient and diversified way, without damaging the ecosystems, obeys an immediate need to produce food and preserve the planet. In this sense, the small farmer requires to guarantee in his crops a cost–effectiveness that allows him to sustain the family economy. Under this premise, the work hypothesis was that the development of a sheep rearing system, in a pear tree crop, allows to use the land more efficiently and to obtain higher economic benefits. To prove this hypothesis, the general objective was to contribute to the diversification of pear production through the development of an integrated system with sheep. As experimental unit a pear exploitation of 1,2 ha was used, with 20 years of establishment, located in the Nuevo Colón municipality, Department of Boyacá, Colombia. The bibliographic review indicated that there was very little information about the use of sheep in fruit plantations, even more limited in the case of pear trees, caused by the conception of fruit growers that sheep destroy the crops. To elucidate the truthfulness of this statement an ethological evaluation was conducted (Stage I) with 9 sheep (24,8 animals/ha), which had free access to the pasture from 8:30 a.m. to 5:30 p.m. The botanical composition and dry matter availability were measured, and a soil analysis was performed. The prevailing pasture was ryegrass (Lolium sp.), with 58,9 % and 9 different species were detected. The availability was 4,11 t DM/ha. The ethological observations showed that the sheep performed their main actions of ingestion and movement during the first morning hours and at the end of the afternoon; while in the hours of more light and heat their fundamental activities were rumination and rest. It was also observed that they did not predate the trees. The initial weight of the animals was 21 kg and mean gains of 209 g/animal/day were obtained. These results suggested that it was advisable to plant improved pastures that guaranteed enough food in quantity and quality. In Stage II, in order to determine the optimum stocking rate to be exploited within this system, the land was prepared with harrow to plant Italian ryegrass (L. multiflorum) and white clover (T. repens), in strips, in a proportion of 70:30. The area was divided into three lots of 0,4 ha to evaluate three stocking rates (15, 30 and 45 animals/ha) during 121 days. The botanical and bromatological composition, pasture availability and daily weight gain of the animals were measured. A methodology was developed to evaluate the presence level of the fungus Venturia pirina. Six species were detected and the one with the highest persistence was ryegrass (80-75 %); while the clover varied from 10 % at the beginning to 20 % at the end, which contributed remarkably to the protein content of the pastureland. The average forage availability was 2,98 t DM/ha. The stocking rate of 30 animals/ha was the best, in the individual gain (83,5 g/animal/day) as well as in the percentage of weight increase (38,82 %). The values of the presence of V. pirina decreased from 6,4 in 2001 to 5,3 in 2002, and to 1,3 in 2003, which was interpreted as the result of a possible beneficial action of the animals in the control of this fungus. When comparing these results to those obtained through the Towsend-Heuberger formula (CIBA-GEIGY, 1981), which measures the infestation percentage and is internationally acknowledged, a high correlation between both was found (0,965). In Stage III, during 83 days, the weight gain was evaluated with a stocking rate of 30 animals/ha, whose value was 169 g/animal/day; this resulted not only from the pasture availability and quality, but also from the application of the experience acquired in the previous trials. The results of the soil analysis during the evaluation period 2001-2003 showed a trend to a favorable change in their values, through an increase of pH, as well as of the OM, calcium, potassium and boron content, and a decrease of aluminum. Nevertheless, the phosphorus content decreased; a response that should be evaluated in time. The economic appraisal showed the advantages of introducing sheep in the pear plantations, by eliminating the costs inherent to weed control and to chemical and organic fertilization, and providing a positive added value, due to the gains obtained when the animals are sold. The cash flow corroborated that the initial investments are recovered in the first year and that the system guarantees a sustained increase of cost-effectiveness, decreasing the economic risks of the farmer. In this Master of Science thesis seven conclusions were drawn and nine recommendations are proposed of complementary studies that should be conducted to define important aspects of sheep management in pear plantations. At the end of the document four annexes are included, which gather results of general interest; among them an integral technology of how to proceed to implant an agroforestry system in a pear plantation, stands out.