Chemical composition and spine occurrence in cactus pear genotypes

Abstract

The spineless cactus 'Orelha de Elefante Mexicana' (Opuntia sp.) is a genotype resistant to cochineal carmine pest (Dactylopius opuntiae Cockerell). However, this clone has many spines, making it difficult to grasp and chew as forage, limiting animal consumption. In addition, the spines cause difficulty in harvesting and cultivation. The objective of this work was to evaluate the chemical composition, digestibility and occurrence of spines of genotypes of 'Orelha de Elefante Mexicana' (Opuntia sp.), and the correlation between chemical composition and digestibility with occurrence of spines. The experiment was carried out at the Experimental Research Station of Agricultural Institute of Pernambuco, located in Arcoverde, Brazil from January 2014 to June 2015. The genotypes Lisa 1, Lisa 2, Seg CV, Seg 1, Seg 2, Seg 3, Seg 4, Seg 5, and Seg 6 were produced in previous selections from seeds of the 'mother-plant'. Soil of the experimental area is classified as Regosol, and rainfall during the experimental period was 771 mm. Fertilization was performed with 20 t organic matter ha(‑1) year(‑1) using cattle manure. Planting was done in January 2014, using spacing of 1.4×0.5 m and a completely randomized design with 10 replications of one plant each. Variables analyzed were chemical composition, digestibility, and occurrence of spines. Evaluations were performed on secondary cladodes of 18-month-old plants. Lisa 1 and Lisa 2 presented greater dry matter (DM) concentration than other genotypes. When compared with Seg CV, the genotypes Lisa 1 and Lisa 2 presented greater DM and in-vitro dry matter digestibility (IVDMD), and lower neutral detergent fiber (NDF) and acid detergent fiber (ADF). Genotypes showed variability in chemical composition, digestibility, and the presence of spines. The presence of spines and glochids showed positive correlation with NDF and ADF concentration and negative correlation with IVDMD and DM, but did not affect crude protein concentration.