Physical and biochemical characteristics of tropical grass and legume pastures grazed by lambs

Large areas of tropical grass pastures are not grazed by lambs because of the difficulties in managing high growth rate swards with high selective animals. The objective of this study was to evaluate the physical and biochemical characteristics of tropical pastures offered to lambs in continuous grazing. An upright grass and a shrub legume were set out in three pasture types and grazed by lambs: (1) aruana grass monoculture (AG-Panicum maximum Jacq. cv. IZ-5), (2) pigeon pea monoculture (PP-Cajanus cajan [L.] Millsp. cv. An & atilde;o) and (3) contiguous swards (CS), half of the paddock with AG (CSAG) and half with PP (CSPP). The pastures were evaluated for structural characteristics, production, nutritional composition and antioxidant concentrations in four periods over 92 days of continuous grazing by lambs. Hand plucking samples, similar to animal diet, were collected for chemical analysis. Regarding height, the PP legume monoculture after 42 days of grazing had uncontrollable growth by the lambs, reaching 1.2 m in height. This same legume but as a CS beside AG (CSPP) was maintained at a lower and similar height throughout the experimental periods. In general, the leaf:stem ratio of the different pastures decreased over the experimental periods from 0.7 to 0.2. In most periods, the CS showed intermediary nutritional quality compared to AG and PP. The alpha-tocopherol content was similar among swards, with an average of 137.2 +/- 13.67 mg/kg of green matter (p > .05). Pigeon pea showed the highest levels of total tannin and condensed tannin at 63 and 92 days (p < .05). The use of tropical grass together with a legume provides a better physical structure of the pigeon pea for grazing lambs than when monoculture of this species.

The authors would like to thank the National Council of Scientific and Technological Development (CNPq) for the doctorate scholarship to the first author, and Coordination of Improvement of Higher Education Personnel (CAPES) for the PhD scholarship sandwich to the first author, process number: PDSE 88881.132015/2016-01. To thank the Center for Research and Technology Agro-food of Aragon (CITA) and Institute of Food Science and Technology (ICTA), for the assistance of laboratory analysis. To thank the Ministry of Science, Technology and Innovation - MCTI and the National Council for Scientific and Technological Development - CNPq, for the financial support to the project.

green panic

pigeon pea

shrub legume

tannin

tocopherol

Published