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| Author(s): |
Luciana Gerdes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. , gráficos, tabelas. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2003-11-13 |
| Examining board members: |
Herbert Barbosa de Mattos;
Carlos Guilherme Silveira Pedreira;
Sila Carneiro da Silva;
Joaquim Carlos Werner
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| Advisor: | Herbert Barbosa de Mattos |
| Field of knowledge: | Agronomical Sciences - Animal Husbandry |
| Indexed in: | Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP |
| Location: | Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; ESALQ t633.2; G366i 82502 T82502 |
| Abstract | |
At Instituto de Zootecnia, Nova Odessa, SP, in a pasture of aruanagrass (Panicum maximum Jacq. cv. Aruana), grazed by sheep in an intensive production system (irrigation, fertilization and rotational stocking), it was introduced a three winter forage species: black oat (Avena strigosa Schreb. cv. Common), italian ryegrass (Lolium multiflorum Lam. cv. Common) and white clover (Trifolium repens L. cv. Zapican) with the objective of increasing the forage supply and its nutritive value during the dry winter period. The mixture was broadcasted sown over the grass on 04-14-00 and 06-07-01 in two years of experiment. From 04-14-00 to 01-18-01 and 06-07-01 to 02-22-02 it was evaluated, in six annual grazing periods, the forage mass, its botanical composition and leaf blades percentage pre grazing, residual mass post grazing, forage accumulation (FA) and mean forage accumulation daily rate (MFADR) in each regrowth period and sward heigth pre and post grazing, the chemical characteristics: crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin and in vitro dry matter digestibility (IVDMD) in the forage on offer and in its botanical components. The experimental design was a completely randomized block (four) with two replications within the block. The treatments were: 1) grass alone and 2) the grass oversown with the mixture of the winter forages. The blocks were grazed by the same group of sheep in sequence for two or three days until the sward height reached to 10-15 cm. The white clover did not establish. In the first year the oversown treatment presented higher total forage mass than the control in the second periods and in the mean of the six periods. The black oat presented higher contribution in the second period and italian ryegrass in the third. The oversown pastures presented higher FA and MFADR than the single aruanagrass pastures, in the second, fifth and in the mean of the six periods. The CP in the forage from the grass pasture alone was greater than the one of the oversown pasture in the third period, and similar in the others. Oat and ryegrass CP was lower in the third period than the ones of the first and second ones. NDF, ADF and lignin in the forage from the grass pasture alone were greater than the ones of the oversown pasture. Oat and ryegrass NDF was lowest in the initial growth periods, increasing in the final. Forage IVDMD from the two treatments were similar in all evaluation periods. In the second year, the total forage mass was similar in the two pasture treatments in all grazing periods and in their means. The black oat contribution was higher in the first period and the one of italian ryegrass in the third. The FA and the MFADR were similar in the two pasture systems. The leaf blades percentage of aruanagrass was similar in the two pastures in all periods and the ones of black oat and italian ryegrass were lower in the final period compared to the preceeding ones, in the two years. The CP in the forage from the grass pasture alone was greater than the one of the oversown pasture in the fourth period, and similar in the others. Oat and ryegrass CP decreased along the grazing periods. NDF, ADF, lignin and IVDMD of the forage from the two treatments were similar in all evaluation periods. Oat and ryegrass NDF, ADF and lignin were greater in the last grazing period. Ryegrass IVDMD from the first two periods were similar and decreased in the final. For the São Paulo State conditions, adequately fertilized and irrigated aruanagrass pastures, when oversown with winter annual forages, yield more than single aruanagrass ones during the dry winter period but with similar nutritive value. Single aruanagrass pastures when fertilized and irrigated present also good forage yields with good nutritive value during this time. (AU) | |