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| Author(s): |
Rosane Barros da Silva Stein
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Pirassununga. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT) |
| Defense date: | 2002-10-04 |
| Examining board members: |
Luiz Roberto Aguiar Toledo;
Fernando Queiroz de Almeida;
Paulo Roberto Leme
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| Advisor: | Luiz Roberto Aguiar Toledo |
| Abstract | |
Sixteen mares of the Mangalarga Marchador breed, ageing from 3.5 to 18.4 years, weighting 394.80 + 46.22 kg were used. The apparent digestibility coefficients (CD) of dry matter (MS), organic matter (MO), crude protein (PB), acid detergent fiber (FDA), neutral detergent fiber (FDN), hemicellulose (HCEL) and gross energy (EB) were determined. The economic viability of the diets with mesquite pod meal (FVA) substituting corn and cob meal (MDPS) was evaluated. Four methods to estimate CDMS were compared: total feces collection (CT) and the use of internal markers: indigestible cellulose (CELi), indigestible acid detergent fiber (FDAi) and acid insoluble ash (CIA). The diets were isoproteic and isocaloric and were composed by Coast cross (Cynodon dactylon cv. Coast cross) hay and concentrate (60:40%). The variation occurred on the level of substitution of MDPS by FVA: 0, 33, 66 and 100%. A randomized complete blocks experimental design with 4 replications per treatment was adopted. The CDMS evaluation estimated by the markers was made by a model considering the bias, i.e., the difference between CDMS estimated by marker and by CT. Blocks did not affect significantly any studied variables. The intake was not affected by the treatments, averaging 1.8% PV (body weigh), 7.02 kg MS/day, 79.84 g MS/kg PV 0.75. The substitution had a second-degree effect on excretion of FDA and EB in feces (p < 0.05). The CDMS, CDMO, CDHCEL and CDPB did not differ between the treatments. The averages were 49.19% (CDMS), 50.19% (CDMO), 56.89% (CDPB), and 35.46% (CDHCEL). The decrease linear effect for CDFDN (p = 0.0105), and second-degree effect for CDFDA (p = 0.0468) and for CDEB (p = 0.0147), was observed in function of the substitution. According of the equations, the max point of digestibility to FDA was obtained with 22.27% of substitution, however to FDN e EB, was obtained with 0%. Between the evaluated markers, FDAi was more accurate. Considering precision, no differences were observed between markers (p < 0.05). On robustness, FDAi and CELi estimatives were affected by dry matter intake and by its own CDMS, whereas CIAs estimative were affected only by CDMS (p < 0.05). Markers recoveries were 98.49, 94.49 and 144.5% for FDAi, CELi e CIA, respectively and, only the FDAi recovery did not differ from 100% (p < 0.05). The ranking of the markers by the evaluation of the concepts (accuracy, precision and robustness) was FDAi > CIA > CELi. The concentrate cost increased in 4.53, 10.64 and 11.60% for the substitution levels of 33, 66 and 100%, respectively, compared to the diets without FVA. The economic viability of substitution of MDPS by FVA occurs since its price/kg is not over 85.95% of the MDPSs price/kg or 70.09% of the corns price/kg. (AU) | |