Indicadores na coleta de digesta omasal e na cinética de trânsito do trato gastrintestinal de bovinos

• Autor(a) principal: Dias, Marcia
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1724
• topic: Fibras indigestíveis; Perfil nictemeral; Proteína microbiana; Non-digestible fibers; Nictimeral profile; Microbial protein; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

It was aimed to evaluate markers and markers systems in omasal digesta collection; to compare the estimate of particles and fluids flow kinetics by different markers and mathematical models; to evaluate the estimate of the flow rate by ruminal emptying technique and by the no-linear mathematical model adjustment; using two roughages (sugarcane and corn silage) and two concentrate levels (0 and 25%) in heifers diet. Three experiments were conducted. In the first experiment, four rumen fistulated Nelore heifers were used, which were confined, fed Tifton-grass (Cynodon spp.) hay ad libitum and 1 kg of concentrate (16% CP) for 32 days, with four periods of four days each. The adaptation to the experimental diet was of seven days and interval of three days between the periods. The four treatments evaluated consisted of four Co-EDTA and YbCl3 infusion times in different omasal digesta phases: one (T1v), two (T2v), four (T4v) and six (T6v) times a day with the same intervals. The times of omasal digesta collection comprehended a period of 24 hours and interval of two hours. The nictimeral profile was determined by the Fourier series model. The Co and Yb average concentration did not differ (P>0.05) among the different infusion times and omasal digesta phases, presenting variation index inferior to 10%. The variation index and the oscillation amplitude for both indicators went smaller for T4v. The variation index were inferior to 10%, with smaller values for iNDF (0.66-2.07%), iADF (1.16-4.46%) and LIPE (0.64- 2.96%) and greater for Cr2O3 (2.52-9.64%) and TiO2 (2.75- 3.49%). Comparing the fundamental dimension of the excretory cycle (c) in omasal digesta phases, excepting the liquid phase, the best values (P<0.05) values were observed for iADF, Cr2O3 and LIPE , corresponding to fundamental periods smaller than 4.5 hours. The indigestible fibers (iNDF, iADF) and LIPE present more stable nictimeral profiles in omasal digesta than Cr2O3 and TiO2. In the second experiment, four Holstein-Zebu heifers, fistulated in the rumen and ileum were maintained in confinement regimen with diet based on Tifton-grass (Cynodon spp.) hay offered ad libitum and 1.2 kg of concentrate (22% CP). The experiment lasted 39 days, with three periods of six days each. The adaptation to the experimental diet and the interval between the periods were of seven days. In each experimental period, total collection of feces (1st to the 3rd day) was realized; collection of omasal and ileal digesta (4th to the 6th day). Three markers systems were compared to evaluate the omasal digesta flow: unique (iNDF, iADF, Cr2O3, TiO2); double (association of Co-EDTA or YbCl3 with the markers of the unique system); and triple (association between Co-EDTA and YbCl3 with the unique system). For estimate of the ileal flow, only the unique markers were used. There was no effect (P>0.05) of the collection period on omasal and ileal flows. The omasal flow was better estimated by iNDF, iADF and associations with the Co-EDTA and YbCl3. In the third and last experiment, four Holstein-Zebu heifers fistulated in rumen and ileum were used in a 4x4 Latin square. The diets consisted of a 2x2 factorial, with two roughages (sugarcane and corn silage) and two concentrate levels (0 and 25% of total diet DM). From the 8th to the 14th day the estimate of digesta flow was estimated with markers, the chrome (Cr) mordent fiber and complexed with európio (Eu) and ytterbium (Yb) to mark the solid phase of the roughages, and the cobalt-etilenodiaminotetracetic acid (Co-EDTA) for the liquid. In the 8th day, collection of ruminal liquid was done and, from the 14th to the 16th day, ruminal emptying. The curves of concentration of solid phase indicators were adjusted to the multicompartimental (G1(n) &#8594; 0) and bi-compartimental (G2 &#8594; G1 &#8594; 0) models and of fluids to the time-independent (G1 &#8594;) and time-dependent (G2 &#8594;) uni-compartimental models. The k2 of the multi-compartimental model was approximately the double of that of the bi-compartimental model, while the k1 were similar. Both in the multi as in the bi-compartimental models, the use of Yb resulted in the least behavior and uniformity of the points among the evaluated markers, while Cr was the one which best represented the data of solids passage rate. Comparing the models, the multicompartimental model was better than the bi-compartimental. The models evaluated for fluids passage rate presented similar behavior, but the asymptotic standard deviation was smaller for the time-dependent model. Chrome and Co-EDTA were good indicators to evaluate particles and fluids passage rate, respectively. The models recommended for particles passage rate was the multi-compartimental (G1(n) &#8594; 0) and, for fluids, the time-dependent unicompartimental (G2 &#8594;). This way, the diets and the methods of estimate particles passage rate were compared using these indicators and models. Greater (P<0.05) DM and NDFap intake was verified in the animals receiving corn silage, and DM and OM intake, when fed with concentrate. There was no effect (P>0.05) of the roughage on ruminal mass, but the concentrate addition reduced (P<0.05) the NDF ruminal mass in total digesta and in solid phase. The CP, NDFap and NFC total digestion coefficients were greater (P<0.05) for sugarcane than for corn silage. The concentrate addition improved (P<0.05) the OM and NFC total digestibility. Rumen pH was higher (P<0.05) for the sugarcane and in the diet without concentrate. The sugarcane presented smaller N-NH3 concentration compared to corn silage and it was not verified any concentrate effect. The omasal digesta collection can be accomplished by the unique system, using iNDF, iADF or LIPE , or the double system with Co-EDTA or YbCl3, infusing every six hours, associated to iNDF or iADF. The digesta sampling can be made every four hours, only in the day period. To estimate the fibrous fraction passage rate it is recommended the chrome and the multicompartimental (Gn) model and, for the one of fluids, the Co-EDTA and the timedependent uni-compartimental (G2) model. The estimate of fibrous fraction passage rate by rumen emptying method, compared to the mathematical models, results in estimate of about the double of the value. The corn silage or the addition of 25% of concentrate in the heifers diet present better results.