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Enzymatic activity of cellulase in tropical pastures managed with forage allowances by Dairy Cattle

Estella Rosseto Janusckiewicz ; Elisamara Raposo ; Bruna Miassi Pereira Russomanno Martins ; Marcela Azevedo Magalhães ; Alan Rodrigo Panosso4 ; Gabriel Maurício Peruca de Melo ; Ana Cláudia Ruggieri
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Soil tillage and management affects the temperature, humidity, aeration and the microbial activity in the soil. In pastures, plant residues and feces and urine of animals are used as substrate, promoting microbial growth and enzymatic activity in the soil. The study evaluates the effect of forage allowances (FA) on cellulase activity in pasture soils of Brachiaria cultivars (Marandu, Xaraes and Mulato) grazeg by non-lactating Holstein cows under rotational stocking. The area is located in UNESP, Jaboticabal, SP. The FA studied were 4, 7, 10 and 13 kg DM 100 kg-1 BW. Experimental design was completely randomized with three replicates and plots subdivided in time. Cellulase activity was estimated by incubating the soil sample with carboxymethyl cellulose and quantification of glucose produced. Samples were collected before grazing in the paddocks from December 2008 to February 2009. After 4 months of the end of the grazing cycles was carried out other sampling to better visualize the enzyme activity through time and in different climatic conditions. So, the evaluations days (ED) were on 1, 21, 42, 63 (summer) and 183 days (winter). Analysis of variance and Tukey's test at 5% probability was performed to compare the means by LS means of SAS. There was statistical difference in the enzymatic activity of cellulase for FA (P < 0.0001), cultivars (P <0.0001), ED (P <0.0001), and interactions FA x ED (P <0.0001) and cultivars x ED(P <0.0001). In FA 4 and 13 kg DM 100 kg-1 BW had higher (P <0.05) cellulase activity at 21 ED with values of 15,50 and 18,77 ?g C.g-1 solo, respectively. In the FA 10 kg DM 100 kg-1 BW the enzyme activity was higher (P <0.05) at 63 ED (17,85 ?g C.g-1 solo). These activities were observed during the summer. However, in FA 7kg DM 100 kg-1 BW higher (P <0.05) activity (18,44 ?g C.g-1 solo) was observed in winter. In Marandu and Xaraes cultivars higher (P < 0.05) cellulase activity was observed at 21 ED with values of 17,10 and 18,48 ?g C.g-1 solo, respectively. In Mulato cultivar this is observed at 183 ED (18,79 ?g C.g-1 solo). Thus, there was no specificity of cellulase activity in relation to the FA and cultivars, but was observed influence of climatic conditions.