Padrões de fermentação da silagem do algodão mocó aditivada com ureia em diferentes tempos de abertura.

Abstract

The potential for forage production in the semiarid region of Brazil is viable as long as there is necessary planning. Choosing correct and adapted cultures is the best choice. The recovery of cultures that was part of ruminant feeding in the past is a way to think about it. In this context, Mocó cotton (Gossypium hirsutum L. r. Marie galante Hutch) presents itself as a crop that returns to the forage production scenario. Armed with references, this research aimed to evaluate the dynamics of fermentation and chemical composition of Mocó cotton silage with urea additives. The experimental design was completely randomized in a 3x3 factorial scheme, with three times of silage fermentation (14, 21 and 28 days) and three levels of urea (0,3 and 6% based on ensiled dry matter), with six repetitions, totaling 54 mini silos. The mini silos were evaluated from a fermentative point of view by the parameters of pH, electrical conductivity, loss by gases, loss by effluent, and dry matter recovery. The bromatological analyzes evaluated dry matter (DM), mineral matter (MM), moisture, organic matter (OM), ammoniacal nitrogen based on dry matter (NNHMS), ammoniacal nitrogen based on total nitrogen (NNHNT), crude protein ( PB), neutral detergent fiber corrected for ash and protein (cPDF), hemicellulose, acid detergent fiber (ADF), cellulose, total carbohydrates (CHOT), non-fibrous carbohydrates (NFC), ether extract (EE) and total digestible nutrients (NDT). Urea increased the pH from 5.56 at the 0% dose to 8.62 at the 6% dose of silage additive, which promoted higher levels of electrical conductivity. The additivation with urea positively influenced (P<0.05) in all the parameters mentioned above. It is worth highlighting the increase in the CP content of the silage from 9.81% at the 0% urea level to 14.81% at the 6% level and the improvement in the FDNcp contents at the 0% dose was 63.62% and went to 69.03 and 68.20 at levels 3 and 6% of additivation. Regarding the days of fermentation, the analysis of variance detected a significant difference (P<0.05) only for DM, moisture, CP, FDNcp, FDA, CHOT and CNF. With a significant interaction (P<0.05) urea x days only for the electrical conductivity, with the increase in the urea dose and as the days went by, the CE levels in the additive silos increased by 1.63; 1.64 and 1.85 dS m-1 at dose 3, and 2.12; 2.17 and 2.30 dS m-1 at the 6% dose, as opposed to the 0% dose of urea which, over the days, promoted a reduction in EC, with the following results: 1.22; 1.20 and 1.18 for 14, 21 and 28 days, respectively. In general, the 3% level of additivation showed results similar to the 6% level, being seen as the best tested. Mocó cotton silage is viable to be used as food for ruminants in the semiarid region, which can lower costs and avoid the purchase of foreign food by producers.