Silagens de cana-de-açúcar aditivadas com torta de algodão e inoculante microbiano em dietas de cordeiros confinados

Abstract

The objective was to evaluate the fermentative and nutritional profile of sugarcane silages added with cottonseed cake (20% fresh matter), heterofermentative inoculant (Weissella cibaria) and a combination of both, which were used in the diet of feedlot lambs to evaluate performance, intake, digestibility and ruminal parameters. Two experiments were carried out. The first experiment was carried out in a completely randomized design in a 4 x 2 factorial scheme (four additives and two opening times), with 4 replications, totaling 32 experimental units. In the second experiment, a completely randomized design was used with two diets consisting of (1) sugarcane silage (control) and (2) sugarcane silage with 20% cottonseed cake. A total of 26 lambs were used, 13 for each treatment, which were confined for 60 days at a private farm in São José dos Cordeiros - Paraiba. An interaction between additive x opening time was observed for pH, where the silages added with cottonseed cake showed higher values (3.6 to 3.8) in relation to the others (<3.6). There were isolated effects for additive and opening time for organic acids, with higher production of acetic acid from silages in the last opening time (240d). Dry matter recovery was higher in silages with cottonseed cake (≈92%), followed by silage inoculated with Weissella cibaria (85%) and control (63%). The silages added with cottonseed cake showed higher values of dry matter (≈38%), crude protein (≈12%), ether extract (≈5%) and lower fiber content, if compared to the others. The inclusion of cottonseed cake in silages is recommended for fermentation improvements and greater dry matter recovery, with a plus of protein supply, however, the exclusive application of the inoculant is a viable possibility because it increases dry matter recovery compared to control silage. In the second experiment, it was observed that dry matter intake did not differ between treatments (≈1620 g/kg), however, dry matter digestibility (64.75%) and average daily gain (202.88 g/day) was higher in diets containing sugarcane silage added with cottonseed cake (P<0.05), resulting in greater total weight gain (8.11 kg) (P<0.05). The animals fed diets containing sugarcane silage added with cottonseed cake showed a lower acetate: propionate ratio (4.2 vs. 2.0 mmol/L) and higher blood glucose content (44 vs. 35 mg/dL). Diets containing sugarcane added with cottonseed cake promoted fermentative and nutritional improvements, with better preservation of nutritive value, resulting in better productive performance of confined sheep.