Uso do resíduo líquido de leveduras da indústria sucroalcooleira na alimentação de vacas leiteiras

Abstract

The aim of this work was to evaluate the effect of using liquid waste from the fermentation process of the sugar and alcohol industry in the feeding of dairy cows. Experiment I was carried out at the ‘Nossa Senhora Abadia’ farm, located in the municipality of Douradina, in the state of Mato Grosso do Sul, Brazil (latitude 22° 14´S, longitude 54° 49´W and 450m altitude), from May to August 2022. Eight crossbred ¾ Holstein × Zebu cows, with an average body weight of 593.5 ± 43.5 kg, rumen fistulated, aged 5 years (± 1), with an average of 3 lactations, and housed in individual stalls, randomly distributed into four treatments in a 4 x 4 double Latin square (DQL). The duration of the experimental trial was 80 days, divided into four periods of 20 days each, with 14 days for adaptation to the diets and management and 6 days for data collection and sampling. The cows were fed twice a day, with ration total mixed diet (TMR), composed of corn silage, oat hay and cereal concentrate, with the addition of different levels of liquid yeast residue 0, 3, 6 and 9 L on a natural basis and adjusted with the addition of water so that all had 9 L of liquid at the end. DM intake in relation to kg/animal/day, body weight, and TDN intake showed a maximum point between 7.50 and 7.53 L. Crude protein intake and digestibility showed an increasing linear effect with the increase in the inclusion of liquid yeast residue in the diet, while NDF intake and digestibility were inversely proportional, decreasing as the inclusion levels increased. DM digestibility showed a maximum point at 4.90 L. Milk production and composition and production corrected for 3.5% fat showed a quadratic effect, with a maximum production point around 4.6 L of inclusion of liquid yeast residue. The ruminal pH and ammonia nitrogen showed a quadratic effect, with a maximum point close to 5.0 L. For methane production, lower production was observed with the inclusion of 3 and 9 L. It is concluded that between 4 and 7 liters of liquid yeast residue can be used in diets for dairy cows in order to maximize the nutritional and productive aspects. Chapter III: The same experimental protocol of Chapter II was used, changing only the experimental diets, containing different levels of crude protein (16.42; 15.55; 12.49; 17.17.32%), based on DM: high true protein without liquid yeast residue; low true protein with liquid yeast residue; low true protein without liquid yeast residue; high true protein with liquid yeast residue. There was interaction between protein levels and liquid yeast residue (N × L) for the variables DM intake kg/day (P<0.001), DM intake% BW, OM intake, OM intake per BW (P<0.025), CP intake, CP intake per BW, NDF intake (P<0.005), and TDN intake (P<0.002), pH (P≤ 0.004), ruminal ammonia production (P≤ 0.031), urinary N excretion g/day (P≤ 0.034), absorbed N balance g/day (P≤0.001), retained N balance g/day (P≤0.001), total purines (P≤0.001), absorbed purines (P≤<0.001), PM synthesis (P≤0.001). DM efficiency (P=0.036), and milk production corrected to 3.5% fat. Regarding DM digestibility, (p=0.005), OM (p=0.010), CP (p=<0.001), and NDF (p=<0.001). For methane production, animals that consumed liquid yeast residue regardless of the CP level presented lower production. Regardless of the protein level, the inclusion of yeast milk improved nutrient digestibility and reduced methane emissions.