Farelo de brassica na alimentação de vacas leiteiras

Abstract

This thesis is divided into 2 chapters. The objective of this study was to investigate the effects of inclusion of crambe meal (CM, 382.4 g crude protein/kg dry matter (DM), 450 mg glucosinolates/kg DM) in the total partial diet (pTMR, 0, 45, 90 and 135 g/kg DM), on the productive performance, nutrient utilization efficiency in dairy cows and cheese preference for untrained consumers. Twelve dairy cows were used: eight crossbred Holstein × Zebu cows (456 ± 91 kg body weight) and four Jersey cows (384 ± 32.29 kg body weight) distributed in three simultaneous 4 × 4 Latin squares with four experimental periods of 21 days each. The pTMR were isonitrogenated (130 g CP/kg DM) and offered ad libitum between milking from 7:00 am and 6:30 pm. Cows between the hours of 19:00 in the afternoon until 6:30 in the morning remained in pastures Panicum Maximum cv. Mombaça (564 g neutral detergent fiber/kg MS and 90.4 g CP/kg DM). Milk yield and pTMR intake were recorded from day 15th to day 21st of each experimental period. The milk samples were collected on days 17th and 18th of each experimental period. Fecal samples from each animal were collected between 17th and 21st to estimate fecal excretion (using titanium dioxide as an external indicator) and for pasture consumption (using indigestible neutral detergent insoluble fiber after 288 ruminal in situ incubation). The inclusion of CM did not affect pTMR intake (P = 0.173, 11.47 ± 0.20 kg DM/day), forage intake (P = 0.185, 0.90 ± 0.07 kg DM/day), CP intake (P = 0.481, 1.49 ± 0.01 kg CP/day), organic matter digestibility (P = 0.254, 0.749 (P = 0.545, 0.747 ± 0.02 g/g), microbial protein synthesis (P = 0.348, 0.83 ± 0.08 kg/d), milk yield (P = 0., 64.2 ± 1.3 g/d), milk yield (P = 0.462; 13.29 ± 0.24 kg/d), nitrogen (N) milk (P = 0.566; 64.2 ± 1.3 g/d), milk urea-N (P = 0.178; 10.6 ± 0.94 mg/dL), N urinary excretion (P = 0.717; 90.9 ± 1.9 g/d), N milk efficiency (P = 0.622; 0.268 ± 0.01 g N milk/g N intake) hepatic function IU/mL (GGT 32.05 ± 2.94, ALT 15.98 ± 0.44 and AST 48.02 ± 5.71), cheese yield (0.21 ± 0.01 kg/kg milk) and sensory analysis (I liked 59.78 , 80.00, 76.00, 77.67% of the tasters). Crambe meal can be up to 135 g/kg DM in pTMR without affects productive performance, efficiency of nutrient utilization in dairy cows and cheese preference for untrained consumers. We used meta-analytical approach to evaluate the effects of replacement of different sources of protein by brassicas meals on milk production and nutrient utilization of dairy cows, from 37 peer-review papers. Canola meal (CM) was unique brassica source founded. The effects were compared by raw mean differences (RMD) between CM diet and control treatment means and weighted by inverse variance using random-effect models. Heterogeneity level was analyzed by I 2 statistic (low ≤ 25%; moderate = 26 to 50%; and high > 50%). In overall, use of CM as protein source increased DM intake (RMD = 0,22 ± 0.12 kg DM/d; P < 0.01; n = 79; I 2 = 9.1%) and crude protein (CP) intake (RMD = 0,14 ± 0.07 kg CP/d; P < 0.01; n = 33; I 2 = 21.1%), both with low heterogeneity, but it did not affect organic matter total-tract digestibility (P = 0.50; n = 12; I 2 = 29.2%). In overall, use of CM increased milk yield (RMD = 0.69 ± 0.35 kg/d; P < 0.01; n = 88; I 2 = 74.9%), but its effect depends on protein sources comparation: CM versus SBM did not increase milk yield (RMD = 0.23 ± 0.66 kg/d; P = 0.50; n = 33), but milk yield was increased with replacement of DDG by CM (RMD = 2.03 ± 1.67 kg/d; P < 0.01; n = 13) and of other protein sources by CM (RMD = 0.82 ± 0.43 kg/d; P < 0.01; n = 42). In overall, CM use did not affect milk protein content (P = 0.08; n = 60; I 2 = 19.5%) and milk fat content (P = 0.20; n = 60; I 2 = 16.9%), but CM increased milk protein yield (RMD = 0,02 ± 0.01 kg/d; P < 0.01; n = 60; I 2 = 0%). Use of CM reduced milk urea nitrogen (N) (RMD = - 0,98 ± 0.31 mg/dL; P < 0.01; n = 22; I 2 = 32.2%) and increase N intake milk efficiency (RMD = 0.22% N milk/N intake ± 0.07 mg/dL; P ≤ 0.05; n = 34; I 2 = 0%), both with low heterogeneity. We concluded that CM is similar protein source to SBM and it is more effective than DDG and other sources (cottonseed meal, corn gluten meal and sunflower meal) to lactating dairy cows.