Resposta de vacas leiteiras à suplementação com bactérias e leveduras

Abstract

The effect of a liquid additive containing a combination of viable microorganisms of lactic acid bacteria, spore forming bacteria and yeasts (S. cerevisiae) grown in a consortium (CBL; Global Health, Brazil/SCD Probiotics, USA) on the digestion, consumption, lactation performance, body temperature and the immune response of dairy cows. Twenty-six Holstein cows (185 ± 141 lactating days) were fed individually with a standardized diet for 14 days and Control or CBL treatments (3.5 mL/kg dry matter total diet) for 56 d, in a covariate adjusted randomized block design with repeated measures over time. The CBL increased DMI (23.5 vs 22.5 kg/d. P < 0.01) and tended to increase the yields of milk (30.0 vs 29.4 kg/d. P = 0.06) and lactose (+ 60 g/d. P = 0.09). Energy-corrected milk/DMI was reduced by CBL (1.25 vs 1.31. P = 0.02). Milk solids concentration and yield did not differ (P ≥ 0.28). Cows fed CBL tended to have higher BCS (3.02 vs 2.91. P = 0.08), but BW did not differ (641 kg. P = 0.27). The CBL tended to reduce the total tract digestibility of the non-fibrous OM (81.2 vs 84.1%. P = 0.08) whereas starch (90.7%) and NDF (48.4%) digestibilities did not differ (P ≥ 0.20). Molar proportion of butyrate in ruminal fluid tended to be reduced by CBL (9.4 vs 10.4%, P = 0.06) as well as total protozoa concentration (P = 0.10). The acetate to propionate ratio (3.1. P = 0.89) and the ruminal microbial yield estimated by the daily urinary allantoin excretion (P = 0.21) did not differ. The CBL reduced the proportion of daily intake in the morning (35.1 vs 40.4%. P = 0.02), increased the proportion in the afternoon (45.9 vs 41.9%. P = 0.03). Rumination and ingestion behaviors did not differ (P ≥ 0.16). The CBL reduced blood urea-N at 0900 h (21.2 vs 25.1 mg/dL. P = 0.01) and tended to reduce at 1630 h (20.1 vs 23.1 mg/dL. P = 0.06) and 2300 h (17.9 vs 20.6 mg/dL. P = 0.09), but did not affect milk urea-N (18.6 mg/dL. P = 0.47). The increase in milk yield and DMI induced by CBL was associated to increased body temperature. Rectal temperatures were increased by CBL at 0900 h (38.3 vs 38.1°C. P < 0.01), 1530 h (38.8 vs 38.5°C. P = 0.01), and 2200 h (38.5 vs 38.2°C. P = 0.02). The frequency of cows with rectal temperature > 39.2°C at 1530 h was 18.2% on CBL and 6.3% on CTL (P < 0.01). Skin temperature tended to be increased by CBL at 0900 h (34.1 vs 33.8°C. P = 0.10) and was increased at 2200 h (35.1 vs 34.7°C. P = 0.02). Sweating rates in weeks 4 (90.4 vs 66.9 g/m 2 /h. P = 0.05) and 5 (103.9 vs 72.1 g/m 2 /h. P = 0.01)) were increased by CBL. Time spent laying down was reduced by CBL (742 vs 813 min/d. P = 0.04). Respiratory rate did not differ (P ≥ 0.34). Immunity in response to a virus/leptospirosis vaccine on d 36 (D0) was evaluated. Interleukin 4 in serum tended to be reduced by CBL on D0 (779 vs 859 pg/mL. P = 0.10) and did not differ on days 7 (D7) and 14 (D14) relative to vaccination (P ≥ 0.26). Interleukin 12 was reduced by CBL on D7 (611 vs 709 pg/mL. P = 0.02), but did not differ on D0 and D14 (P ≥ 0.27). Interferon gamma and Interleukin 10 did not differ (P ≥ 0.20). At D0, the concentration of monocytes as a proportion of leukocytes tended to be increased by CBL (3.8 vs 5.7%. P = 0.10). Milk SCC was increased by CBL (49,500 vs 67,000 cells/mL. P = 0.03). The CBL induced a greater increase in DMI than in milk yield, decreasing feed efficiency, and had minor effects on digestibility and ruminal fermentation profile. The increase in DMI and milk yield induced by CBL was associated to increased body temperature and sweating rate, minor alterations in immunity markers, and increased milk SCC of cows with low SCC.