Suplementação de vacas leiteiras com óleos essenciais

Abstract

The inclusion of essential oils in diets of dairy cows may improve rumen fermentation efficiency and performance, due to its antimicrobial and therapeutic properties. Two experiments were conducted to investigate the inclusion of a Blend of microencapsulated essential oils (BEO) composed of carvacrol, cinnamaldehyde, eugenol and capsaicin on lactation performance, nutrient digestibility, ruminal fermentation profile, ingestive behavior, blood acid-base balance, body thermoregulation, fatty acid profile in milk, sensorial analysis of milk and systemic variables of dairy cows. In experiment 1, 28 cows were allocated to a group either CTL (No feed additive) or MOE (150 mg/kg of TMR DM) for 56 d. In experiment 2, 30 cows were distributed among the treatments: CTL, BEO (200 mg/kg of TMR DM) or monensin (MON. 15 mg/kg of TMR DM) for 58 d. In both experiments the additives were included in the TMR twice a day. In experiment 1, BEO increased feed efficiency (1.53 vs. 1.62) with a decrease of 600 g/d in dry matter intake and an increase of 700 g/d in milk yield. Cows fed BEO sorted in favor of short feed particles in the morning. The BEO reduced the ratio between acetate and propionate in rumen. The supplementation with BEO tended to increase the digestibility of non-NDF organic matter and meal size, and reduced the daily secretion of 18:2 trans-10, cis-12 and 18:0 iso fatty acids in milk. In the milk sensorial evaluation, 58.7 % of the consumers correctly identified the milk sample from cows fed BEO. In experiment 2, milk protein yield and body weight were improved by BEO. The supplementation with BEO tended to increase milk yield from 33.0 to 34.4 kg/d in comparison to CTL and energy-corrected milk from 31.3 to 32.6 kg/d compared to MON. The proportion of acetate was increased, whereas the butyrate and methyl butyrate were reduced by BEO. The MON depressed the microbial protein synthesis and tended to reduce acetate to propionate ratio in the rumen relative to BEO. The feed additives promoted an increase in the area and diameter of the caudal artery. Cows fed BEO tended to reduce rumination time and increased the number of meals in the afternoon. Blood urea nitrogen was highest in BEO cows four hours after the first feeding of the day comparing to CTL. In both experiments, the inclusion of BEO increased the oxygen content in the blood and the sweating rate. There was a decrease in the proportion of cows with rectal temperature ≥ 39.2 °C at 1400 and 2000 h in experiment 1 and at 1600 and 2200 h in experiment 2. Rectal temperature tended to be lowest in BEO cows at 1400 h relative to CTL in the experiment 2. Supplementation with BEO improved lactation performance relative to non-supplemented cows, and promoted a decrease in the sweating rate and body temperature of dairy cows.