Effect of essential and vegetable oil blend supplementation on animal performance, feed intake, rumen fermentation and rumen microbial populations of crossbred steers finished in a pasture system

Abstract

Recent years have seen a general increase in consumer concern regarding the profile of additives in animal feed and food sources, prompting the industry to study essential oil blends that have been promoted to replace synthetic products. This study evaluated the effect of essential oil blends supplementation on animal performance, feed intake, rumen fermentation and rumen microbial populations in crossbred steers finished in a pasture system. A total of 40 steers (½ Bons Mara vs. ½ Nellore) with a mean age of 20 ± 2.0 months and a mean body weight of 416.9 ± 5.56 kg were distributed in a completely randomized design with five diets and eight replications per diet. The five experimental diets were: CONT – basal diet, and oil blend inclusion in dosages of 1500, 3000, 4500 or 6000 mg/animal/d. Animal performance was similar among diets. The forage intake, crude protein, neutral detergent fiber, ethereal extract, non-fibrous carbohydrates, and the digestibility of crude protein, neutral detergent fiber, and non-fibrous carbohydrates were greater when essential oil blends were fed to steers. There was an increase in the concentrations of rumen ammonia nitrogen, and propionic and isovaleric volatile fatty acids when essential oil blends were used. The microbiological population of the rumen was similar among the five diets. Our results suggest that the inclusion of doses above 1500 mg/animal/ is high for livestock grazing on temperate pasture, further studies are needed to identify a promising dose to replace antimicrobial additives.

Carcass characteristics and meat evaluation of cattle finished in temperate pasture and supplemented with natural additive containing clove, cashew oil, castor oils, and a microencapsulated blend of eugenol, thymol, and vanillin

“…However, no information on the influence of NAs on carcass characteristics was found on animals finishing on pasture. Usually, this characteristic is related to the live weight of animals at slaughter, and no differences were observed in this experiment 26 . Feeding for a short time during finishing, even with the use of additives, does not alter these variables, which would be more susceptible to age, gender, genetic variations or drastic modifications to protein and energy synthesis 27 …”

“…0.64 mmol dL −1 NA, P < 0.05) and isovaleric acid (6.16 CON vs . 6.29 mmol dL −1 NA, P < 0.05) in the rumen of animals receiving NAs in the diet 26 . Propionic acid is the major glycogenic fatty acid and isovaleric acid is indicative of proteolysis and deamination of food protein, resulting in liquid energy available for deposition of lean tissue.…”

“…However, protein synthesis is dependent on the carbohydrates and nitrogen available in the diet 33 . There was a quadratic effect ( P < 0.05) on the intake of non‐fibrous carbohydrate (CON 1.88; NA15 2.01; NA30 1.67; NA45 1.69; and NA60 1.63 kg d −1 ) and crude protein (CON 1.24; NA15 1.31; NA30 1.13; NA45 1.13; and NA60 1.10 kg d −1 ) 26 . These data may explain the quadratic effect on the amount of carcass muscle.…”

“…36 These results can also be explained by the greater synthesis of volatile propionic acid (0.59 CON vs. 0.64 mmol dL −1 NA, P < 0.05) and isovaleric acid (6.16 CON vs. 6.29 mmol dL −1 NA, P < 0.05) in the rumen of animals receiving NAs in the diet. 26 Propionic acid is the major glycogenic fatty acid and isovaleric acid is indicative of proteolysis and deamination of food protein, resulting in liquid energy available for deposition of lean tissue. These factors led to an increase in the animals' energy efficiency for meat production.…”

“…Usually, this characteristic is related to the live weight of animals at slaughter, and no differences were observed in this experiment. 26 Feeding for a short time during finishing, even with the use of additives, does not alter these variables, which would be more susceptible to age, gender, genetic variations or drastic modifications to protein and energy synthesis. 27 The mean value of SFT (4.1 mm) observed for the treatments met the standards required by the Brazilian slaughter industry (3-6 mm), but individual mean values did not differ (P > 0.05) among treatments.…”