Nutrient digestibility, ruminal fermentation, and milk yield in dairy cows fed a blend of essential oils and amylase.

Autor: Silva GG; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil., Takiya CS; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil; Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506., Del Valle TA; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil., de Jesus EF; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil., Grigoletto NTS; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil., Nakadonari B; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil., Cortinhas CS; DSM Produtos Nutricionais Brasil S.A., São Paulo 01451-905, Brazil., Acedo TS; DSM Produtos Nutricionais Brasil S.A., São Paulo 01451-905, Brazil., Rennó FP; Department of Animal Production and Animal Nutrition, University of São Paulo, Pirassununga 13635-900, Brazil. Electronic address: francisco.renno@usp.br.
Jazyk: angličtina
Zdroj: Journal of dairy science [J Dairy Sci] 2018 Nov; Vol. 101 (11), pp. 9815-9826. Date of Electronic Publication: 2018 Aug 23.
DOI: 10.3168/jds.2018-14789
Abstrakt: Two experiments were carried out to evaluate a blend of essential oils (EO) combined with amylase as an alternative to ionophores and its potential for reducing the use of antibiotics in the dairy industry. In experiment 1, 8 rumen-cannulated Holstein cows (576 ± 100 kg of body weight, 146 ± 35 d in milk, and 35.1 ± 4.0 kg/d of milk yield at the start of the experiment) were assigned to a 4 × 4 Latin square experiment with 21-d periods to determine the influence of feed additives on total apparent digestibility of nutrients, ruminal fermentation, N utilization, microbial protein synthesis, blood glucose and urea concentrations, and milk yield and composition in dairy cows. Treatment sequences assigned to cows in each block included no feed additives (control; CON); monensin (MON) added at 13 mg/kg of diet dry matter (DM); a blend of EO supplemented at 44 mg/kg of diet DM; and EO treatment combined with α-amylase at 330 kilo novo units/kg of diet DM (EOA). Differences among treatments were studied using orthogonal contrasts as follows: CON versus feed additives (MON, EO, and EOA), MON versus EO and EOA, and EO versus EOA. No differences were detected in nutrient intake and digestibility in cows. In general, feed additives decreased ruminal NH 3 -N concentration of cows, notably when diet was supplemented with MON. Furthermore, feed additives increased ruminal concentrations of acetate, butyrate, and branched-chain fatty acids. Cows fed treatments containing EO and EOA exhibited lower pH, higher NH 3 -N, and a trend to greater total volatile fatty acid concentration in the ruminal fluid compared with cows fed MON. Treatments containing EO increased ruminal butyrate concentration compared with MON. No treatment × time interaction effect was observed on ruminal fermentation measurements. Cows fed diets supplemented with feed additives had greater efficiency of N transfer into milk (milk N:N intake), whereas cows fed EOA exhibited greater N transfer into milk than those fed EO. Treatments had no effect on milk yield and composition, but feed additives increased the milk yield efficiency (milk yield divided by dry matter intake), whereas treatments containing EO had similar milk yield efficiency compared with MON. For experiment 2, 30 multiparous Holstein cows (574 ± 68 kg of body weight, 152 ± 54 d in milk, and 30.9 ± 4.1 kg/d of milk yield at the start of the experiment) were enrolled to a randomized complete block design experiment. The MON, EO, and EOA treatments were randomly assigned to cows within blocks (n = 10), and feed additives were provided throughout a 9-wk period. No differences were found in nutrient intake and digestibility, but cows fed EOA tended to exhibit greater dry matter intake than those fed EO. Blood metabolites and milk production were not affected by treatments. However, cows fed MON or EOA had greater milk protein content than those cows fed treatments containing EO. Feeding EO with or without amylase had similar response to feeding MON in terms of feed intake and milk yield, with a small negative effect on milk protein yield when feeding EO alone. Feed additives increased the concentrations of acetate, butyrate, and branched-fatty acids in ruminal fluid, whereas treatments containing EO had greater ruminal butyrate and NH 3 -N concentrations. Therefore, either EO or EOA can replace MON in diets of dairy cows while maintaining performance.
(Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: