A group of researchers in Brazil evaluated the use of an oil blend made with cashew nut shell liquid (CNSL) and castor oil (CO) on feed intake and milk production in dairy cattle as compared to cattle getting monensin sodium (MON). The team published their results in the journal of Animal Feed Science and Technology.
“The objective of this study was to compare the effects of a mixture of CSNL and CO with MON on nutrient intake and total tract apparent digestibility, ruminal fermentation, milk yield and composition, N utilization efficiency, microbial protein synthesis, and blood metabolites of lactating dairy cows,” said the researchers in the study. “The hypothesis was that the FO blend could replace MON in dairy cow diets without reducing the productive performance.”
The group found that that the oil blend could produce similar or favorable results to the use of monensin in dairy cattle diets.
“Neither rumen microbial N synthesis nor blood glucose concentration were changed by the supplements,” they said. “FO decreased blood urea concentration compared to CON [control] or MON, besides increasing milk yield without altering nutrient intake; thus, it might be an alternative to monensin in lactating cow diets.”
Why functional oils?
Monensin was banned for use as a growth promoter in the EU leading to interest in natural compounds that could act as a replacement, said the researchers. Functional oils, like CNSL and CO are extracted from plants and considered to provide health benefits in addition to nutritional properties.
Both oils have generated interest as potential rumen modulators as they have demonstrated anti-inflammatory, anti-oxidative, and gastro-protective elements in addition to antimicrobial effects, they said.
“Cashew nut shell liquid is a by-product of the cashew industry containing phenolic compounds that inhibit Gram-positive bacteria growth and allow the proliferation of Gram-negative bacteria, thereby increasing ruminal propionate production (Van Nevel et al., 1971 and Ipharraguerre and Clark, 2003),” they said. “Watanabe et al. (2010) reported that CNSL linearly increased the total volatile fatty acid (VFA) concentrations and propionate production in an in vitro fermentation study.”
Castor oil has high levels of ricinoleic acid, which has antimicrobial effects, said the researchers. A commercial product with both oils has been used in Brazil as an anti-coccidial for broilers and has been tried in some ruminants but little is known about how it might influence dairy cattle performance.
Study details
In the trial, 24 dairy cows were divided into groups and given one of three diets for a period of 21 days – 14 for acclimation and seven for sampling – before diets were rotated, said the researchers. Six of the cows also were ruminally cannulated to establish ruminal fermentation.
The diets included a control total mixed ration, and that diet with either 500mg/kg dry matter (DM) functional oil or 22mg/kg DM of monensin sodium, they said. Supplements used were commercially available.
Feed, ort, fecal, urine and blood samples were collected during each of the three seven-day sampling periods and analyzed, they said. Ruminal samples were taken on day 20 of each feeding cycle.
Milk yield was noted daily, samples were taken on days 15, 16 and 17 of each period and checked for fat, protein and lactose amounts, they said. Milk was also analyzed for milk urea nitrogen and the nitrogen (N) excreted was calculated.
Cows were weighed on days 7 and 21 of each period and microbial N synthesis was established, said the researchers.
Results
Dietary supplements did not alter nutrient intake, digestibility for the feeds or milk urea nitrogen, said the researchers. And, both improved ruminal propionate molar proportion when compared to the control with the FO supplement generating the highest propionate concentration.
Branched-fatty acids were lowest for cows getting the MON supplement, and the ratio acetate to propionate was similar among diets, they said. Milk production was improved by both supplements, milk N excretion was increased, and cows getting FO had more milk lactose than those getting MON.
The functional oil blend “however, shifted ruminal fermentation towards energetically most efficient routes, increasing propionate production and consequently improving milk yield,” they said.
The feed additive also lowered blood urea levels, said the researchers. It was found to be a viable dietary replacement for MON that did not reduce milk production.
Source: Animal Feed Science and Technology
Title: Influence of a blend of functional oils or monensin on nutrient intake and digestibility, ruminal fermentation and milk production of dairy cows
DOI: 10.1016/j.anifeedsci.2016.06.003
Authors: E. Ferreira de Jesus, T. Del Valle, G. Calomeni, T. Silva, C. Takiya, T. Vendramini, P. Paiva, G. Silva, A. Netto, F. Rennó,