A team of researchers from the State University of Maringá in Brazil examined the use on dairy cattle of supplemental flaxseed oil containing a propolis-based product (PBP) with, or without, vitamin E. The group looked at additive influence on milk production and blood lipoperoxidation.
“So the objective of this study was to determine the effects of adding a propolis-based product in the presence or absence of vitamin E to the flaxseed oil-containing diets of lactating cows on the peroxidation of blood lipids, fatty acid composition and oxidative quality of milk,” said the researchers.
The group found that the supplements did not alter dry matter intake, but did change the concentration of certain fatty acids in the milk produced. The additives also improved antioxidant activity of the milk, but did not preserve milk fat from oxidation.
“Under the studied conditions, PBP and vitamin E supplementation resulted in improvements in the fat quality of milk, the oxidative properties of milk and the blood resistance to oxidation,” the researchers said.
Why propolis extract, vitamin E?
Propolis is a product generated by worker bees containing enzymes and beeswax, said the researchers. It is used to protect a hive from disease and invasive pests.
It also is high in plant phenolic compounds that contain beneficial biological properties like antioxidants and antibacterial actions, they said. It can be used as a feed additive to meet consumer expectations regarding safety of animal products.
A form of propolis found in Brazil is derived from the Baccharis dracunculifolia and is associated with a growth reduction for certain rumen bacteria, reducing rumen populations of ciliate protozoa in buffalo and improving antioxidant qualities in milk, they said.
Additionally, lipid supplementation can be used to meet cow needs and boost levels of polyunsaturated fatty acids (PUFA), monounsaturated fatty acids (MUFA) and conjugated linoleic acid (CLA), said the researchers. But those fats can promote a rancid flavor in milk and adding lipids may generate risk of blood lipoperoxidation and oxidative stress.
“The combination of phenolic compounds from plants and vitamin E was studied in cows in order to investigate the occurrence of complementarity between them and to protect against blood lipid peroxidation,” they said. Vitamin E is fed for its lipid-soluble antioxidant and oxidative-stress reducing abilities, they added.
Researchers formulated four diets for the feeding trials, which were used for 21 days – 14 for acclimation and seven days for sampling, they said. The feeds included a control diet with corn silage and soybean meal concentrate, that diet with flaxseed oil at 25g/kg of dry matter (DM), a diet with flaxseed oil and PBP at 1.2g/kg DM and a diet containing flaxseed oil with PBP and vitamin E at 375 IU/kg DM.
Diets were fed to four cattle, then rotated, they said.
Milk samples were collected from days 15-19 and analyzed for protein, fat, lactose, milk urea nitrogen, somatic cell counts (SCC), milk fatty acid concentrations and antioxidant parameters, they said. Blood was taken on day 18 of each feeding period.
Supplement use did not alter the DM intake, chemical composition of milk, SCC or milk urea nitrogen content, said the researchers.
“The use of propolis-based products in diets containing flaxseed oil for cows in mid-lactation showed benefits on blood lipoperoxidation, CLA concentration in milk and transfer of antioxidants into milk,” they said. “The associated use of PBP and vitamin E had positive effects on milk CLA and blood cholesterol.”
Adding both PBP and vitamin E boosted amounts of fatty acids trans9-18:1, cis9, trans11-18:2 and the overall CLA levels, they said. Additionally, the supplements increased the total polyphenol concentration.
“Adding flaxseed oil to diets increased total cholesterol and HDL [high-density lipoprotein] in comparison to the control diet; however, when supplemented with PBP, there were reductions in HDL and total cholesterol concentration in blood,” said the researchers. “Providing the PBP along with vitamin E also decreased HDL and total cholesterol in the blood.”
Adding PBP to the dairy cows’ diets improved antioxidant activity of milk, but did not prevent milk fat from oxidizing, they said. The test diets did not alter glucose amounts, triglyceride levels or copper-induced oxidation in the blood.
“Adding PBP to the diet increased the time to reach the maximal rate of oxidation,” they said. “The PBP and vitamin E combination did not influence the maximal rate of oxidation or DC [dendritic cells] accumulation in the blood.”
Source: Livestock Science
Title: Antioxidant effects of a propolis extract and vitamin E in blood and milk of dairy cows fed diet containing flaxseed oil
Authors: Nadine Santos, Emerson Yoshimura, Erica Machado, Paula Matumoto-Pintro, Paula Montanher, Jesuí Visentainer, Geraldo dos Santos, Lucia Zeoula