AAFC-Lacombe

Why conduct beef fat research?

• A 1200 lb steer with ½ inch backfat, average muscling, yields a 750 pound carcass.

• The 750 pound carcass yields approximately:– 490 pounds boneless trimmed beef– 150 pounds fat trim– 110 pounds bone

• Marbling fat is highly prized and is used to determine carcass value (grades A, AA, AAA, Choice).

• The value of trim fats is much lower than marbling and considered mostly a low vlaue waste.

• Our beef fat research tries to change fat content and composition to add carcass value.

• Beef fat has been scorned by health officials due to saturated fatty acid (SFA) content, and its association with cardiovascular, diabetes and other diseases.

• We’re interested in investigating ways to improve the healthfulness of beef fat

• In the past few years, the tide has shifted, and the healthfulness of lean beef is recognized to be on par with other protein sources such as chicken.

• The most consumed beef product is still, however, ground beef with 15-30% added trim fat.

• We’d like to convert the 150 lbs from low to highly valued healthy products.

• Our interests are in parallel development of health and economic value

• To realize the potential, we have to pay attention along the development continuum….

Beef Composition

• A more realistic way to improve the composition of beef fat might be by adding a PUFA source to the diet.

• Flaxseed’s a good choice due to it’s high content of omega-3 fatty acids (alpha-linolenic acid)?

• Research has been done on this in the past and the results were quite variable.

• We fed steers either 0 or 10% flaxseed in a barley grain based diet with 20% hay for 120 days.

Both ~4% total fat

• When compared to a pig trial feeding 10% flax for 80 days…

Rumen MicrobesDiet Rumen outflow

Starch & Fibre Volatile fatty acids

Low quality PTN & NPN (eg urea)

Microbial PTN & ess. amino acids

Polyunsaturated fatty acids (PUFA)

Saturated fatty acids

PUFA Biohydrogenation = Detoxification

Rumen bacteria

SOAP

Saturated FatFirm Tallow

PUFA

SFA

85-90%Efficient

Our research is aiming to reduce conversion to SFA

PUFA Hydrogenation

PUFA

SFA

85-90%Efficient

1. We try to preserve PUFA

2. We also try to increase healthy intermediates like Rumenic Acid (CLA) and Vaccenic acid (t11-18:1) Anticarcinogenicimprove blood lipid profilesanti-inflammatory properties

PUFA Hydrogenation

Besides CLA and VA, there are at least 30 other BH products!

PUFA

SFA

• We’re trying to figure out:– Production strategies to change BHP

levels– Which of these BHP are “healthy”

• This info is needed to get BHP recognized by Health Canada and to establish amounts needed for things like health and enrichment claims

Feeding studies toincrease hydrogenation

Intermediates

RumenMicrobiology

Health StudiesObesity + Diabetes

Cell culture: fat and cholesterol synthesis

and inflammation

Meat QualitySensory Properties

NIR for rapidanalysis

Genomic testing

Hydrogenation IntermediatesMethods for

isolating Intermed.

Drs. Dugan/Block/Baron

Dr. Aalhus

Drs. Prieto/Uttaro/Aalhus

Drs. McAllister/Guan

Prof. GuanProf. Proctor

Dr. Dugan

Drs. Vahmani/Dugan/Meadus

Anti-mutagenic activity(Ames Testing)

Dr. Yang

Feeding Studies

– We’re still working on getting conditions right to produce high and consistent levels of ALA BH products.

– But it’s a complex process with many interactions

Fat/Oil

Composition

AmountAvailability

Pro

tein

Fibre

Starch

Vit

&

Min

Processing

Bacterial Profile

Growth

Competiti

o

n

Rate of passage

Meal Frequency

Genetic controls

Endog

enou

s

secr

etion

sFeed IntakeMetabolism

Rumination

Fat synthesis

Rapid Analysis• Comprehensive analysis of beef fatty acids is done using a

combination of gas chromatography and high performance liquid chromatography.

• It takes about 6 hr of machine time plus time for sample and data processing.

• These methods are too slow to be used for quality control and sorting of high value carcasses and tissues.

Rapid Analysis• We’ve been testing NIRS (near infrared-reflectance

spectroscopy) to measure fatty acids in a few seconds.• NIRS uses wavelengths in the NIR region (500-2500nm), and

the pattern of wavelengths reflected from samples is used to predict composition.

• To date NIRS explains as much as 80% of the variation in sample BHPs, and as more samples are analyzed, we’re hoping for stronger preditions.

Rapid Analysis• Another problem we’ve had to address is the large amount

of between animal variation we see. • If you’re feeding flaxseed to cattle for an extended period, it

would be good to be able to sort out which ones deposit high levels of BHP.

• We found by measuring BHP in red blood cells we can accurately predict final tissue BHP within 2 months.

• We now seeing if we can measure BHP in blood using NIRS.

Vaccenic Acid%

Vacc

enic

Aci

d

Rumen Microbiology

• Getting the rumen microbiology right will be a key to high and consistent levels of BHP in beef.

• Pathways for biohydrogenation have been worked out using bacteria isolated from the rumen

• But several other species are likely involved, haven’t been cultured and we don’t know how they interact.

• To tackle the problem we’ve taken advantage of advances in genomic technologies which have greatly increased the speed and reduce the cost of DNA sequencing.

Rumen Microbiology

• This involves pyrosequencing the 16s rRNA gene that has species-specific signature sequences.

• Using this , we were the first to demonstrate that the content of Vaccenic Acid in beef is correlated to 9 bacterial genera.

• We’re hoping to develop a rumen bacterial fingerprint to identify cattle that will deposit high levels of BHP, or develop a direct fed microbial to yield high and consistent levels of BHP in beef.

Health Studies• A key to developing health and economic value of beef

fat is to be able to increase the content of healthy BHP, and show that they have value when consumed in whole fats.

• This info is required to enable health and source claims.• For work in this area we’ve collaborated with Prof.

Spencer Proctor who is the Director of the Metabolic and Cardiovascular Diseases Laboratory at the U of A.

• We fed BHP enriched beef fat to rats that develop obesity and diabetes.• BHP enriched fat did not reduce blood triglycerides or

cholesterol, but did reduce fasting plasma insulin.

• Further studies are planned to establish levels of BHP required for beneficial effects, and their mode of action.

Health Studies

Isolating BHP• To determine the effects of individual BHP, you have to

be able to isolate and test them.• We recently published a method to isolate several BHP

from beef fat using a combination of silver-ion solid phase extraction and semi-preparative HPLC

Isolating BHP• We’re also examining the potential to fractionate

biohydrogenation products using molecular distillation

Cell Culture Studies• When isolating small quantities of BHP, the most convenient

way to test their effects is in cell culture.• We’ve developed fat and liver cell culture models to do this. • Our initial studies focused on trans fatty acids. • Trans fatty acids have been in the news because they

increase bad cholesterol and reduce good cholesterol in our blood.

Cell Culture Studies

• Most people studying trans fatty acids have used eladic acid (t9-18:1), which is the most concentrated in partially hydrogenated vegetable oil (i.e. margarine)..

• We’re interested in vaccenic acid (t11-18:1) and other trans fatty acids found in beef fat when feeding forages or flaxseed.

Cell Culture Studies• We’ve found in cell culture the “ugly” trans turn on genes fat

and cholesterol synthesis

• BUT other trans found when feeding flax (t11-, t13-, t14-, t15- and t16-18:1) don’t, and their effects are similar to oleic acid (major FA in olive oil).

• We’re continuing our work to characterize the effects of the trans fatty acids, and starting work with other BHP with more complex structures (i.e. dienes and trienes).

RNA Micro -Array

Study Support:

Peer Review Program

Collaborators

VernBaron

JonMeadus

HushtonBlock

DaveRolland

TimMcAllister

SpencerProctor

JenniferAalhus

Bethany Uttaro

NuriaPrieto

CletosMapiye

TylerTurner

PayamVahmani

• The cast of many others from the the beef unit, abattoir and meat labs that do much of the hard work…

Xianqin Yang

Leluo Guan