P Moate, R Williams, W Wales, J Jacobs, R Eckard, M Hannah

Methane emissions unaffected when DHA fed to cows

What is DHA ?

Docosahexanoic acid = DHA = C22:6

Omega-3 fatty acids in fish oil and algae Has health benefits ?

Heart disease, Cancer, Alzheimer’s disease

Background Large quantities of algae meal are likely to soon

become available in Australia.

Commercial algae farms now being set-up to grow large quantities of algae by capturing CO2 from coal burning power plants.

The algae intended as cattle feed or source of biodieselwww.mbdenergy.com/catalogue/c5/p75/cp4

Is algae meal containing DHA a suitable feed supplement for dairy cows?

Algae meal contains ~17% crude protein and 50 % fat

Up to half of the fat may be DHA

DHA in vitro reduced methane (CH4) emissions by 80%

When cows fed 73 g/cow/day of DHA from algae meal, DMI,

milk yield and milk fat% were all reduced by 50%

No studies have examined effects of feeding algae meal high in DHA on CH4 emissions

Objectives• To determine if an appropriate dose of algae meal

high in DHA can be fed to dairy cows so as to reduce CH4 emissions without reducing DMI, milk yield or production of major milk constituents.

2. To determine if feeding DHA to dairy cows will enhance the concentrations of individual healthy fatty acids (DHA and CLA) in milk.

Experimental design and TreatmentsFour treatments, 8 cows per treatment.

All cows fed approximately 6 kg DM of concentrates (containing the algae meal) and ad libitum lucerne hay.

The algae meal contained 20% DHA

TreatmentsD0: (0 g/cow/day DHA)

D25: (25 g/cow/day DHA)

D50: (50 g/cow/day DHA)

D75: (75 g/cow/day DHA)

Cows introduced to diets over 7 days, then fed experimental diets for further 23 days

Measurements Dry matter intake measured daily Milk yield measured daily Milk composition measured one day per week Individual cow methane emissions measured

in respiration chambers on days 22 and 23.

DPI Respiration Chambers

Results

Influence of dose of DHA on dry matter intake and milk production*

* means followed by different letters differ significantly (P < 0.05)

Treatment D0 D25 D50 D75

Total intake (kg DM/cow/day) 22.1ab 22.4a 21.3b 20.5b

Milk (L/cow/day) 22.6 23.5 22.6 22.6

Milk fat (kg/cow/day) 1.08a 0.90b 0.83b 0.85b

Milk protein (kg/cow/day) 0.79 0.78 0.76 0.76

Milk fat (g/L) 49.7a 37.8b 37.0b 38.3b

Milk protein (g/L) 34.8 33.8 33.6 33.7

Influence of dose of DHA on methane emissions*

* means followed by different letters differ significantly (P < 0.05)

Treatment D0 D25 D50 D75

Total methane (g /cow/day) 543 563 553 520

Methane (g/kg DM intake) 22.6b 23.5ab 24.5a 24.4ab

Methane (g/L milk) 24.9 22.1 24.3 23.4

Methane (g/ kg fat & protein) 287 333 350 331

Influence of dose of DHA on concentrations ofspecific milk fatty acids (fatty acid % of Total fatty acids)*

Treatment D0 D25 D50 D75

C18:0 (Stearic) 6.7a 4.7b 2.0c 1.4c

cis-9, trans 11 C18:2 (CLA) 0.36c 1.09b 1.79a 1.87a

C20:5 (EPA) 0.078c 0.066c 0.106b 0.171a

C22:6 (DHA) 0.035d 0.361c 0.604b 0.914a

Total de novo 51.5b 50.2c 52.7ab 53.8a

Total saturated 75.5a 70.9b 70.9b 72.5b

Total mono-unsaturated 19.0b 21.2a 19.7ab 17.9b

Total poly-unsaturated 5.4c 7.9b 9.4a 9.5a

* means followed by different letters differ significantly (P < 0.05)

SummarySupplementary feeding DHA to dairy cows

Did not reduce methane emissions

Did not reduce milk yield

Milk fat% and fat yield were decreased ~ 25%

But milk fat was healthy, it was enriched in:● omega 3 fatty acids (DHA and EPA)

● poly-unsaturated fatty acids

● CLA

Conclusions Feeding DHA not suitable for reducing

CH4 emissions

Algae meals low in DHA still require testing for suitability as cattle feed

What happens in vitro does not always reflect what happens in vivo

In vivo testing is essential for all novel feeds

Reducing Emissions from Livestock Research Program

Reducing Emissions from Livestock Research Program

This project is funded by the Australian Government's Climate Change Research Program and the following organisations