Dairy cow performance can be increased by targeting fatty acid supplementation to stage of lactation according to a report from Dr Richard Kirkland, global technical manager for Volac Wilmar Feed Ingredients.

While it has long been known that fat supplementation in dairy rations provides essential energy supply, ongoing research to optimise nutrition in year-round calving herds has highlighted the effects of individual fatty acids on milk yield, milk fat content, body condition score and fertility.

“There are five major fatty acids found in ruminant diets, and each one is utilised differently within the animal. Based on where a dairy cow is in her production cycle, different fatty acids will support different aspects of performance,” explains Dr Kirkland.

“Because targeting specific fatty acid requirements for individual cows is infeasible in a year-round calving system, producers can opt for a multi-purpose fat supplement that is balanced to optimise nutritional needs of the entire herd.”

To effectively improve milk yield, milk fat, fertility and BCS throughout lactation, he said farmers should utilise a multi-purpose fat with an optimum ratio of C16:0 (palmitic acid) to C18:1 (oleic acid).

When offered during mid to late lactation, C16:0 induces insulin resistance in body tissues to increase partitioning of nutrients to milk, which in return improves milk and milk fat production. C18:1 is particularly beneficial in early lactation as it increases insulin which increases the partitioning of nutrients to improve body condition and has also been proven to boost fertility by promoting egg and embryo development. The C18:1 fatty acid also improves digestibility of total diet fat which increases energy supply.

In a recent study at Michigan State University in the USA, the effects of altering the ratio of C16:0, C18:0 (stearic acid) and C18:1 were evaluated. Mid-lactation cows were offered one of four treatments, with fat supplements added at 1.5% of dry matter, see table below.

Production data for cows offered three different fatty acid supplements

Treatment 1 2 3 4 Significance

No fat supplement 80% C16:0 40% C16:0 : 40% C18:0 45% C16:0 : 35% C18:1

Milk yield (kg/d) 44.6 46.9 46.3 46.5 P=0.01

Milk fat (%) 3.62 3.69 3.60 3.53 P=0.01

Milk fat yield (kg/d) 1.60 1.70 1.64 1.64 P<0.05

Liveweight gain (kg/d) 0.82 0.84 0.70 1.05 P<0.05

BCS change 0.07 0.07 0.04 0.11 P<0.05

Plasma insulin μg/l 0.84 0.85 0.87 0.94 P<0.01

On average, fat supplementation increased milk yield by 1.9 kg per cow per day. However, cows offered the 80% C16:0 supplement significantly outperformed the other treatments in milk fat production.

Further data from this study showed the beneficial effect of C18:1 on total fatty acid digestibility compared to the other treatments. Cows offered the higher C18:1 supplement (treatment 4) also had the greatest improvements in body condition score (BCS) and liveweight gain.

“In isolation, C16:0 induces insulin resistance to increase the partitioning of nutrients to milk at the expense of BCS and can have negative effects on egg development leading to reduced fertility. However, C18:1 directs energy to BCS and promotes egg development, thus boosting fertility,” says Dr Kirkland.

“In the correct ratio, C16:0 and C18:1 fatty acids balance milk production and body condition during early lactation. As the cow transitions into later stages of lactation, high-C16:0 supplements are useful to increase milk fat while C18:1 supports fertility.”

Sourcing the right fat supplement

While a balanced multi-purpose fat supplement is a great way to optimise cow performance with a simple one-product solution, fatty acids must be rumen-protected.

“Rumen protected fats have been manufactured to avoid interference with fibre digestion in the rumen. If unprotected, fatty acids can physically coat fibre and reduce its digestion in the rumen,” concluded Dr Kirkland.