by Deborah Jeanne Sergeant

Nutrition during the transition period of lactating cows can make a big difference in animal health. Jonas de Souza, Ph.D., of Perdue Agribusiness Animal Nutrition, presented “Fatty Acid Nutrition During the Transition Period” as a recent webinar.

“What is the main result in feeding different fatty acids in the diet and why is it important during the transition period?” de Souza asked. “There’s a chemical and metabolic change that happens during this time. There’s a huge demand for nutrients that increases during this period.”

This includes 2.7 times more glucose, 4.5 times more fatty acids, two times more amino acids and three times more energy. During transition, “the negative nutrient balance can result in inflammation and oxidative stress that can impact lactation performance,” de Souza said.

Some farmers turn to fatty acid supplementation for early lactation cows. De Souza said most of the research performed in the late 1980s and early 1990s said farmers should include fat in the ration during these times.

“Fat doesn’t provide much benefit during the first five to seven weeks of lactation,” de Souza said. He recommends leaving fat out of the diet immediately postpartum and that the lack of early lactation response seems to be related to depression in feed intake, which offsets any advantage that may be gained by increasing the energy density of the diet.

“A lot of the initial trials that didn’t show benefit of supplementing fat was because of the high level of fat,” he said. “Some believe we should not be feeding supplement because of negative energy balance and there’s already too much fat circulating. When we think about the metabolism of fatty acid, the fat we feed is circulated. We have to understand that the metabolism of this fatty acid is different than we feed in a diet and what is being mobilized in the cow. It’s about the degree of that mobilization.”

He noted different fatty acids have different metabolic effects. The digestibility and how they’re partitioned is not the same.

“You have fatty acid that will be partitioned to a great degree to mammary gland for milk fat,” de Souza said as one example. Other fatty acids go to support maternal health and energy.

De Souza also spoke about research combining palmitic acid and oleic acid as a pre- and post-calving supplement compared with a no-fat control group.

“When we look to the results, when we feed fat or these particular supplements, there was a decrease in feeding days,” de Souza said. “Because of the decrease in feeding days, you can imagine what happened to the energy balance. As we feed the supplement either pre-calving or pre-/post-calving, we put the cows in a more negative energy balance.”

Feeding a palmitic and oleic fatty acid supplement early in lactation (at 6 weeks ) as 2.3% of digestible matter showed increase in energy intake and the predicted energy balance similar between diets.

The next study group of cows was fed only in early lactation and post-calving and fed fatty acid at 2.3% of dietary matter. “This agreed with the early research that indicated we should look at the timing of supplementation,” de Souza said.

Feeding the supplements during carryover decreased milk yield and cumulative milk yield, but did not affect dry matter intake.

De Souza said the research shows “inconsistent responses during early lactation. The idea to feed fats to improve energy balance isn’t validated by research. Most studies did not observe an advantage on energy balance.”

He added that the effect of other forage on fatty acid supplementation “is a factor we should try to understand. Production level is important when we involve different fat supplements.”

The main response of feeing palmitic acid is increasing milk fat, independent of the level of production. Since some producers want higher milk fat for a premium price, it’s worthwhile to look at this effect.

De Souza said little research has looked at palmitic acid and early lactation cows. The research indicated the time of introduction of the fatty acid supplement was important.

“When we feed palmitic acid after those 24 days of lactation, we did see an increase in milk production that we didn’t see in the first two weeks,” de Souza said. “We observe a consistent fat response in the first 24 days of lactation.

“It’s important to consider when we are feeding these supplements,” he continued. “Feeding them together can direct some to milk and some to cows.”

Since these are animals delivering calves and beginning lactation, supporting their health holds merit.

De Souza said for post-peak cows, combining palmitic and oleic fatty acids may help with body weight gain and plasma insulin. Feeding multiparous cows 80% palmitic and 10% oleic acid at a fatty acid rate of 1.5% dry matter of diet, compared with 70%/20%, 60%/30% and a control group with no supplementation for the first 24 days of lactation showed similar results as the previous studies.

“The cows did not lose extra condition at the end of lactation,” de Souza said.

Even after the cows stopped receiving the extra fat, they still enjoyed residual benefit from the supplement.

He also considered when the cows received the supplement. “The response seems to be better when we feed through those first 10 weeks of lactation,” de Souza said.

The group receiving 60%/30% had an increase in the production of milk and there was no disadvantage to body fat.

Research involving abomasal infusion of oleic acid in fresh cows also provided insights. The oleic acid at 60 grams/day was infused four times daily. Adipose tissue on the flank was sampled at days 6, 12 and 14 and glucose tolerance was tested at day 15.

“Results suggest that oleic acid supplementation immediately postpartum may reduce lipolytic responses and improves insulin sensitivity of AT in early lactation dairy cows,” de Souza said.

Omega-3 and omega-6 supplementation is also on the mind of many dairy producers. De Souza looked at altering the ration between omega-6 and omega-3.

“There is a positive effect when you do that from 14 days of lactation,” he said, “and there’s a positive effect of feed intake and milk fat in milk.”

Supplementing omega-3 increased dry matter intake in early lactation and changing omega-6 and omega-3 strategies pre- and post-partum benefit reproduction. De Souza wants to next look at combining omega-3 and omega-6 supplementation with other feeding fatty acid strategies.

“This is probably one of the future research lines,” he said. “How can we complement the effects of omega-3 with oleic fatty acid and palmitic acid?”

He added that when feeding fatty acids, “you’re feeding much more than calories,” he said. “You need to understand the specific effects fatty acids have.”

He listed yield of milk and milk components, maintenance of body condition, nutrient digestion, nutrient partitioning, reproduction and health as items affected.

He wants more producers to consider fatty acids in diets for transition cows; to design a nutritional program around the farmer’s objectives; to evaluate the effects of individual fatty acids and commercial fatty acid supplements; and realize the tangible factors not measured daily in the milk tank, like reproduction, body weight and energy balance.