Bacillus-based feed additive may improve dairy milk efficiency, boost health

The use of Bacillus pumilus in dairy cattle feed may improve milk production efficiency and improve health during transition.

Researchers from the University of Illinois in the US studied the effect of the additive, a direct-fed microbial (DFM), on dairy cattle to determine the influence of B. pumilus​ 8G-134 on pre- and postpartum cows and to see if would improve cases of subclinical ketosis.

The period from three weeks before a cow gives birth to three weeks after tends to be the time a cow can most easily become ill, said Filipe Cardoso, professor in the department of animal science at the University of Illinois. Anything that can be done, through the use of additives or management practices, to improve the health of cows during that window is important.

“With this, it was not just how that period was affected by DFM, but how would that set up the cows through mid-lactation,”​ he told FeedNavigator. When cows get sick during that period, in addition to treatment costs, it tends to reduce the amount of milk they produce and can delay their ability to be bred, he added.

The goal of the project was to examine use of DFM in improving health for cows transitioning between late pregnancy into the lactation period, said researchers. “We postulated that the Bacillus DFM might affect the rumen or intestinal microbiota or modulate the immune system, thereby affecting DMI [dry matter intake], nutrient supply, metabolic responses, and productive efficiency,”​ they said.

“Cows receiving DFM tended to have lower incidence of subclinical ketosis than cows receiving CON [a control diet],” ​they said. “Cows fed DFM tended to have higher feed conversion and evidence for greater immunity than CON. Supplementation with B pumilus 8G-134 may provide benefits for transition cow health and milk production efficiency.”​

Experiment details​

In the experiment, 43 Holstein cows were given one of two diets for a period from day 21 before expected delivery through day 154 after calving, researchers said.

The total mixed ration diets included a control treatment with a top dress of 28g maltodextrin and that diet with the direct-fed microbial (DFM) included in the 28g of maltodextrin carrier, said researchers.

Cows were milked three times a day and the milk weights were recorded, said researchers. Samples were collected weekly and analyzed for fat, protein, and lactose.

Milk samples from the first week post-calving were tested for immunoglobulins IgA, IgG and IgM, and they were looked for in blood samples from days 5 and 14 post-calving, they said.

Additionally several health disorders were checked for, including retained placenta, displaced abomasum, clinical ketosis, clinical mastitis (MAST) and clinical metritis (MET), they said. Both general appearance and fecal scores were recorded daily while body weight and body condition were noted weekly.

Blood samples were collected on days 5 and 14 post-calving, to test for subclinical ketosis, they said. They were also used to test for haptoglobin [a protein produced by the liver] levels, with those having more than 150 ug/mL being considered positive.

Results​

Cows getting the treatment had a lower serum haptoglobin concentration levels than control group cows on day 14, post-calving, researchers said. And treated cows had higher levels of IgA in their milk for the first week after calving.

Although the group didn’t specifically test the cows’ colostrum, with the higher levels of IgA in the milk, there is a chance that their calves may be better protected against disease, said Cardoso. “That will be one of the things that I will be interested to see more in depth – how are we changing the colostrum? And, how are those calves preforming?”​ he added.

Cows on the DFM diet also had higher yields of milk, fat-corrected milk, along with energy-corrected milk, milk fat and milk protein during the second week of lactation, said researchers. However, no overall difference in milk yield and milk components was established.

“We always have an idea that when you feed something it’s going to change a lot, and that’s what kind of didn’t happen,” ​said Cardoso. “We didn’t have a lot more milk out of this, perhaps in the beginning of lactation there was more milk, but what surprised us was the feed efficiency and feed conversion.” ​

Dry matter intake (DMI), body weight (BW) and body condition scores were not altered by the treatment, said researchers. But, the efficiency of cows getting the treatment was improved by 0.1kg milk per kilogram of dry matter, based on fat-corrected milk and energy corrected-milk.

The cows getting the feed supplement were better able to convert feed into milk production, added Cardoso.

There also was a greater tendency at day 5 post-calving for control group calves to have subclinical ketosis and for them to be positive in relation to haptoglobin levels at day 14, said researchers.

What’s next?

There are still a few questions to answer regarding the effects of using the feed supplement, said Cardoso. Including how the bacteria are interacting with the cows’ rumens and intestinal tracts.

The product also may be a way to help decrease the dependency on antibiotic use, by boosting the health of the cow and possibly the calves, he said. “If you’re having more antibodies in the milk, are you going to have healthier calves and need fewer antibiotics – that remains to be seen.”​