Pelleted, treated feeds may boost digestion in growing cattle

Pelleted feeds and calcium oxide treatments may boost performance and digestion in growing cattle, say researchers.

A team of researchers explored the use of pelleted feeds that included dried distiller grains (DDG) and corn stover harvested using a new method in diets for growing cattle. The group also tested ingredient digestibility.

The by-products were tested for use as feed ingredients after being treated with calcium oxide, said corresponding author James MacDonald associate professor of ruminant nutrition at the University of Nebraska. 

In the trials, the group examined interaction of harvesting method, use of a chemical treatment and processing method on the total-tract digestibility and overall growth performance of cattle.

The team from the University of Nebraska published results of the two studies in The Professional Animal Scientist​​​. 

They found use of a complete pelleted feed instead of a typical growing diet produced similar or improved digestibility for cattle along with greater weight gain and final body weight, but there was a drop in the gain to feed ratio when cattle were allowed unlimited access to feed.

Why pelleted feed?​

The trigger for the research was the fact there is a lack of dairy feed alternatives when corn prices are high, MacDonald told us.

And the researchers noted there is growing interest in exploiting corn stover: The increase in farm land and corn yields means there is more corn residue for potential use in feed. It has been noted for its low digestibility, but new technology has improved the stover harvest process and the quality of baled corn residue.  

Treatments like calcium oxide also can be added to corn residue to boost digestibility, they said. And reducing particle size prior to such treatment may add additional benefit.

Pelleting small particles makes them easier to work with, store and transport, said the researchers. The process of pelleting also can be used to minimize the need for mixing growing rations.  

Previous research done by Peterson et al., 2015 reported that a pelleted feed including alkaline-treated corn stock dried distiller grains with soluables (DDGS) boosted body weight (BW), average daily gain (ADG) and dry matter intake (DMI) when compared to diets where no alkaline treatment was used, said the researchers. The other work also saw improvement in the gain to feed ratio (G:F) depending on treatment use.

However, new processes to generate pelleted feeds making use of DDGS and corn stover have been developed, the researchers reported.

For the project, the team also worked with a company, Pellet Technology, that is looking to design crop-residue based pellets for producers, said MacDonald.  ​

Trial details​

The first experiment focused on testing digestibility of pelleted feeds using a calcium oxide (CaO) treated corn stover and DDGS versus a traditional growing diet, said the researchers.

Six steer were fed one of four diets comprised of: the negative control (NEGCON) with 60% untreated corn stover, 18% modified distillers grains with solubles (MDGS), 18% distillers solubles and 4% supplement; the positive control (POSCON) which had 60% CaO treated corn stover, 18% MDGS, 18% distillers solubles and 4% supplement;  CONV a pelleted feed including CaO treated corn stover, DDGS, and 4% supplement; and MOG which was pelleted feed containing treated corn stover, DDGS and supplement but harvested in a different manner to the CONV diet, they said.

The corn stover in the CONV diet was conventionally harvested and baled, while the MOG stover was harvested at the same time as the corn in that field, they said. Both diets were processed by Pellet Technology while the POSCON and NEGCON were generated at the university.

Cattle had 14 days on each feed, with collections happening during the last five days, said the researchers. Fecal matter was analyzed for total-tract digestibility.

In the second experiment, 360 yearling steer were fed by one of three methods for 92 days, said the researchers. Initial and final body weights were recorded, orts were collected for dry matter analysis and BW, DMI, ADG and G:F were calculated.

The diets used were NEGCON fed ad libitum, and CONV, they said. The trial CONV diet was fed either ad libitum (PELAL) or in a paired manner matching the dry matter amount from NEGCON.

Both completely pelleted diets had 15% corn silage added on day 28 to prevent bloat in the cattle, they said.

The team did see some bloating results from the PELAL diet, said MacDonald. However, those dissipated when the group added additional silage to the diet to increase the roughage content.

“I don’t know that every producer would feed a pellet for the full diet - they’d add other fiber and that’s what we did,”​ he said.

Results​

In the digestion study, no DMI differences were found for the four diets, said the researchers. But, the CONV diet tended to reduce DM digestibility compared to the MOG diet.

NEGCON had the lowest digestibility with POSCON being somewhat better, an improvement attributed to the CaO treatment, they said. Total-tract digestibility of organic matter (OM) followed a similar pattern with MOG having the best digestibility and NEGCON the worst.

In the second trial, there were no major differences found in BW, DMI or ADG for the NEGCON and paired diets, said the researchers. Steer getting the PELAL diet had the best DMI and ADG and largest final body weight.

The PELAL group also saw a decrease in feed efficiency, which was a typical response, said MacDonald. “If you let them eat all they want to eat they’ll eat more but feed efficiency is reduced – that’s a pretty classical response with a pelleted feed,”​ he added.