Straw may offer gold for drought feed

By Aerin Einstein-Curtis contact

- Last updated on GMT

©iStock.com/jowil
©iStock.com/jowil

Related tags: Cattle

Wheat straw supports young cattle growth, production when included in a diet with wet corn gluten feed, says US researcher. 

A team of researchers at Kansas State University ran a set of experiments using ammoniated wheat straw as a trial ingredient the diets of growing calves.

The work was part of an effort to find low-cost alternative feed ingredients after a period of drought, said Dale Blasi, professor in the department of animal sciences and industry and extension specialist at Kansas State University and manager and director of the KSU Beef Stocker Unit and Animal Identification Knowledge Laboratory.

“In the Beef Belt there was significant drought,”​ he told FeedNavigator. “The availability of roughages [was low], and [they were] very high in price.”

His group examines practical ways to help producers meet their challenges, he said. The research to design an alternative ration that would work during similar conditions is part of that effort.

The experiments included a feeding trial with beef calves and a digestion analysis with a group of heifers, he said.

The group found there were no differences between the use of regular wheat straw and ammoniated wheat straw, said Blasi. Neither did quite as well as the alfalfa/prairie grass control diet; however the gain to feed results were close.

Why straw?

The group looked at the use of wheat straw because there already is a significant body of literature regarding the inclusion of ammoniated wheat straw in the diet of adult beef cattle and gestating beef cattle, said Blasi. “It can constitute a significant amount of their dry matter,”​ he added.

Ammoniated wheat straw is one that has been treated with anhydrous ammonia, he said. The process takes about two to four weeks and the product can last up to a year.

The treatment improves the digestibility of the straw and its use by the cow, said Blasi. However, little work had been done exploring the use of the feed ingredient with juvenile or developing cattle.

Another reason for the interest in an alternative feed ingredient during a drought situation is that more traditional products like alfalfa can see price increases, he said.

Alfalfa hay during the most recent drought went for about $210 a ton, and normally it is about $100 a ton, said Blasi. Similarly, alternative forages like prairie grass sold for about $150 a ton, where a typical price is $60-70.

In some parts of the US, like Kansas, producers should be aware of the possibility of drought and plan for it, he said. The state faces drought conditions about every five to seven years and has a shallow enough soil bed that crop stress can be seen after even a short spell of dry weather.

“Next time we’ll be better prepared to help people when they try to formulate their diets in the least cost fashion,”​ he said.  

The study 

In the first experiment, 288 beef steer were given one of three diets for a period of 56 days, said the researchers.

Steer were weighed on arrival, at the start of the experiment, on day 28 and at the end of the experiment, they said. Dry matter intake, average daily gain (ADG) and the gain to feed ratio (G:F) were established.

The diets included 40% wet corn gluten feed and 30% of either ammoniated wheat straw or wheat straw and a control diet included 30% of an alfalfa/prairie grass blend, said Blasi.  

The group also ran a digestibility experiment where all three diets were fed to a group of six fistulated heifers for a period of 15 days, said the researchers. Ten days were used for adaptation, fecal collection was done on four days and rumen fluid was sampled on the final day.

That work was done to potentially generate the data to help explain the results from the initial growth experiment, said Blasi. “Those help us to explain what we observe in the live animal study,”​ he added.

Results  

The group found no differences between the results from the diets that included the wheat straw and ammoniated wheat straw at those levels, said Blasi.

“The reason we feel that there was no benefit from the ammoniated product was because of the nitrogen levels from the 40% wet corn gluten feed – it provided enough nitrogen,” ​he said. “With untreated wheat straw crude protein is 3-5% and when you ammoniate wheat straw you typically see the crude protein content to be 9-12%, it’s urea, it’s not a true protein but it’s nitrogen.”

In the first trial no differences were found in dry matter intake for any of the diets, said the researchers. ADG was the same for steer getting the straw diet, but lower than the control group.

The G:F ratio and final body weight were similar for steer getting either straw supplement, but were outperformed by the control group, they said.

However the gain to feed ratio was similar for all three diets in the first part of the trial, the researchers said. And, during the latter half the control group score was 0.184 and the other two diets had scores of 0.168.

The difference in weight gain and in cost of production would need to be evaluated by producers before deciding to use straw in their diet, they said.

In the second experiment, cows had higher dry matter intake when getting a diet that included straw, said the researchers. The ammonia treatment was not seen to have an effect on acid detergent fiber or organic matter, but dry matter digestibility tended to be improved for the control diet.

Ruminal pH was the same for both diets with straw, and both were higher than the pH generated by the control diet, they said.

Straw can provide roughage for a total mixed ration, said Balsi. And it offers a potential way to use a by-product.

“It’s good news if you’re growing cattle and you use at least 40% of wet corn or [dried] distillers [grains] you can anticipate you don’t have to invest in the cost of the plastic, or time and labor or anhydrous ammonia,”​ he said.

Source: The Professional Animal Scientist

Title: Evaluation of ammoniated wheat straw during a receiving and growing period for beef cattle

DOI: 10.15232/pas.2015-01448

Authors: E.R. Schlegel, S.P. Montgomery, J.W. Waggoner, C.I. Vahl, E.C. Titgemeyer, W.R. Hollenbeck, D.A. Blasi

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