High-grain feedlot finishing diets improve feed conversion efficiency and produce high-quality, well-marbled beef.
Corn has traditionally been the dominant feed grain in Central and Eastern Canada and the U.S., while barley is more common in Western Canada. The structure of corn starch means that it will generally be digested more slowly than barley. Corn is usually steam-rolled to level the playing field for digestibility and animal performance, while simpler and less costly dry rolling is adequate for barley.
Corn has become more common in Western Canadian finishing diets in recent years due to decreasing barley acres, increasing corn acres and corn imports. This has led some feedlots to install steam-rollers for corn. Research is underway to learn if steam-rolling improves digestibility and animal performance for barley-based diets.
Read Also
The Canadian Cattle Association’s international advocacy efforts
Global ag policies affect Canadian food policy, so the Canadian Cattle Association participates in international and domestic forums
High-grain diets must be managed carefully to avoid abnormal feeding behavior, rumen acidosis and liver abscesses that can negatively affect animal health and welfare. Forage (typically silage) is fed as a fibre source to help maintain normal rumen function, but this can come at the expense of feed intake and efficiency.
Finding the right forage-to-concentrate ratio is tricky, and a feedlot animal’s fibre requirements may go beyond just a minimum fibre level. Not all forages and fibres are the same. The important thing might be to provide the right level of the right kind of fibre. For example, fibre length is important. Fibre that is too short won’t be “physically effective” — it won’t provide the “scratch factor” that stimulates rumen activity. That’s why distillers grains can’t replace roughage in a finishing diet. Its particles are too fine to be physically effective.
But the chemical makeup of the fibre is also important. In recent years researchers have been looking more closely at neutral detergent fibre (NDF). Some forms of NDF can be digested. But NDF that is bound to lignin (which acts like rebar to help plants stand up) is much less digestible.
Some NDF will resist microbial digestion for up to 240 hours in the rumen. This is called undigestible NDF. Tim McAllister and coworkers at Agriculture and Agri-Food Canada (AAFC), the University of Guelph and the University of Saskatchewan studied how barley rolling method and undigestible NDF levels affect animal performance and digestive health in finishing diets (Effect of undigestible neutral detergent fibre concentration in finishing diets containing dry-rolled or steam-rolled barley for feedlot steers; doi.org/10.1093/jas/skae392).
What they did: Four-hundred Angus-cross steers averaging 970 lb. were fed finishing diets (89 per cent grain, six per cent roughage, five per cent supplement) in 32 small pens at AAFC Lethbridge. Each pen received one of four diets containing either dry- or steam-rolled barley (processing index = 70 per cent) as the energy source mixed with either barley silage (low undigestible NDF) or barley straw (high undigestible NDF) as the roughage source.
The high undigestible NDF (straw) diet contained 16 per cent more undigestible NDF than the low undigestible NDF (silage) diet, as well as six per cent less protein, and two per cent less starch. All diets contained 10 per cent roughage. Physically effective fibre levels were 15 per cent higher in the barley silage than in the barley straw (84 per cent versus. 73 per cent), but the undigestible NDF levels were 85 per cent higher for the barley straw than the barley silage (26.8 per cent versus 14.5 per cent). The point is that the main difference between the roughage sources was the undigestible NDF.
Cattle were fed once daily for 112 days. Rumen pH was monitored throughout the experiment in six steers per diet. Growth performance, feed conversion, individual feeding behaviour, rumen pH, carcass data and liver abscess scores were collected.
What they learned: The method used to roll the barley didn’t matter much, but undigestible NDF level affected feeding behaviour and rumen health.
Growth performance (feed intake, average daily gain and gain:feed) was unaffected by either barley grain rolling method or by uNDF level.
Feeding behaviour wasn’t influenced by either barley grain rolling method, but steers fed the high undigestible NDF (straw) diet spent more time at the bunk, ate more slowly and had briefer meals more often.
Rumen pH wasn’t affected by barley grain rolling method. Steers fed the high undigestible NDF (straw) diet had a higher (less acidic) rumen pH than steers fed the low undigestible NDF (silage) diet. The steers fed the high undigestible NDF diet experienced less ruminal acidosis. They spent three fewer hours each day at below pH six, 4.5 fewer hours below pH 5.8, and 12.5 fewer hours below pH 5.2 than those fed the low undigestible NDF diet.
Carcass traits such as carcass weight, dressing percentage and lean yield, were unaffected by barley grain rolling method or undigestible NDF level. Significantly more steers fed dry-rolled barley graded AAA/USDA Choice than steers fed steam-rolled barley (82 versus. 70 per cent). But other studies haven’t seen this, so this result shouldn’t be taken to the bank. Quality grade was unaffected by undigestible NDF level.
Liver abscess score was unaffected by either barley grain rolling method or by undigestible NDF level. Steers fed the high undigestible NDF diet had 15 per cent fewer severe liver abscesses than steers fed the low undigestible NDF diet, but this difference was not statistically significant.
What does this mean to you? Steam-rolling is important for corn, but it doesn’t offer any clear benefit for barley compared to traditional dry-rolling. But undigestible NDF levels do appear to be important. Without changing the level of roughage in the diet, this research team was able to improve rumen conditions by increasing undigestible NDF in the diet.
At this point, undigestible NDF can only be measured using rumen incubation experiments, so it is not a practical measure yet. Physically effective fibre is a lot simpler, quicker and less costly to assess than undigestible NDF, so it will probably remain the gold standard for the time being.
Bottom line: After a big problem is solved, the solution often seems obvious. But developing cost-effective solutions to big problems is rarely simple, fast or easy. Finding ways to cost-effectively optimize feed efficiency, animal health and welfare all at the same time is a big challenge, and efforts to solve it will continue.
The Beef Cattle Research Council is a not-for-profit industry organization funded by the Canadian Beef Cattle Check-Off. The BCRC partners with Agriculture and Agri-Food Canada, provincial beef industry groups and governments to advance research and technology transfer supporting the Canadian beef industry’s vision to be recognized as a preferred supplier of healthy, high-quality beef, cattle and genetics. Learn more about the BCRC at www.beefresearch.ca.
