There can be, upon occasion, a gulf between academic recommenda- tions and practical application. In the cold and hard reality of what works in a challenging and competitive world, mistakes are costly, recommendations are constantly scrutinized, and con- sultants are under pressure to deliver results. And what makes sense in an aca- demic setting can sometimes fall short when the wheels start to roll.
That was the snapshot that Judson Vasconcelos and Mike Galyean, re- searchers in the animal science depart- ment at Texas Tech University, Lubbock, TX, were looking for in their 2007 survey of nutritional recommendations of feed- yard consulting nutrition- ists. The survey canvassed 29 nutritionists who, between them, formulate the rations for nearly 70% of the cattle on feed in the U.S.
Overall, the researchers say, the variation among re- sponses was not large, which indicates the consultants were all using similar information sourc- es and applying the information consis- tently. Their primary information source is the National Research Council (NRC) 1984 and 1996 recommendations, com- bined with other published sources, such as the Cornell Net Carbohydrate and Protein System, and their own data and observations. Here, among other things, is what the survey found:
Energy. “Our respondents seemed to recognize the greater energy value of steam-flaked corn and consid- ered steam-flaked corn to increase in NEg concentration by an average of 10.9% compared with dry-rolled corn, and 6.8% compared with high-mois- ture corn,” says Vasconcelos, who is now with the University of Nebraska at Scottsbluff. In contrast, the 1996 NRC ta- bles suggest an increase of only 4.5% for steam-flaked vs. dry-rolled corn, and no difference in the net ener- gy concentration between high-moisture and steam- flaked corn.
“Thus, although most (83%) of our nutritionists used the NRC as their source comof information on energy values, they deviated substantially from NRC estimates of NEg values for processed grain.”
Grain. Corn was the grain of choice for all 29 nutritionists, but corn in the form of co-products is now a fixture in feedyard rations. Eighty-three percent of the nutritionists use grain co-products in finishing diets, with wet distiller’s grains, dry distiller’s grains with solubles (corn, sorghum or both), wet corn gluten feed and dry corn gluten feed the main ingredients. The range of inclusion was wide – from 5% to 50% – with an average of 16.5%.
Protein. Another area in which the nutritionists differed from the NRC recommendations is in the use of degradable intake protein (DIP). “Most of them are not formulating for degradable intake protein, which was surprising for us,” Vasconcelos says. DIP is the type of protein digested in the rumen by the microbial population. A good example of a feedstuff high in DIP is urea.
Undegradable intake protein (UIP), the other type of protein, is not broken down by ruminal microorganisms and “escapes” ruminal degradation, moving on to the small intestine for digestion. Cottonseed and soybean meal are high in UIP.
DIP in the ration is important to ensure that the feedstuffs are providing sufficient protein to allow the rumen microorganisms to do their thing. That’s particularly important when cattle are on a highly fermentable diet, such as steam-flaked corn, Vasconcelos says.
However, if you’re formulating a feedyard diet for DIP, you have to do a lot of estimating because there is no widely accepted laboratory test that provides definitive levels. Thus, most nutritionists prefer to look at the total protein requirements rather than formulate for varying degrees of degradability.
When looking at nutrient composition for finishing diets, the average crude protein recommendation was 13%. The primary sources of plant-based protein were either generally described as byproducts or specified as distiller’s grains or gluten feed. In addition, some nutritionists still use more traditional sources of protein such as cottonseed meal and soybean meal.
Roughage. The survey showed a slight seasonal variation in roughage, with nutritionists using slightly less (an average of 8.3%) roughage in the ration in the summer than in the winter, when roughage averaged 9%. The primary roughage source was corn silage, with 41% of nutritionists indicating this as their first choice, followed by alfalfa at 31%.
Minerals. “Gen-erally, most major and trace mineral recommendations fell within a range of 1 to 2 times the NRC recommendations,” says Vasconcelos. “However, a slight trend for oversupplying nutrients was observed, perhaps reflecting some degree of a desire to err on the side of caution and provide a safety net for both the consultant and the producers they serve.”
However, the survey did show that nearly all the nutritionists didn’t add phosphorus (P) to the diet. “Thus, our data suggest that feedlot nutritionists have responded to environmental concerns by decreasing P supplementation to cattle,” Vasconcelos says.
In addition, the survey looked at recommended cattle-management systems. “With our respondent’s clients, those who sorted cattle into outcome groups were the majority (41%),” Vasconcelos says. “The most common time of sorting was at arrival for 37% of the clients, re-implant for 29% of the clients, and other times for 28%.”
According to Vasconcelos, sorting by body weight was most common, with 61% of responses indicating they used this method. Ultrasound was used by 8.5%, while 24% used other unspecified methods.
“All consulting nutritionists were responsible for their clients’ implant strategy,” he says. The recommended maximum number of days on a terminal estrogen/trenbolone acetate implant was 100 days for 14 of the 29 nutritionists surveyed. Seven recommended 120 days, seven went to 130 days, and one took the cattle to 140 days.
Most nutritionists recommended an average of 21 days to adapt newly arrived cattle to a high-concentrate diet, Vasconcelos says, regardless of method used. The vast majority of the nutritionists surveyed recommend a multiple step-up diet to adapt cattle, using an average of three rations, each fed for seven days. Two-ration blending was used by four nutritionists, while two used a combination of a step-up and two-ration approach. The initial level of roughage in the step-up rations ranged from 27.5% to 46%, with an average of 40%.
And finally, the survey revealed a truth everyone in the cattle business can appreciate – consultants, like their clients, are getting older. The largest percentage of respondents, 35%, have been in practice for more than 26 years, with 28% practicing for 16-26 years. Based on that, Vasconcelos says, “I assume in the next five to 10 years, we’re going to see a big turnover in nutritionists.”
While data from the survey provide a snapshot of practices used by feedyard nutritionists, its value may be longer lasting than that. The results, which show where academic recommendations and practical application merge, and, more importantly, where they don’t, should aid in the development of future NRC models and recommendations.