Part One of this series, featured in the Fall/Winter 2007 Beef Performance Edge, focused on the optimum mineral mix needed for cattle grazing wheat pasture, management strategies to reduce occurrence of bloat and tetany, and the strategic use of ionophores and antibiotics.  Part two will focus on feed and forage supplementation strategies to maximize performance on wheat pasture.

To determine the potential profitability of wheat pasture grazing enterprises, one must be able to predict cattle breakevens with some degree of accuracy.  A number of factors should be considered when calculating breakevens, and predictable performance is one of the key precursors.  Performance is directly related to intake and average daily gain, which are particularly challenging to predict because of large variations in weather and forage standing crop.  Supplemental feeding reduces some of this variation, thereby stabilizing cattle performance which makes predictions somewhat more reliable.

Supplementation of cattle grazing wheat pasture should be considered in the following instances:

• To provide a more balanced nutrient supply and/or inclusion of other feed additives (i.e ionophores, antibiotics, bloat preventatives, etc.).

• To increase stocking rate by reducing forage intake with alternative feed.

• To provide feed when forage availability is limited.

Over the years, university, private, and commercial research groups have investigated a multitude of supplement strategies to improve cattle performance on wheat pasture.  These strategies have ranged from providing additional protein and/or energy via individual commodities, mixes of commodities, or commercial feeds in meal or pellet form. 
 

Protein Supplementation

As a refresher, there are basically two types of protein:

• Degradable intake protein (DIP), which is degraded in the rumen by the microorganisms.

• Undegraded intake protein (UIP) or ‘bypass’ protein, which resists degradation in the rumen and bypasses directly to the true stomach and small intestine.

After DIP is broken down by rumen microbes, it moves to the small intestine where it can be absorbed and used by the animal, similar to UIP.  The ruminant’s total requirement for protein is met through a combination of DIP and UIP.

Non-protein nitrogen (NPN) is another ‘nitrogenous’ compound and form of DIP that can be used to partially meet the protein requirement of ruminant animals.  Bacteria inhabiting the rumen can readily utilize NPN compounds, such as urea and biuret (an ADM Alliance Nutrition exclusive NPN source), to make proteins needed by the animal.  However, adequate amounts of energy and an optimum rumen environment are needed by the microbes to effectively convert NPN to functional protein for the animal.  If these conditions do not exist, the NPN is less efficiently utilized and essentially lost through the bloodstream, liver, kidneys, and urine. 

Typical wheat forage crude protein values will be in the range of 25-35% and the average crude protein requirement for stocker cattle is only 12-14% (dry matter basis). However, 17-33% of the protein in wheat is in the form of NPN.  Research studies conducted with cattle on wheat pasture have shown that approximately 50-75% of total forage nitrogen (protein) disappeared from the rumen at rates of 16-19% per hour.  While crude protein levels appear more than adequate for growing stocker calves, its rapid degradation may essentially lead to a deficiency of protein moving to the small intestine and available to the animal.

These findings prompted the recommendation to supplement stockers on wheat with a form of bypass protein from sources such as cottonseed meal, distillers or brewers grains, gluten meal, etc.  More research in this area is needed, as the few trials conducted to date are limited and somewhat inconsistent.  However, improvements in performance have been noted when as little as 0.1 lb of UIP per day have been provided.  This minute amount could easily be incorporated into a free-choice mineral mix or block, such as #532 or #537 MoorMans® Mintrate® RU  Block.  Commercial research comparing the Mintrate Blocks to a typical mineral and vitamin mix is shown in Table 1.

Table 1  Effects of Supplemental Protein on Wheat Pasture Forage
Treatment	Total Head	Total Days on Wheat	In- Weight, lb	Out-Weight, lb	Total Gain, lb	Average Daily Gain, lb
Mineral Mix *	1367	97	458	692	233	2.41
Mintrate Block **	620	91	473	715	242	2.66

  *1440 gm/ton lasalocid; targeted consumption 0.084 – 0.277 lb/head/day
**300 gm/ton monensin ; targeted consumption 0.34 – 1.33 lb/head/day

 

Energy Supplementation

Wheat pasture is a highly nutritious, palatable forage high in protein, energy, and most minerals.  However, its high moisture content makes it difficult for grazing cattle to consistently meet their daily dry matter intake requirements.  In addition, its high protein content, in relation to its energy content, makes the cattle less efficient and actually results in reduced nitrogen (protein) utilization.  When calculating energy and protein requirements for stocker cattle on ample wheat pasture, energy is the first-limiting nutrient when targeting consistent gains over 2 lb per head daily.  Providing moderate amounts of supplemental energy will not only improve cattle performance, but will allow for increased stocking rates and flexibility for the enterprise. 
 

Silage

When available, corn and sorghum silages are excellent forage supplements for stockers on wheat pasture. In other words, they can be used to increase stocking density or improve performance when wheat pasture is limited.  In several studies, providing silage allowed initial stocking densities to be doubled without affecting stocker gains.  To determine how much silage to feed, one can figure that each dry matter pound of silage provided will reduce dry matter intake of wheat forage by 0.66 lb.  Refer to Table 2 for more detailed instructions on how to calculate actual feeding amounts based on silage and wheat forage dry matter.  Silage additionally has a positive associative effect on wheat forage digestibility.  So, not only can stocking rate be increased, but producers also get more ‘bang for their buck’ out of wheat pasture.      

Table 2	Calculating Wheat Pasture Replacement by Silage
Input Estimates:
** Corn or Sorghum Silage = 35% dry matter/65% moisture
** Wheat Pasture Forage = 25% dry matter/75% moisture
Calculating As-Fed Values:
** 1 lb of silage dry matter = 1 ÷ (35% ÷ 100) = 1 ÷ 0.35 = 2.86 lb As-Fed
** 0.66 lb of wheat forage dry matter = 0.66 ÷ (25% ÷ 100) = 2.64 lb As-Fed
Answer:

 

Dry Hay

Feeding hay is a common practice during inclement weather when wheat pasture is covered with snow or inaccessible to cattle.  Some producers, however, provide low-quality roughages (wheat straw, corn stalks, cotton burrs, etc.) continuously when wheat pasture is abundant.  They believe that additional dry forage will help reduce bloat, improve utilization by slowing rate of passage, and/or reduce the ‘washy’ appearance (loose stools) of cattle on wheat pasture.  Unfortunately, research has shown that intake of low-quality forages is minimal (0.15-0.9 lb/head/day) and has absolutely no effect on gain, forage intake, passage rate, or bloat occurrence.  While low-quality forages have no value when wheat pasture is moderate to abundant in quantity, higher quality hays are recommended and beneficial when wheat forage is severely limited or inaccessible. 
   

High-Starch Versus High-Fiber By-product Supplements
 

Essentially, there are two types of energy feeds:

• High-starch commodities such as corn, sorghum, wheat, barley, and oats

• High-fiber by-products such wheat middlings, soybean hulls, corn gluten feed, distillers grains, etc.

Most all by-product feeds are the ‘left-overs’ that remain after an ingredient to be used for ethanol production or human consumption is removed from a commodity.  In the majority of cases, the starch component of the raw material is removed and the remaining components become more concentrated.  As a result, most by-product feeds are higher in fiber, fat, and protein than the raw product from which they originated.  Although the rapidly-digested starch is removed from the product, fiber in the form of cellulose remains and is highly digestible by the ruminant animal.  Consequently, the energy content of these by-product feeds is not very different from the energy value of the whole grain from which it originated.  

The negligible amount of starch in by-products is an important factor when one considers the effect of rumen microbial population on forage digestibility.  The microbes inhabiting the rumen are starch or fiber specific and total numbers of each vary depending on the ruminant’s diet.  In other words, if the diet is primarily forage-based, the microbial population will be comprised primarily of fiber-digesting microbes and vice versa for a starch-based concentrate diet.  When a high-starch supplement is introduced to a forage-fed animal, there are not enough starch-digesting microbes available to efficiently utilize the supplemented starch.  The high-fiber by-products, however, are primarily fiber-based and require the same fiber-digesting microbes already inhabiting the rumen.  Typically, by-product feeds will yield better conversions and fewer digestive disturbances than high-starch supplements in forage-based diets. 

Most early research on wheat pasture focused on grain-based supplements fed at 1-1.5% of body weight (dry matter).  On average, stocking densities were increased 1.25 to 2-fold and average daily gain improvements ranged from 0.1-0.66 lb.  Dry matter conversions were relatively high and ranged from 6.7-10.3 lb of supplement per pound of gain per acre.

More recent research has focused on wheat pasture supplements comprised of one or a combination of high-fiber by-product feeds.  A very thorough, three-year study conducted at Oklahoma State University compared a high-fiber energy supplement to both a corn-based, high-starch supplement and an unsupplemented control fed to growing cattle on wheat pasture.  The two supplements were hand-fed at 0.75% of body weight (dry matter), six days per week, and stocking rates were increased 22-44%.  Over the three-year period, average daily gain during the five-month grazing seasons was increased by energy supplementation (regardless of type of energy supplement) by an average of 0.33 lb (Table 3.).

 

Table 3	Three-Year Average Daily Gain Response to
	Energy Supplementation on Wheat Pasture
	------------------------- Supplement Type -----------------------
	High-Starch	High-Fiber	None B
	Corn Based A	By-Product A
ADG C	2.31	2.38	2.03
A  Actual supplement intake averaged 0.65% of body weight dry matter
B Unsupplemented cattle were provided a free-choice mineral/vitamin mix
C ADG = average daily gain Source: Oklahoma State University

 
Supplement conversions did not differ between the two types of supplements and averaged approximately 5 lb of supplement per pound of gain per acre.  Conversion of the corn-based supplement was substantially lower than what had been noted in previous research studies.  However, the supplement was fed at lower levels (0.75% of body weight versus 1-1.5% of body weight) which likely resulted in less of an effect in the rumen microbial population and more efficient utilization. 

With both the high-starch and high-fiber supplements being relatively equal in performance, it is recommended that producers buy the least expensive product delivered to the bunk. If the goal is to maintain normal stocking rates while improving performance, one should target feeding 0.25-0.5% of body weight (typically 2 lb/head/day) of an energy-based supplement.  By increasing supplemental feeding to 0.75-1% of body weight, stocking rates can be increased by 30-35% with no adverse effects on daily gain. And finally, during times of limited forage availability, the energy supplement should be fed at 1.25-1.5% of body weight.  If adequate bunk space is available for all the cattle to eat at once, hand-feeding on a daily basis has been shown to improve feed conversion by 33% over using self feeders.  It is additionally recommended that feed increases begin a couple weeks before the pasture forage is depleted to prevent overgrazing and poor performance. 
    

Stocking Rates and Ideal Forage Mass

Ideal stocking rates vary considerably from year-to-year and pasture-to-pasture.  However, fall/winter stocking rates often range from 250-500 lb of animal per acre. 

With typical stocker calves (350-550 lb), this would be about 1-2 acres per head.  During the spring, wheat pasture typically flourishes and will support 500-1000 lb of animal per acre or basically 1.5-2 times the fall/winter rate.  During optimum years, late spring graze rates as high as 1,400 lb of animal per acre have been noted.    

While research is limited, there have been several research studies conducted to determine minimum levels of forage mass required to maintain gains of stocker cattle on wheat pasture.  A Texas Agricultural Experiment Station and Texas A&M University study determined that when herbage mass of wheat declined below 800 lb of dry matter per acre, steer gains started declining when supplement was not provided.  Additional research conducted at Oklahoma State University determined that forage intake and average daily gains begin to decrease when wheat forage allowance drops below 20 to 24 lb of dry matter per 100 lb of body weight per day.  In other words, if a producer is running 500 lb of calf to the acre, a minimum of 100-120 lb of forage dry matter (500-600 lb of as-fed pounds of 20% dry matter wheat forage) per acre is required to sustain gains.  Dry matter of wheat forage varies throughout the grazing season (Figure 1) and should be considered when estimating total amount of forage available.  For additional assistance with estimating forage mass, contact your local university/extension office or your ADM Alliance Nutrition sales representative or specialist. 
 

         

 

Supplement Form and Feeding

Due to relatively low inclusion rates, type and form of supplement do not appear to significantly affect performance.  In both research and commercial settings, cattle seem to consume high-fiber based products more readily than high-starch varieties.  In hand-fed situations, this difference is noteworthy during inclement weather and/or where bird predation is a concern.  Corn-based supplements are more attractive to birds and substantial contamination from excreta is not uncommon in both hand and self-fed situations. 

When comparing meal and pellet supplement forms, there was not a statistical difference in intake between the two in self-fed programs. Target levels of intake from self-feeders, however, were more closely achieved when meal forms were utilized.  When hand-feeding practices are implemented, pelleted supplements are typically consumed more readily, segregation is minimized, and bunk life is improved.         

When managed correctly, both hand and self-feeding practices work well in wheat pasturing enterprises.  Hand-fed cattle will need to be fed regularly (every day or every-other day) and preferably at the same time each day.  Adequate bunk space should be available so that all animals can eat at the same time.  This is a more labor intensive practice, but intakes and performance are typically higher and more consistent when compared to self-fed animals.  In addition, the cattle are bunk trained per-se and feeding during inclement weather is much easier. 

The use of self-feeders is less labor intensive and primarily requires regular checking of the feeders for feed availability, flowability, and removal of accumulated fines.  It is imperative that the feeders never run empty and that cattle are not forced to consume stale feed or fines.  Intakes are more variable in self-fed situations and should be monitored closely throughout the feeding period.  Salt and magnesium oxide are two products typically used to limit consumption and amounts will need to be adjusted as cattle adapt to the higher levels and as forage quantity and quality change.
 

Conclusion

Performance is the key to profitability in wheat pasturing enterprises.  There are a number of variables that affect performance, which makes ‘forecasting’ profitability potential quite difficult.  Supplementing cattle on wheat pasture not only enhances performance, but will improve the accuracy of predictions of performance.  When coupled with sound management practices, implementing some of the strategies suggested in this and the previous publication should ensure optimum profitability potential from wheat pasture. 
 

ADM Alliance Nutrition has a wide range of minerals and supplements specifically designed to enhance cattle performance in wheat pasture feeding programs.  Talk to your local ADM Alliance Nutrition dealer, sales representative, or specialist today to see how we can help you “make the most of your wheat”!