AN INTRODUCTION TO FLOURY GRAIN
Feeding dairy cows and balancing rations is both art and science. Productivity balanced with profitability controls what feed stuffs we select and how we put them together. When walking the floor of a dairy parlor, you often may see undigested corn kernels in cow manure. Because corn is a key part of most cows’ diets, it can be frustrating to see how much is not being digested – and is ultimately wasted. For many farmers, these undigested kernels become expensive fertilizer. Does it have to be this way? Photo courtesy of Tom Kilcer
Consider how corn hybrids developed. During the 1970’s the rapid growth of corn exports led corn breeders to select hybrids that would stand up to the rigors of the overseas shipping process. The goal was a harder, more vitreous corn kernel that would not break or grind into a powder during an extensive shipment. This need naturally led to harder kernels, which are ideal for export. But could the hardness of these kernels be the reason they cannot be thoroughly digested? This is one of the issues that will be addressed in the following pages as we examine what floury grain is and the differences between floury (soft) corn kernels and vitreous (hard) corn kernels.
INDEX Page 2: Physical Properties
Page 13: Calf Starter Trial
Page 2: Chemical Properties
Page 14: Feed First
Page 5: Reactions in Digestion
Page 16: Extended Harvest Window
Page 9: Rate of Digestion and Rate of Passage
Page 16: Reactions in Poultry
Page 11: Why is Rumen Degradability Important? 1
Page 18: Conclusion/Contact Info
WHAT IS FLOURY GRAIN? PHYSICAL PROPERTIES
The term “floury� refers to the soft, white, starch texture of the grain in the corn kernel. Most corn kernels contain both floury and vitreous starch structures. What distinguishes a floury hybrid from a standard vitreous corn hybrid is the relative amounts of floury starch and vitreous starch in the kernel. Floury hybrids have less vitreous material in the kernel.
When a corn kernel is dissected, the difference between a floury hybrid and a vitreous hybrid can be clearly seen.
Masters Choice has developed a proprietary evaluation process that aids in floury hybrid selection. chemical PROPERTIES
As a phenotypic trait, floury grain is the reflection of the underlying genes in the kernel. Although the expression of floury grain may be influenced by environmental factors, it is generally linked to the presence of one of the following genes: 1. Opaque 1 2. Opaque 2 3. Floury 2 4. Sugary 2 5. Soft Endosperm (h1) 6. Amylose-extender 7. Waxy-1 Sugary2 (wx1su2) Each of these genes affects the amount of starch storage proteins, or prolamin, in the kernel. All cereal grains have some form of storage protein, and the protein in corn is zein. Zein, like all storage proteins, is highly indigestible because it is degradable only in an alcohol medium solution. Although a protein, zein negatively affects the soluble protein in corn silage. 2
Corn has four unique zein proteins: Alpha (α-zein), Beta (β-zein), Delta (δ-zein) and Gamma (γ-zein). 1. alpha (α-zein)
More information is readily available on the α-zein protein than the other three proteins, so understanding of this zein protein is the greatest of the four zein proteins. A number of reports have described in some detail the composition and possible role the individual zeins [reviews by Shewry et al. (58-60)]. The most important change in the presence of zeins was the development of opaque mutants. These mutants resulted in the decrease or disappearance of the α–zeins with equivalent in creases in γ– and σ–zeins. In addition, there were increases in lysine in nonstorage proteins. These mutants resulted in a much softer endosperm with lower protein content. However, the introduction of high-protein, soft endosperm hybrids called Quality Protein Maize presented breeders with the opportunity to select for a range in protein or hardness, which would be targeted at specific end-uses. More is discussed on breeding later in this review.
Opaque mutants first described in the 1960s (101) have been shown to affect maize hardness by producing a softer endosperm with reduced protein and increased lysine content (38, 40, 46, 47, 79, 102-105). The biochemical effect of these opaque-2 mutations resulted in changes in zein content, which affects hardness. The αα–zein was not expressed, and there were increased levels of γ– and σ–zein.
Earlier research into maize has uncovered important biochemical aspects in relationship of protein content and composition to hardness. The presence of particular zein fractions affects hardness, with the absence of α–zein resulting in softer endosperm. Hardness has also been shown to be influenced by cultivar and environment, with both of these factors impacting hardness through affects on protein and/or starch. Opaque-2 mutants along with other mutations can affect hardness from variation in gene expression of particular protein or starch components. Breeders are aware of the genetic and environmental affects and can select for high-yield soft or hard types. 3
From this selected information, we can gain a general understanding of how this knowledge of the α-zein can be used. We now know that the absence of this protein correlates positively with the softness of the corn endosperm. Researchers have been examining how this knowledge can be applied in the selection of corn hybrids for specific end uses. 2. beta (β-zein)
From this selected information, we can gain a general understanding of how this knowledge of the α-zein can be used. We now know that the absence of this protein correlates positively with the softness of the corn endosperm. Researchers have been examining how this knowledge can be applied in the selection of corn hybrids for specific end uses. 3. delta (δ-zein)
From the little information that is available about the (δ) zein protein, we know that the presence of this protein with the γ-zein protein correlates somewhat with increased hardness in the kernel. …The sequences of outer zein (γ) could be important in binding zein to starch. Increase in the methionine level, particularly in the γ– and σ–zeins, has been shown to increase hardness….
4. gamma (γ-zein)
Gamma zein has been linked not only to harder kernels but also to the presence of lysine. ….In this study, we observed the 2 hypotheses to be ostensibly correct. When random corn hybrids were ensiled over an extended period (240d), hydrophobic zein proteins intrinsic to the starch protein matrix were substantially degraded, especially γ-zein proteins that cross-link starch granules together. Degradation of hydrophobic zein proteins in the ensiling process appears to be best explained by chronic proteolytic activity because inoculation, which yielded greater lactate and acetate concentrations in HMC, had no effect on the degradation of hydrophobic zein proteins in HMC…. 4
Measuring prolamin content is far from an exact science, but it is easy to see and feel the difference between hybrids that are low in prolamin versus those that are higher in prolamin content. Although the physical characteristics of prolamin make it ideal for use in plastic coatings, it’s hard, heavy, glassy nature makes it less than ideal for feeding. But the feeding potential of vitreous hybrids can be improved by ensiling them for several months before feeding, which breaks down the prolamin, allowing more of the starch to become available. Compared to vitreous hybrids, however, floury hybrids require much less time ensiling, so they are available for feeding much faster and with less or no loss in milk production.
An electron microscope displays prolamin encapsulating startch molecules.
WHAT IS FLOURY GRAIN? reactions in digestion
Passage Rate One of the first things we notice when comparing floury grain to vitreous grain in digestion is that floury grain hangs in the rumen longer. One reason for this may be that the hard, heavy vitreous particles have higher specific gravity, which can cause them to pass through the rumen faster than the floury particles. By allowing more time for digestion in the cow’s rumen, floury grain allows more starch to be absorbed in the rumen – rather than to pass though the digestive tract. 5
Corn grain with vitreous endosperm tended to increase ruminal passage rate of starch (21.2 vs. 16.2% per h; P<0.10; Table 6). We thought that floury corn grain might disperse in the liquid fraction and possibly increase rate of starch passage from the rumen. However, rate of starch passage from the rumen and ruminal liquid passage rate (mean -20% per h) were not correlated across cow period means (r=0.03; P<0.86). Faster ruminal starch passage rate in this experiment is likely because of greater density of vitreous corn grain; more vitreous flint corn grain was more dense than less vitreous dent corn grain (Philippeau et al., 1999a), and greater particle density decreases mean ruminal retention time (Lechner-Doll et al., 1991). Faster rate of starch digestion and a tendency for slower rate of ruminal starch passage for floury corn grain vs. vitreous grain resulted in a lack of treatment effects on ruminal starch turnover rate. Efforts have been made to increase the ruminal digestion of starch by feeding it as high-moisture corn instead of as dry grain. The thinking has been that this approach may result in higher ruminal digestion, because it causes the starch to pass from the rumen more slowly, allowing for more complete digestion.
Rate of Starch Passage %/hr
As shown in Table 1 (in a controlled experiment) the high-moisture (HM) vitreous grain passed from the rumen twice as slowly as the dry vitreous grain. Notice as well that the dry floury grain passed Rate of Passage: Starch Ying and Allen, 2005 J. Dairy Sci 88S:393 24 twice as slowly as the 21.8 dry vitreous grain. Dry > HM (P <0.01) 20 Finally, it is important Vitreous > Floury (P < 0.01) Interaction: NS to note that when both 16 high-moisture vitreous and high-moisture 12 10.9 floury grain were fed, 10.2 the floury grain main8 tained its advantage 4.1 over vitreous: ruminal 4 passage rate was less 0 than half that of the Dry Floury Dry Vitreous HM Floury HM Vitreous high-moisture vitreous grain. Table 1 6
Rumen Degradability Considerable research has shown that floury grain characteristically stays in the rumen longer than vitreous grain and also degrades more easily in the rumen. The latter is largely due to the fact that the starch structure in floury grain is more digestible. Ruminal starch digestibility was greater for floury corn grain treatments because starch in floury endosperm digested at a rate of 21.9% per h vs. 12.9% per h for vitreous endosperm (P<0.01; Table 6). Philippeau et al. (1999a) reported that dent hybrids (51.4% vitreous) degraded faster than flint (71.8% vitreous) hybrids in situ (P<0.001). Starch in floury endosperm is associated with a digestible protein matrix that is easily degraded by ruminal bacteria (Kotarski et al., 1992). In contrast, starch granules in vitreous endosperm are embedded in a protein matrix that can resist enzyme hydrolysis (Rooney and Plugfelder, 1986). Vitreous protein matrix is more resistant to digestion because ruminal bacteria digest zein proteins more slowly than glutelin proteins (Romagnolo et al., 1994) and vitreousness of corn grain is positively correlated with concentration of zein protein and negatively correlated with true glutelin protein concentratio in corn grain (Philippeau et al., 2000). Because the protein matrix in floury endosperm is more easily hydrolyzed, greater microbial penetration of the starch granule occurs to increase rate of starch digestion. In this experiment, vitreousness (% of total endosperm ) of corn grain was 3.0 and 67.2% for floury and vitreous hybrids, respectively (Table 2), which represents the 2 extreme endosperm compositions of corn hybrids commercially available in the United States. Starch Digestibility Decreases as Vitreousness Increases 90
Dent Flint
Starch Digestibility %
80 70 60 50 40 20
30
40
50
60
Vitreousness %
70
80
According to Allen and Taylor, floury grain can be digested at nearly twice the rate of vitreous grain â&#x20AC;&#x201C;in large part due to the protein matrix of each hybrid type. In floury grain, the protein matrix is more easily degraded, whereas it takes more time for the vitreous matrix to be degraded. This allows for greater microbial penetration in floury hybrids, resulting in an increased rate of starch digestion.
Philippeau and Michalet-Doreau, 1997
As shown in Figure 1 (above), taken from an article by Dr. Charles Sniffen, as vitreousness increases, starch digestibility decreases. 7
Floury endosperm improved total tract DM and OM digestibility because of increased starch digestibility. Contrary to our hypothesis, no interaction of treatments for any measure of starch or fiber digestion occurred. Vitreous corn grain fermented more slowly and passed from the rumen faster, resulting in decreased ruminal starch digestibility…..Greater ruminal starch digestion in floury grain diets and lower ruminal pH for floury grain and bm3 corn silage did not affect ruminal fiber digestion kinetics, and a positive relationship between ruminal starch and dNDF digestibility suggests interactions among microbial populations in the rumen. Endosperm type of corn grain can affect digestion kinetics and site of starch digestion.
Floury corn hybrids also have better total tract dry matter digestibility due to their increased starch availability. This explains why fewer kernel pieces are seen in the manure when feeding floury grain to livestock; kernels are more fully digested instead of passing through the digestive tract. Recent research has evaluatead corn germplasm for differences in starch degradability (phillippeau and Michalet-Dorea, 1997; Correa et al, 2002; Johnson et al, 2002; Taylor and Allen, 2005) to improve corn grain and silage utilization by ruminants. Rumen degraded starch supplies energy to the animal through volatile fatty acid production and metabolism, and also contributes to protein metabolism through microbial mass, whereas post-ruminal starch is degraded to glucose (Hall, 2002).
Although effects of both maturity stage and corn germplasm type were observed for vitreousness and degradability, germplasm type had the strongest influence. This was particularly true for zero-hour disappearance and the ruminally degraded fraction. The results also suggest that endosperm carbohydrate properties other than virtuousness affect corn degradability. Endosperm Effects on Ruminal Starch Digestibility
DRY
HIGH MOISTURE
Floury
Vitreous
Floury
Vitreous
1006
1171
1198
1414
Vitreousness %
8.6
81.0
0.0
40.5
7h IVSD %
52.5
44.1
67.9
52.2
Apparent ruminal
69.6
51.6
87.7
76.2
Mean Particle Size
Digestibility %
Figure 2 – showing that apparent ruminal digestibility is much lower with vitreous grain than with floury grain – was also taken from Dr. Sniffen’s article.
8
Kernel vitreousness, the ration of vitreous to floury endosperm has been used to assess the type of corn endosperm (Ngonyamo-Majee et al., 2008a,b). Increased kernel vitreousness reduced ruminal in situ corn starch degradation(Philippeau and Michalet-Doreau, 1997; Correa et al., 2002; Ngonyamo-Majee et al., 2008b). Kernel vitreousness was lower and ruminal in situ starch degradation was greater for dry corn with floury or opaque endosperm than with normal dent endosperm (Ngonyamo-Majee et al., 2008a,b). Taylor and Allen (2005a) reported greater ruminal and total-tract starch digestibilities in ruminally and duodenally cannulated lactating dairy cows for floury (3% vitreousness) versus normal dent (67% vitreousness) endosperm dry corn. The above excerpt from an article on the influence of endosperm types in digestion reaffirms what Figure 1 (see page 9) showed: dent corns are more ruminally degradable than flint, and those with floury or opaque endosperm are even more degradable than regular dent corn. So, the softer the kernel, the more digestible the kernel. Starch that is broken down in the rumen supplies energy in the form of volatile fatty acid (VFA) production and metabolism. Another benefit that will be discussed more in-depth later is the contribution this makes to protein metabolism through increased microbial yield. rate of digestion and rate of passage: combined view
As we now see, floury grain has two distinct advantages over vitreous grain: a slower rate of passage and greater digestion within the rumen. So we can start to formulate what the overall difference between the two can look like when comparing ruminal starch disappearance. Through correspondence with Dr. John Goeser (Rock River Labs, WI), we began experimenting with various hypothetical scenarios to show the theorietical differences between vitreous (flinty) and soft (floury) corns. In the first scenario we assume a difference in rate of digestion (Kd) of 10% per hour â&#x20AC;&#x201C; setting the Kd for flinty corn at 15% and the Kd for floury corn at 25% â&#x20AC;&#x201C; and used a static passage rate (Kp). As shown in the table below, the total ruminal starch availability varied by more than 10 percentage points. 9
Scenario 1: Equal passage rate but different digestion rates Endosperm Type
Kd
Kp
Rumen Starch D
Flinty
0.15
0.08
65.2
12.5
Floury
0.25
0.08
75.8
12.5
Rumen Retention Time (hours)
In the second scenario, we assumed identical total ruminal starch availabilitiey, so we had to adjust the rate of passage (Kp). To achieve identical total ruminal starch availability, rumen retention time for the flinty variety (20.9 hours) was nearly twice that for the floury variety (12.5 hours). Keep in mind that according to Mike Allenâ&#x20AC;&#x2122;s work, the passage rate of .048 per hour required for the flinty variety to equal the rumenal starch degradability of the floury variety is completely unrealistic for hard varieties.
Scenario 2: Retention time required for equal digestion Endosperm Type
Kd
Kp
Flinty
0.15
0.048
75.8
20.9
Floury
0.25
0.08
75.8
12.5
Rumen Starch D
Rumen Retention Time (hours)
For the third scenario, we wanted to replicate a real-life situation to the extent possible so we could compare ruminal starch availability for floury corn and flinty corn. We retained the Kd rates for flinty corn and floury corn at 15% and 25% respectively. Then we set the Kp rate for flinty corn at slightly less than twice that of the floury corn, similar to what we have seen in other studies. The result was that ruminal starch digestion for floury corn was more than 20 percentage points greater than that of flinty corn.
Possible real scenario that dense (flinty) corn passes faster Endosperm Type
Kd
Kp
Flinty
0.15
0.10
60.0
10.0
Floury
0.25
0.06
80.6
16.7
Rumen Starch D
Rumen Retention Time (hours)
10
why is rumen degradability important?
Starch digested in the rumen is more efficiently utilized for milk production than starch digested anywhere else in the digestive tract because most benefits of starch digestion in the rumen come from microbial protein synthesis. Controversy exists as to the benefits of ruminal vs. postruminal starch digestion. Ruminal starch digestion is needed to provide substrate for microbial growth and propionate as a glucose precursor for milk synthesis but can reduce ruminal pH and inhibit fiber digestibility if starch fermentation is too rapid. If ruminal starch degradation is too rapid, flux of propionate to the liver might limit DMI if it is oxidized rather than used for gluconeogenesis (Oba and Allen, 2003c). Shifting starch digestion to the intestines can theoretically provide more glucose to the animal but infusion experiments have suggested that increasing small intestinal glucose absorption may not increase glucose available for milk production (Knowlton et al., 1998; Arieli et al., 2001). Instead, increased glucose may be used for tissue retention (Reynolds et al., 2001) or may be oxidized to CO2 (Knowlton et al., 1998). Microbial Yield Microbial cells are the primary source for metabolizable amino acids, which are important for milk synthesis and maintenance. Because ruminal starch digestion promotes microbial growth â&#x20AC;&#x201C;which is key to milk production â&#x20AC;&#x201C;it is important to maximize the digestion of starch in the rumen. Rumen microbes ferment dietary carbohydrates and protein to obtain Adenosine Triphosphate which in turn is the major source of energy required for microbial growth. The two major reactions of rumen fermentation are volatile fatty acids and microbial cells; the former are a primary source of metabolizable energy the latter the primary source of metabolizable amino acids for maintenance and milk synthesis. The efficiency with which dietary nutrients are converted to energy and protein for tissues and milk synthesis varies considerably and is not high. The question then is: Does feeding floury grain versus hard grain have an affect on microbial yield and if so, what is the effect on overall milk production? 11
Rock River Labs compared two Masters Choice hybrids, one a floury hybrid and the other a harder grain hybrid. The microbial yields for the two hybrids are shown in the following table, which also shows the difference in their 7-hour in-situ starch scores (an indication of starch availability). As the table shows, the floury variety, MC4210, had a much higher microbial yield than the hard variety, MC6460 - documenting the superiority of floury corn in promoting microbial yield in the rumen. Sample ID MC4210 MC6460
Total SH, HE, D Rock River Microbial Yield Hardness Rank Labs In-Situ 7h
84 (floury) 104 (hard)
49 33
1937 1804
â&#x20AC;&#x153;If one compares corn silage using CPM, a drop in 7hr starch degradability from 78% down to 70% will result in a 41 g drop in microbial MP supply and a decrease in microbial efficiency creating a 5 lb. decrease in milk.â&#x20AC;? -Dr. Charles Sniffen, Fencrest
As this quote from Dr. Charles Sniffen shows, a drop in microbial MP supply can have a major affect on your milk potential. This is one area where you will see a big difference in the feeding of floury versus vitreous corn hybrids. This also shows the importance of ruminal degradation of starch, which, as discussed earlier, is much higher in floury grain hybrids than in flinty or vitreous hybrids. Nutrient Uptake Calves undergo substantial developmental changes in the early days of their lives, which directly affect future productivity levels. South Dakota State University conducted a study to see if floury grain would have an impact on the calf starter fed during these formative days. In 2013, in a calf starter trial that Dr. Dave Casper performed at the university, 30 Holstein heifers were fed from one day to 42 days (when a majority of their diet was milk replacer) on one of two diets. The test diet contained 40% Masters Choice (MC) ground, shelled, floury corn. The control (C) contained 40% dry matter (DM) basis, ground-shelled, common elevator corn. Both experimental calf starters were formulated to contain 24% crude protein on a DM basis and were fed to ad libitum consumption as pellets starting on day 1. 12
From Cornell, Dr. Mike Van Amburg’s research on “Early Life Management and Long-term Productivity of Dairy Cattle”, he observed: “…increased nutrient intake prior to 56 days of life resulted in an increased milk yield during the first lactation that ranged from 1,000 to 3,000 additional pounds compared to restricted fed calves during the same period.” He explained that,”20% of the variation in the first milk lactation could be explained by growth rate to weaning.” Any increase in weight gain or ADG from birth to weaning can significantly increase the productivity of the calves later in life. The results of the calf starter trial are shown in the following table. The calves that were fed MC floury grain gained on average, four more pounds than the control group of calves –for a weight advantage of more than 10% in their formative days.
2013 CALF STARTER TRIAL SOUTH DAKOTA STATE UNIVERSITY
Weight Gain of MC-Fed Calves vs. Control Fed Calves Let’s also consider the differences in nutrient 89.3 89.5 Beginning Weights digestibility and mineral 1.49 1.62 Average Daily Gains digestibility for the two groups of calves in the trial. As shown 52.6 57.2 Total Gain in the following tables, both 141.9 146.74 Ending Weights (42d) nutrient digestibility and mineral digestibility were higher for the calves that were fed the Masters Choice floury grain than for those fed the control diet. Recorded Data (lbs)
MC-Fed Calves
Control Calves
Comparison of Nutrient Digestibility Nutrient
13
Control
MC
SEM
P<
DM
86.2
94.5
1.08
0.01
CP NDF ADF
85.2
91.1
1.17
0.01
55.6
65.2
4.42
0.11
54.2
68.5
3.49
0.02
Hemicellulose Starch
58.0
58.7
6.28
0.92
98.4
99.4
0.28
0.04
Comparison of Mineral Digestibility Nutrient Ca P Mg S Mn Fe Cu Zn
Control
MC
SEM
P<
67.1
80.3
3.01
0.01
82.4
87.2
2.46
0.20
53.1
71.6
4.65
0.01
79.2
87.3
1.82
0.01
65.3
77.0
4.67
0.06
39.1
51.6
4.45
0.05
81.8
65.7
5.85
0.06
47.4
63.6
6.20
0.04
Though we do not yet have an answer for why we are seeing these benefits in calf starter when using floury grain, they are interesting and warrant further investigation. It is especially intriguing when you consider the small percentage of the calf starter that floury grain makes up.
FEED FIRST Characteristically, silage that has ensiled longer feeds better. But producers occasionally find themselves in situations where they must feed relatively “new” corn silage. When feeding this newer corn silage, a decrease in milk production, or a “fall slump,” can result. However, floury grain often can be fed sooner after chopping than more vitreous corn silage hybrids. As mentioned previously, the γ-zein proteins that cross-link starch granules together require an extended period of ensiling so that the prolamins break down and the starch becomes digestible. Because floury hybrids have fewer of these proteins that cross-link the starch, they can be fed sooner - without a drop in milk production. A
B
Starch Granules
Compare these two photos, and notice the disappearance of the prolamin protein matrix in the corn in photo B.
Some data from Cumberland Valley Analytical Services (CVAS) further shows how starch availability increases with time in ensiling and then tapers off with no additional benefit. 14
Starch â&#x20AC;&#x153;This nutrient should be relatively stable over time. Some increase may be perceived as the absolute quantity stays constant and total dry matter drops slightly over time through continued fermentation and nutrient conversion. However, the IVSD7 (in vitro starch digestibility at 7hrs incubation) will increase as the protein matrix protecting the starch structure is broken down over time. There is a recognized relationship between increasing levels of ammonia and increasing starch digestibility.â&#x20AC;? Corn Silage, 3-Week Rolling Average, New England and Mid-Atlantic Storage Week
DM
CP
Sol P
NDF
Sugar
Starch
IVSD7
Sep
0
36.7
8.30
2.30
36.90
1.53
37.12
62.56
Sep 22
3
35.2
8.36
3.26
38.82
1.30
33.80
65.89
Oct 11
6
36.2
8.22
3.35
38.30
1.08
35.09
70.57
Nov 3
9
36.4
8.15
3.61
38.50
0.94
35.28
72.42
Nov 24
12
36.4
8.13
3.89
39.05
0.91
34.84
74.41
Dec 11
15
37.3
8.20
4.09
39.54
1.19
33.59
75.22
Jan 5
18
36.0
8.23
4.31
39.39
0.92
34.31
76.88
Jan 26
21
36.4
8.15
4.33
38.96
0.88
35.54
76.32
Feb 16
24
36.5
8.14
4.42
38.52
0.80
35.08
76.83
Mar 9
27
36.5
8.08
4.39
38.50
0.85
35.02
76.58
Data from the CVAS Fermentometer
MC Lineup Avg. MC4050 MC5250 MC535 MC590 MC4560 MC527 CVAS Samples CVAS Samples CVAS Samples CVAS Samples CVAS Samples
75.09% 75.79% 76.03% 77.97% 75.10% 81.00% 83.10% 65.89% 70.57% 72.42% 74.41% 75.22%
28 28 28 28 28 270 240 21 42 63 84 105
This table shows the results of the 7-hour starch test for Masters Choice floury grain samples and CVAS samples. Note that some of the Masters Choice samples, for example, for MC4560 and MC527, had much higher starch availability levels than those for the CVAS samples. The CVAS samples took more than 100 days to reach the same starch availability levels that the Masters Chocie floury samples achieved in only 28 days.
Early starch availability is the key reason that floury grain can be fed earlier in the season, without losing milk production. Again, the availability of starch in floury grain contributes to microbe production in the rumen without the need for extensive ensiling time.
15
EXTENDED HARVEST WINDOW One advantage of floury grain that we are learning more about is the potential for an extended harvest window. Although the ideal time for harvest is still around 32%-36% dry matter, starch availability for floury grain does not drop off nearly as sharply as for vitreous grain. In this experiment, corn samples were ground through a 4mm Wiley screen, which may have lowered the sensitivity of the in situ assay to detect differences in degradation between HM and BL. Corn hybrids of high vitreousness may have a greater decrease in starch digestibility in response to delayed harvest than hybrids with low vitreousness (Johnson et al., 2002). MC 2011/2012 45+ Samples
CVAS 10/1/13 - 11/20/13
DM%
7hr Starch
DM%
7hr Starch
28
78.34
28
69.8
32
79.09
32
71.1
36
77.03
36
71.4
42
74.88
42
67.5
46
73.16
45
66.3
Source: Cumberland Valley Analytical Services Study
As shown in this table, the floury hybrids (those in the left column) not only had a higher starch availability than the overall hybrid average to start. In addition, starch availability drops much more slowly in the floury hybrids as they matured past 36% dry matter â&#x20AC;&#x201C; allowing greater flexibility with regard to time of harvest.
REACTIONS IN POULTRY Though we have predominately been looking at floury grain and its performance in dairy cows, there have been studies showing the advantages floury grain has when fed to other livestock. We will look at a few of these advantages over the next couple pages. To this point, we have considered the performance of floury grain in dairy cows. Some studies have shown the advantages of floury grain when fed to poultry. In 2011 and 2012, the University of Illinois performed two rooster assays to determine the true metabolizable energy (TME) of various corn hybrids. In both studies, the roosters were fasted for 26 hours to empty their intestinal tracts of all digestive residues from previously consumed feed. The roosters were then divided into either three (2011 test) or two (2012 test) groups and tube-fed 30 grams of one of the test corn varieties. All corns were ground to a similar particle size. 16
After the tube feeding, the roosters were returned to individual cages where total excreta was collected for 48 hours. The excreta were then freeze-dried, ground and analyzed for gross energy and nitrogen, and a TME was calculated for each rooster. In the 2011 test, in which there were three corn varieties, the most floury variety provided TME measurements that exceeded the two other varieties by a range of 41-52 kilocal/kilogram. This advantage is roughly the same as the gain in kcal/kg that can be achieved with many commercial feed additive enzymes on the market. In the 2012 study, in which one hard variety and one floury variety were tested, the floury variety had a 30-40 kilocal/kilogram advantage over the hard variety. In 2012, Ana-Lab in Fulton, IL conducted a monogastric digestibility analysis on dry ground samples of floury corn and hard endosperm corn. Several floury and hard samples were ground to 3mm, which is similar to hammer mill and some to .8mm which is essentially dust, before being weighed and dropped into a vat containing simulated mono-gastric fluid. The samples were removed eight hours later and then weighed again. At the 3mm grind, the floury grain had a 17% increase in starch absorption which is representative of digestion. At .8mm grind â&#x20AC;&#x201C;much finer than one can reasonably be expected to grindâ&#x20AC;&#x201C;the floury endosperm hybrids maintained a 6.5% advantage in absorption over the hard endosperm corn.
17% Increased Digestion 17
.8mm Grind 6.5% Increased Digestion
3mm Grind
Hard Endo
Floury Endo
Hard Endo
Floury Endo
CONCLUSION As is the case with much of the agricultural industry, especially with regard to livestock and livestock feeding, there are many unresolved questions. What we do know about floury grain, however, is that it shows an advantage over hard grain in digestion through a slower passage rate, a higher rate of digestion and increased microbial production. Other advantages of floury grain are the option for feeding earlier in the season without extended ensiling time as well as the potential for an extended harvest window. If you have information or data that would contribute to our understanding of floury grain, or questions about what you have read here, please contact us through our website, www.flourygrain.com, or by emailing us at: info@flourygrain.com. Please watch our website for updates and new information as it becomes available.
CONTACT US You may also reach out to the following people for more information on this topic: Mark Kirk Kevin Koone Nutritional Research Manager Director of Research & Development mark@seedcorn.com kevin@seedcorn.com Scott Harris Jonah Atkins Sales Manager Marketing Manager scottharris@seedcorn.com jonah@seedcorn.com www.seedorn.com info@seedcorn.com 866-444-1044 We will also be posting updates and new information to www.flourygrain.com.
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