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IMAIZE grain for dairy cows

maize grain for dairy cows

THE NZ FAMILY OWNEDMAIZE SEED BUSINESS

WELCOME

CONTENTS

02 INTRODUCTION

03 NUTRITIONAL BENEFITS FOR DAIRY COWS

03 Feed value relative to other concentrates 04 Rate of starch digestion & other nutritional benefits 05 Impact of maize grain on milk protein 06 Impact of feeding maize grain on cow condition score & reproductive performance 07 Substitution rates (concentrate vs. forage)

08 environmental benefits of feeding maize grain

08 Reduced dietary nitrogen

09 economic benefits of feeding maize grain

09 Milk response rates (DM or energy basis) 10 Increasing milk protein

11 other benefits of feeding maize grain

11 Labour 11 Convenience 11 Reliability of supply 11 Price stability

1 2 Maize grain options for dairy cows

13 Dry grain 13 Alkagrain 13 High moisture corn 13 Earlage

14 feeding guidelines for maize grain

14 Feeding rates 14 Acidosis

15 processing dry maize grain for dairy cows

15 Methods of processing maize grain 15 Roller, hammer and disc mills 16 Comparing hammer mills & roller mills 17 Steam flaking and steam rolling 17 Impact of particle size on starch digestion & milk production 17 Grain processing targets 17 Time between processing and feeding

18 in-shed feeding systems

18 Benefits and limitations 19 Cost of in-shed feeding systems 19 Suppliers of in-shed feeding systems

20 sourcing maize grain

20 Economics of growing maize grain

21 references

INTRODUCTION During the past decade New Zealand dairy farms have intensified, with farmers milking more cows per hectare and producing more milk per cow. Feed demand per hectare has increased at a greater rate than pasture supply and as a consequence, there has been a move away from all-grass towards farm systems that strategically use supplementary feeds.

While many farmers have recognized the benefits of feeding home-grown or purchased forages such as maize silage, there has been a large increase in the use of concentrates fed, mainly through in-shed feeding systems. In-shed feeding systems are convenient, allowing farmers to easily feed concentrates during milking by simply pushing a button or pulling a cord. While feeding forages normally requires some forward planning, concentrates can usually be purchased as required.

There are a range of concentrates available on the New Zealand market including grains, dairy meal, molasses and palm kernel extract. Maize grain is increasing in popularity with dairy farmers. It has a number of key advantages over other grains and concentrates.

key advantages of maize grainFive key advantages of maize grain over other grains and concentrates include:

It is the highest quality commonly-used concentrate with higher energy levels than other grains, molasses, palm kernel extract and the majority of dairy meals.

It is more slowly digested in the rumen than other grains, decreasing the risk of acidosis.

It has a high starch content which drives milk protein percentage. Since milk protein is worth substantially more than milk fat, this increases milksolids returns.

1

23

It’s low nitrogen content means it can be used to reduce urinary nitrogen levels, decreasing nitrogen leaching.

Maize grain is locally grown which means its price and supply is not subject to the exchange rate or overseas demand.

4

5

02

nutritional benefits for dairy cowsfeed value relative to other concentratesHigh producing cows have a high energy requirement and they must be fed high amounts (kgDM) of high energy density feeds.

A concentrate is a feed with a high concentration of energy. It contains highly digestible components like starches, sugars, other readily available carbohydrates, and fats or oils. Concentrates are mostly processed, i.e. ground, kibbled or pelleted and have very little physically effective fibre. Concentrates create less pasture substitution than forages (such as fresh crops, silages or hay) and they can add additional energy and other nutrients to fill deficits in the diet.

Pasture quality varies throughout the season and pasture-based diets can be deficient in energy and/or protein at times of the year. The composition of the base diet which in New Zealand is usually pasture, will determine the best concentrate option to feed.

Concentrates which are commonly available in New Zealand include dairy meals, maize or cereal grains (wheat and barley), molasses and palm kernel expeller (PKE). Maize grain has higher energy content than other grains and many other commonly available concentrates.

Concentrates have differing sources of energy. Some feeds deliver energy via sugar (e.g. molasses) or fibre and fat (e.g. PKE). Maize grain energy comes mainly from starch. The nutrient composition of feeds (Figure 2) influences how they are digested and the end products of digestion affect milk component levels (Figure 4).

Rate of starch digestion and other nutritional benefitsAlthough starch and sugar deliver high density energy, over feeding can cause a negative animal health effect known as acidosis. Acidosis occurs when high levels of sugar or starch are converted to large quantities of acid by the rumen microbes. This results in a fast reduction in rumen pH with negative effects on rumen digestion. While the amount of starch or sugar fed is critical, the speed and extent of starch digestion also influence the risk of acidosis. Maize starch is less risky than many other starch types because it is digested more slowly and to a lesser extent in the rumen.

Figure 1: Typical energy values of New Zealand concentrates1,2

Figure 2. Typical nutrient composition of concentrates3

Figure 3. Rumen degradability of maize grain compared with wheat grain4.

120

100

80

40

60

20

0 6 12

Hours in situ

18 24 30 36 42 48

Rum

en de

grad

ation

(%)

Wheat Maize

12.0

13.0

12.5

13.5

14.0

11.0

11.5

10.0

10.5Met

aboli

sable

Ener

gy C

onte

nt (M

JME/

kgDM

)

MaizeGrain

Barley Wheat Typical Dairy Meal

Oats Molasses Palm Kernel

13.6

13.0

12.6

12.0

11.5

11.0 11.0

Dairy Meal*

Molasses

Oats

PKE

Barley

Wheat

Maize Grain

0% 20% 40%

% Nutrient Composition

60% 80% 100%

Starch %DM

Soluble Sugars %DM

NDF %DM

CP %DM

Fat %DM

03 04MAIZE grain for dairy cows

nutritional

An extended research project in Germany demonstrated that maize starch is digested in the rumen to a lower extent than wheat starch. This resulted in a healthier rumen pH reflected also by a higher rumen digestion of fibre which is a typical indicator of rumen health.

a and b Values are significantly different from each other (P<0.05)

Table 1. Effects of different concentrates (containing 87% maize grain or 87% wheat) on rumen digestion5

MAIZE WHEAT

Starch digested in rumen (%) 76a 95b

Rumen pH 5.8a 5.5b

Crude fibre digestion of diet in rumen 76a 69b

Table 2. Effect of carbohydrate type on milk and milk component yields6

pasturestarch

(maize grain)fibre (broll)

sugar (molasses)

Drymatter intake kg/day 14.9 17.6 18.1 16.1

Pasture kgDM/day 14.9 13.7 13.5 14.9

Concentrate kgDM/day 0 3.9 4.7 1.2

ME intake MJ/day 2119 2369 2516 2214

Milk yield kg/day 23.14 27.7 26.21 23.56

Fat yield kg/day 1.03 1.07 1.16 1.06

Crude protein yield kg/day 0.8 1.01 0.94 0.79

Impact of maize grain on milk protein Feeding starch, fibre or sugar based feeds has an effect not only on rumen digestion, but also on milk yield and milk composition.

A New Zealand study6 investigated the effects of feeding different types of concentrates in addition to pasture:

Ê Starch – maize grain

Ê Fibre – broll (wheat middlings)

Ê Sugar – molasses

While energy intakes were similar between starch and fibre feeds, there were significant differences in milk yield and composition.

Maize grain feeding resulted in higher milk and milk protein yield. The authors concluded: “Early lactation cows offered energetically similar supplements differing in carbohydrate type responded differently in milk and milk component yields. Compared with an unsupplemented pasture diet, starch-based supplements increased milk and milk protein yield, but did not affect fat yield, whereas fibre based supplements primarily increased milk and milk fat yield. Bolus doses of sugar (molasses) did not affect milk or milk component yields in this study6”.

Pasture Starch (maize grain)

Fibre(broll)

Sugar(molasses)

20

21

22

0

0.2

0.4

0.6

0.8

1

1.2

1.4

23

24

25

26

27

28

29

milk

yield

kg/d

milk

solid

s yiel

d kg/

d

Milk Yield kg/day Fat Yield kg/day Crude Protein Yield

Impact of feeding maize grain on cow condition score and reproductive performanceThe benefits of having cows in better condition (the target is condition score 5.0 for mature cows and 5.5 for two and three year old cows) are substantial. A cow calving at condition score 5.0 will produce on average 12 kg more milksolids than a cow that calves at condition score 4.0. Cows that are fatter at calving cycle earlier, have higher in-calf rates and are more likely to give birth to a heifer calf the following year.

Figure 4. Impact of feeding different supplement energy types on milk yield and composition6

Figure 5. Relationship between BCS at calving and annual milksolids production7


nutritional

Milk

solid

s pro

duct

ion kg

/cow

Calving BCS

400

425

450

475

2 3 4 5 6 7 8

Impact of feeding maize grain on cow condition score and reproductive performance CONTINUEDFollowing the post-calving period of body condition score (BCS) loss, cows begin to gain BCS. The rate of gain is affected by both genetics and nutrition. In general high milk production cows gain less BCS than low yielding cows, while milking cows fed supplement that contains non-structural carbohydrates (i.e. starch and sugar) gain more BCS than cows fed pasture alone. With the decline in mid-season pasture quality (and possibly insufficient quantity), BCS gain slows down or cows lose BCS once more. This loss of BCS is different to the loss in BCS post-calving and can be minimised by ensuring pasture quality is high or by providing the cow with high quality supplementary feeds when there is insufficient pasture7.

Cows selected for high milk production preferentially partition nutrients to milk production and not to BCS gain. BCS increases much more quickly when cows are offered supplements to pasture after they have been dried off. However different feeds are used with different efficiencies for BCS gain. Energy in autumn pasture is used inefficiently for gaining BCS. Energy from feeds like pasture silage, palm kernel extract (PKE) and maize silage are used 50% more efficiently7.

Substitution rates (concentrate vs. forage)When grazing cows are fed supplements, pasture drymatter intake usually decreases. The rate at which pasture is replaced by supplements is known as the substitution rate.

Forage supplementation decreases pasture drymatter intake more than concentrate. Trials have shown that the substitution rate ranged from 0.84 kg to 1.02 kg for grass silage supplementation and from 0.11 kg to 0.50 kg for concentrate supplementation8.

In practical terms this means that feeding concentrates to grazing cows will reduce pasture intake, on average 0.3 kgDM pasture/day for each kgDM concentrate eaten. It will lift total energy intake and enable cows to produce more because metabolisable energy intake is the first limiting factor for milk production for most New Zealand cows.

Feeding forage (e.g. pasture, cereal or maize silage) results in higher pasture substitution rates than feeding concentrates. This reduces grazing pressure and can be used to manipulate farm pasture cover levels reducing overgrazing.

environmental benefits of feeding maize grain

Reduced dietary nitrogenThroughout the majority of the year New Zealand’s ryegrass-clover pasture contains more than 20% crude protein. At times, especially in the spring and during the autumn flush, pasture protein level can exceed 30% crude protein. Lactating cows require 14–18% crude protein to support milk production. While nitrogen excretion in milk and dung increases linearly with dietary nitrogen intake, nitrogen concentration in the urine increases exponentially as nitrogen intake increases9, 10. Put simply, the more nitrogen cows eat above requirements, the more they excrete in the urine and urinary nitrogen levels may be as high as 1000 kg N per ha.

Table 3. Effect of feed source on N output in milk, dung and urine in absolute and relative terms (in parenthesis)11.

type of silage n intakea n output kgn/cow (% intake)

(kgN/COW) Milk Dung UrineLucerne 37 6 (16) 8 (22) 23 (62)

Pasture 24 6 (25) 7 (29) 11 (46)

Cereal 16 6 (38) 5 (31) 5 (31)

Maize 12 6 (50) 3 (25) 3 (25)

Environment Waikato data shows that for a farm producing 850 kg MS/ha, using 100 kg fertiliser N with effluent applied to the land, 69% of the nitrogen loss comes from urinary nitrogen. Feeding a low protein feedstuff such as maize silage (7.5% crude protein) or maize grain (8% crude protein) in conjunction with high protein pasture dilutes dietary protein content and reduces nitrogen excretion by the cow (Table 3).

a Based on 1tDM/cow.

Maize grain can be grown in lower risk areas and fed in sensitive catchments to decrease dietary and therefore urinary nitrogen.

Figure 6. The relationship between daily total N intake and N output in dung, milk and urine10.

3000

50

100

150

200

250

300

350

350 400 450 500 550 600

N intake (g/day)

N ou

tput

(g/d

ay)

07 08

environmental

Urine

DungMilk

Table 4. Seasonal milksolids response to supplements (on a drymatter and energy (MJME) basis)12

time of season milk response rate*

(gMS/MJME) (gMS/kgDM) @11MJME

Spring 8.0-12.0 90-130

Summer 7.5-11.0 90-120

Autumn 7.0-8.0 80-90

* Residuals <6 clicks (1,350 kg DM/ha) if no supplement fed

Table 5. Estimated milk revenue ($ in bold) from feeding 1 tDM of different supplements fed through an in-shed feeding system16.

feed percent of extra milksolids is: milk price ($/kgMS)

Fat Protein $5.50 $6.50 $7.50

PKE 75 25 $370 $440 $510

Barley 25 75 $570 $675 $780

Maize grain 20 80 $675 $800 $920

*Adapted from Roche and Hedley, 2011. Supplements – the facts to help improve your bottom line. DairyNZ Technical Series July, 2011 p 6-10. Assumes grazing residuals of 1,500-1,600 kgDM (7-8 clicks on RPM). Responses decline when residuals are higher than 1,600 kgDM (i.e. cows are better fed). For a full list of assumptions see http://www.dairynz.co.nz/file/fileid/37671.


economic benefits of feeding maize grain

economic

Milk response rates (DM or energy basis)The response rate to supplements varies depending on a number of factors including the type of supplement, the time of the year when it is fed, pasture cover levels and the total drymatter intake.

Strategic feeding (e.g. using feeds to extend lactation or to fill feed deficits during the lactation) will normally generate a higher milksolids response rate than feeding continuously throughout the lactation.

DairyNZ’s Facts and Figures for New Zealand Dairy Farmers12 gives a range of possible response rates to good quality supplements (>10.5ME) fed with low (<15%) wastage (Table 4).

Data collected from 60 seasonal supply farms situated in the lower North Island and South Island was used to determine the response to grain being achieved under commercial conditions15. On average the farms fed 179 kg grain per cow per year with the range between 0-952 kg/cow/lactation. Average milksolids production was 435 kgMS/cow with a range from 310-595 kgMS/cow. The average response to grain was 88 g MS/kgDM fed in the 2009-10 season and 146 g MS/kg fed in the 2010-11 season. The average response over the two years was 117 g MS/kgDM grain. The short-term response to grain varied between seasons with the response rates being:

Ê Spring (50 – 54 g MS/kgDM grain fed)

Ê Summer (141 – 193 g MS/kgDM grain fed)

Ê Autumn (116 – 138 g MS/kgDM grain fed)15

Increasing milk proteinInformation published by DairyNZ16 shows that milk production is determined by the amount of energy a cow eats but the composition of the milksolids she produces is affected by the type of supplement fed.

Ê When cows are fed a starch or sugar-based supplement, they produce more milk protein.

Ê When cows are fed a fibre based supplement, they produce more milk fat.

Since milk protein is worth two to three times more than milk fat, starch and sugar based supplements will deliver more milk revenue than fibre-based supplements.

A number of New Zealand trials have measured the milksolids response of cows fed grain:

Ê In the 1.75 t MS/ha trial, Herd 6 was fed a total of 1,247 kg maize grain per cow during the lactation. The milksolids response rate was 99 g MS/kgDM fed or 7.6 g MS/MJME13.

Ê Penno et al. (1996) offered rolled maize to grazing dairy cows in a two year farmlet experiment. At a stocking rate of 3.24 Friesian cows per hectare annual milk yields were increased by 76 g MS/kgDM of grain fed. When stocking rates were increased to 4.48 cows per hectare annual response rate was increased to 88 g MS/kgDM grain fed14.

Ê In a further farmlet trial Friesian cows stocked at 4.41 cows per ha conducted over three complete seasons the milksolids response was 96 g MS/kgDM grain. Penno concluded that full lactation responses of 7.5 g MS/MJME can be expected when grain is offered to dairy cows grazing restricted amounts of pasture14.

milksolids response of cows fed grain

Table 6. Composition, harvest, processing and storage method of maize production options17

maize product compositionharvesting and

processing method

storage method

me mj/kgDM

Earlage

100% kernels +100% spindle + 80 - 100% husks+ <20% stover

Precision chopper with ear picker

Silage (bunker, bag or bale)

12.5

High Moisture Corn 100% kernels Combine and millSilage

(bunker, bag or bale)13.6

Dry Maize Grain 100% kernelsCombine, drying and cracking or grinding

Dry grain in bins 13.6

Table 7. Nutritional value of maize product options18

maize productdrymatter

%starch

%dmndf %dm

crude protein %

Earlage 55-65 50-60 20-25 8-10

High Moisture Corn 68-72 69-72 8-10 10

Dry Maize Grain3 89 75 9 8

LABOURThere is minimal labour required to feed maize grain through an in-shed feeding system compared to feeding silage or hay or grazing a green-feed crop. Usually the person milking the herd can “push a button” or “pull a cord” to feed each row of cows.

ConvenienceMaize grain is convenient to feed in that it can be ordered when required and delivered within a few days. In many cases payment for the grain is due at the end of the month by which time the grain has been fed and a milk return generated. This is very good for cashflow.

Reliability of SupplyThere is an established maize grain industry in New Zealand ensuring year-round supply of maize grain as and when required.

price stabilityThere are a large number of factors that impact the NZ landed price of imported feeds such as palm kernel. These include:

Ê Production costs at origin.

Ê World demand for the product.

Ê Shipping costs.

Ê Exchange rate.

Locally grown maize grain prices are subjected to less variation with the pricing being determined only by growing costs and local demand relative to supply. While the price of imported feeds tends to change on a daily basis, maize grain price is more stable over time.


other benefits of feeding maize grain

maize grain options for dairy cows

Maize grain can be fed as earlage, high moisture corn or dry grain. Product form has implications for pricing, logistics, losses and feed value.

other benefits options

feeding guidelines for maize grain

feeding ratesMaize grain feeding rates will vary depending on the age and production level of livestock and the amount and type of other feeds in the diet. General recommendations are as follows:

Ê Feed a maximum of 30% of the total drymatter intake as maize grain*.

Ê Start at lower rates (e.g. 1 kg maize grain per cow per day) and increase the feeding rates gradually over 7-10 days.

Ê Feed a maximum of 2.5 kgDM maize grain in a single feed.

* Feeding rates will be lower in diets that contain other sources of carbohydrates (e.g. other grains, dairy meal, molasses or high sugar or starch byproducts). Talk to your local veterinarian or nutritionist for farm specific advice.

Acidosis can occur when cows are fed either too much starch or sugar, or where the starchy/sugary feed has been introduced too rapidly into the cow’s diet. Starch and sugars are digested quickly by microorganisms in the rumen of the cow. The end products of this digestion are acids, which the cow then uses for energy. However, when a cow eats a lot of starchy or sugary feeds and/or she is not accustomed to these feeds, she produces dangerous levels of lactic acid, becomes ill, and in severe cases can die.

To reduce the risk of rumen acidosis always:

Ê Introduce high starch or sugar feeds into the diet slowly.

Ê Watch total dietary levels of starchy or sugar feeds.

Ê Ensure that the diet contains adequate levels of long (functional) fibre.

Ê Ensure that individual animals cannot gorge high risk feeds.

acidosis

feeding


dry grainMaize grain is normally harvested at 23-26% moisture (74-76% DM), transported to a drier and air dried to 14% moisture (86% DM). Dry grain has advantages for transport because very little water has to be shipped. It is also very stable and will hold its quality for long periods as long as it is kept dry. Dry grain needs to be processed to allow cows to efficiently utilise the nutrients it contains (see pages 15-17 for more details).

The feed value of dry grain is characterised by high energy density and a lower rumen degradation rate when compared to high moisture corn (HMC) or maize earlage.

13 14

Maize grain is normally harvested at 23-26% moisture (74-76% DM), transported to a drier and air dried to 14% moisture (86% DM). Dry grain has advantages for transport because very little water has to be shipped. It is also very stable and will hold its quality for long periods as long as it is kept dry. Dry grain needs to be processed to allow cows to efficiently utilise the nutrients it contains (see pages 15-17 for more details).


Alkagrain maize is a mix of maize grain and patented pellets which contain a unique mix of urea, soya and a specialist enzyme that breaks down urea to give off ammonia which is a powerful preservative. Maize grain is harvested at 65-82% moisture, processed, mixed with the pellets and stored in an airtight AgBag. Alkagrain maize has a higher protein content and higher digestibility than dry maize grain.

High moisture corn is typically harvested when the maize grain is between 68-72% drymatter using a combine. The grain is rolled prior to fermentation. The key advantages of high moisture corn are that it can be harvested prior to normal grain harvest maturity, there is no drying cost and it is very high in feed value. Dr. Mike Hutjens (University of Illinois, USA) likens this product to “rocket fuel”.

High moisture corn is not as easy to transport as dry grain. It must be ensiled and there is a loss in drymatter during the ensiling to feed-out process. High moisture corn has a potential for aerobic instability (heating at feed-out time) and because it has a relatively high moisture content for a concentrate, it will not flow through most in-shed feeding system.

Maize earlage is an ensiled product that has a feed value and yield that falls between that of maize grain and maize silage. It is normally harvested at 55-65% drymatter using a snapper head on a forage harvester. Earlage is normally harvested several weeks prior to grain harvest and because it is an ensiled product there is no requirement for drying. Earlage delivers some physically effective fibre which makes it safer to feed than other concentrate options. Earlage must be ensiled and there is a loss in drymatter during the ensiling to feed-out process. It contains more water and is less energy dense than dry grain so the transport cost per unit of energy is higher. Earlage has a potential for aerobic instability (heating at feed-out time) and it will not flow through in-shed feeding systems.

Figure 9: Ensiled high moisture corn

Figure 10: Earlage

Figure 7: Dry, processed maize grain

Maize grain feeding rates will vary depending on the age and production level of livestock and the amount and type of other feeds in the diet. General recommendations are as follows:

Feed a maximum of 30% of the total drymatter intake as maize grain*.

Start at lower rates (e.g. 1 kg maize grain per cow per day) and increase the feeding rates gradually over 7-10 days.

Feed a maximum of 2.5 kgDM maize grain in a single feed.


Acidosis can occur when cows are fed either too much starch or sugar, or where the starchy/sugary feed has been introduced too rapidly into the cow’s diet. Starch and sugars are digested quickly by microorganisms in the rumen of the cow. The end products of this digestion are acids, which the cow then uses for energy. However, when a cow eats a lot of starchy or sugary feeds and/or she is not accustomed to these feeds, she produces dangerous levels of lactic acid, becomes ill, and in severe cases can die. To reduce the risk of rumen acidosis always:

Introduce high starch or sugar feeds into the diet slowly.

Watch total dietary levels of starchy or sugar feeds.

Ensure that the diet contains adequate levels of long (functional) fibre. Ensure that individual animals cannot gorge high risk feeds.

Above: Cows eating of mix of feeds including maize grain and maize silage.

Figure 8: Alkagrain maize

13 14








Figure 10: Earlage













13 14








Figure 10: Earlage













13 14








Figure 10: Earlage













alkagrain maizeAlkagrain maize is a mix of maize grain and patented pellets which contain a unique mix of urea, soya and a specialist enzyme that breaks down urea to give off ammonia which is a powerful preservative. Maize grain is harvested at 65-85% drymatter, mixed with the pellets, processed and stored in a bag, under cover in a shed or in a silo. Alkagrain is preserved in an alkaline state. It has a higher protein content and is claimed to have higher ME and higher digestibility than dry grain maize.

high moisture cornHigh moisture corn is typically harvested when the maize grain is between 68-72% drymatter using a combine. The grain is rolled prior to fermentation. The key advantages of high moisture corn are that it can be harvested prior to normal grain harvest maturity, there is no drying cost and it is very high in feed value. Dr. Mike Hutjens (University of Illinois, USA) likens this product to “rocket fuel”.

High moisture corn is not as easy to transport as dry grain. It must be ensiled and there is a loss in drymatter during the ensiling to feed-out process. High moisture corn has a potential for aerobic instability (heating at feed-out time) and because it has a relatively high moisture content for a concentrate, it will not flow through most in-shed feeding systems.

earlageMaize earlage is an ensiled product that has a feed value and yield that falls between that of maize grain and maize silage. It is normally harvested at 55-65% drymatter using a snapper head on a forage harvester.

Earlage is normally harvested several weeks prior to grain harvest and because it is an ensiled product there is no requirement for drying. Earlage delivers some physically effective fibre which makes it safer to feed than other concentrate options.

Earlage must be ensiled and there is a loss in drymatter during the ensiling to feed-out process. It contains more water and is less energy dense than dry grain so the transport cost per unit of energy is higher. Earlage has a potential for aerobic instability (heating at feed-out time) and it will not flow through in-shed feeding systems.




Figure 10: Earlage

Table 8. Comparison between hammer mills and roller mills19

hammer mills roller mills

advantages

Produce a wide range of particle sizes Energy efficient

Work with any friable material and fiber Uniform particle-size distribution

Less initial purchase cost compared to roller mills Little noise and dust generation

Offer minimal expense for maintenance

Generally feature uncomplicated operation

disadvantages

Provide less efficient use of energy compared to the roller mill Little of no effect on fibre

May generate heat (source of energy loss) Particles tend to be irregular in shape and dimension

May create dust and noise pollution May have high initial cost (depends on system design)

Produce greater particle size variability (less uniform) When required, maintenance can be expensive

comparing hammer mills and roller mills

Figure 11. Roller mill (left) and hammer mill (right)

Figure 12. Maize particle size distribution – roller mill vs. hammer mill20


processing dry maize grain for dairy cows

processing

When unprocessed maize grain is fed to dairy cows 15-30% will pass through the digestive tract as undigested whole grain and therefore it must be processed to maximise its feed value. Processing grain disrupts the kernel and exposes the nutrients to rumen fermentation and lower gut digestion. Reducing the particle size or increasing starch solubility (such as in gelatinised or high moisture grain) increases the rate and level of rumen fermentation and digestion.

Methods of processing maize grainThere are a number of different mechanical methods that can be used to reduce the particle size of maize grain. In New Zealand the most common are the hammer mill and roller mill although other options include disk mills, steam-flaking and steam-rolling.

Roller, hammer and disc millsThe advantages and disadvantages of hammer mills and roller mills are shown in Table 8.

One of the key benefits of roller mills is that they tend to produce very evenly sized particles with fewer fines (less dust) and large particles which may pass through the cow undigested. Disc mills are a compromise between roller mills and hammer mills. They produce more noise and fines than a roller mill but less noise and fines than a hammer mill.

Perc

ent o

n

US Sieve Size

Roller Mill - 712u Hammermill - 708u

04 6 8 10 14 20 30 40 50 70 100 140 200 270 Pan

5

10

15

20

25

30

35

Delivery device

Delivery device

Hammers

Rod

RotorScreen

Take-away

Roll pair

Second roll pair

in-shed feeding systems

systems

A recent market research survey showed that 28% of New Zealand dairy farmers in Canterbury and the North Island have an in-shed feeding system. The key benefits and limitations of in-shed feeding systems are shown in Table 9.

Table 9: Benefits and limitations of in-shed feeding systems

benefits limitations

High utilisation with energy dense feedsMilk returns can be variable depending on the payout and the milksolids response

More accurate dispersion of minerals to every cowAt times it can be hard to source some concentrate feeds. (e.g. during a drought)

With new meal feeding technology individual cows can be allocated feed depending on their milk production level.

Feeding concentrates in the shed can, depending on the feed, cause unsettled milking (flies, cows not wanting to leave shed etc.)

Minimal labour. It is relatively easy to adjust feeding rates and cows can normally be fed by simply pushing a button or pulling a cord.

Cows cannot be stood off pastures and it is impossible to feed large quantities of feed or forages through a meal feeding system. Feeding dry cows can be a hassle.

Every cow has the opportunity to eat an equal amount of feed Intake is limited to a maximum of 4-5 kg/DM

Repairs and maintenance costs are typically very lowDue to the price per unit of energy farmers need to achieve greater milk response rate per kgDM fed for concentrates when compared to forages.

Figure 13. Effects of grinding vs. rolling and extent of maize starch digestion22


Steam flaking and steam rollingSteam-flaking and steam-rolling gelatinise starch by heat and steam application. However, the degree of “cook” is highly dependent on the amount of moisture, pressure, and heat actually obtained. Steam-rolled grain is usually steamed for 10-15 minutes to increase grain moisture. Then it is rolled into a thick flake with a density around 47.5 kg/hL. Steam-flaked grain is steamed for 30-60 minutes in a vertical steam chamber to increase grain moisture to 18-20%. Then it is flaked through rollers to a density of around 30- 37.5 kg/hL. Lower flake densities indicate more extensive processing and starch gelatinisation. Caution should be used against over-processing. In some studies, feeding low density flaked grains has resulted in lower production because of problems with intake and acidosis21.

Impact of particle size on starch digestion and milk production Maize that is finer ground has a higher digestibility than coarse ground maize. Fine grinding will increase total tract and rumen starch digestion and reduce small intestine starch digestion.

In a USA feeding trial, ground maize (568 micron particle size) or rolled maize (3458 micron particle size) was fed to lactating cows at 5.6 kg maize grain per day22. When compared to the rolled maize, the ground maize had 8% higher total tract digestibility, 16% more starch was digested in the rumen and 8.5% less starch was digested in small intestine (i.e. smaller particles shifted the site of digestion from the intestines to the rumen22) (Figure 13).

Perc

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ge st

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%)

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Rolled Ground

Small Intestine Large Intestine

0

10

20

30

40

50

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70

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53.5

69.8

31.9

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Grain processing targetsA fine line exists between maximum rumen performance and an unhealthy rumen environment particularly where a high amount of starch or sugar is being fed. The ideal amount of grain processing will depend on a number of factors including the amount of grain being fed, the frequency, the grain feeding system and the type and amount of forage in the diet.

Dr Mike Hutjens (University of Illinois) makes the recommendation that maize grain in USA dairy cow rations is ground to 1100 microns. He says, “To determine if your dry maize averages 1100 micron, take a cup of it and sift through a baker or kitchen flour sifter. If 2/3 of the grain passes through the screen, it is about 1100 microns”23.

Time between processing and feedingProcessed maize grain will hold its quality for long periods when stored in a clean, dry place.

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Cost of in-shed feeding systemsThe approximate capital cost of a meal feeding system including a hammer mill for a 60-bale shed is $70,000. Costs are as follows:

Suppliers of in-shed feeding systemsThere are a large number of suppliers of in-shed feeding systems in New Zealand. The table below includes some suppliers, but there are many others.

Table 10. Approximate cost of feeding supplements through a meal feeding system.

$/year

Interest ($80,000 @ 6%) $4,800

Depreciation (assume 20 year life) $4,000

Repairs and maintenance $700

Power $2,000

Total $11,500

Cost per kgDM (assuming 200 tDM/year ) 5.75 c/kgDM

Table 11: In-shed feeding system suppliers in New Zealand

company website phone

Advanced Feed Solutions Ltd www.advancedfeedsolutions.co.nz 03 215 9437

Central Silo Systems Ltd www.centralsilosystems.co.nz 06 358 5805

Corohawk www.corohawk.co.nz 0800 763 555

Landmore Agri Ltd www.landmore.co.nz 07 873 8900

Permbrand 2013 Ltd www.permbrand.co.nz 03 347 3171

PPP Industries Ltd www.pppindustries.co.nz 0800 901 902

REL Group (Integrated Farming Solutions) www.relgroup.co.nz 03 302 7305

Sonoma Enterprises www.sonomaenteprises.co.nz 09 551 0959

Delaval www.delaval.co.nz 0800 222 228

Table 12: Estimated cost per kgDM for a dairy farmer growing their own maize grain 2014/201524

InputsIndicative costs

($/ha)my costs

($/ha)

Soil testing 7

Base: Lime @ 1t/ha 70

Base fertiliser (300 kg/ha) + application 245

Cultivation 370

Pioneer® brand P0021 @ 94,000 seeds/ha 430

FAR levy 8

Seed insecticide treatment (Poncho®) 130

Starter fertiliser 250 kg/ha DAP + application 220

Planting 150

Pre-emergence weed control 60

Post-emergence weed control 70

Side-dressing 250 kg/ha urea + application 220

Spraying (two applications) 80

Harvest: Combine 380

Interest on $2,060 @ 10% for 8 months 140

Total costs (inputs + interest) $2,580

There are a significant number of grain companies who can supply whole or processed maize grain. Talk to your local maize planting or harvesting contractor or call 0800 PIONEER (0800 746 633) to speak to a pioneer representative & find the supplier closest to you.

Some farmers are choosing to grow their own supply of maize grain on farm or a run-off. Alternatively the crop can be harvested as earlage or high moisture corn. The latter two products are not suitable for feeding in most meal feeding systems.

Economics of growing maize grainThe cost of growing maize grain is shown in Table 12. Storage and processing costs must be added to give an estimated total cost per kgDM maize grain.

Table 12 continued on next page


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Table 12: Estimated cost per kgDM for a dairy farmer growing their own maize grain 2014/2015 continued24

Yield (t/ha wet) 12.14 13.29 14.45 15.61 16.76

Yield t/ha dry (14% moisture) 10.50 11.50 12.50 13.50 14.50

Cartage 50 km @ $18 per wet tonne 219 239 260 281 302

Drying (from 24% to 14%) @ $47 per wet tonne 571 625 679 734 788

Total cost/ha (growing to drying) $3,369 $3,444 $3,519 $3,595 $3,669

Maize grain cost ($/tonne of dry (14%) grain) 321 299 282 266 253

Cost per kgDM* 37.3 34.8 32.7 31.0 29.2

* Some grain companies can dry and store the maize grain on your behalf delivering it in smaller quantities throughout the season. The cost of storage and processing of the maize grain must be added to determine the final cost per kgDM.

References1Holmes et al, 2003. Milk Production from Pasture, Massey University, New Zealand

2Kolver, E. 2006. PKE – Economically priced supplement. Dexcelink Autumn 2006. *Dairy meal composition varies depending on the type and amount of components used in the mix.

3Kolver, E. 2000. Nutrition Guidelines for the high producing cow. Ruakura Farmers Conference pg 17-28. The nutrient composition of PKE and molasses are taken from DairyNZ Farmfact 1-71 and from the Agrifeeds website respectively.

4Rodehutscord 2003. Proceedings of the 2nd Pioneer Silage Conference, Brehna, Germany

5Matthé, A. 2001. Nutrient conversion in the digestive tract of ruminants after corn or wheat starch application in different amounts. p. 58 & 160. Ph. D. thesis, Univ. Giessen and Federal Agric. Research Center Braunschweig, Germany.

6Higgs et al., 2011. The effect of carbohydrate type on milk and milk component yields in early lactation dairy cows. Proceedings of the New Zealand Society of Animal Production 71:23-27

7DairyNZ. 2012. DairyNZ body condition scoring. The reference guide for New Zealand dairy farmers http://resources.dairynz.co.nz/DownloadResource.aspx?id=502

8Bargo, F., L. D. Muller, E. S. Kolver, and J. E. Delahoy. 2003. Invited Review: Production and digestion of supplemented dairy cows on pasture. J. Dairy Sci. 86:1-42.

9Castillo et al, 2001. The effect of protein supplementation on nitrogen utilisation in lactating dairy cows fed grass silage diets. Journal of Animal Science 79:247-253.

10Kebreab et al, 2001. Nitrogen pollution by dairy cows and its mitigation by dietary manipulation. Nutrient Cycling in Agroecosytems 60:275 – 285.

11Ledgard, S. 2006. Nitrogen management – why is it important and what can we do about it? Proc. 2006 Dairy3 Conference 4: 23-31.

12Dairy NZ, 2010. Facts and Figures For New Zealand Dairy Farmers pg 32-33

13Macdonald, K. 1999. Determining how to make inputs increase your economic farm surplus., Ruakura Farmers Conference

14Penno, J.W.; Bryant, A.M.; Macdonald, K.A. 1996. Effect of nitrogen fertiliser and supplements on pasture production and milksolids yield from dairy farm systems. Proceedings of the New Zealand Society of Animal Production 56:236-238.

15De Klerk, H. 2012. Milk Response to grain achieved by NZ pasture based farmers. SIDE Conference Proceedings pg. 327 -341.

16Roche, J. Hedley, P. 2011. Supplements – the facts to help improve your bottom line. DairyNZ Technical Series July, 2011 p 6-10.

17Mahlkow-Nerge, K. 2002. Earlage and Corn Cob Mix. Is their inclusion in high maize diets useful? Milchpraxis 4/2002 pg. 197-200.

18Hutjens, M. 2011. Harvest sooner with snaplage. Hoards Dairyman Aug 2011 p 529

19Koch, K. 2002. Hammer mills and roller mills. Kansas State University, May 2002

20Heimann. M. 2008. Advantages and disadvantages in particle size reduction techniques. American Soybean Association International Marketing, Singapore. http://www.asaimsea.com/index.php?language=en&screenname=__docs_Past%20Conference%20Papers%7CFTNW08

21De Ondarza, M. 2003. Grain processing. http://www.milkproduction.com/Library/Articles/Grain_Processing.htm

22Remond, D., Cabrera-Estrada, J.I.; Champion, M.; Chauveau, B.; Coudure, R.; Poncet, C. 2004. Effect of corn particle size on site and extent of starch digestion in lactating dairy cows. J. Dairy Sci. 87:1389-1399.

23Hutjens, M. 2008. Dairy strategies with expensive corn. The Dairy Site Wed 29th October, 2008. http://www.extension.org/pages/8994/dairy-strategies-with-expensive-corn

24Pioneer® brand Maize for Grain 2014 - 15

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Pioneer® brand products are provided subject to the terms and conditions of purchase, which are part of the labeling and purchase documents. ®, TM, SM, Trademarks and service marks of Pioneer Hi-Bred International, Inc. The information in this publication is general in nature only. Although the information in this publication is believed to be accurate, no liability (whether as a result of negligence or otherwise) is accepted for any loss of any kind that may arise from actions based on the contents of this publication. © 2014, Genetic Technologies Limited. No part of this publication can be reproduced without prior written consent from Genetic Technologies Limited.

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