Technical information - nutrition

Molasses Rations for Beef Cattle



by Alex ASHWOOD

BRAHMAN NEWS JUNE 2008 Issue #159

The availability and price of stockfeeds is influenced by various domestic and international factors which impact on farm profits and the purchasing power of beef producers.

Whilst the ABARE Outlook (07-08) for winter cereals was better than the previous year, the estimated production is expected to be 42 per cent below the five year average.

Since this production prediction, adverse seasonal conditions led to a further deterioration in the winter crop potential. Subject to seasonal conditions and the area sown the 2008-2009 yields are expected to increase.

The Queensland and NSW 2008 sorghum crop forecast predicted an increase of 80 per cent on the previous year. The anticipated yields however may have to be revised downwards following excessive rainfall in central Queensland in February 2008 despite the bumper yields in south east Queensland

Additionally, it is predicated that the increased cost of fertilizer and fuel will seriously affect the areas sown to winter and summer crops in 2008-2009.

The area of cotton is estimated to have declined significantly (56 per cent) due to lack of irrigation water and areas sown are the lowest since the 1982-83 season.

Subsequently, variable crop harvests, increased costs and fluctuations in supply will negatively impact on the price beef producers have to pay for stockfeeds.

Note:

  1. The table clearly demonstrates the percentage rise in the cost of feed grains delivered in bulk to Sydney (Land Rural Press)
  2. Regional prices (per tonne) for whole grain (March 2008) clearly indicate the increased cost of grain to beef producers eg corn ($420); Barley ($375); Triticale ($390); Oats ($450), Sorghum ($305)
  3. The price rises are accentuated even further when producers purchase processed grains from feed merchants (eg $500-$535/tonne - Feb 2008).
  4. Furthermore the competition from the biofuel sector and increased global demand for grains and protein meals suggests that the present high costs of stockfeeds (Table 1) are unlikely to drop in the medium - long term (2009 - 2012).

Context

To enable stock to reach their full production potential they must be properly fed as young stock for growth and adult stock for performance (milk and/or meat).

Where cattle require supplementary and/or production feeding properly balanced by product feeds can provide suitable alternatives to the more expensive
traditional feedstuffs.

Often poor quality roughages are low in feed nutrients (ie energy, protein, minerals) and due to low digestibility and reduced total dry matter intake (TDMI) insufficient nutrients are available for growth and production.

Where there are adequate quantities of roughage nutrient intake can be improved with fortified molasses diets.

These diets can be formulated to supply additional energy, minerals and protein to improve the growth and production of various categories of stock.

Ingredients

The key ingredients in fortified molasses diets include molasses, true protein, urea and minerals.

Molasses

Molasses comprises of plant sugars and when fed at moderate levels is a suitable source of energy for beef cattle. It is also a useful source of sulphur which is essential when feeding non-protein nitrogen (npn) diets. Cane sugars are more soluble than grain starches which is advantageous when feeding urea (npn).

Table 1: Increased prices of Feed Grains

Barley $/T Oats $/T Sorghum $/T Maize $/T Wheat $/T Triticale $/T
1980-81 139 141 135 171 151 N/A
1990-91 123 107 136 167 135 125
2000-01 173 136 162 186 171 176
2006-07 294 367 271 338 289 297
Differences 121 231 109 152 118 121
($) 01-07
Differences 69 169 64 81 69 68
(%) 01-07
Source: Australian Commodity Statistics (2007)

Table 2: nutrient values of molasses

ME (MJ/kg DM) 11 - 12
CP% (crude protein) 2 - 3
CF% (crude fibre) 5
DM% (dry matter) 75
P - phosphorus (g/kg DM) 1.0
Na - sodium (g/kg DM) 2.2
Mg - magnesium (g/kg DM) 4.7
S - sulphur (g/kg DM) 6.5
K - potassium (g/kg DM) 31.7
Ca - calcium (g/kg DM) 6.0
Note: 1kg of molasses = 0.6 litres; 1 gal = 7kg; 1 litre = 1.5kg

Low in true protein, phosphorus (P) and sodium (Na) (Table 2), npn – molasses rations require supplementation with these key nutrients.

Energy is the most limiting & important part of a cows diet

Molasses contains adequate levels of calcium (Ca) and when combined with phosphorus supplements containing calcium there is no need for further calcium supplementation.

Molasses Toxicity

Molasses is most effectively utilised in rations with adequate roughage intake and the molasses intake does not exceed 25% of the diet (eg a 500 kg cow consumes 2.5% of her weight (ie 12.5 kg DM) and can effectively use 3 kg of molasses).

Molasses toxicity can be a serious issue with high molasses intakes (ie greater than 40 per cent DM) particularly if the molasses is diluted and/or fermented.

The symptoms of molasses toxicity are rapid breathing and muscular weakness followed by staggering, coma and death.

In high molasses diets with cows grazing succulent pastures, scouring and bloating can be a problem.

TRUE PROTEINS

Most proteins are broken down in the rumen by micro organisms and the products produced are used for production and maintenance.

Protein is the second most limiting nutrient in a cows diet

Protein sources differ in the rate they are digested (degraded) in the rumen. It is suggested that protein sources (particularly the protein meals) that are less degradable in the rumen (Table 3) are more beneficial for highly productive stock particularly when they are grazing low quality pastures. Selection of protein sources need to be based on availability, price and the ease they are incorporated into molasses mixtures.

Table 3 bypass potential of various sources of protein

Low Medium High
Barley Peanut meal Cottonseed meal
Oats Sunflower meal Meatmeal (1)
Wheat Soyabean meal
Ryegrass Linseed meal
Silage

Note:

1) Meat meal has a high bypass (ie low degradability in the rumen) but is banned from stock feeding

2) Cost of crude protein ($/kg) = cost of feed ($) ÷ crude protein content (DCP%)

3) Traditional “energy” feeds provide a high proportion of true protein in the diet.

Urea

Urea can stimulate digestion and improve total dry matter intake when cows are grazing roughages with a low crude protein content (ie less than 10 per cent CP).

In low protein diets urea can be an effective source of nitrogen

Urea is 46 per cent nitrogen and 50 kg of urea theoretically contains the equivalent of 143 kg of protein (kg nitrogen x the conversion factor – 6.25 ie 23 kg N x 6.25 = 143.7 kg).

The rumen conversion of npn to protein depends on a number of factors, the most important are a suitable source of energy and sufficient sulphur.

Prilled urea should not be diluted with water

Prilled urea fertiliser is used at 2-3 percent by weight of the molasses (ie 20-30 kg/tonne of molasses). Urea must be introduced gradually, ie 0.5% week 1, 1% week 2, 2% week 3 and 3% week 4. (Note: at peak intake maximum intake should be less than 60 gms/cow/day).

Urea Toxicity

Urea can be highly poisonous if intakes are greater than 3 per cent of the mixture particularly if the stock are unaccustomed to npn diets. Symptoms include rapid breathing, uncoordinated gait followed by rigidity/paralysis and rapid death (within 2 hours). Urea poisoning is caused by:-

  • Inadequate mixing in the molasses
  • Accumulation and intake of undissolved granules
  • Excessive intakes of molasses – npn mixture
  • Dilution of the molasses with water leading to drinking and high intakes
  • Miscalculation of the amount of urea added to the molasses.

Remedies are only partially successful and quick action is essential. A suggested drench (limited success) comprises of 1 litre of vinegar followed after signs of recovery with ½ litre of molasses and ½ litre of warm water. Urea poisoning is reduced by:

  • Gradual introduction of stock to npn – molasses mixtures
  • Satisfying the mineral requirements of stock prior to feeding molasses and npn (reduces cravings)
  • Thorough mixing of the correct levels of urea
  • Limitors (eg salt) to avoid excessive molasses intake
  • Sufficient troughs to allow easy access of stock
  • Avoid feeding in wet periods and protect troughs from dilution by rain
  • Molasses troughs should be located away from stock watering sites

Minerals

Low quality roughages generally have low levels of minerals with reduced availability further limiting the intake of key nutrients for production. Minerals that are required in molasses – npn and low quality roughage diets include phosphorus (P), sodium (Na) and copper (Cu). The additional cost of mineral supplementation is generally offset by improved production and reproduction. The nutritional requirements for macro minerals are shown in Table 4.

Table 4: MACRO MINERAL REQUIREMENTS FOR BEEF CATTLE

Mineral gms/kg DMI
Calcium (Ca) 2.0 - 11.0
Phosphorus (P) 1.0 - 3.8
Chlorine (Ci) 0.7 - 2.4
Magnesium (Mg) 1.3 - 2.2
Potassium (K) 5.0
Sodium (Na) 0.8 - 1.2
Sulphur (S) 1.5
Source: CSIRO 2007

Note: Mineral requirements are given as a range (Table 4). The higher values are for rapidly growing and lactating animals and the lower value for maintenance or low levels of production (see Table 5 for P and Ca examples).

Phosphorus (P)

Phosphorus is essential for energy utilisation, bone health and conception rates. Poor intakes of phosphorus can lead to suppressed appetites, lower feed intake and reduced production and reproduction. Table 5 shows the P requirements for various categories of stock.

Table 5: RECOMMENDED Ca & P ALLOWANCES FOR CATTLE

Class of stock Weight (kg) Gain gms/day P gms/day Ca gms/day
Weaner (growing) 150 0.5 6.2 9.2
150 1.0 10.9 16.0
300 0.5 7.4 11.5
300 1.0 11.7 17.7
400 0.5 8.5 13.7
400 1.0 13.2 20.0
Adult (cow) 500 0.0 4.3 9.0
Additional Requirements
Lactation Allowance: In general add 1.9gms Ca and 1.4gms of P for each 1 litre of milk
Pregnancy Alowance: Months 5 - 6 (2.3gms Ca & 1.1gms P)
  Month 7 (5.3gms Ca & 2.2gms P)
  Month 8 (8.7gms Ca & 3.6gms P)
  Month 9 (13.2gms Ca & 5.7gms P)

Table 6: suitable phosphorus sources and adjustment rates

Product Ingredient Phosphorus Content (5) Adjustment Rate
Kynofos 27® Mono and dicalcium phosphate (50 : 50) 21 -
Buphos® Mono and dicalcium phosphate (67 : 33) 21 -
Palaphos® Dicalcium phosphate 15.3 X1.25
DCP Dicalcium phosphate 18 X1.12

Note: the rate adjustment shown is the amount by which you will need to multiply the figure given in Table 7 eg if you use DCP for 30 weaners you will need 2 kg (Table 6) x 1.12 (Table 5) = 2.24 kg DCP

Macro ammonium phosphate (MAP) and diammonium phosphate (DAP) are not recommended for stock since they contain fluorine and if fed for extended periods can cause fluorosis.

Moderate intakes of undiluted molasses have insufficient levels of phosphorus

Alternative sources of phosphorus include mono and dicalcium compounds which are low in heavy metals (fluorine and cadmium) are mixed with molasses at 1-2 per cent by weight (Table 6).

Sodium (Na)

Very rarely are there clinical symptoms but sodium deficiencies can lead to reduced appetite and weight loss. Stock in tropical and subtropical climates where substantial sweating occurs have much higher sodium requirements than cattle in cool climates.

Additionally, tropical grasses usually have lower levels of sodium than temperate grasses (eg the sodium content of kikuyu is only 1/10 that of ryegrass.

Salt intake should not exceed 5 per cent of TDMI which is far in excess of stock requirements. Stock have fairly good mechanisms to eliminate excess salt but high salt intakes can lead to digestive disorders.

Potassium (K)

Potassium is closely related chemically and nutritionally to sodium. Whilst stock have high nutritional requirements for potassium, the high levels in molasses and tropical pastures reduces the need for supplementation in undiluted molasses diets.

Sulphur (S)

Sulphur is necessary for optimal microbial growth and sulphur is particularly important in npn diets. Fortunately sulphur levels are adequate in molasses reducing the necessity for sulphur supplementation.

Where sulphur supplementation is necessary sodium sulphate, calcium and magnesium sulphate are suitable compounds.

Magnesium (Mg)

Magnesium has a key role in numerous enzyme systems especially involving energy transfer and utilisation. Like calcium, magnesium reserves are mobilised from bone reserves. Whilst molasses and cottonseed meal have higher levels of magnesium than grains, with fast growing tropicals additional magnesium may be necessary 2 weeks prior to calving where there is “slow” calving syndrome in heifers (eg 100 gms Epson salts + 50 gms gypsum/animal/day).

Trace Minerals

As the name suggests, trace (micro) minerals are necessary in small amounts (ie mg/kg) for normal function but if fed in excess can be toxic. Subject to location the key trace minerals are copper and selenium.

Copper (Cu)

In certain localities low levels of copper can reduce reproductive performance. Where deficient, copper sulphate at the rate of 14 gms/2.5 kg urea can be included into the molasses mixture. A more effective source of copper is by injection. Like many minerals, copper can be lethal if administered incorrectly.

Fortified Molasses

Urea-molasses supplements improve the nutritional intake of stock grazing low quality roughages. However, stock with high levels of production (growth/milk) require extra protein and minerals, ie fortified molasses mixtures.

Fortified molasses mixed on farm, can be an economic and nutritional alternative to higher priced stock feeds. Other options include a wide range of commercial molasses based products (eg Anipro 81c/L and Prolix 55c/L – Northern Rivers NSW - 2008).

When npn-molasses, mineral and protein mixtures are fed it is important to:

  • Ensure that the stock have access to adequate roughage since fibre is necessary for rumen function.
  • Commence with a mineral-molasses mix to prevent stock over eating initially to satisfy possible cravings for minerals.
  • Incorporate the correct amount of urea, following an introductory schedule (previously discussed ie 3% over 4 weeks)
  • Prilled not granulated urea must be thoroughly mixed in non diluted molasses plus minerals.
  • Protein meals should be added last to ensure the npn and minerals are well mixed
  • Intake should be monitored. With excessive consumption, the amount of urea in the mix needs to be reduced (ie maximum intake/cow/day = 60 gms). Any protein deficiencies as a result of lower urea content can be met with additional true protein.
  • Prevent the possibility of diluted mixtures (rain) and excessive intakes (drinking).

Bottom Line

If used correctly fortified molasses mixtures are a nutritional, economic feed for beef cattle grazing roughages low in energy, protein and key macro minerals. Nevertheless, fortified molasses rations require the following considerations:

  • To meet the production requirements for high performance (growth and/or milk) additional true protein is required.
  • For maintenance and low-moderate levels of production there is no value in including additional true protein if the ration contains 12-13 per cent crude protein.
  • With diets with >10% CP there is little benefit in adding npn but minerals and true protein may be required for high performance.
  • Urea utilisation requires the inclusion of a readily available supply of carbohydrates (energy) eg molasses.
  • Energy utilisation is dependent on protein intake but excess true protein is an expensive energy source.
  • Stock unfamiliar to npn are more likely to develop toxicity symptoms and urea must be thoroughly mixed and introduced gradually (see previous notes).
  • Urea should only supply one third of the total dietary protein and a maximum of 50-60 gms/cow/day. Additional protein requirements can be met with true protein (eg cottonseed meal) particularly young stock.
  • Diets comprising of low quality roughages do not have sufficient energy and protein for effective rumen function.
  • Energy is the main limiting nutrient to production but optimal utilisation requires a balanced intake of protein and minerals.
  • Reduced intake and deficiency in nutrient intake (energy, protein and minerals) occurs with roughages with <65% digestibility. Low digestible feeds lead to the accumulation of undigestable material, ie “rumen-fill” is reached before nutritional requirements are met”.
  • Key macro minerals (eg P) are necessary to improve the effectiveness of fortified molasses rations and meet stock nutritional requirements.
  • Molasses (ex mill) is available seasonally. Since molasses is difficult to handle proper storage, mixing and feeding out equipment is essential to efficiently use fortified molasses mixtures.

Table 7: FORTIFIED MOLASSES RATIONS ON LOW QUALITY PASTURES

Class of stock Molasses (kg) Cottonseed Meal (kg) Urea (kg) Phosphorus (kg)
(a) 30 cows with calves at foot to improve lactation and reproduction 250 50 7.5 (2.4%) 3
(b) 30 cows in late lactation to improve condition score (CS) 250 25 7.5 (2.6%) 3
(c) 30 springing cows and heifers to improve CS 250 - 7.5 (2.8%) 2
(d) 30 weaners (200kg) to improve growth (Note: urea fed at a maximum of 2%) 125 50 2.5 (1.3%) 2

Note:

  • These amounts should be fed twice per week (ie approximately 20.7 kg/cow/week (a,b,c) or 2.9 kg/day and weaners approximately 11.9/weaner/week (d) or 1.7 kg/day.
  • Should stock consume their allocation do not provide extra mixture.
  • Salt can be added to suppress intake.
  • See Table 5 for phosphorus adjustment rates for the various P supplements