BRAHMAN NEWS DECEMBER 2008 Issue #161
By-product feeds are generally available seasonally in large quantities, frequently vary in composition and often incur a high transport and storage cost. Often by-product feeds are nutritionally imbalanced and contain inadequate or too much of a particular nutrient.
Correcting nutritional imbalances and examining the unit costs of feeds are critical to the cost effectiveness of the feed and its efficient use in cattle rations both for production and drought survival feeding.
This is an energy and protein supplement. Its high protein (20-25%) content, high moisture content (75%) and reasonable fibre content (17%) make it a suitable supplement in high grain-low roughage diets. At $60-$80 per net tonne, the price on a dry matter basis is between $250-$320 per tonne.
The energy content of 10-12 MJ/kg DM, virtually nil protein, reasonable calcium and low phosphorus means that in low quality roughage diets molasses needs to be supplemented with protein and phosphorus. Molasses is sticky and heavy and difficult to handle.
Commonly known as 'white' or 'fuzzy' cotton, WCS is a useful source of energy (14 MJ/kg DM) and protein (22% CP).WCS is a very good source of several nutrients but has certain properties which restrict its use in beef cattle diets to 3kg per cow per day.
The actual availability depends on crops surplus to mill requirements or damaged crops (eg frosts). A major concern is the possibility of pesticide intake if the cane is harvested too low to the ground and the soil contains chemical residues.
Sugar cane diets have much in common with molasses based diets. The principle source of energy is sugar and the protein content is extremely low (2% CP). With high fibre (NDF) levels, low digestibility, an ME content of 6-8 MJ/kg DM and low levels of all major and minor minerals, the production benefits of feeding cane depend on the quality of the accompanying ration (eg feed lot diet).
This is the fibrous residue remaining after the sugar juices have been extracted from sugar cane. It is widely used as a fuel in factory boilers and in the landscape industry.
Spraying bagasse with a 30% solution of sodium hydroxide increases its digestibility from 30 to 50%. Treated alkali bagasse fed at 10% of the TDMI and supplemented with high levels of protein and energy has been successfully fed in feedlot situations but weight gains have been lower than diets with better quality roughages.
Rice bran contains 12.5% crude protein, 12% crude fibre and 13.5% oil and is an attractive feed when fresh. Rice polishings is a finely powdered material with a similar energy and protein values but lower in fibre than bran.
Both bran and polishing can replace up to 25% of the grain supplement. In "fast" grain diets (eg wheat), polishings need to be fed carefully. Rice hulls are not recommended since they contain high levels of indigestible fibre and have a low energy content (3.5 MJ/kg DM). The hulls also have sharp edges that cause irritation to the digestive tract.
The outer shell of almonds are hammer milled to produce a product with high levels of non effective fibre, low crude protein (5%) and medium levels of ME (10.5 MJ/kg DM). Unlike macadamia meal, almond hulls have a low oil content (2%).
Macadamia meal is the by-product of macadamia shell and nut waste and provides an additional source of energy when fed to beef cattle. Since macadamia meal has a high oil content (15-20%) it is best fed in restricted quantities to cattle. High levels of fats/oils in the ration can reduce the digestion and intake of roughages and lead to reduced levels of production.
It is suggested that the maximum level of intake with stock grazing pastures and roughages is 10-15% of the total dry matter intake/day (TDMI). For example:
Some supplements and by-products already have high levels of fats/oils (eg whole cotton seed, palm kernel meal, bakery waste). With these feeds m/m intake should be restricted depending on the level of fat intake of the feedstuffs in the ration.
With high molasses diets (ie greater than 20% TDMI) the inclusion of m/m in the diet can compound the possible reduction of roughage digestion and intake.
Macadamia meal (m/m) like most by-product feeds has benefits and limitations. In pasture/crop based diets which contain 2-4% fat, m/m is best fed at a maximum of 10-15% TDMI to provide additional energy to improve production and weight gains.
Unless obtained and transported at low cost these products may not be economically attractive. Vegetable by-products need to be introduced gradually to stock and special care has to be taken to prevent overfeeding and digestive disorders (eg scouring). Choking can also be a problem with some vegetables (eg potatoes and pumpkins).
Hominy meal is the co product of maize milling. It has a high energy value (14 MJ /kg DM), 10% oil and 11% CP. It is a high energy feed suitable for all stock but needs to be introduced gradually to prevent digestive upsets.
The use of by-product feeds depends on their availability, cost, nutritional value, palatability and most importantly the absence of undesirable contaminants (eg pesticide residues).
As with all new feed products, by-product feedstuffs should be introduced gradually over a period of 10 days to improve acceptance by stock and reduce the problems associated with digestive disorders.
In general, the feeding of by-product feeds will require some degree of supplementation to balance nutritional deficiencies. It should also be noted that some by-product feeds when fed in combination (eg high oil and high sugar content feeds) can accentuate feed disorders and nutritional imbalances.