Introduction
Concentrates (also mixed feeds, compound feeds or concentrate mixtures) play an important role in modern dairy cattle feeding. Usually, as a basis of most dairy production systems, concentrates are used as a supplement to roughage. Although a specific ingredient can be called concentrate, practically it is a mixture of several ingredients mixed in a way as to cover requirements (energy, proteins, minerals and vitamins) of an animal at the least possible costs. The quantity and proportion of ingredients can vary (economics!), but the feeding value of a final concentrate should be kept constant according the requirements.
5.1 The Necessity for Concentrates
In high yielding dairy cattle, it is very difficult (or impossible) to meet nutrient requirements for maintenance and (high) production from only roughage. Poland experiences a constraint in production and utilization of roughage (in aspects of quantity, quality and economics). The digestibility of roughage is often low. This depresses the DMI. The quantity may be limited, and causes an increased demand and/or quality of concentrates. High yielding dairy cows need a better quality diet (tighter protein: energy ratio) than low yielding animals.
In comparing energy and protein requirements for a 600 kg cow at different production levels, respectively 1, 5, 10, 20 and 40 kg (all at 4% butterfat), results are presented in table
5.1.
Table 5.1: Energy & Protein for a 600 Kg Cow at Various Milk Yields (4%)
Requirements for: FUM DCP (gram) FUM / DCP
1 kg milk only 460 63 1 : 7.3
maintenance only 5013 390 1 : 12.8
maintenance + 1 kg milk 5450 450 1 : 12.1
maintenance + 5 kg milk 7250 710 1 : 10.2
maintenance + 10 kg milk 9500 1020 1 : 9.3
maintenance + 20 kg milk 14100 1650 1 : 8.5
maintenance + 40 kg milk 23800 2910 1 : 8.2
Not only the required amount of food increases with increasing production, but also the quality of the requirements increases (DCP : FUM ratio getting tighter).
Conclusion
More and better quality concentrates are necessary when
Roughage is of lower quality and/or is offered to a limited amount The animal produces moreConcentrates, as their name implies, are feedstuffs with a high energy and/or protein content per kg and a high digestibility (> 70%), and are consequently very suitable to increase the overall nutrient concentration of the ration. If the use of high amount of high quality concentrates is financially attractive depends on the economic context, in which the dairy production takes place (milk prices, subsidies, government politics etc.). The supply of concentrates besides roughage tends to increase the voluntary intake (DMI) under ad lib roughage feeding systems (increases overall digestibility), although some substitution of roughage for concentrates will take place in feeding systems, that offer a high amount of roughage (see Chapter 6).
5.2 Types of Concentrates
Of course the type of concentrates required depends very much on the quality and quantity of roughage offered to the different classes of animals. In general the following types of concentrates can be distinguished:
Early weaner mixture: for young calves up to 5-6 months (minimum till one month after weaning), with a minimum DCP content of 18-20%
Young stock mixture: for young stock from 6 months till ± 1½ years of age, with a minimum DCP content of 15-17%
Medium protein mixture: for young stock till calving, dry animals and possibly animals in late lactation, with a DCP content of 12-14%
High yielding mixture: for cows in early lactation (up to 12-15 weeks), with a minimum DCP content of 15-17%, to allow for high milk production from mobilized body reserves (milking from the back)
Standard mixture: for high yielding cows in the second lactation stage, or medium yielding cows, with DCP content of 12-14%
As concentrates are usually used as a supplement in balancing a roughage diet, the actual quality (expressed in DCP %) depends on the actual amount and quality of roughage offered. Although single ingredients can be used, mixtures of ingredients are more common. In supplementary concentrates it is necessary:
To reach the proper ratio of protein : energy per category of livestock; To supply deficiency quantity of protein and energy (production level); To include possible deficiency of minerals and vitamins;
To reach the most economical mixture (least costs calculation);
To counter balance certain characteristics of individual ingredients, such as taste, fat content, certain substances like gossypol, laxative aspects such as molasses (see also Table 5.2).
In many cases protein is the main lacking ingredient, especially in high potential yielding cows. More over, protein is usually the most expensive ingredient. Therefore, economics may not allow to express the genetic potential of a high yielding cow.
5.3 The Essentials of a Good Concentrate Energy
Concentrate (mixtures) should have an energy content of over FUM 1000 per kg DM as to have a minimum possible production response of at least 2 kg of milk per kg of concentrates. If a concentrate contains less than FUM 1000 per kg, it indicates a high CF or ash content. A high CF/ash content is not desirable when roughage is of medium/low quality. This generally is the case. CF reduces the feed density and digestibility following by an increasing heat- production and consequently depresses appetite. Especially brans, hulls and chaff of cereal grains have a high CF content. A high CF content indicates adulteration (chaff, husks, sand, sawdust) as a result of poor or/and unhygienic handling. In order to increase energy value and/or to improve the taste, molasses could be added as to avoid diarrhoea (up to maximum 15% for adults and 5% for calves).
Fat
Good concentrate contains at least 3% crude fat, accomplished by the inclusion of by- products from oil-seeds. However, under warm and humid conditions the fat may quickly become rancid affecting the keeping quality. Rancidity affects the intake as the product becomes less palatable.
Crude Fibre (CF)
Concentrates for calves (early weaner mixture) should not contain more than 9 % CF, as the rumen of the young calve is not yet completely functioning. Cotton seed cake can not be included in the concentrate for young calves, as the gossypol in the cake acts as a poisonous substance for calves.
Minerals
Inclusion of at least 3% mineral mix is desirable. The mineral mix should contain the major- and trace-elements. The recommended quantities depend on local conditions, such as soil type, type of forage, type of concentrates, production level. Furthermore, it is recommended to provide NaCl (common salt) ad lib, either as a “lick” or dissolved in water (2½ % = 2½ kg salt in 100 litre water).
Vitamins
In indoor cattle keeping systems, vitamin D may have to be supplemented in the concentrates (calves, young stock). If rations are devoid of fresh, green, leafy materials extra vitamin A may have to be supplied (calves, young stock). In general, inclusion of 0.1% vitamin AD3 preparation is recommended.
Consistency
To reduce losses and to stimulate quick intake, concentrates could be offered as a thick porridge. The porridge should not be prepared more than 4 hours before milking/feeding. Dry meal (without the availability of drinking water) increases losses and reduces the speed of intake and possibly the overall appetite. It is therefore not recommended.
5.4 Quality and Maximum Allowance of Ingredients
Proper information should be available and obtained about the quality of ingredients as to allow to compose a balanced mixture at least-costs.
Table 5.2: Some Maximum Allowances of Ingredients in Concentrates for Rations in Which Concentrate Has a Maximum of up to 50% DM
Product Maximum % in mixture
Maize by-products 40-50%
Wheat by-products 25%
Rice ban 0-20%
Malt germs 10%
Coconut products 50%
Groundnut cake 20%
Cottonseed cake 20% (not for calves)
Sunflower cake 10%
Rapeseed cake 10% (goitrogenic substances)
Molasses 15% (5% for calves)
Sugars 5%
Slaughter by-products limited
Fish meal 5%
In general, ingredients should be checked for mould, soil contamination and residues (e.g. sweet potatoes and cassava). But also particular aspects have to be considered. Examples are:
Gossypol contents in cottonseed products Aflatoxin in peanut products Goitrogenic substances in rapeseed
Hairy seeds like cottonseed, should be decorticated (hairs/fibres
removed)
Sugars / molasses can only be used in limited quantities: it may cause
diarrhoea;
Sugars may depress utilization of the ration it results in excessive amounts of methane gas. It either escapes unutilized and/or causes a decrease of the pH in the rumen, to fall below level 6;
Mouldy and/or
sour products are to be taken care off;
Maize and rice products used in mixed feeds should be limited in quantity.
It might result in production of (very) soft butterfat, which turns rancid quickly;
Soya beans in large quantities are undesirable due to their high fat con-
tent;
Sesame and sunflower
products are less tasty. Ratio of some ingredients depend on the percentage of hulls and husks.
5.5 Mixing of Concentrates
Mixing of concentrates can be done on the farm or in special plants. Mixing on the farm can be done simply by using a spade. It is best to start with the ingredient taking part in highest proportion. The remaining ingredients are added in order of decreasing proportion, minerals and vitamins last. Then the mixing can start, using the spade to make the mixture as homo- geneous as possible. The incorporation of urea in these “home-made” mixtures is not recommended because of the risk of poisoning.
5.6 Calculating Compositions
Nowadays, most mixed feeds are composed with the aid of computers, which are able to combine several ingredients in such a way, that the cheapest mixture with the desired feeding value is obtained with similar DM values.
5.6.1 Composing A Ration From Two Ingredients
In composing simple rations from two ingredients, it is possible to use the “Pearson Square Method”. An example of this method is presented, using DCP content. It is also possible to do this with energy (FUM). The procedure for calculation is as follows
-Make a square and place the desired DCP % of the mixture in the centre of the square-Place the DCP % of the 2 available ingredients at the upper (A) and lower (B) left-hand corners of the square.
-Place the DCP % of the 2 available ingredients at the upper (A) and lower (B) left-hand corners of the square.
-The difference between the figure in the left-hand corner and the desired DCP
% is placed in the diagonal right-hand corner of the square. The figure at the upper right-hand corner is the number of parts of feed A that must be used and the figure at the lower right-hand corner the number of parts that must be used of feed B.
Example
A mixed feed with 16% DCP in the DM is required. Available ingredients are:
Maize meal 7% DCP, 1210 FUM
Soya bean cake 40% DCP, 1150 FUM
To solve this problem and obtain the mixture with 16% DCP, the Pearson Square Method is used in the following way:
– Maize meal 7 24 parts A
The mixture consists out of 24 parts maize meal and 9 parts soya bean cake.
Or, when expressed in percentages: maize meal 72.73 % (24/33 * 100 %) and soya bean cake
27.27 % 9/33 * 100 %). The ratio of soya bean cake and maize meal is: 72.73/27.27 = 1 kg : 2.67 kg.
To check the level of the DCP%:
– maize meal 24/33 * 7 % DCP = 5.09% DCP
– soya bean cake 9/33 * 40 % DCP =
Total DCP % 10.91% DCP
16.00% DCP
The FUM content of this mixture is:
16 (40-16)
– Soya bean cake 40 9 parts B
33 total parts (7-16)
(in weight)
The mixture consists out of 24 parts maize meal and 9 parts soya bean cake.
Or, when expressed in percentages: maize meal 72.73 % (24/33 * 100 %) and soya bean cake
27.27 % 9/33 * 100 %). The ratio of soya bean cake and maize meal is: 72.73/27.27 = 1 kg : 2.67 kg.
To check the level of the DCP%:
– maize meal 24/33 * 7 % DCP = 5.09% DCP
– soya bean cake 9/33 * 40 % DCP =
Total DCP % 10.91% DCP
16.00% DCP
5.6.2 Composing a Ration From Three Ingredients
For reasons of economics and overall feeding value it may be attractive to mix three available ingredients (with similar or converted DM contents) into a concentrate with a certain minimum required nutritive value.
Example: a concentrate is required with a medium protein content of 130 gram DCP/kg and the following ingredients are available:
Ingredients FUM (per kg DM) gram DCP (per kg DM)
– wheat bran 818 125
– maize meal 1210 65
– soya bean cake 1150 460
How to make the required mixture (13% DCP)?
First, the difference is calculated between the desired DCP and the content of each ingredient:
– wheat bran 125 – 130 = – 5
– maize mea l70 – 130 = – 65
– soya bean cake 460 – 130 = + 330
Two of the ingredients contain less than the desired DCP contents and one ingredient contains more. These differences are to be combined in such a way that they add up to about zero. Then the mixture has its desired DCP content.
– wheat bran 125 – 130 = – 5
– maize mea l70 – 130 = – 65
– soya bean cake 460 – 130 = + 330
Two of the ingredients contain less than the desired DCP contents and one ingredient contains more. These differences are to be combined in such a way that they add up to about zero. Then the mixture has its desired DCP content.
Difference Multiplication Balance
– wheat bran -5 1 – 5
– maize meal – 65 5 – 325
– soya bean cake+ 330 1 + 330
7 0
The multiplication factors indicate which proportion each ingredient contributes to the desired concentrate (13% DCP in DM). The desired concentrate consists out of 1/7 wheat bran, 5/7 maize meal and 1/7 soya bean cake. It is possible to check if the answer is correct. If 7 kg DM of the desired concentrate is made, then the total protein content is: 7 * 130 = 910 gram DCP.
Very informative