Introduction
It is difficult to compare different animals, and animals of different ages, with each other with regard to feeding and grazing. To make comparison possible, different types of livestock are converted to the same unit.
The feed intake capacity (DMI) depends on live weight, production level and quality of feed. The quantity is expressed in terms of dry matter (DM).
Standard figures are indicated for protein (DCP) and energy (FUM) requirements, divided for maintenance and production. These figures are known as feeding standards. In addition, standard values are given for various feedstuffs.
The variation in quality amongst feedstuffs can be immense. Specially, nutritive values can differ very much from the indicated averages! On top of that, there can be big variation in efficiency of food utilization between individual animals. There is no such thing as a standard cow. Therefore, feeding standards do have limited values. Feeding standards should be used as a guideline to individual requirement. The exact figures in the booklet should not be used as such! The figures are applicable as an average for big numbers of cattle with an expected average result. The actual performance of animals (condition and production) should be the base in feeding management. An experienced manager uses the standard values, but final decision will be influenced by actual performance. This allows the animal to proof its production capacity (within economic boundaries) and provide the manager with a proper tool for animal selection. Selection which is based on production performance of an individual animal.
6.1 Livestock Units
To make comparison possible, animals are converted to the same unit. This is called Livestock Unit (LU). One LU denotes the feed requirement of a standard animal of a certain live weight (usually 550 kg). With LU it is possible to compare feed needs for sheep, goats, calves and other animals with those of dairy cows. LU helps to calculate and plan the quantity of feed for a herd during a certain period. It also helps to determine how many animals can be placed on a certain field.
Type of livestock LU Norm (average Dutch herd)
Cow in lactation 1 88%
Cow dry 1 12%
Heifer > 18 month 0.8 40%
Yearling 12-18 month 0.6 14%
Calf 3-12 month 0.4 20%
Calf 1-3 month 0.3 20%
Calf 0-1 month 0.3 10%
Bullock 0.8
Donkey 0.7
Sheep, goat 0.1
Horse, buffalo, mule 1.0
Camel 1.1
6.2 Nutrient Categories
Nutrients can be categorized in 5 areas:
Water (not an actual nutrient)
Dry matter (containing the nutrients, expressed as DM) Energy (Nett Energy, expressed as FUM)
Protein (we will use digestible crude protein, expressed as DCP) Minerals and vitamins
6.2.1 Water
Although water is not considered as a real nutrient, it plays a vital role in the functioning of the body, milk production, and the total intake of food (DMI). The daily requirement of water is influenced by a number of factors, such as:
type of food offered (DM content)
physiological state of animal (lactating, pregnant) mineral content of ration
environment: temperature, humidity, and ventilation/shade temperature of drinking water
DMI
A shortage, or uneven supply of drinking water, has a direct consequence on the DMI. In order to maximize DMI, ad lib supply of fresh water (cool in warm seasons/climates) should be available to the animal for 24 hours per day. For maintenance, a dairy cow requires between 30-100 litres per day. For milk production, a cow requires 1-2 litres of water extra for every one litre milk production. The water requirement is estimated as 3½-4 kg per kg DMI (in temperate climates till 21 C) plus 1-2 litres water for every kg milk produced.More water may be required in warmer climates/seasons, also depending on the cattle keeping system (grazing, 0-grazing, housing, shade, humidity, ventilation). Peak demand (40% of total) usually occurs between 15.00 and 21.00 hours. This aspect has to be considered for the size of the trough (holding capacity, drinking space), pipe-size etc. as to supply sufficient water during the peak-demand period.
Table 6.2: Water Allowances for Cattle
Kg water per kg DMI Environmental temperature (C)
Class of animal
< 16 16-20 > 20
Calves up to 6 weeks 7 8 9
Cattle (growing/adult, pregnant/non-pregnant) 5.4 6.1 7
Daily water intake (kg/head)
Lactating cows; 600 kg; milk yield (kg/day)
10 81 92 105
20 92 104 119
30 103 116 133
40 113 128 147
6.2.2 Dry Matter Intake (DMI)
DMI is most important in animal production, as the DM contains the nutrients. A high
production will lead to an increased appetite and vice versa. The DM of a feedstuff has a slight influence on total DMI. Moderate dry (30-50% DM) and tasty feedstuffs allow highest roughage intake. Dairy ration formulation requires an estimation of DMI. The following 3 formulas are used to predict DMI of lactating cows fed on mixed diets with roughages and concentrates.
Formula 1 is considered for cows in mid and late lactation. The first 6-10 weeks lactation, DMI values are to be reduced by 2-3 kg DMI/day (energy-gap).
Formula 1: DMI = 0.025 W + 0.1 Y * 1 kg DM
DMI= dry matter intake (kg/day)
W= live weight (kg)
y= milk yield (kg/day)
Example
A cow of 500 kg and 20 kg milk production. The predicted DMI will be:
DMI = 0.025 * 500 + 0.1 * 20 * kg DM ——————–12.5 + 2 * 1 kg DM
————-14.5 kg DM/day
Formula 2 is based on a mixed diet of roughage and concentrates:
Formula 2: Adult cows: DMI = 8 + M/5 + Y/1,000 * 1 kg
Heifers: DMI = 6 + M/5 + Y/1,000 * 1 kg
DMI= dry matter intake (kg/day)
M= milk production per day (kg)
Y= milk production per year (kg)
Both formulas are acceptable to large dairy cattle breeds only. Another approach is to base expected DMI under conditions of ad lib roughage feeding supplemented with concentrates. Formula 3 does not only predict DMI, but also divides DMI according to the type of feed (roughage and concentrates).
Formula 3: DMI from roughage = 1.8 – 2½ % of live weight
DMI from concentrates = 1% of live weight
Maximim DMI
The maximum DMI is assumed to be 3½ % of the live weight, although it is recognized that DMI may as high as 4% (during and just after the lactation peak) for a short period. Fluctuations of roughage intake (1.8-2½ %) are mainly caused by the production potential of the animal and the quality (digestibility and palatability) of the roughage and apparently not completely balanced by a higher or lower intake of concentrates. This means, that the nett- result of a lower intake of poor quality roughages is mainly reflected in a lower milk production and/or reduced growth rates and loss of condition.
DMI out of roughages
The DMI out of roughages may be reduced if more concentrates are offered. This is the so- called “forced-substitution” effect: the DMI from roughages is partly substituted by DMI from concentrates, although the nett-result is an increase in total DMI. On average 1 kg concentrates (= 0.9 kg DM)
Feeding system Concentrate kg Decrease in kg DMI out of roughage p/kg concentrates
Grazing 0-6 0,3
7-12 0,5
13 and over 0,7
Zero-grazing 0-4 0,3
4-8 0,5
9 and over 0,7
More explanations
and an example of
calculation of “forced-substitution” is given in
exercise/example 2 under point 5.1. The decision about how much DM from roughages the management should allow to be “substituted” by DM out of concentrates will mainly depend on economics and possibly quality and availability of roughages. In Poland the availability of roughages can be limited and/or sometimes expensive. The free choice of management exists only there where plenty good quality roughages are available at a competitive price in relation to concentrates and offered ad lib to the animals. Limited amounts of roughages of medium quality will however limit the production level of the cow. The ratio roughage: concentrate may become too narrow for a proper functioning of the rumen and/or the overall ration quality may not be sufficient for (very) high production levels.
6.2.3 Energy
Energy requirements for dairy production are expressed in Feed Units Milk production (FUM). The FUM of a feedstuff is a figure which indicates how many kg barley equals the amount of nett energy for milk production in 1 kg of feedstuff. As a rough rule, a 600 kg cow producing 15 litre per day requires for maintenance 5013 FUM and 460 FUM for producing 1 kg milk. For each 50 kg weight plus or minus 600 kg a correction has to be made: – for FUM +/- 300 / 50 kg weight
For calculating the requirements for FUM we can use the following equation: FUM= (maintenance + milk production) = (5013 + 440 M + 0.7293 M2)
For practical use we can approach the FUM calculation by the next equation FUM = 5000 + 460 M
In the equations above is M the milk production in kg per day expressed in kg Full Cream Milk (FCM). FCM milk has a fat content of 4% per kg.
To calculate the FCM amount for milk with a devition in fat content we can use the following equation:
FCM 4% fat = (0.4 + 0.15F) * m
F = fat content (%)
m = real milk production
6.2.4 Protein
Crude Digestible Protein (DCP) needs are expressed in gram. As a very rough rule, a 600 kg cow requires for maintenance 390 gram protein and 63 gram protein for producing 1 kg milk.
For each 50 kg life weight plus or minus 600 kg a correction has to be made:
– for DCP +/- 25 / 50 kg weight
For calculating the requirements for DCP we can use the following equation: DCP= (maintenance + milk production) = ((3.33 G + 1000) * 0.13) + 63 M
G = life weight M = kg FCM
For practical use we can approach the DCP calculation by the next equation DCP = 390 + 63 M
6.2.5 Minerals and Vitamins
Due to the local situation and prevailing soil conditions, quantities may vary. An indication for mineral and vitamin requirements of cattle is given following table.
Mineral or vitamin Requirements p/day Requirements p/kg
Ca 0.032 W + 2.4 Y gr. 3.5 – 5.5 gr.
P 0.042 W + 1.5 Y gr. 3.0 – 4.0 gr.
Na 7 + 0.5 Y gr. 1.0 – 1.5 gr.
Mg (2.5 + 0.12 Y) * A gr. 2.0 – 5.0 gr.
K 0.03 W * 2 Y gr. 8.0 gr.
Cl 0.04 + 1,2 Y gr. 3.5 gr.
I (iodine) + 0.25 Y mg. 0.6 mg.
Mn – 25.0 mg
Zn – 25.0 mg.
Cu – 10.0 mg.
Vit. A 24,000 + 1,500 Y IU 2,000 – 3500 IU
Vit. D 10 W IU 300 – 500 IU
6.3 The Need for Nutrients
The nutritional requirements for dairy can be subdivided as follows:
Maintenance Production
Growth – to reach maturity
– during lactation to reach majority
– to improve condition
Pregnancy
Milk production
6.3.1 Maintenance
Nutrients are used to keep the body in good health and to maintain its temperature without bodyweight gain/loss. Majority of nutrients are used by muscles to:
pump hundred of litres of blood each day + breath
squeeze hundreds of kilograms food and water in the digestive system (eating, swallowing, ruminating, contractions, and digestion)
moving in order to collect the food continuously repair of worn-out tissue
The nutrient requirements for maintenance depend on the bodyweight and the feeding system. The bodyweight of an animal can be “measured” by weighing, measuring and observation.
Weighing balance or weighing bridge. A very accurate method during the growth-period till maturity (fluctuations at maturity depend on condition). Regular weighing will be required to determine the bodyweight and to check if the targeted growth-rate per day is reached. Weighing should be done at least once in 3 months and in order to reduce the chance of bodyweight fluctuations it is advised to carry out the exercise always at the same time of the day e.g. early morning, after feeding (and milking) to avoid stress in the warm climates.
Measuring tape and yard stick. This system gives a reasonably accurate indication of the bodyweight and special of the growth of an animal (gain per day).
Observation and estimation by “eye”. It needs a lot of experience to “develop an eye” for correct estimating. It is not reliable for estimation of body weight gain in relation to feed requirements.
Live weight (kg) DM (kg) FUM (units) DCP (gram)
400 5.55 3812 290
450 6.06 4112 315
500 6.56 4412 340
550 7.04 4712 365
600 7.52 5013 390
650 7.98 5313 415
700 8.44 5613 440
750 8.89 5913 465
The maintenance requirements mentioned are to be used for “indoor feeding” systems. In yard systems, with frequent handling (milking, weighing, feeding), requires an increase of 10-15%. If the animals are properly housed, no extra nutrients for maintenance will be required during winter time (no direct wind, good ventilation, dry floor with some dry bedding.
6.3.2 Production
Production is divided into growth, pregnancy and milk production.
The body condition of a cow can be estimated by the “condition-scoring” system. Judgement is based on the appearance of the tail head (fat deposits or lack of it) and indicated by a score from 0-5. Detailed information on the condition-scoring system is given in Appendix 5.
Growth, to reach maturity
Growth allowance depends on the policy of age at first calving (required growth rate per day) and consequently required bodyweight at age of first service.
Special care should be given to the feeding of young stock during the period immediately after weaning. Usually the offered quality of the food is insufficient and calves suffer a severe setback, which may take a long period to recover. Conditions usually improve again at an age of 1 year, when the rumen is sufficiently developed. By that time however, the retarded growth will have a lifelong negative effect on the production capacity of the animal. Special care should be taken not to feed mouldy hay, as this affects rumen development.
Age 1st Age 1st Target Weaning Days and Growth
calving
(month) service
(month) weight at 1st service
range (kg) weight at 10
weeks (kg) gain (kg) weaning service
days kg gain rate/day weaning
service min. av.
24
15
350-375
70-75
390
275-300
770
800
30 21 400-425 70-75 570 325-350 615 640
36 27 450-475 70-75 755 375-400 530 550
Cont’d
Days and gain during
Bodyweight
Required
Bodyweight
first 7 mths pregnancy (*) pre-calving (**) growth rate
months 7-9 post-calving
(kg) days gr/day (kg) (gram/day) (kg)
160 215 750 565 – 590 1,000 500-525
135 215 630 590 – 615 1,000 525-550
110 215 515 615 – 640 1,000 550-575
Growth allowances during lactation till maturity
In animals calving for the first time at ± 24 months of age, the development of the body continuous. Maturity is normally reached at the end of the second lactation (at an age of ± 4 years). The extra nutrients required for continued growth (growth allowance) till maturity for these animals are:
during first lactation: 600 FUM and 80 DCP extra per day
during second lactation: 300 FUM and 40 DCP extra per day
If an animal calves for the first time at 36 months, an extra growth allowance is only required during the first lactation until the animal reaches maturity at 4 years of age. This growth allowance during this first lactation is 10 % of the total maintenance requirement.
The growth allowances during lactation come on top off normal maintenance and production requirements.
Growth to improve condition
Due to the energy-gap (negative energy balance) incurred during early stage of lactation, causing loss of condition, requires regaining of bodyweight. This loss of bodyweight is to be gained during the middle and late stage of lactation and possibly during the dry period.
A high yielding adult cow is expected to lose 30-60 kg bodyweight during early lactation (1-1½ points in condition score). Efficiency of feed utilization for growth is higher during lactation than during the dry period. The required growth per day for the regain bodyweight losses depends on the policy of the lactation and dry cow feeding management (see Chapter 8).
6.3.2.1 Pregnancy Allowance
It is common to include some extra nutrient allowance during the last two months of pregnancy (months 8 and 9). Fetus development (including fluids and placenta) is ± 20 kg at 7 months, 35 kg at 8 months, and 65-70 kg at 9 months. In lactating cows, this pregnancy- allowance will coincide with the dry period after the previous lactation (last two months before calving). The amount for pregnancy-allowance depends on the condition of a cow after completing her lactation (look at the condition-scoring, maximum allowed conditi
on- scoring target is 3-3½ (see Chapter 8).
In advanced dairy management systems, the tendency is to bring animals in a good condition during the last stage of her lactation (more efficient food utilization). If the animal is a first calver (heifer), the total allowance for growth and pregnancy during the last two months of pregnancy should be sufficient for a daily growth of ± 1,000 gram per day.
An animal should not be too fat at calving time (max. condition score 3-3½). Animals that are too fat at calving time will have a poorer performance (at calving and during the following lactation), since they become more susceptible to certain diseases (see Chapter 8.1.2.1-3).
Actual feeding levels for growth and pregnancy are to be decided following close observation of actual performance and condition. The above mentioned figures serve merely as guidelines.
6.3.2.2 Nutrient Requirement for Milk Production
The total amount of nutrients required for milk production depends on the actual or desired amount of milk production in kg/day and on the quality of the produced milk (butterfat %).
The requirement per kg milk with 4 % fat is:
0.37-0.41 kg DM
460 units FUM
63 gram DCP
For each ½ % butterfat more or less, add or subtract 0.065 units FUM and 4 gram DCP per kg of milk.