SOME PRACTICAL ASPECTS OF FEEDING DAIRY COWS

1. Which are the Priorities for Feeding Dairy Cattle?

Different categories of animals have different feed requirements. It is difficult to meet these different demands in practice when all animals are running together. Furthermore it is important to avoid wasting feed when it is in short supply and when some foodstuff is not essential for certain groups . Preferential feeding of stock may be possible however when fodder is fed from a store, or if it is cut and carried ( green pasture ), or silage/supplementary feeding to grazing cattle. The categories of dairy livestock that should be ranked with high priority in preferential feeding practices are:

1.1 Newly calved cows:

This category of stock must enjoy first priority in preferential feeding using high-quality ration: grasses of high digestibility and feed value and I or good quality-silage , both supplemented with rich-value feeds such as copra meal and spent grain. The milking cow is in energy deficit during early lactation because their appetite is lowest at calving and it only increases to a peak around the fourth month of lactation. This deficit is compensated by large mobilisation or loss of the body fat during the first two months after calving. figure 20. demonstrates the relationship between milk yield, body weight change and appetite for a high-producing cow.

The dairy farmer has to recall that this obligatory mobilisation in the beginning of lactation is closely associated with the dairy genetic potential of the cow, and is therefore very high in animals such as Friesian cows. Consequently, if feed is in short supply when fresh calved, the body condition of these cows can be lost dramatically resulting in long term negative effects on cow performance: delayed conception after mating, decrease in milk production and short lactation. This phenomenon is frequently observed where beef cows are clearly in good condition as compared to skinny Friesian cows in early lactation period.

In conclusion, the dairy farmer must ensure good feeding levels of his cows in early lactation

combined with good body condition at calving (this implies also good feeding in late lactation)

play a key role on overall milk production. These management practices facilitate higher peak yield in early lactation and a higher total lactation yield is achieved as well. The peak yield is

critical, because for each litre obtained at peak the overall lactation increases by 150 litres.

1.2 The calf:

The calf should begin eating grass as early as possible after being born, but it needs high quality easily digestible forage and protein rich supplement, for growth and development.

1.3 Growing Dairy Females - Heifers:

This is the second most important group of cattle concerning ranking priority for preferential feeding. If underfed when young, they will not reach full body development and expected liveweight at maturity and their breeding performance may be negatively affected for life. They should be well fed in order to increase weight by quick body growth that can enable them to produce their first calf at an early age. Friesian heifers must reach 350 - 380 kg live weight at 16 - 18 months and should be mated at that age bracket for their first calving to take place at 25 - 27 months.

1.4 Pregnant cows:

This is the third most important dairy cattle group when ranking feeding priority. As indicated above, cows will usually lose some weight following calving as their milk production increases and appetite is low. Hence they need to have body reserves at calving to meet resource mobilisation during early lactation, The rapid calf growth in the last weeks of pregnancy development is also another very important period in pregnant cows. She should receive relatively high quality fodder especially during the last two months of pregnancy to meet requirements of the growing calf and to increase her own body reserves.

2 How can Farmers Formulate rations for their own dairy cows?

The cost of producing milk is closely linked to feeding costs. In order to reduce the cost of feed and produce cheaper milk, dairy production must utilise larger amounts of cheaper feed but of good quality such as well managed grass-legume pastures, supplemented with locally available feed ingredients. In order to benefit from the dairy potential of cows, the farmer should take the following steps in formulating a dairy diet:

(i) First, identify local feed resources based on their nutrient characteristics or composition. For example, energy, protein and determine appropriate levels of inclusion in the diet. This information could be obtained from text books ( literature values ), from the laboratory (chemical analysis ) or the values indicated in Table 13, presented in Section 21.

(ii) Secondly, determine the nutritional needs of cows, based on age, live weight and production. Those information could be obtained from text books or the tables 10, II, 12 in earlier sections of this book.

(iii) Thirdly, formulate the ration which would be composed from a basal diet ( may be pasture and I or silage) and feed supplements by balancing nutrient supply to cow needs.

Let us take an example of how to calculate a ration for dairy cows grazing Batiki Bluegrass under coconut plantation. Proceed as follows:

a. The data required are as follows:

- Weight of cow e.g. 500 Kg

- Milk yield per day e.g. 10kg

- Butterfat content e.g. 4.0 %

Table 18

c. To calculate the MJ ME and Kg CP. necessary for production of milk.

-It is found that for this cow - with 4.0 % milk fat content- MJ ME is 5.3 and Kg CP. per kg milk is 0.085.

-Multiplied by the quantity of milk produced per day the following requirements are estimated: ME: 10kg milk / day X 5.3 MJ 1Kg = 53.0 MJ I day, CP: 10 kg milk I day X 0.085 Kg/Kg = 0.85 Kg I day

d. To add needs for live weight loss.

- Allowance for visual assessment must be made for skinny and bad looking animals by adding 5 to 20 MJ ME per day according to results of visual assessment ranking. (see Figure 17.)

- For the purpose of this example 10 MJ and 0.16 Kg CP are accounted.

e. The total ME and CP required is estimated by adding up all figures, which have been calculated.

Table 19.

f. To estimate probable total dry matter intake (DM):

- Total dry matter intake depends on the live weight of the animal, its level of milk production, its stage of lactation and quality of diet.

- As a rule of thumb DM intake is 2.5 to 3.0 kg per 100 kg of body weight for milking dairy cows and 1.5 to 2 kg for dry cows. For the purpose in this example 2.7% is used e.g. Cow Weight = 500 Kg, DM intake= 13.5kg/day

- If the DM intake is 13.5 kg I day, therefore the necessary energy content per kg DM in total ration ( ME ) must be 8.5 MJ so as to meet the cow requirements. The result is obtained as follows:

Total energy requirement divided by total dry matter intake, e.g.

113.8 MJ ME divided by 13.5 Kg DM /day 8.5 MJ ME/Kg DM.

This would be very difficult to reach.

g. Nutrient Supply from Batiki Bluegrass

- Our problem cow obtains its nutrients from the daily ration that is eaten. It is necessary therefore to know the composition of feeds and their intake. The former can be obtained from table whereas it is often difficult to estimate feed intake from pasture.

- Let us assume this cow while grazing pasture can achieve a 50 kg daily intake of fresh vegetative Batiki grass and without any supplement. The supply of nutrients from this foodstuff and the amount of milk that can be produced with such ration are:

 

 

Table 20.

 - Calculate the daily quantity of DM from the feed by multiplying AxB.

- Multiply this answer by C to get the ME supplied by the feed.

- Do the same for CP. Multiply the DM supplied by the feed per day ( A x B ) with D to get the quantity of CP fed daily.

- The ME from the feed ration meets the requirements for maintenance and 2 7 kg of milk (14.2 MJ/kg/5.3 MJ/kg ) and the CP fed is enough for maintenance and 4.4 kg of milk ( 0.377 kg CP/0.085 Kg CP).

- Calculate the feed supply: Total requirements - batiki grass Ration supply: 113,8 MJ 65.0 MJ = 48.3 MJ and 1.433 kg CP - 0.800kg CP = 0.633kg CP.

In conclusion, it is evident from this example that grass within this such value is insufficient to meet the milk potential of the above cow and therefore feed supplements must be added. In this case distribution of copra meal (2 kg) and spent grain (10 kg) or Silage A (15 kg of high-quality silage, see Section 22 ) may easily cover the deficit and provide a balance between feeding level and animal requirements.

3 Some Practical Examples of Dairy Cow Rations

It is difficult to control the grazing intake of milking cows under grazing conditions where quality of native and improved grasses varies markedly throughout the season. However, the intake of animals can be controlled when they are penned or tethered and the fodder is carried to them.

Therefore farmers should practice a cut-and-carry feeding system, to supplement the grazing intake of high-producing cows and especially those newly calved. A recommended practice is to grow a block of hybrid elephant grass Penisetum purpureum, which is considered a highly productive perennial grass [with good dry season performance] and suitable to cut-and-carry systems. Also local types of elephant grass, guinea grass, Guatemala grass, leucaena and some wild shrub legume varieties such as Adananthera sp, and Albizia sps. are well suited to cut and carry. More information on cut and carry systems can be found elsewhere in this book.

In all cases of feeding systems: grazing or cut-and-carry green forage, farmer should strive to gain skill in assessing grass quality so that the amounts of feed supplements may be estimated.

Some suitable rations are hereafter presented where basal diet is fresh grass grazed or cut and fed to penned cows. We draw the attention of farmers that the former are presented as a mere approximation, because the quality of the sown and wild grasses can vary dramatically. For further details farmers should request information from the Livestock Advisory Service.

3.1 For growing heifers to reach breeding age as quickly as possible (16 to 18 months.)

- grazing pasture under coconut plantations

- free access to feed blocks

- 0.5 kg of copra meal

- 5 to 10 kg of silage B (Medium-quality silage making, see Section 22)

Note: the last feed supplement [silage] can be given from 15 months.

3.2 Dry Cows and Pregnant Cows up to 7 months

- grazing improved pasture under coconut plantations

- free access to feed blocks

Note: if there is grass shortage due to overgrazing or dry season, these cows can receive 15 kg of silage B (B (Medium-quality silage making, see Section 22)

3.3 Cows in the last two months of pregnancy:

- grazing improved pasture under coconut plantations

- Free access to feed blocks

- 1 to 2 kg of copra meal (depending on body condition)

- 5 to 10 kg of silage A (High-quality silage making, see Section 22 ) (depending on body condition)

Note: (i) if there is a pasture shortage due to overgrazing or dry season, the cow should be fed 15 to 20 kg silage and I to 2 kg of copra meal, depending on body condition;

(ii) Two weeks before calving the cow should be fed the same type of ration that she would receive at and after calving period but in reduced quantity, so as to adapt its stomach to the new diet.

3.4 Lactating Dairy Cows:

Case 1: Basal diet while grazing improved pasture under coconut plantations:

Milk Yield per day (kg)

5 10 15 20 25

Feed Supplements

per day (fresh kg)

Copra meal 1 2 3 3 3

Spent grain 5 10 15

Silage A (30% DM) 10-15 15-20 20-25 20-25

Note: (i) Cows can have free access to feed blocks;

(ii) Cows eating more than 10 kg spent grain and 20 kg of silage A, should have enough fibrous materials, for example some dried wild grasses;

(iii) Quantities of spent grain and silage A can be reduced if improved pasture is young, and of good quality;

(iv) In order to give newly calved cows maximum opportunity to express their dairy potential, those cows should be not be fed according to their milk yield, due to their lowest appetite they must receive in addition to unrestricted grazing 15 kg spent grain and 25 kg silage A and 3 kg of copra meal. when there is refusal of feed, left-overs can be fed to other cows.

Case 2: Basal diet is chopped Elephant grass (cut-and-carry system). Milk Yield per day ( kg)

5 10 15 20 25

Feed stuffs

per day ( fresh kg)

Chopped Elephant grass 40 40 40 50 50

Copra meal 1 2 3 3 3

Spent grain

Silage A (30%DM) 10 15 25 25

Note: (i) Cows can have free access to feed blocks,

(ii) In order to give newly calved cows maximum opportunity to express their dairy potential, those cows should be not fed according to their milk yield, due to their low [depressed] appetite they must receive freely the following ration: good quality mixed fresh green grass (40 to 50kg) and silage A (20 to 30kg), 3 kg of copra meal and 10 to 15 kg spent grain. whenever feed is refused or left-over it should be fed to other cows.

4 Are there other points to be outlined on dairy cow feeding?

4.1 Be careful with changes in feed quality and type:

Ruminant animals develop micro-organisms in the rumen to break down the complex organic compounds of plant materials to simpler substances. Different micro-organisms are needed for different plant materials. Hence, changes in diet of animals should be made gradually as far as possible to allow the mixture of rumen micro-organisms populations to change in composition and thus be able to cope efficiently with changes in the diet. This re-organisation takes time.

Avoid sudden changes to the diet. The micro-organisms are seriously affected, especially if silage and spent grain or other energy rich supplements are abruptly increased. Arrange for a change of diet to take place gradually over two weeks at least.

4.2 Avoid over-feeding at one meal:

Avoid feeding large amounts of feed supplements in one meal, Silage A, spent grain, copra meal and other rich-energy supplements, are fed each day in large amounts, especially to high-yielding cows; these amounts should be evenly spread at regular feeding times. This practice must be observed especially during weekends Remember that dairy cows are creatures of habit and that their digestive system works more effectively if a regular feeding pattern is maintained.

4.3 Regular adjustment of feeding plan:

The rate of decline of milk yield, as well as the body condition of the animal, should be regularly monitored and adjustments introduced to feeding norm. Otherwise over-feeding would lead to excessive fattening instead milk production.