Balanced ration is a prerequisite for successful dairy farming. An animal of high genetic potential will become a medium milk producer if feed is not properly balanced. When the feed is not properly balanced, it leads to low milk production, lower growth in heifers, impaired reproduction and low immunity. In Punjab, the majority of farmers keep animals under mixed farming system doing both crop production and animal husbandry. Such farmers rely more on crop residues like wheat straw and paddy straw for feeding to animals. Crop residues are inherently low in essential nutrients and animals subsisting on these produces lower quantity of milk. On the other hand, the farmers who take dairy farming as their main profession tend to feed more balanced ration and their milk production per animal is higher. Before formulating a balanced concentrate feed, the following points need to be kept in mind:
- Type of forage being fed – Non legume fodders are low in protein but high in energy whereas legume fodders are high in protein, calcium and phosphorus but low in dry matter
- Quality of forage fed – Mature, dry fodders are low in digestibility and in energy and other essential nutrients
- Milk yield and milk fat % of the target animal
- Stage of lactation and body condition score – In late lactation, animals with good body condition score (3.0 or above) require less energy in their ration
- Body weight of the animal
- Age of cow, whether first calver and growing or mature cows
Advantages of TMR feeding
TMR is a feed for dairy animals, in which green fodder, especially silage is mixed along with concentrate in proportion and composition, to make it a balanced ration for a particular group of animals. Thus, in ruminants the mixing of roughage and concentrate portion of the feed as a blend i.e. TMR, has several advantages, like;
- It is very suitable on silage-based feeding system.
- It maintains rumen pH in favorable range (above 6.0).
- The incidence of lameness in the herd is reduced.
- Animals eat balanced ration in every bite.
- There is an increase in fat % in milk and also milk yield by 3-5%.
- The unpalatable materials can be mixed in TMR at higher proportions without affecting the intake of animals.
- Feeding operation can be mechanized, thereby reducing the labor requirement.
Cow’s requirement for nutrients
Cow’s requirement of energy, protein, calcium and phosphorus depend upon body weight and milk production.
To calculate the energy required for 20 kg milk with 3.5% fat.
0.70 Mcal NEL/kg milk x 20 = 14
9 Mcal is required for maintenance for 500 kg animal
Total requirement is 9 + 14 = 23 Mcal NEL/d. For first lactation animals, we have to give growth allowance also. For 500 g/d growth, 2.4 MCal NEL and 320 g/d protein is required. This will add in addition to the requirement for maintenance and milk production. Protein requirement for milk production is 85 gm/kg milk in cows.
Environmental temperature also plays a role in energy requirement. Exposure to cold increases the energy requirement of the animal.
The starting point in balancing the dairy cow ration is to know the quantity and quality of green fodder/silage/hay. For example, if we have green sorghum silage at optimum stage of harvest, it will have 25% dry matter, 8% crude protein and 0.9 Mcal NEL/kg DM. In early lactation, we fix forage concentrate ratio at 60: 40 for medium yielders (approx. 4000 kg milk/lactation) and 50: 50 for high yielders (approx. 6000 kg milk/lactation). Taking the example of a cow having 500 kg body weight and producing 20 kg milk per day, we can proceed in the following manner:
DMI = 17 kg/d (Table-1)
From Green fodder = 8.5 kg
(50% of DMI)
Crude protein from green = 8.5x 0.08 = 0.68 kg
Energy = 7.65 MCal NEL
For making concentrate mixture of required crude protein per cent, Pearson square method can be used. It is described below:
Pearson square method
First fix the
ingredients 2.0% bypass fat
1.5% mineral mixture
1% salt
4.5% molasses
0.5% buffer
0.1% toxin binder
0.1% yeast
0.05% chelated trace minerals
0.25% limestone powder
Total = 10
These 10 parts of concentrate will not supply any protein, therefore, balance 90 kg should contain 23.76 kg crude protein
Then select energy ingredients like maize, wheat bran and deoiled rice bran. Give weighted value to calculate the crude protein % of these energy ingredients. Here we have taken 50% maize, 25% wheat bran and 25% deoiled rice bran. The crude protein per cent in these are 9, 13 and 16%, respectively. The average CP of grain mix will be
(50 x 0.09) + (25 x 0.13) + (25 x 0.16) = 11.75%
Similarly, protein mix of mustard cake is (70%) and soybean meal (30%) having CP % of 36 and 45%, respectively. Their average CP will be 38.7%.
Then applying the Pearson square method:
Maize (50%) + Wheat bran (25%) + DRB (25%)
Grain mix required:
Maize = 41.08 x 0.5 = 20.54 kg
Wheat bran = 41.08 x 0.25 = 10.27 kg
DRB = 41.08 x 0.25 = 10.27 kg
Protein mix required
Mustard cake = 48.92 x 0.7 = 34.24 kg
SBM = 48.92 x 0.3 = 14.68 kg
The final composition of concentrate mixture Parts per 100 kg
Maize 20.54
Wheat bran 10.27
DRB 10.27
Mustard cake 34.24
SBM 14.68
Mineral mixture 1.5
Salt 1.0
Buffer 0.5
Toxin binder 0.1
Yeast 0.1
Chelated MM 0.05
Molasses 4.5
Bypass fat 2.0
Limestone powder 0.25
Vit Ad3 0.5 gm
The quantity of concentrate ingredients per animal per day was calculated by taking proportion of each ingredient from 8.5 kg daily concentrate allowance. For example, the above concentrate contains 20.54 % maize in it. The daily maize intake by the animal will be 8.5×0.2054=1.75 kg.
If we take DM level (92% approx.) in to consideration then
8.5
On as such basis the conc. offered /ani/d = ——= 9.24 kg
0.92
Feeding of TMR to milking cows
- Feed TMR twice in summers during cooler hours of the day.
- In winter one-time feeding could be practiced.
- Make sure that there is always 2-3% residue left in the manger which could be fed to dry animals.
- Check the quality of silage from lab periodically.
- It is difficult to design a TMR on green fodder because the quality changes frequently but on silage-based feeding system the quality of roughage remains similar for longer periods and accordingly calculation could be done.
Properly balanced ration not only increases the milk production but also lowers the cost of milk production as well as it provides balanced ration with higher efficiency of conversion of ration DM to milk solids. On an average, the dairy ration should be balanced on fortnightly basis depending upon change in milk production and quality and quantity of available green fodder.
by RS Grewal and Jaswinder Singh, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana
