(Instruction Handout used for Western Kenya, 2016)

Karen L Jacobsen, BS, DVM, MS

www.KarenJacobsen.net,  706-340-0999 USA cellular,  email: KLJVET@gmail.com

1. How much does the cow weigh?
2. Weigh tape the cow, measuring chest girth, also called heart girth.
3. Use Table 1 below to estimate body weight.

Example:  A Friesian cow with a Chest Girth of 187 cm weighs about 500 kg.

1. Body Condition Score the cow to be sure she is in the normal range.

Use BCS scale of 1-5:

BCS 1 = Extremely Thin

BCS 2 = Thin

BCS 3 = Normal

BCS 4 = Fat.

BCS 5 = Extremely Fat

See the Normal Lactation Curve (See "Tables for Hand Rations" on Left Sidebar of this website). 

BCS Normal values:

Calving:  BCS 3.0 – 3.5

Peak Lactation:  BCS 2.5 – 3.0 (maximum loss of 0.5 BCS)

Dry-Off:  3.0- 3.5

NOTE:  The cow must not be thin at calving.  Since she cannot consume enough Dry Matter to reach Peak Lactation, she must use energy from her backfat.  Thus, loss of 0.5 BCS is normal, but if the cow is thin at calving, she will become emaciated at peak lactation.

1. How many liters (L) of drinking water does the cow need?

Rule of Thumb:

1 L/ 10 kg body weight + 1.5 L/kg milk

Example:  450 kg cow, producing 20 kg milk

45 L + 30L = 75 L water needed/day

NOTE:  Drinking water needs increase dramatically as ambient temperature increases.

• How much Dry Matter (DM) should the cow eat per day?

Rule of Thumb:

Dry cows & growing heifers: 2.0– 2.5% of body weight in kg

Lactating cows:  3.0% to 4.0% of body weight in kg.  Higher intakes are needed for higher production.

Example:  450 kg (990 lb) cow, producing 20 kg (44 lb) of 4.0% fat milk needs 17 kg DM (from Table 2).

(The table is recommending 3.78% of the 450 kg cow’s body weight.)

1. What are the cow’s nutrient requirements for Energy & Protein, Calcium, Phosphorus?
2. Requirements for this cow (Use Table 2):

161 Mj ME

1826 g CP

75 g Ca++

59 g Phos

1. Consider age, breed, stage of lactation, & climate.

1. What feeds are available, and what are the nutrient values of these feeds?

Ideally, all feeds should be analyzed at least monthly, but in the absence of this information, values from tables can be used for an estimation.  (Be aware that actual values can vary greatly from table values.) 

5. Fodders (also called Forages, Roughages): Grass, Hay, Silage:  See Table 5.
6. Dairy Meal, Grain, Concentrates, Byproducts: See Table 6.

Example: The feed available are:

1. Napier Grass: 20%DM, 7.9 Mj ME/kg DM, 98 g CP/kg DM (9.8% CP)
2. 6% CP Dairy Meal: 90%DM, 9.1 Mj ME/kg DM, 156 g CP/kg DM
3. Mineral/Vitamin Premix: 90% DM

1. Will energy requirements be met if the forage is the sole feed? Divide the Energy requirement of the cow by the Energy content of the Forage.

Example:  161 Mj ME/7.9 Mj ME/kg DM = 20.38 kg DM is needed to provide enough Energy.  (It cannot be the sole feed because maximum DMI is 17 kg.)

NOTE:  Be sure the cow receives adequate “Effective” Fiber  (consider quality of forage, “scratch factor,” rumen fiber mat, “tossed salad” appearance of final feed).

• Will energy requirements be met with a forage/concentrate ratio of 50/50?

Example:     8.5 kg forage DM (Napier grass) x 7.9 Mj ME/kg DM = 67.15 Mj ME

8.5 kg concentrate DM (Dairy Meal) x 9.1 Mj/kg DM = 77.35 Mj ME

                                                                                                   Total     = 144.50 Mj ME

Thus, energy is still deficient for maximal milk production for this cow. 

Try replacing some of the Dairy Meal with a higher energy byproduct, Cassava Peels (Table 6).

With this “Trial & Error” method, it easiest to make a table:

• What is the DM of the feeds being fed?

1. Estimating DM using tables can be VERY inaccurate, especially for wet feeds.
2. For wet feeds, measure the DM content by weighing the feed before and after dehydrating the feed.
3. Methods for dehydrating wet feeds (see KarenJacobsen.net ):
   1. Microwave oven
   2. Food dehydrator
   3. Hair dryer vortex (home-made funnel plus hair-dryer)
   4. Other

1. How much to feed of each ingredient (on an As Fed basis)?

Rule of Thumb: Divide the desired kg of needed DM by the % DM of the feed, expressed as a decimal.

Example: 

Napier Grass: 20%DM       8.5 kg/.20 = 42.5 kg As Fed

Dairy Meal:     90%DM       5.5 kg/.90 =  6.1 kg As Fed

Cassava Peels:  87% DM    3.0 kg/.87 =   3.4 kg As Fed

                      TOTALS:         17.0 kg DM    52.0 kg As Fed

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Table 1.  Estimating Dairy Cow & Heifer Weight by Chest Girth

Dr. Karen L. Jacobsen,  www.FARMLLC.org,  USA cell:  706-340-0999 

Table 2. Daily nutrient requirements for a dairy cow by cow weight and milk production

Table 3a. Daily nutrient requirements for dairy youngstock. 

 (See "Tables for Hand Rations" on Left Sidebar of this website)

Table 4.   Requirements of minerals, trace-elements and main vitamins for different categories of cattle.

 (See "Tables for Hand Rations" on Left Sidebar of this website)

Table 5. Quality of some commonly available roughages in Kenya

 (See "Tables for Hand Rations" on Left Sidebar of this website)

Table 6. Quality of some commonly available concentrates and by-products in Kenya

 (See "Tables for Hand Rations" on Left Sidebar of this website)

References:

 http://www.infonet-biovision.org/AnimalHealth/Animal-nutrition-and-feed-rations

http://192.156.137.110/ssafeed/