Animals: Nutrition

Getting the nutrition right for your herd is important.

Care should be taken that an optimal Body Condition Score (BCS) is achieved (5 for cows and 5.5 for heifers and 3 year olds). Cows require approximately 20% of their empty body weight (at condition score 3) in metabolisable energy every day for the last month precalving to avoid condition score loss. However, in situations where feed is scarce or expensive, the lactating cow should take priority over the dry cow for feed.

 


Energy and protein

Energy is the key driver of milk production.  In practice high protein pastures meet the protein requirements for high milksolids production.  The table below shows when protein may limit production for cows fed high quality pasture.

Nutrients first - limiting milk production on high quality pasture diets
Kg milk/cow/day
Approx. kg MS/cow
Nutrient first limiting milk production
20
1.6
Energy (protein in pasture >18%)
25
2.0
Energy (protein in pasture >24%)
30
2.4
Energy and protein
35
2.8
Protein

Fibre

Fibre is the primary source of energy for grazing animals, but is also required to stimulate chewing and siliva production.

Neutral Detergent Fibre (NDF) is the most commom measure of fibre used for animal feed analysis. It measures more than 90% of the structural components in plant cells (i.e. lignin, hemicellulose and cellulose).

For cows grazing only high quality pasture the minimum NDF requirements are 28-32%.

In diets containing large amounts of finely ground grain and by-products or precision chopped silages, recommended fibre levels have been further refined to include the term 'effective fibre' (eNDF). This term is used to describe the fibre that is most effective at promoting chewing. For example, the fibre in fresh pasture or silage (pasture, cerial or maize) is very effective and the fibre in cerial grains in 0% effective in promoting chewing. However, currently there is no accurate way to measure eNDF of long forages (fresh pasture, or grass or cerial silage), hence eNDF figures have not been included in the feed table.

Nutritional guidelines for all pasture, pasture + supplement and total mixed ration (TMR) diets

Note: For energy refer to feed demand

Protein

Good quality all-pasture diets
kg milk/cow/day
kg MS/cow/day
Protein content of diet required % DM
20
1.6
18
30
2.4 24
Pasture + supplement, TMR
kg milk/cow/day
kg MS/cow/day
Protein content of diet required % DM
20
1.6

16

(65% degradable, 35% bypass, 32% soluble)
30
2.4

18

(65% degradable, 35% bypass, 32% soluble)
As a general rule for all diets

(% diet DM)
Early lactation
18
Mid lactation
16
Late lactation
14
Dry cow
12

 

Fibre

As a general rule for all diets

(% diet DM)
Minimum NDF
35
Minimum effective fibre (eNDF)
17
Pasture + supplements, TMR

(% diet DM)
Minimum NDF
27-33
Minimum effective fibre (eNDF)
20
Minimum ADF
19-21

 

Soluble carbohydrate

Pasture + Supplement, TMR

(% diet DM)
Maximum total soluble carbohydrate
38
Maximum starch
30

 

Fat

Pasture + Supplement, TMR

(% diet DM)
Maximum additional unprotected fat 3
Maximum additional protected fat
3

 

Macro minerals

All diets for high production - (2 kgMS/cow/day)

Mineral content of diet required (%DM)
Calcium
0.6-0.8
Phosphorus
0.3-0.35
Magnesium
0.22-0.28
Potassium
1.0+
Sulphur
0.23
Sodium
0.20
Chlorine
0.25
 
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