Defining Nutrient Density

An article entitled The 2010 USDA/HHS Guidelines — A Rather Bizarre Definition of “Nutrient Dense”  discusses human nutrition but the principles the author discusses relate to all species.    Production Ostrich require nutrient dense rations, so it is important to understand the meaning of nutrient density.

So what do we mean by Nutrient Dense?  Usually the amount of nutrients provided in a given weight.

Using domesticated ostrich as an example, rations are made up of a combination of ingredients to ensure the birds receive adequate daily nutrient intake and ensuring these nutrients are in their correct balance and ratios to each other and within the weight that the bird can consume in a single day.

The table below is a simple example illustrating how Lucerne varies in quality.  A kilo of lucerne can yield very differing nutrient levels depending on the stage of growth (maturity) it was cut and how it was dried.  The more mature it is when cut the greater the fibre and the less digestible that fibre becomes.  The table illustrates how as the protein reduces per kilo as the fibre increases.  Lucerne provides many essential vitamins and minerals....these all drop as the fibre increases.

Comparative Nutrient Density of Lucerne

Lucerne Quality Protein Fibre Calcium Phosphorous
22% Premium 22% 23% 1.80% 0.32%
20% Good 20% 26% 1.60% 0.29%
18% Average 18% 29% 1.40% 0.24%
15% Mature 15% 34% 1.30% 0.21%
13% Very Mature 13% 38% 1.18% 0.19%

Therefore, many of the nutrients lost in that kilo of lucerne have to be provided by a different ingredient that is denser and will be more expensive.   When the quality is too low, it may not be possible to achieve adequate nutrients within the ration within limits of the daily consumption of the birds fed.

The industrialisation of human food has resulted in the processing of many ingredients.  This has resulted in many by products as the processing removes unwanted elements of the ingredients.  Examples are wheat bran, sugar beet pulp, citrus pulp, grape residue or hominay chop.  Some by products can have a place in small amounts in a ration, but others have no place in a ration as they take up space in the ration whilst providing very few nutrients.  Whilst a certain amount of fibre is essential in a ration, the source of that fibre must provide other essential nutrients that are usable by the birds.

Many of these by products can be very cheap when measured by price per tonne, but when measured by nutrient content they can be extremely costly as they provide so few nutrients for that space they take up in the ration.   When measured by the cost in lost production, and even poor health, they can be prohibitively expensive.

Ostrich require rations that are more nutrient dense than other production species because their daily consumption of feed is much lower when expressed as a percentage of their body weight - see illustration below. This makes it even more critical to use only ingredients that provide the best balance of nutrients and why there is no room in their rations for ingredients that are not to the best quality they can be if commercial levels of production are to be achieved.

Comparative Feed Intake [Courtesy: Blue Mountain Feeds]
comparative feed intake

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