Nowaday, as you know,using
the natural forms of vitamins and minerals instead of the synthetically
produced ones. Both micro- and macroalgae have potential as mineral additives
to replace the inorganic mineral salts that are most commonly used in the
animal feed industry. It has been suggested that the natural forms are more
bio-available to the animal than the synthetic forms and can be even altered or
manipulated via the process of bio-absorption.
Mineral
rich seaweed has been incorporated in commercial salmon feeds at 15 % in
lieu of manufactured vitamin and mineral pre-mixes (Kraan, Mair 2010). Final
tests suggested that salmon fed the “seaweed” feeds appeared to be healthier,
more active; flavour and texture were improved which may have been due to the
bromophenolic compounds found in seaweeds. Elsewhere, Enteromorpha
prolifera and Cladophora
sp., when added to the feeds of laying hens, positively influenced
egg weight and egg shell thickness (Michalak et al. 2010).
The vitamin content of algal
biomass can vary significantly among species. Ascorbic acid shows the greatest
variability according to Brown and Miller (1992), although this may have been
due to differences in processing, drying and storage of algae, as ascorbic acid
is very sensitive to heat. This highlights the drawback of supplying essential
micronutrients via natural sources, i.e. there is too much variability arising
from the combined effects of different algal species, growing season, culture
conditions, and processing methods to reliably supply the required
micronutrients in a pre-determined fashion. Accordingly, algal biomass mainly
offers a supplementary source rather than a complete replacement for
manufactured minerals or vitamins in animal feeds.
In both aquaculture and agriculture,
producers commonly rely on formulated feeds to ensure optimal growth, health
and quality of the farmed animal. Given the economic importance of feeds and
feeding, nutritionists therefore need to develop nutritionally balanced diets
using commonly available raw ingredients. Once there is reliable data on the
nutrient and energy requirements of the target species for a given production
performance, specific feeds can be formulated and feeding regimen established.
Typical compositions of feed
and feed/gain ratio are summarised in table 2 for several farmed terrestrial
and aquatic animal species. This table just provides an overview, as different
feed formulations are used depending on the production stage of the target
species. Since protein is generally one of the most expensive feed ingredients,
targeted rations are used and the amounts of protein in the diet are reduced as
the animals grow. As can be seen, feeds for aquatic animals are more energy and
nutrient dense than those for terrestrial animals. Due to this, fish need to be
fed less to support each unit of growth, as is indicated by the lower feed
conversion ratio (FCR).
Table 2: Typical
composition of formulated feeds for livestock and several species of commercial
fish (on as fed basis) and feed/gain ratio
|
% Crude Protein
|
% Crude Lipid
|
% Crude Carbohydrate
|
Metabolisable Energy
MJ/kg
|
FCR*
|
Poultry
|
21.0
|
5.0
|
60
|
13.0
|
2.2
|
Pigs
|
16.0
|
5.0
|
60
|
12.5
|
3.0
|
Cattle
|
12.0
|
4.0
|
65
|
10.1
|
5.8
|
Salmon
|
37.0
|
32.0
|
15
|
21.0
|
1.0
|
Sea bream
|
45.0
|
20.0
|
20
|
19.1
|
1.6
|
Tilapia
|
35.0
|
6.0
|
40
|
13.5
|
1.5
|
Shrimp
|
35.0
|
6.0
|
40
|
13.5
|
2.0
|
* Feed conversion ratio = feed consumed (dry) / live weight
gain
Traditionally, fish meal and fish oil have
been a substantial component of feeds at least in aquaculture, however this
source is finite. With fish meal and fish oil prices increasing, there has been
a growing interest in partial or complete replacement of fish meal by alternative
protein sources of either animal or plant origin. Raw materials other than fish
meal are selected for their nutritive value, balance of amino acids,
digestibility of proteins, lipids and quality of fatty acids, absence of
anti-nutritional factors, availability and cost and lipid rich algae biomass is
being considered as one of the alternative ingredients of the future (Lupatsch
2009).
To help in assessing algae as a
potential source of protein and energy in the form of carbohydrates and lipids,
table 3 compares the typical nutritional profiles of commercially available
animal feed ingredients with some selected micro- and macroalgae.
Typical
composition of commercially available feed ingredients and algae species (per
dry matter)
|
% Crude Protein
|
% Crude Lipid
|
% Crude Carbohydrate*
|
% Ash
|
Gross Energy MJ/kg
|
Fish meal
|
63.0
|
11.0
|
-
|
15.8
|
20.1
|
Poultry meal
|
58.0
|
11.3
|
-
|
18.9
|
19.1
|
Corn-gluten
|
62.0
|
5.0
|
18.5
|
4.8
|
21.3
|
Soybean
|
44.0
|
2.2
|
39.0
|
6.1
|
18.2
|
Wheat meal
|
12.2
|
2.9
|
69.0
|
1.6
|
16.8
|
Spirulina
|
58.0
|
11.6
|
10.8
|
13.4
|
20.1
|
Chlorella
|
52.0
|
7.5
|
24.3
|
8.2
|
19.3
|
Tetraselmis
|
27.2
|
14.0
|
45.4
|
11.5
|
18.0
|
Gracilaria sp1
|
34.0
|
1.5
|
37.1
|
26.9
|
13.4
|
Gracilaria sp2
|
10.0
|
0.9
|
50.1
|
34.0
|
11.2
|
Ulva lactuca1
|
37.4
|
2.8
|
42.2
|
17.4
|
15.7
|
Ulva lactuca2
|
12.5
|
1.0
|
57.0
|
24.5
|
11.2
|
Schizochytrium3
|
12.5
|
40.2
|
38.9
|
8.4
|
25.6
|
* Carbohydrates calculated as the difference % DM – (%
protein + % lipid + % ash)
1 Cultured in effluent of fish tanks
2 Collected from natural habitat
3 Commercial product, Martek Biosciences
As noted
above, the costs of fish meal and fish oil are steadily increasing. Thus, if a
source of protein-rich or lipid-rich algal meal came onto the market at an
affordable price, the animal feed industry would certainly consider using it
based on existing evidence of the nutritional value of algal biomass.
So, now we can see the nutrional value and the necessary with reasonable and affordable cost, Should
all of animal feed manufactures consider these ingredient in final complete mix
pellets products?
for more information, please contact :
Ms. Rach
HP: +84 915 601 238
Skype: agri.quatic
EM: agriquatic@gmail.com