Seaweed as an alternative feed resource for livestock
By-Bornalee Handique
PhD scholar, Division of Animal Nutrition,
ICAR-Indian Veterinary Research Institute
Bareilly, Uttar Pradesh-243122, India
Abstract
Due to huge livestock population in our country there is deficit of feed to feed the present livestock. Moreover available some feed resources lack of nutritional values. Therefore there is urgent need of alternative feed resources to fill the gap between demand and supply. Marine macroalgae popualrly known as seaweeds have been used to feed livestock for thousands of years and that is evident from Ancient Greece and in the Icelandic Sagas. They are rich in organic minerals, complex carbohydrates, proteins, lipids, vitamins, volatile compounds and pigments. Many researchers reported that supplementation of seaweed in livestock diet improved weight gain, reduced methan emission, anti oxidant, anti inflamatory, antiviral and prebiotic activity. Therefore, seaweed can be used as an alternative feed resource to improve the productivity of livestock.
Introduction
Socio-economic development and national economy of our country are largely depending on livestock and fisheries sector. According to 20th livestock census the country have 535.78 million livestock population comprising of 192.49, 109.85, 74.26, 148.88, 9.06 and 851.81 million of cattle, buffalo, sheep, goat, pig and poultry population, respectively. Due to huge population pressure both in human and livestock, there is a severe shortage of feed and fodder in the country and for which animals suffer from the malnutrition. In order to meet the gap between availability and requirement of feed, the new alternative feed sources are needed to be used to overcome the shortage of feeds to some extent. There are many potentially valuable feed resources having significant nutritional value which are available inexpensively in large quantity. Aquatic plants can be one of the sources of non-conventional feed resources to feed the livestock. Marine macroalgae popularly known as seaweeds are available in sufficient amount in coastal areas even during draught period. Macroalgae gained prominence during 13th century, after the invention of agar-agar in Japan and alginic acid in European continent. In India, agar-agar gained importance as seaweed chemical during the 2nd World War. Seaweeds have been used to feed livestock for thousands of years and that is evident from Ancient Greece and in the Icelandic Sagas. Seaweed collections are mainly centred along the south-eastern coast of India from Rameswaram to Kanyakumari.
Types of seaweed
Seaweeds belong to three different groups, empirically distinguished since the midnineteenth century by the Irish botanist William H. Harvey (1811-1866) on the basis of thallus (thalli) colour: red algae (phylum Rhodophyta, class Rhodophyceae), brown algae (phylum Ochrophyta, class Phaeophyceae) and green algae (phylum Chlorophyta, classes Bryopsidophyceae, Chlorophyceae, Dasycladophyceae, Prasinophyceae, and Ulvophyceae) (El Gamal, 2012). Red and brown algae are almost exclusively marine, while green algae are also common in freshwater (rivers and lakes) and even in terrestrial (rocks, walls, houses and tree bark in damp places) situations.
Seaweed cultivation and harvesting
Seaweeds grow on different types of environments and depend upon water salinity, nutrients, water movement, temperature and light. The species that propagate vegetatively their pieces are tied to ropes or net and sunk at root bottom of the pond unattached or held in situ by a fork-shaped tool (in sediments) or sand-filled tubes (in sandy soil). They are harvested either by removing the whole plant or by removing most of it but small pieces that are used as seed store are left behind for further cultivation. In brown seaweeds, which mainly reproduce sexually only the massive sporophyte form is harvested (McHugh, 2003). Seaweeds once harvested must be rapidly handled to avoid mould formation.The wet seaweed is passed through hammer mills so as to scale back it to fine particles and it is dried in a drum-dryer starting at 700-800ºC. Seaweed meals should have a final moisture level of about 15% and will be stored in sealed bags.
Importance of seaweed
Seaweeds are markedly rich in organic minerals, complex carbohydrates, proteins and low molecular weight nitrogenous compounds, lipids, vitamins, volatile compounds and pigments (Makkar et al., 2016). They have been used as an additive to livestock feeds because they are the richest source of minerals (Ito and Hori, 1989). The brown seaweeds are traditionally used for treating thyroid goiter as they are rich source of iodine. Seaweeds contain 10–20 times more minerals than land plants and thus potential sources of minerals (Makkar et al., 2016). But they also contain heavy metals and some minerals are in toxic concentration that may interfere with availability of other minerals (Cabrita et al., 2016). Seaweeds are rich source of sodium, potassium, magnesium, chlorine, sulfur, phosphorus, iodine, iron, zinc, copper, selenium and molybdenum (Okab et al., 2013).
Table 1: Biologically active compounds present in seaweed extracts
| Compounds | Action |
| Galactans | Prebiotics, anti-bacterial, antiviral and
anti-tuomr |
| Fucoidans | Anti-inflammatory, antibacterial, anti-
viral and anti-oxidative |
| Laminarin | Prebiotics, anti-bacterial, antiviral and
anti-oxidative |
| Alginate | Thickening, stabilizing, anti-inflammatory and anti-bacterial |
| Lectin | Anti-inflammatory, anti-bacterial and anti-viral |
| Omega -3 fatty acids | Prevents heart blockages |
| Carotinoids | Beta- carotene is a strong antioxidant |
| Phycobiliprotein | Anti-oxidative, anti-viral, anti-inflammatory and neuroprotective |
| Phenolic acid flavonoids | Anti-oxidative |
| Florotannins | Enhance host disease resistance and
anti-oxidative |
| Organic minerals | Ca, K, Mg, Cu, Zn and I |
Effect of seaweed in ruminants
The use of seaweeds in livestock feed increased growth rate and feed conversion efficiency in ruminants. An improved mineral status was found in dairy cattle particularly iodine and selenium in blood and milk supplemented with seaweed. Supplementation of seaweed reduced enteric CH4 production. Anti-methanogenic activity of seaweeds could be attributed to their richness in phenolics (notably phlorotannins in brown seaweeds) and plant secondary metabolites. Phlortannins bind with proteins and carbohydrates and reduce their degradability in the rumen causing reduction in microbial population and fermentation.
Effect of seaweed in non-ruminants
Supplementation of brown seaweeds (Ascophyllum nodosum) in broiler diet increased growth performance. Inclusion of seaweed in broiler diet reduces abdominal and subcutaneous fat thickness thus improving breast meat quality. Inclusion of Sargassum enhanced polyunsaturated fatty acids and n-3 fatty acids and overall improves the meat quality. Green seaweed Epiactis prolifera included at 1–3% resulted in improved egg production and quality, it increased weight, shell thickness, yolk colour and reduced cholesterol in yolk. It also resulted in a lower E. coli load in faeces suggesting better animal health.
Conclusion
Feed cost and availability of quality and quantity of feed is the major constraint to feed the present livestock. Marine macroalgae or seaweed has anti inflamatory, antiviral, prebiotic activity and improve health of the animals. Moreover seaweed increases the growth rate and feed efficiency. Therefore inclusion of seaweed in livestock diet is an alternative feed resources to increase production and to meet the demand of feeds to feed the livestock.
References
Cabrita, A.R., Correia, A., Rodrigues, A.R., Cortez, P.P., Vilanova, M. and Fonseca, A.J. 2016. Assessing in vivo digestibility and effects on immune system of sheep fed alfalfa hay supplemented with a fixed amount of Ulva rigida and Gracilaria vermiculophylla. J. Appl. Phycol. 1-11.
El-Gamal, A.A., 2012. Biological importance of marine algae. In: Kim, S.-K. (Ed.), Handbook
Of Marine Macroalgae: Biotechnology and Applied Phycology.
Ito, K. and Hori, K. 1989. Seaweed: chemical composition and potential food uses. Food Reviews International. 5: 101-144.
McHugh, D.J. 2003. A guide to the seaweed industry FAO Fisheries Technical Paper. FAO of the United Nations, Rome. 441.
Makkar, H.P., Tran, G., Heuze, V., Giger-Reverdin, S., Lessire, M., Lebas, F. and Ankers, P. 2016. Seaweeds for livestock diets: a review. Anim. Feed Sci. Technol. 212: 1-17.
Okab, A.B., Samara, E.M., Abdoun, K.A., Rafay, J., Ondruska, L., Parkanyi, V., Pivko, J., Ayoub, M.A., Al-Haidary, A.A., Aljumaah, R.S. and Peter, M. 2013. Effects of dietary seaweed (Ulva lactuca) supplementation on the reproductive performance of buck and doe rabbits. J. Appl. Anim. Res. 41: 347-355.
