Energy and protein contents in pastures at different times of the year and feeding to meet animal nutrient requirements

Malau-Aduli, Aduli E.O. (2007) Energy and protein contents in pastures at different times of the year and feeding to meet animal nutrient requirements. In: Proceedings of the 16th Annual Conference of the Grasslands Society of Southern Australia, Tasmania Branch (16) pp. 39-52. From: 16th Annual Conference of the Grasslands Society of Southern Australia, Tasmanian Branch, 2007, Launceston, TAS, Australia.

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Pasture is an integral part of ruminant animal production In Southern Australia where rainfall is relatively high, animal production systems rely heavily on pastures to produce milk, wool and meat because it is by far, cheaper than grain-feeding. However, the profitability of a pasture-based enterprise like any other livestock venture, depends on the efficiency with which the animals utilise the nutrients from pastures to meet their requirements for maintenance and production. One of the key decisions in a grazing enterprise is how to manage the feed available in order to minimise costs and maximise output of animal products. Setting stocking rate to annual pasture production and matching feed available to animal requirements are the key elements to ensure that this is achieved. However, as the season changes, so does the nutrient composition of pastures. Furthermore, nutrient requirements vary depending on the age and physiological state of the animal. Schut et al. (2006) reported that the nutritional value of pastures declines by 0.03 and 0.06 MJ ME/kg DM/day for leaves and stems respectively at 18°C, but this decline is negligible at 12°C.Therefore, livestock farmers require detailed information about the feedstuffs of their herds in order to best achieve production goals, whether they are concerned with economic efficiency, nutrient efficiency or maximum yields.

From an animal nutrition perspective, the most important components of pasture quality are energy, dry-matter digestibility and crude protein contents. Among the chemical components of forage dry matter, carbohydrates account for the single largest proportion at around 70–80% (Abe, 2007). These carbohydrates are a major source of energy and are generally classified into structural and non-structural carbohydrates. Neutral Detergent Fibre (NDF) is a measure of the amount of structural carbohydrate in the plant and includes both digestible (hemicellulose), less digestible (cellulose) and indigestible (lignin) components. ADF – Acid Detergent Fibre is the amount of indigestible carbohydrate. Voluntary dry matter intake is critical to animal performance because cell wall concentration of forages is negatively associated with intake of forage diets due to ruminal fill. Beck et al. (2007) reported that when in situ or in vitro NDF digestibility increased by 1% in corn silage diets, dry matter intake increased by 0.17 kg and milk yield increased by 0.25 kg. For the purpose of this paper, the focus is on the following three main attributes; Metabolisable Energy (MJ/Kg), Protein (%) and Fibre (%) contents of pastures in relation to animal requirements in different physiological states.

Item ID: 54921
Item Type: Conference Item (Non-Refereed Research Paper)
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Date Deposited: 07 Aug 2018 23:37
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070204 Animal Nutrition @ 100%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8304 Pasture, Browse and Fodder Crops > 830406 Sown Pastures (excl. Lucerne) @ 100%
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