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Quantifying the Water and Energy Usage of Individual Activities within Australian Feedlots
The Australian red meat industry, as with most primary industries, is coming under increasing pressure from both the community and government to document and justify its impacts on the environment. Currently, a lack of credible supply chain data prevents the industry from being able to respond in a meaningful manner.
Meat and Livestock Australia (MLA) has undertaken a project (FLOT .328) to measure environmental costs associated with the production of one kilogram of meat from modern Australian feedlots. As part of this project, factual information data on water use was obtained via a detailed on-line survey of feedlot inputs and outputs including cattle numbers, intake and sale weights and dressing percentages. Annual water usage was estimated on the basis of one kilogram of dressed hot standard carcass weight gain while in the feedlot (kg HSCW gain).
In this context, HSCW gain is the difference between total dressed carcass weights of cattle leaving the feedlot less the estimated total dressed carcass weight of cattle entering the feedlot. Whilst total annual clean water records by lot feeders are usually good, little data exists on actual usage levels in individual components viz drinking water, feed processing, cattle washing. More information is required on the water usage of individual components before these figures can be reliably reported and before water use efficiency activities can be undertaken.
The purpose of this study is to quantify the clean water usage and indirect and direct energy usage from individual feedlot activities. Eight feedlots were selected representing a cross section of geographical, climatic and feeding regimes within the Australian feedlot industry. The sub-system boundary as defined here is the feedlot site itself plus the transport component of bringing cattle and feed into the feedlot and delivering cattle from the feedlot. Water meters and/or power meters were installed at eight feedlots to allow an examination of usage by individual activities. The major clean water usage includes cattle drinking water, feed management, cattle washing, administration, repairs and maintenance and dilution of effluent.
Similarly, activities that use a significant amount of energy include water supply, feed management, waste management, administration and repairs and maintenance. The water and power meter data collected were supplemented with existing data collected on-site including fuel consumption (diesel, LPG) and cattle performance data. Performance data included market types, incoming and outgoing liveweights, dressing percentages, feed data and other parameters that allow HSCW gain to be estimated. Information was collected on a monthly basis. At most feedlots, intensive assessments of minor water use operations were undertaken.
Activities that were investigated this way included trough cleaning, hospital cleaning, induction yard cleaning and vehicle washing. These minor activities are too numerous to monitor economically using inline water meters. The data was analysed to obtain water and energy use associated with a number of feedlot indices including a per-head basis, per tonne grain processed and per kilogram of hot standard carcase weight gain (kg HSCW gain). A breakdown of resource use within the major feedlot activities and associated operations is provided. This report covers the issue of water usage by feedlots. Total annual clean water use (without dilution of effluent) ranged from 30-104 L/kg HSCW gain over the period March 2007 to February 2008 for the seven feedlots in which water usage was measured. This is a similar range to that found in earlier work (34-90 kg/HSCW gain) by Davis & Watts (2006). Drinking water contributed about 90% of the total water usage in the months when no cattle were washed. This reduces to about 75% during months when cattle washing is undertaken.
As expected drinking water consumption is driven by rainfall and heat load. During rainfall, drinking water consumption is suppressed and increases to maximum levels during periods of high heat load. The average drinking water consumption across all feedlots for March 2007 to February 2008 ranged from 31 L/head/day to 47 L/head/day, with an average in the order of 40 L/head/day. Feedlot E, located in a subtropical environment, had the highest average drinking water consumption of 48 L/head/day, whilst Feedlot B which experiences cold winters, mild summers and high rainfall when compared with other feedlot locations, had the lowest drinking water consumption of 31 L/head/day. These levels are less than the often quoted figure within the industry of an average of 65 L/head/day. It is believed that the 65 L/head/day figure is based on the maximum daily requirement of 5 L per 50 kg LWT, hence representing the water requirements of a 650 kg beast.
The maximum monthly drinking water consumption recorded at an individual feedlot was 70 L/head/day during January 2008 and the minimum of 4 L/head/day was recorded in June 2007. The relationship between drinking water consumption, heat load index and rainfall is clearly evident on a daily basis. During periods of rainfall, drinking water consumption is suppressed, whilst during periods of high heat load, drinking water is at its highest. Feed processing water usage is the second highest consumer of water in feedlots where no cattle washing is undertaken.
Three different feed processing systems are represented within the seven feedlots and included tempering, reconstitution and steam flaking. Feed processing is about 4% of water usage and is dependent on the grain processing system employed at the feedlot. This figure can vary from month to month depending on the management of the various systems. Feed processing water usage ranges from 90 to 390 L/t grain processed. Water added to the grain ranges from 45 to 90% of the total water used. For tempering only systems, the water added to the grain is similar to the total water used. Hence, it has a very low volume of unaccounted for water. The difference between measured water and water added to grain is defined as unaccounted for water. For reconstitution, an average of 40 L/t grain is unaccounted whilst water usage and unaccounted for water within steam flaked systems is variable with an average figure of 225 L/t grain unaccounted. Therefore, in steam flaking, if the tempering component water usage is reflected in additional water in the grain, the majority of unaccounted water can be attributed to the process of steam generation and delivery. A number of factors will influence feed processing water usage including the system employed, grain type, target moisture and management of the system.
Cattle washing is the second highest consumer of water in feedlots in months when it is undertaken. The total water usage in some feedlots comprises clean and recycled water. Cattle washing can contribute up to 25% as a function of HSCW gain of the total water usage. Cattle washing water used from 800 L/head to 2600 L/head. However, a monthly water usage up to 3900 L/head was recorded at one feedlot. Recycled water can account for 50 to 75% of the total water usage. The water required for cattle washing is dependent on the dirtiness of the cattle and the cleaning requirements. Administration water usage comprises that used in office and staff amenities and for watering of lawns and gardens.
Average administration water usage ranged from 0.6 to 3.2 L/kg HSCW gain over the period March 2007 to February 2008. Administration represents a small proportion of the total usage, representing about 2% and is driven primarily by the volume of water irrigated onto lawns and gardens. The sundry water losses ranged from 0.03 L/head/day to 4.1 L/head/day. Evaporation from water storages, water trough cleaning and road watering are the three largest sundry water uses. Variation between feedlots may be explained by feedlot design (surface area open water storages, size of troughs), location (climate) and management operations including frequency of trough cleaning and road maintenance (dust control)
|Contract No.||Title||Start date||End date||Funding type|
Improving water and energy use efficiency in the Australian feedlot Industry
Water and energy usage for individual activities within Australian feedl ots
This page was last updated on 06/07/2018
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