Summary
1.The Premium Grains for Livestock Program (PGLP) was established in 1996 as a jointly funded grains and animal industries project. The project arose because of the rapidly increasing demand for grain by the intensive livestock and dairy industries and concern from these industries about a reliable supply of grain meeting quality specifications for their industries. Grain growers had traditionally seen feed grains as down graded grains unsuitable for human consumption and were not encouraged to produce grains for livestock because of the lower price frequently obtained. However, much of the feed grain available was of insufficient quality for animal industries to meet production specifications and deadlines. Consequently, following several joint industry meetings, the grains and animal industries recognised the opportunity to develop an animal grains industry based on the measurement of quality and appropriate payment for this quality. PGLP has been funded by the Grains R&D Corporation, Meat and Livestock Australia, Australian Pork Limited, Rural Industries R&D Corporation through the Chicken Meat Program, Australian Egg Corporation Limited, Ridley Agriproducts and Dairy Australia. The principle objectives of PGLP were to:
-Identify the characteristics of grains that made them most suitable for different forms of animal production.
-Develop a process, based on the rapid measurement of grain quality, for the rational trading of grains for livestock within Australia which provides just rewards to both the grain growers and livestock producers.
2.PGLP has been a unique Project, involving scientists from a wide range of backgrounds and disciplines in the most comprehensive effort yet undertaken to understand the characteristics of cereal grains that determine their nutritional value for different classes of livestock including sheep, feedlot cattle, pigs, broiler chickens and laying hens. Cereal grains, because of their high starch content relative to other ingredients, are offered to animals primarily as a source of readily available energy. The most important outcomes from the program are an understanding that the grain characteristics most suitable for production vary widely between animal types, the development of rapid near infra-red spectroscopy (NIR) calibrations for measuring most of these characteristics and the ability to predict the impact of grain type and on animal performance so the economic value of any grain sample can be determined for each major livestock industry. A number of case studies were conducted to determine how best this information can be made available to grain growers, traders and end-users for development of a process for the rational trading of grains for livestock in Australia with the added value being shared equitably across the feed grain industry chain. The NIR calibrations developed within PGLP have been licensed to the Pork CRC for commercial exploitation across the whole feed grain value chain in Australia. A Business Plan setting out the tasks required to help ensure the calibrations will be used as the main basis for trading grains in Australia has been prepared.
3.Prior to commencement of research, a critical review was undertaken in 1996 of current information then available on factors influencing the nutritional value of cereal grains for different livestock species to ensure that novel approaches to the research and best practice methodology were adopted throughout the life of the Program. Over 3300 grains, primarily wheat, barley, oat, triticale and sorghum, with a wide range in chemical and physical characteristics thought to influence their nutritional value for livestock have been collected from germplasm archives, plant breeders, specifically grown cultivars and farmers. The samples included frost damaged, partially germinated and drought affected grains as well as more normal well-grown and irrigated grains. All grains were scanned with NIR and the extent and rate of digestion of components in selected grains examined with in vitro systems simulating rumen fermentation and intestinal digestion. Approximately 194 grains selected on the basis of NIR scans, in vitro analyses, genetic background or growing conditions were fed to animals including sheep, cattle, pigs, broiler chickens and laying hens. About 40 of these individual grain samples were offered to ruminants (sheep/cattle), pigs, broilers and layers where voluntary intake and digestibility of the grains were measured. Twenty four grains were fed to sheep at maintenance and cattle ad libitum. The regression equation relating digestibility of grains within the two animal types was used to estimate the digestibility and calculated metabolisable energy (ME) content for cattle of all grains offered to sheep except sorghum. Comprehensive chemical and physical analyses have been conducted on all grains fed to animals. There were approximately 110 analyses conducted on each sample and coved the range in grain characteristics that are likely to have the greatest influence nutritional value for different animal types. Light and scanning electron microscopy were used to examine the physical structure of some grains. Common grains were used across animal and in vitro experiments and thorough statistical procedures used to account for errors associated with experimental variation when determining final corrected values used in analyses for this report.
4.The value of a grain as a source of energy to an animal depends on the total amount of energy made available for metabolism (MJ/d), which is determined by the energy available from digestion (available energy content of the grain, MJ/kg) and by the amount of grain consumed in the diet (kg/d). Traditionally, only available energy content of the grain has been considered because of its importance in formulating diets. However, animal productivity is determined by the total intake of available energy. Thus, throughout PGLP, grain characteristics that influence both the available energy content and total available energy intake have been considered. Analysis of the results shows that the two measures of available energy are poorly correlated for all animal types examined. Characteristics of a grain that influence digestion are either not the same as those that affect voluntary feed intake or they have a different magnitude of effect on feed intake.
