Australian barley, wheat and sorghum as alternative grains in pig diets in Asia

World grain production is dominated by corn followed by wheat, rice, barley and sorghum.  These grains are used for a variety of purposes including human food, brewing and distilling, animal feed and ethanol production. Although corn is dominant there are significant volumes of wheat and barley available for animal feeding.

Wheat production in China and India is high (over 100 million tonnes/year) but is largely consumed domestically. Production is also high in the EU, Russia, USA, Canada and Australia and substantial volumes of this production are available for export.

Barley production is prominent in the EU, Russia, Australia and Canada, also with significant quantities available for export.  In the 2020/21 harvest period, Australia will produce 31.2 million tonnes wheat and 12.0 million tonnes barley plus a variety of legumes (peas, lentils, lupins, chickpeas and beans) and canola as the dominant oilseed. Production of corn and soybeans in Australia is quite low. The feed ingredient profile used in stockfeed manufacturing in Australia is quite broad utilising multiple cereals (wheat, barley, sorghum, triticale, corn, rye, rice) and a number of legumes (peas, lupins, faba beans, chickpeas, lentils, mung beans and vetch), animal proteins including meat meal, bloodmeal, fishmeal and milk powders, vegetable proteins (mainly canola meal, imported soybean meal, sunflower meal, cottonseed meal) and a range of milling offals from wheat, rice, oats, corn and legume processing, the full spectrum of synthetic amino acids and a number of food industry by-products. All this demonstrates the flexibility that exists in pig feed formulation to meet the nutrient specification of diets and maintain the performance of pigs.

The various grains we choose as the cereal base of diets are different and these differences are highlighted in Table 1, showing the typical proximate analyses of the various grains. The obvious points arising from the comparison are that barley is lower in energy due to its high fiber and lower starch content. This is not a major concern as the energy shortfall can be made up with added fat or used as means to regulate energy intake. The fiber in barley is not viewed as a negative diluent but rather as a positive factor promoting gut integrity.

From a protein point of view, barley is generally higher than corn and often less than wheat but the biological value of the protein (the content and balance of essential amino acids) is quite high. The significance of this is that when barley replaces corn, there is less need for added soybean meal to supply amino acids which is of significant economic value, while soybean meal is expensive. The standardised ileal digestible (SID) amino acid content of the various grains at typical protein content is presented in Table 2.

However, due to varying climate and soil conditions as well as agronomic practices, the composition of feed grains can vary. There can be as much variation within a grain type as there is between grain types. So although barley is generally considered to be lower in energy than wheat, a good heavy barley can involve a higher digestible energy value than an average wheat. Consequently, to facilitate accurate feed formulations, it is imperative that this variance is monitored. A recent collaboration of the livestock industries in Australia, has resulted in a major advance in feed milling technology in the form of a NIR calibration to facilitate real time assessment of the energy value (and other nutrients) of cereal grains and oilseed meals called AusScan. In one pass, this service can record ileal and fecal digestible energy values, the fecal DE intake index, major nutrients (moisture, protein, fat, fiber, starch, ash), fiber characterisation (crude, NDF, ADF), non-starch polysaccharide (NSP) characterization (arabinoxylans, beta-glucans, both soluble and insoluble) and the hydration capacity of the material. With complementary amino acid data, a comprehensive nutrient description can be applied to each feedstuff. The range in faecal digestible energy values recorded by AusScan is summarized in Table 3.

Although corn has traditionally been the main grain used in Asian pig diets, Australian barley presents itself as a very competitive alternative. Features of Australian barley include:

A significant point of differentiation between barley and corn is its content of soluble beta-glucan. This has the potential to reduce digestibility but is easily remedied with the inclusion of readily available beta-glucanase enzymes which hydrolyse the beta-glucan to its constituent sugars and remove its viscous properties.

All cereal grains store phosphorus in the form of phytate-P. This phosphorus is released during germination by the action of endogenous phytase enzymes. Animals do not have endogenous phytase enzymes but by dietary supplementation of phytase and NSP enzymes, all the potential antinutritional aspects can be nullified and full digestion and nutrient availability restored.

Grind size is important in the utilization of all cereals and barley is no exception. An average particle size of 0.6 – 0.8 mm for weaners and 0.8 -1.0 mm for more mature pigs is a good balance between maximizing digestion and maintaining gut integrity.

The pig is a very adaptable omnivore that can utilize a wide range of feedstuffs effectively and feed formulation is more about nutrient delivery than ingredient use. A megajoule of energy or a gram of SID-amino acid can come from any source with equal efficacy. With a full appreciation of the available nutrient content of feedstuffs and any peculiar constraints to use, the prime determinant of selecting the preferred grain base to the diet is the relative cost of delivering the necessary nutrients.

Example diets have been presented in Tables 4,5,6 and 7. These show how a pig grower diet can be formulated to the same nutrient specifications using the various grains as the sole grain base or in combination in Australia. Examples are also shown for Thailand, Philippines and Vietnam demonstrating the partial or complete replacement of corn with either barley, wheat or sorghum.

The pig has an ability to utilise a broad range of feedstuffs and although corn is the traditional cereal base, it is not essential and with increasing international trade, other grain alternatives have emerged as economic options.

Australia is enjoying a very productive barley harvest this year resulting in significant quantities being available for export at competitive prices.

The domestic Australian pig industry will make good use of this barley with the opportunity also presenting itself to near Asian neighbours and is well worth considering.