Differences in the chemical composition and digestibility of cereal hay and straw produced in a Mediterranean rainfall area of South Africa
Chemical composition and digestibility values were obtained to provide a database for accurate values of hay and straw types produced in the Western Cape area of South Africa. Straw and hay samples were collected from 10 different localities in the Swartland and Rûens areas of South Africa. Barley hay had the highest IVOMD value (753.2 g kg-1), followed by wheat (744.9 g kg-1), triticale (720.4 g kg-1) and oats (697.7 g kg-1). Wheat hay had the highest TDN value (670.7 g kg-1), with oats having the lowest value (627.5 g kg-1). Oats was higher in NDF (602.8 g kg-1) compared to the other hay types. ADF values of barley (297.9 g kg-1), oats (342.4 g kg-1) and triticale (323.0 g kg-1) differed significantly. Oat straw had a much higher IVOMD value (392.0 g kg-1) compared to the other straw types. Barley had the lowest IVOMD value (293.2 g kg-1). The TDN value of oats (444.8 g kg-1) was higher than for the other straw types. Barley straw had the highest NDF value (817.7 g kg-1), which differed from oats (781 2 g kg-1) and triticale (795.4 g kg-1). There were significant differences in the ash, CP, IVOMD, TDN and ADF contents of straw produced in the Swartland and Rûens areas. Ash, CP, IVOMD and ADF values of cereal straw samples were higher when produced in the Rûens. NDF values were higher in cereal straw samples from the Rûens, except for barley (from the Swartland), which had a higher NDF value. The TDN value of cereal straw was higher for the samples collected in the Rûens compared to those from the Swartland, although wheat and triticale showed higher TDN values when sampled in the Swartland. These differences should be taken into account when hay and straw from the different areas are used in formulating a balanced diet. This accentuates the importance of routine analysis of hay and cereal straw before use in diet formulations.