A study on the optimal fermentation conditions for mixed by-products in livestock feed production

Increase in global prices of grains further adds to difficulties in feeding livestock. Total Mixed Ration (TMR) formulated with food and agricultural by-products is considered as alternative animal feeds. However, it has associated problems particularly but not limited to decomposition due to high moisture content in most of them. To solve this problem, fermentation technology was brought up on TMRs. However, the fermentation condition may vary depending on the composition of the TMRs. This study set out to identify and determine a fermentation condition which can be applied regardless of the TMR composition. The Taguchi method L₉ (3⁴) orthogonal array was adopted in this research. The study considered 3 levels of 4 controllable factors (temperature, moisture content, bulk density, and fermentation period) and 2 uncontrollable factors (compositions and ratio of TMR samples). Quality score was calculated using the silage quality assessment method by analyzing pH and organic acid content (lactic acid, acetic acid, and butyric acid). Fermentation 40 L volume chamber (ϕ 300 × 400 H) was built and three TMR samples were fermented for the validation test. Results indicated that animal feed formulated with by-products had the highest quality score at a fermentation temperature of 20 °C, moisture content of 50%, a bulk density of 0.6 kg/m³, at 96-h fermentation period. This fermentation condition delivers the silage quality score of over 82 regardless of the composition of the materials used in formulating the feed.