Fermentation of Whole Grain Sorghum (Sorghum bicolor (L.) Moench) with Different Dry Matter Concentrations: Effect on the Apparent Total Tract Digestibility of Energy, Crude Nutrients and Minerals in Growing Pigs

SIMPLE SUMMARY: Due to climate change and pests as result of maize monoculture, the need of diversification of crop rotation forces researchers to look for alternative grains for animal nutrition. Furthermore, grain fermentation may increase the nutritional value of feed and, simultaneously, decrease costs of feed conservation because the necessity for grain drying and associated energy costs are reduced. In this context, the cultivation and integration of early harvested and fermented sorghum grain in pig diets might be an interesting strategy for the substitution of maize. Therefore, we tested the nutritional value of three varieties of fermented sorghum grains with gradual differences in total dry matter, in a Latin-Square experiment comprising growing pigs. Results indicated there is a potential for improving the nutrient digestibility of sorghum-based pig diets by using early harvested and fermented whole sorghum grain with lower dry matter concentration. Especially the need for inorganic phosphorus supplementation and, hence, the fecal phosphorus emissions were significantly reduced. ABSTRACT: This study investigated the effects of sorghum ensiled as whole grains with different dry matter concentrations on the apparent total tract digestibility (ATTD) of energy, crude nutrients and minerals in growing pigs. Whole grain sorghum batches with varying dry matter (DM) concentrations of 701 (S1), 738 (S2) and 809 g kg(−1) (S3) due to different dates of harvest from the same arable plot, were stored in air-tight kegs (6 L) for 6 months to ensure complete fermentation. Subsequently, 9 crossbred barrows (34.6 ± 1.8 kg; (Duroc x Landrace) × Piétrain)) were used in a 3 × 3 Latin square feeding experiment. Diets were based on the respective sorghum grain silage and were supplemented with additional amino acids, minerals and vitamins to meet or exceed published feeding recommendations for growing pigs. The ATTD of gross energy, dry matter, organic matter, nitrogen-free extracts, and crude ash were higher in S1 compared to S3 treatments (p ≤ 0.05), while S2 was intermediate. Pigs fed S1 showed significantly higher ATTD of phosphorus (P) compared to all other groups while ATTD of calcium was unaffected irrespective of the feeding regime. In conclusion, growing pigs used whole grain sorghum fermented with a DM concentration of 701 g kg(−1) (S1) most efficiently. In particular, the addition of inorganic P could have been reduced by 0.39 g kg(−1) DM when using this silage compared to the variant with the highest DM value (809 g kg(−1)).