Use of crude glycerin in dairy goat feeding and its effects on milk and cheese performance and quality

This study aimed to assess the impact of stepwise dietary inclusion of crude glycerin (CG) on the productive traits of dairy goats and the quality of their milk and cheese. Sixteen Saanen goats, averaging 55 ± 6 kg live weight and 45 days in milk, were allocated into four simultaneous Latin squares (4×4) and fed on diets containing 0 (control), 50, 100, and 150 g/kg of CG in the dry matter (DM). A linear decrease (P < 0.05) was observed in DM, crude protein (CP), neutral detergent fiber (NDF), and non-fibrous carbohydrates intake with increasing CG levels in the diet, with a significant reduction (P < 0.05) noted at 100 and 150 g/kg of CG. Additionally, CP digestibility, nitrogen balance, and plasma urea nitrogen decreased (P < 0.05) with CG inclusion. Milk yield corrected for 3.5 % fat, total solids content, and total fatty acid (FA) amounts in goat milk decreased (P < 0.05) with 100 and 150 g/kg of CG. Furthermore, inclusion of 150 g/kg of CG decreased (P < 0.05) fat content in "coalho" cheese, although cheeses from goats fed up to 50 g/kg of CG showed superior (P < 0.05) appearance, global impression, and purchase intention. The CG inclusion increased (P < 0.05) short and odd-chain FA contents while decreasing (P < 0.05) long-chain and polyunsaturated FA levels in goat milk. Overall, we recommend incorporating up to 50 g/kg of CG in dairy goat diets as it does not affect milk and "coalho" cheese performance and quality.