Effects of pre-ensiling treatments on feed choice and short-term dry matter intake of lucerne silages by goats

Abstract

The three pre-ensiling treatments dry matter (DM) concentration, wilting intensity and sucrose addition have recently been shown to affect the chemical composition of lucerne (Medicago sativa L.) silages (LS) with highest true protein preservation and improved fermentation quality when lucerne was wilted with high intensity to 35% DM concentration and ensiled with the addition of sucrose. Provided that ruminants prefer these LS to those produced under other pre-ensiling conditions, an improved provision of dietary energy and nutrients may be achieved. However, information on how such pre-ensiling treatments influence the feed choice and DM intake (DMI) of ruminants is lacking and thus, feed choice trials with ten Saanen-type wethers were conducted. The LS were tested in two separate trials split by the factor sucrose addition. In both trials, the animals first passed an adaptation period receiving each differently pre-treated LS (n = 4) and lucerne hay that served as a control for one day to gain forage-specific post-ingestive responses. Subsequently, each possible two-way combination of forages was offered to the animals to determine the forage preference, i.e. 30-min and 3-h DMI. The DM concentration affected the feed intakes at both time points with greater preference for 35% DM LS than for 25% DM LS and a higher consumption was observed for sucrose-treated LS than for untreated LS when related to control lucerne hay. In contrast, wilting intensity showed no influence on DMI. The higher intake of high DM or sucrose-treated LS was likely related to the superior silage quality as indicated by high negative correlations of DMI and non-protein nitrogen, ammonia-nitrogen, acetic acid, butyric acid and gamma-aminobutyric acid concentrations.