Feed preference, daily intake, and laying performance of captive-born Sardinian partridges (Alectoris barbara barbara Bonnaterre, 1790) offered whole defrosted mealworms (Tenebrio molitor L., 1758) as raw feed material with diet

The competence to locate natural feeding sources is one of the main limiting factors for survival in the wild, especially for captive-born birds. Therefore, environmental enrichment through the diet can be strategic before their release into nature. In this research, a feeding trial was undertaken to evaluate the potential use of yellow mealworm (Tenebrio molitor L.) larvae (TM) provisions to captive bred couples of Sardinian partridges (Alectoris barbara barbara Bonaterre, 1790) during the laying period. Twenty-four couple-caged Sardinian breeding partridges were enrolled during the laying period (April–May 2019) and randomly allotted to two feeding groups of 12 couples each: (a) the control (CON) group was fed a conventional complete pelleted diet for laying quails; (b) the yellow mealworm enriched group was additionally fed 5% whole, defrosted TM larvae (TM5%) on top of the same amount of the control diet. As a prerequisite, partridges were unaccustomed to eating mealworms before the start of the trial. Daily feed intake (DFI), bodyweight (BW), and number of laid eggs (LE) were monitored over five weeks of experimental feeding. Partridges fed the TM5% diet displayed a higher preference for whole mealworms (first choice and complete consumption) than expressed for the CON pelleted feed. Differences in daily dry matter intake (p = 0.028) between CON and TM5% groups were observed (DMI: 42.6 ± 1.73 vs. 43.4 ± 1.62 g, respectively); the final body weights (BW) (p = 0.098) of birds in the CON group was higher than those in the TM5% group (435 ± 36.9 vs. 416 ± 36.3 g, respectively). Differences in daily energy intake relative to BW (p < 0.001) as well as relative to metabolic weight (BW0.75) (p < 0.001) were observed between groups, but this was not followed by higher BW, probably due to the absence of grit and inaccessible nutrients and energy (larval exoskeleton). No difference in the average LE per week and egg weight was observed between CON and the enriched TM5% groups, though in the last weeks, a statistically lower number of eggs was laid in TM5% group. Our results suggest that whole yellow mealworms can be a promising feed material to broaden the spectrum of competence for natural feeding sources with similar physical form and nutritional characteristics available in the environment.