Effects of diet on body condition
The weavers which fed on grains and fruits significantly lost more body mass between week 0 (before diet restriction) and week 8 (at the end of diet restriction) compared to the weavers that were fed on grains and insects (Fig. 2A, F 4, 183 = 2.63, p = .036, Table 2). This pattern was similar between sexes (Fig. 2B, F 1, 183 = 1.17, p = .282, Table 2 & Table S3B). Body mass decreased significantly upon diet restriction (between week 0 and week 2) only in weavers fed on grains and fruits, but weavers fed on grains and insects maintained their body masses throughout the experiment (Fig. 2A, Table S3A) and this was similar for males and females (Fig. 2B, F4, 183 = 1.29, p = .275, Table 2 & Table S4).
Muscle size was similar between the weavers fed on grains and fruit, and those fed on grains and insects before diet restriction in week 0 (Fig. 3A), but upon diet restriction, the muscle size of the weavers fed on grains and fruits significantly became lower than those fed on grains and insects (Fig. 3A, F 4, 183 = 8.32, p < .001, Table 2) and this pattern differed marginally between sexes (Fig. 3B, F 1, 183 = 3.04, p = .083, Table 2 & Table S3B): females deprived of insects lost more pectoral muscle mass than males of the same group. Muscle size decreased significantly after diet restriction in week 6 (t = 6.88, p < .000, Table S3A), and 8 (t = 3.70, p = .010, Table S3A) in the weavers fed on grains and fruits, but weavers fed on grains and insects maintained their muscle sizes throughout the experiment (Fig. 3A, Table S3A). This pattern was similar for males and females (Fig. 3B, F 4, 183 = 1.76, p = .138, Table 2 & Table S4).
Overall, the fat score was similar between the weavers fed on grains and fruits, and those fed on grains and insects before diet restriction in week 0 (Fig. 4A). After diet restriction, the weavers fed on grains and insects significantly accumulated more fat compared to the weavers fed on grains and fruits (Fig. 4A) but, this was sex dependent (Fig. 4B, F1, 183 = 4.26, p = .040, Table 2). As such, fat scores did not differ significantly (t = - 0. 05, p = .000) between diet treatments for females but, males fed on grains and insects accumulated more fat than those fed on grains and fruits (Fig. 4B, t = - 2. 94, p = .019, Table S3B). For both treatments, fat reserve increased after diet restriction from week 2 – 8 and differed between weeks (Fig. 4A, F1, 184 = 3.31, p = .012, Table 2 & Table S3A) and this was similar for males and females (F 1, 183 = 1.30, p = .273, Table 2 & Table S4).
Diet treatment had no effect on PCV (F 1, 183 = 0.06, p = .808, Table 3), however, PCV increased significantly over the course of the experiment in both diet treatments (Fig. 5A, F 4, 183 = 12.54, p < .001, Table 3 & Table S5) and this was similar for males and females (Fig. 5B, F 4, 183 = 0.09, p = .986, Table 3).
Similarly, diet had no effect on HBC (F 1, 183 = 0.28, p = .597, Table 2), but HBC increased significantly during the experiment in both diet treatments (Fig. 6A, F 4, 183 = 16.34, p < .001, Table 3 & Table S5). This pattern was similar between sexes (Fig. 6B, F 4, 183 = 0.09, p = .985, Table 3).