Effects of mulberry leaves on blood biochemical parameters and histopathology in rats

Mulberry (Morus alba) is a high-quality protein resource, which contains various anti-nutritional factors and biological active substances that could pose certain risks when present in animal feed. Therefore, the safety of mulberry for use in feed and the appropriate allowable concentration in feed requires investigation. This study aimed to observe the possible toxic responses in Sprague-Dawley rats (SD) rats administered a long-term gavage of mulberry leaves and thus evaluate its safety in addition to providing a basis for the development and utilization of mulberry leaves. Sixty SD rats were selected and divided according to the randomized complete block design. Doses of 1 and 2 g·kg^–1 of mulberry leaf extract were administered, as the low and high dose, respectively, in addition to a solvent control group. There were ten male and ten female SD rats in each group. The gavage treatment and recovery periods were 28 days and 14 days, respectively. When the gavage treatment and recovery period ended, the rats were collected to determine the biochemical, organ coefficient, and histopathology indexes. The results showed that most indicators of the physical symptoms in SD rats showed no significant difference compared with those in the control group (P > 0.05). Factors that remained unchanged in each dose group were the biochemical, organ coefficient, and histopathology indexes. However, a few individual indicators were observed to be abnormal, but these were due to normal physiological phenomena and had no toxicological significance. Thus, it was preliminarily verified that mulberry leaves are safe for use in feed. Under the conditions of this experiment, the NOAEL (no-observed-adverse-effect-level) of the mulberry leaf was found to be 2.00 g·kg^–1.