Effects of Different Pellet Feed Hardness on Growth and Reproduction, Feed Utilization Rate, and Environmental Dust in Laboratory Mice

Abstract

Objective To study the effects of different pellet feed hardness on the growth and reproduction, feed utilization rate, and environmental dust in laboratory mice. Methods One hundred of fifty 50 3-week-old SPF-grade C57BL/6JGpt and 150 ICR laboratory mice were randomly divided into three groups, with an equal number of males and females. They were fed diets with different hardness of 18.62 kg, 23.15 kg, and 27.89 kg. Body weight, feed utilization rate, and dust levels in cages were recorded and calculated for mice aged 3-10 weeks. Forty-five 6-week-old male mice and ninety 4-week-old female mice from each strain were randomly divided into three groups and fed pellet feeds with three different hardness levels. After 2 weeks of adaptation to the same hardness feed, the mice were paired at a 1∶2 male-to-female ratio and monitored for reproductive data for 3 months. Results At the age of 4 weeks, the body weight of male C57BL/6JGpt mice in 23.15 kg group was significantly higher than that in the 18.62 kg and 27.89 kg groups (P0.05). For both strains, feed utilization rate for males was higher than that for females across different feed hardness groups at all weeks of age (P0.05). However, the monthly production index of C57BL/6JGpt mice first increased and then decreased with the increase of feed hardness, while that of ICR mice increased with increasing feed hardness, though these differences were not statistically significant (P>0.05). Conclusion Different strains and genders had different tolerance to feed hardness. C57BL/6JGpt mice are more adapted to lower hardness feeds, while ICR mice are better suited to slightly higher hardness feeds.

Keywords

• laboratory mice
• pellet feed hardness
• growth and reproductive performance
• feed utilization rate
• environmental dust