Litter Size Lab Report

The primary objective is to determine the effects of litter size on growth in mice. There are numerous factors that affect both litter size and growth rate of mice. The goal is to evaluate these elements and how they affect the growth rate and weights during different stages after birth. I hypothesize that the growth rate as well as the weights for small litter pups and males will be larger than the big litter pups and females following the stages post-parturition. I believe this will occur due to the fact males tend to be larger in size and weigh more than females. Smaller litters receive more attention and care from the dam which results in getting more milk in order to grow overall.
Introduction:
Animal reproduction is crucial for the
Data was separated between small litters which contained 6 to 7 pups and large litters which contained 13 to 17 pups. Next, the average weight per pup was determined by dividing the total litter weight by the number of pups in the litter. The average weight per pup among all the dams for both small and large litters was calculated by adding all the 6 average pup weights and then dividing by 6. Standard deviation was calculated for the average weight per pups for small and large litters. The standard deviation was plotted as error bars to demonstrate the range deviated from the average. The p-value was calculated to understand how significant the average weights were and if I could accept my hypothesis or not. The p-values was calculated by conducting a t-test. If the p-value was less than 0.5, the two different data sets can be accepted as significantly different which therefore allows one to accept their hypothesis. All these steps were completed for days 1, 21, and 42. In order to calculate the pre-weaning growth rate for both small and large litters, I subtracted the average pup weight between all dams on day 21 from the average weight on day 1 and then divided by
The male’s growth rate and weight was more than the female pups. This data supports my predictions. I hypothesized that the growth rates and weights for the small litter and male pups would be higher than the large litter and female pups. The increased growth rates and average weights for the small litter shows that maternal behavior has a great influence on the successful development of young. In another study, it was observed that the body weight decreased in large litter size pups during the lactation period (Tanaka 1998). Researchers reported that mouse dams with smaller litters spent more time in the nest and licking individual offspring resulting in a higher growth rate (Tanaka 1998). Dams with larger litters spent more time eating and drinking which can be a factor as to why large litter sizes have a smaller growth rate and body weight. These results are quite similar to the results of this study and provide insight as to why large litters have smaller rates than small litters. It is important to keep maternal behavior in mind when evaluating weights of litter size during weaning and puberty stages among