Abstract
Simple SummaryThe current study compares two different commercially available nutritional supplements promoted as caloric support for weanlings for acceptability and effect on weight and survival in mouse pups and lactating dams in the peri-weaning phase with standard diet mash or no supplementation. Our aim was to provide an independent characterization of nutritional supplementation on survival and weight gain in a commonly used mouse strain. These factors influence animal welfare and are essential for the success of a general breeding program. Similarly, supplementation in the peri-weaning phase can alter early nutrition depending on type, which can introduce unintentional confounding that affects the reliability of subsequent experimental outcomes. This study was also designed to consider pragmatic aspects including timing, cost-effectiveness, diet composition, and practicality in an effort to identify supplements capable of optimally supporting pup growth and survival for various research applications in diverse animal use programs.This experiment was conducted to investigate the effects of common commercially available dietary supplementation in the peri-weaning period on feed intake, growth, and survival in C57Bl/6J mouse pups and lactating dams. A total of 96 pups and their dams were randomized to the control group or one of three nutritional supplement treatment groups: (i) control group without supplementation, or (ii) weanling-targeted Clear H2O gel (Gel), (iii) transgenic-targeted Bio-Serv dough (Dough), or (iv) dam diet as a mash (Chow), in the peri-weaning period (from 11 to 28 days). Stool was observed daily for a dye marker indicating supplement consumption. Pups were weaned at 21 days and followed for a total of 42 days. No pup morbidity or mortality was observed. There was a higher proportion of pups consuming dough and gel earlier than chow (p = 0.0091). The majority of treated pups (>95%) were consuming the supplement by day 23 (range 15–23), suggesting interplay between organoleptic properties of the supplement and pup maturity. All groups gained weight, with typical sexual dimorphism observed in the growth curves. Dough treatment led to significantly higher average daily gain in male pups (0.64 ± 0.03 g/d) as compared with controls (0.58 ± 0.03 g/d). The highest average daily gain in all groups was observed pre-weaning between days 21 and 28. Compared with controls, the weight gain slope was significantly higher in the Dough and Chow treatment groups and lower in Gel treatment groups, with a more pronounced effect in males. In this study, the composition of nutritional supplementation was the dominant factor in increasing the growth trend as opposed to energy density. Peri-weaning supplementation with Dough and Chow treatments improved pre- and post-growth performance in a comparable way and was more effective than Gel treatment during adaptation to solid feeding. Proper application of supplements to support weanlings can directly improve welfare and limit unintended experimental variability.
Highlights
Nutritional supplementation is a common practice for supporting laboratory mice that have special needs due to age, health status, phenotype, or experimental design [1,2,3]
Nutritional supplementation has been anecdotally promoted as a way to increase neonate weight gain, improve maternal success, reduce pup mortality through the weaning period, and support mice with developmental delays
This animal was not a member of the three litters which received a foster pup to make a total of six neonates
Summary
Nutritional supplementation is a common practice for supporting laboratory mice that have special needs due to age, health status, phenotype, or experimental design [1,2,3]. The cost, ease of delivery, palatability, sterility, advertised purpose, on-site experience, and perceived beneficial effects are some of the factors that influence choice of supplement For these reasons, nutritional supplementation strategies in mice are largely empirical and vary even within a single institution. Nutritional supplementation has been anecdotally promoted as a way to increase neonate weight gain, improve maternal success, reduce pup mortality through the weaning period, and support mice with developmental delays. This is especially relevant in the increasingly sought-after transgenic and knock-out mouse models where genetic changes may manifest as abnormal anatomy or behavior affecting feed intake. Changes in postnatal development and growth long-term have been observed during intentional experimental manipulation [11,12,13,14,15]
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