Effect of feed restriction on the environmental variability of birth weight in divergently selected lines of mice

Abstract

Background Selection of mice for decreased environmental variability of birth weight has achieved higher survivability and larger litter size as a correlated response to canalized selection, which suggests higher welfare and robustness, and animals that are more homogeneous. However, in these studies, animals were not exposed to an environmental challenge. To demonstrate the advantages of this mouse line with a low environmental variability of birth weight, animals from two divergent lines (high and low variability of birth weight) were subjected to feed restriction. The objective of this study was to use these divergent lines to compare their response in terms of robustness against an environmental challenge. At weaning, 120 females, i.e. four full-sib females from 10 random litters of three consecutive generations of selection, were chosen from these divergent lines. The total number of females was divided into four groups, which were subjected to a feeding regimen by imposing different levels of feed restriction (i.e. 75, 90 and 85% of full ad libitum feed across three generations, respectively) in different combinations during the growth and reproduction periods. Results Animals from the “low” line were less sensitive to a change in feed level than those from the “high” line. Regarding reproduction, the “low” line performed better in terms of number of females having parturitions, number of parturitions, and litter size. Imposing a feed restriction on female mice during their growth period did not affect the birth weight of their pups. The “low” line was preferred because of its higher reproductive efficiency and survival under an environmental challenge. Conclusions Selection for decreased environmental variability of birth weight produces animals that are less sensitive to environmental conditions, which can be interpreted as having greater robustness.

Selection Response in a Divergent Selection Experiment for Birth Weight Variability in Mice Compared with a Control Line

“…However, it was not proven if selection was balanced between the lines, or one of the lines perhaps did not response or the lines had responded with a different magnitude. This is a significant issue, as selection for reducing the variability has been shown to have great benefits, unlike the high line variability [ 12 , 13 , 14 ]. This was possible to check through the control line.…”

“…They also showed that this selection criterion had direct effects in other interesting traits in livestock such as litter size, weaning weight, and survival [ 6 ]. As a result of the divergent experiment, two divergent lines were created, with the low line presenting benefits in production [ 12 ], animal welfare [ 6 ], heritability [ 11 ], and robustness traits [ 13 , 14 ].…”

Impact of selection for birth weight variability on reproductive longevity: A mice model

“…Low line animals performed better in reproductive indicators but marked lower BW. This reduction in the individual weight was accompanied by an increase in litter size and survival at weaning (Formoso‐Rafferty et al., 2018) without negative impact in the weaning weight nor in the weight at the beginning of the reproductive age in this mice population (Formoso‐Rafferty et al., 2019). This impact of the selection on body weight seemed to be a consequence of a statistical scale effect, since a lower variability results in a lower mean (Tatliyer et al., 2019), but this did not negatively affect the total litter weight (Formoso‐Rafferty et al., 2016b).…”

“…They also showed that this selection criterion directly affected other interesting traits in livestock such as litter size, weaning weight and pup survival (Formoso‐Rafferty et al., 2016b). The experiment led to two divergent lines with the low line presenting benefits in production (Formoso‐Rafferty et al., 2016b), animal welfare (Formoso‐Rafferty et al., 2016a), the increase in heritability due to reduced residual variance (Formoso‐Rafferty et al., 2017) and traits usually considered robustness indicators such as feed efficiency (Formoso‐Rafferty et al., 2018, 2019). However, the implications of uniformity on reproductive longevity are still unknown.…”

Embryo survival and fertility differ in lines divergently selected for birth weight homogeneity in mice

“…Also, important was higher reproductive longevity reported with a threefold probability of performing a new parturition in the homogeneous line relative to the heterogeneous line (Formoso‐Rafferty et al, 2022). The advantage of the L‐line is added to the ones already found, such as litter size, weaning weight, and survival, presenting benefits in production (Formoso‐Rafferty et al, 2016b), animal welfare (Formoso‐Rafferty et al, 2016a), heritability (Formoso‐Rafferty et al, 2016b), and robustness traits (Formoso‐Rafferty et al, 2018, 2019).…”