Two mouse lines selected for large litter size display different lifetime fecundities

Abstract

We recently described two outbred mouse lines that were selected for large litter size at first delivery. However, lifetime fecundity appears to be economically more important for the husbandry of many polytocous species for which mouse lines might serve as bona fide animal models (e.g., for pigs). In the present study, we compared the lifetime fecundities of two highly fertile mouse lines (FL1 and FL2: >20 offspring/litter at first delivery) with those of an unselected control line (ctrl) and two lines that were selected for high body weight (DU6) and high protein mass (DU6P) without selection pressure on fertility. We tested the hypothesis that selection for large litter size at first parturition would also increase lifetime fecundity in mice, and we observed very large differences between lines. Whereas FL1 and ctrl delivered up to 9 and 10 litters, none of the DU6 and DU6P females gave birth to more than 5 litters. In line with this observation, FL1 delivered the most pups per lifetime (85.7/female). FL2 females produced the largest average litter sizes (20.4 pups/litter) in the first four litters; however, they displayed a reduced number of litters. With the exception of ctrl, litter sizes declined from litter to litter. Repeated delivery of litters with high offspring numbers did not affect the general health of FL females. The presented data demonstrate that two biodiverse, highly fertile mouse lines selected for large litter size at first delivery show different lifetime reproductive fitness levels.

Dietary intervention improves health metrics and life expectancy of the genetically obese DU6 (Titan) mouse

“…Increased pancreatic fat might have implications for the onset of type 2 diabetes 54 , which is frequently associated with insulin resistance 21 .Importantly, obesity is known to be associated with reduced life expectancy and various conditions related to aging, such as inflammation [55][56][57][58][59][60] . Indeed, we found that Titan mice exhibited a shorter lifespan compared to control mice, which is in line with a recent study showing that female Titan mice show a reduced lifetime fecundity compared to the unselected control mice 61 .…”

Endocrine and molecular factors of increased female reproductive performance in the Dummerstorf high-fertility mouse line FL1

“…Females of FL1 ovulate approximately twice as many oocytes compared to ctrl females ( Spitschak et al 2007 ). Remarkably, the FL1 females do not only deliver a high number of pubs in the first pregnancy, but they are also able to deliver large litter sizes with a high reproductive mating rate over a long-time period without health issues ( Langhammer et al 2021 ). Integrating these three parameters, FL1 females have by far the highest Silver fecundity index (the most reliable index for evaluating the reproductive performance of mouse strains) that has ever been described in literature ( Silver 1995 , Langhammer et al 2021 ).…”

Genomic characterization of the world’s longest selection experiment in mouse reveals the complexity of polygenic traits

“…1 A,B, F,G, Additional file 2 : Figure S1). Even though these two trait-selected lines have achieved comparable litter sizes at first delivery (>20 offspring) [ 20 ], their reproductive lifespan differs, with 5.8 and 2.7 litters in average per lifetime for DUK and DUC, respectively [ 20 ]. A remarkable level of divergence has been achieved by the increased body size lines (Fig.…”

“…All these lines are still maintained, but selection only continues for DUK, DUC and DU6. Due to the long span of this selection experiment, lines have been given alternative names (Table 1 , Additional file 3 [ 6 , 8 , 10 , 20 – 41 ]: Table S1) and selected at variable intensities (Additional file 2 : Figure S2).…”