Study of failures in a rabbit line selected for growth rate

Abstract

Selection for growth rate is negatively related with reproductive fitness. The aim of this work was to analyse the causes of fertility failure in rabbit does selected for growth rate and characterised for reproductive deficiencies (line R). In the experiment, 82 does were divided into 2 groups: naturally mated (NM) and artificially inseminated (AI), to relate luteinizing hormone (LH) concentration with ovulation induction and pregnancy rate by laparoscopic determination. Additionally, in 38 of these females ovulation rate and metabolites determination (leptin, NEFA, BOHB and glucose) were analysed and perirenal fat thickness measurement and live body weight (LBW) determined. The results showed that all ovulated does (both NM and AI) presented higher concentrations of LH than non-ovulated females. In addition, non-ovulated females showed high levels of leptin and BOHB, as well as LBW. Females from line R have an inherit reduced fertility due to ovulation failure as a consequence of a reduction in LH release, which could be explained by a heavier body weight and higher leptin concentrations.

Feed restriction regime in a rabbit line selected for growth rate alters oocyte maturation manifested by alteration in MSY2 gene expression

“…A previous study showed that naturally mated females presented higher failures in ovulation rate due to a decreased LH release (Naturil‐Alfonso, Lavara, Millán, et al., ). These authors hypothesized the existence of an insufficient neuroendocrine reflex in the hypothalamus–hypophysis system to trigger adequate GnRH secretion.…”

“…Previous studies have shown that rabbit females selected for growth rate have severe reproductive problems, which start with ovulation failures (Naturil‐Alfonso, Lavara, Millán, et al., ; Vicente et al., ). These females have been shown to weigh 26% more than maternal or other lines/breeds not used in meat production (De la Fuente & Rosell, ).…”

“…In this sense, several studies in females from a rabbit synthetic line selected for growth rate over 36 generations demonstrated a significant reduction in the ovulation frequency (30%) in comparison with New Zealand white (Naturil‐Alfonso, Lavara, Millán, et al., ; Vicente et al., ). These ovulation failures have been related to reduced LH plasma concentrations (Naturil‐Alfonso, Lavara, Vicente, & Marco‐Jiménez, ; Vicente, Viudes‐de‐Castro, García, & Baselga, ; Vicente et al, ; Viudes‐de‐Castro & Vicente, ).…”

Optimization of Resource Allocation to the Genetic Type in Reproductive Rabbit Does

“…Females from this line are bigger and fatter than females from maternal lines Naturil-Alfonso et al, 2016). Cardinali et al (2008) showed that extreme body condition (both very low and very high) was related with poor sexual receptivity and fertility.…”

“…To improve the reproductive performance of R females, we hypothesized that they could be over-fat and animal-fat enriched diets, which do not promote body reserves accretion, could be beneficial to improve their fertility (Naturil-Alfonso et al, 2016). Moreover, as animal-fat enriched diets promote milk yield, we expected that Diet AF would improve survival of the offspring during lactation.…”