Long-term implications of feed energy source in different genetic types of reproductive rabbit females: III. Fitness and productivity

Abstract

The specialization process associated with genetic selection could be associated with functional disorders, affecting the reproductive success of females (fitness). We hypothesized that by modulating energy acquisition and allocation of females we could balance productivity and reproductive success. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66) maternal line specialized in prolificacy, LP (n=67) generalist maternal line, R (n=70) paternal line specialized in growth rate. We fed each genetic type with two diets specifically designed to promote milk yield (AF) or body reserves recovery (CS). We controlled females between their first and fifth reproductive cycles, recording traits related with productivity and fitness of females. H females fed CS had on average 11.2±0.43 kits with an individual weight of 54±1.2 g at birth and 525±11 g at weaning. Their conception rate when multiparous was 44% and their survival rate at the end of the experiment 30%. When they were fed AF, the individual weight of kits was 3.8 g heavier (P<0.05) at birth and 38 g heavier at weaning (P<0.05), the conception rate when multiparous increased 23 percentage points (P<0.05) and the survival rate at the end of the experiment 25 percentage points (P<0.05). LP females fed CS had on average 10.8±0.43 kits with an individual weight of 52±1.2 g at birth and 578±11 g at weaning. Their conception rate when multiparous was 79% and their survival rate at the end of the experiment 75%. When they were fed AF, it only increased individual weight of kits at weaning (+39 g; P<0.05). R females fed CS had on average 8.4±0.43 kits with an individual weight of 60±1.2 g at birth and 568±11 g at weaning. Their conception rate when multiparous was 60% and their survival rate at the end of the experiment 37%. When they were fed AF, they presented 1.4 kits less at birth (P<0.05) but heavier at birth (+4.9 g; P<0.05) and at weaning (+37 g; P<0.05). Therefore, we observed that genetic types prioritized different fitness components and that diets could affected them. In this sense, seems that more specialized genetic types, were more sensitive to diets than the more generalist type.

Changes in Body Reserves, Non-Esterified Fatty Acids, and Leptin during the Reproductive Lifespan of the Rabbit Female

“…It is well known that the development of rabbit females is related to the development of fetuses in the first reproductive cycles, i.e., for nulliparous and primiparous animals [38]. This agrees with the increment in PFT from 12 weeks of age until the second delivery.…”

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation

“…It has been reported that fat-enriched diets favour milk yield, whereas starch-enriched diets favour body reserve gain (Pascual et al, 2003). This is the first of three consecutive scientific papers that aim to evaluate the hypothesis that the effect of energy source of the diet varies with the genetic type, having implications in the way each genetic type acquires and allocates resources over time, their immunological status or their fitness and productivity (see companion papers Arnau-Bonachera et al, 2017;Penadés et al, 2017). Specifically, in the present work we studied: (i) the way three genetic types, widely differing in their genetic background, acquire and allocate resources.…”

Long-term implications of feed energy source in different genetic types of reproductive rabbit females. II. Immunologic status

“…H rabbit does are very dependent of their body condition, as they need to be able to feed very large litters. However, excessive fat deposits can also be counterproductive, as they diminish fertility and increase mortality (Arnau-Bonachera et al, 2017a and2017b). On the contrary, LP animals do not depend on their body condition as much as H animals, mainly because they have developed several different mechanisms to modulate their responses and keep the energy homeostasis balance without reducing their fertility, while being able to maintain most of their litter alive until weaning.…”

“…Notwithstanding the evidenced impact of genetic selection on the robustness of the animal, it has also been suggested that the use of a fat-enriched lactation diet could contribute to improving the maturity of the immune system of young rabbits at weaning (García-Quirós et al, 2014) and, therefore, their general health status towards the growing period. In this conceptual framework, this is the second of three consecutive papers (see companion papers Arnau-Bonachera et al, 2017a and2017b) that were designed to provide a context in which animals from three different genetic types and fed with two distinct dietsbut housed and bred in the same conditions-could be systematically studied and compared throughout their reproductive life (from the first artificial insemination to the sixth parturition). In that context, this paper is mainly focused on the study of the immunological status of the animals.…”