Additive genetic and maternal effects on litter traits in rabbits*

Abstract

Additive genetic and maternal effects were estimated for several litter traits in rabbits. A total of 457 litters of 3267 animals from a reciprocal crossbreeding experiment were analysed by an animal model using a derivate-free REML procedure. Heritability estimates for litter size at birth, weaning and slaughter ranged from 0.09 to 0.25, for litter-weight traits from 0.00 to 0.13 and for preweaning and postweaning mortality rates from 0.00 to 0.19. Additive genetic contribution to the variation in a litter trait was found to be higher at birth and during the postweaning period than during the suckling period. Maternal effects accounted for approximately 10 % of the variation in most of the preweaning litter traits. Live litter size at birth was found to be the main source of variation in preweaning traits, explaining between 2.3 % and 43.2 % of the total variation. Heritability estimates and genetic correlations indicated live litter size at birth to be a useful selection criterion for the improvement of litter traits in rabbits. Our results indicated that a litter size of approximately 11 would be optimal before litter size at weaning and litter weight at weaning began to decline. Genetic selection for live litter size at birth would result in significant improvement in litter size and litter weight at later ages. ZUSAMMENFASSUNG: Schätzung additiv-genetischer und maternaler Effekte auf Wurfmerkmale beim Kaninchen An insgesamt 457 Würfen mit 3267 Einzeltieren, die aus einem reziproken Kreuzungsversuch stammten, wurden additiv-genetische und maternale Effekte für zahlreiche Wurfmerkmale anhand eines Tiermodells (DFREML-Methode) geschätzt. Heritabilitätsschätzungen wurden für Wurfgröße und Wurfgewicht zu unterschiedlichen Zeitpunkten (Geburt, Absetzen und Erreichen des Schlachtgewichts) aurchgeführt. Der additiv-genetische Variationsanteil an der Gesamtvariation war dabei bei der Geburt und nach dem Absetzen höher als während der Säugezeit. Die Schätzungen schwankten bei der Wurfgröße zwischen h(2) = 0,09 und h(2) = 0,19 und beim Wurfgewicht zwischen h(2) = 0,00 und h(2) = 0,13. Für die Verlustrate bis zum Absetzen betrug die Heritabilität h(2) = 0,00 und für die Verlustrate vom Absetzen bis zum Erreichen des Schlachtgewichts h(2) = 0,19. Durch maternale Effekte wurde bis zum Absetzen ungefähr 10% der Variation in den untersuchten Merkmalen erklärt. Bei Einbeziehung des Merkmals Lebendwurfgröße bei der Geburt in das Tiermodell ließen sich 2,3-42,3 % der Gesamtvariation in den Wurfmerkmalen in der Säugezeit beschreiben. Die Heritabilitätsschätzungen und die Schätzung genetischer Korrelationen deuten daraufhin, daß die Lebendwurfgröße bei der Geburt ein erfolgsversprechendes Selektionskriterium für die Verbesserung von Wurfmerkmalen beim Kaninchen darstellt. Die vorliegenden Ergebnisse zeigen an, daß eine Lebendwurfgröße von 11 Jungtieren anzustreben ist. Bei größeren Würfen nimmt die Wurfgröße und das Wurfgewicht beim Absetzen wieder ab. Genetische Selektion auf Lebendwurfgröße bei der Geburt verspricht eine signi...

Performance of purebred and crossbred rabbits in Australia: doe reproductive and pre-weaning litter traits

“…However, we need to have genetic correlation estimates before drawing any conclusions about genetic relationships among these pre-weaning litter traits. Krogmeier et al (1994) reported a significant negative correlation between NW and individual birth weight, which was not the case in the present study. A significant negative relationship between ABW and TLBW suggested that an increase of TLBW was mostly due to an increase in NB, despite the decrease in ABW.…”

“…However, selection decisions based on NW seem to be more http://www.publish.csiro.au/journals/ajar promising because of the high CV and as it would take into consideration both pre-natal and post-natal genetic and environmental effects. Krogmeier et al (1994) also demonstrated that a larger litter size led to a significant decrease in individual weight traits and weight gains, and also stated that litters with a high number of live-born animals also showed a higher number of animals weaned. So, greater prolificacy lead to a deterioration in growth of individual rabbits, but was accompanied by an increased total weight in the litter.…”

Faecal microbiota and functional capacity associated with weaning weight in meat rabbits

“…As shown in Fig. , we estimated that gut microbiome could explain 9.22–16.16% of the variation in weaning weight, and these effects are similar to the effects that host genetics have on weaning weight (8.3–13.9%) (Krogmeier, et al , ; Lukefahr, et al , ). This suggests that we should pay more attention to the effect of gut microbiome in the rabbits for both breeding and meat production purposes.…”

Additive genetic and maternal effects on postweaning growth and carcass traits in rabbits

“…K halil et al (1986) reviewed heritability estimates for BW at different ages, and found that estimates differed widely and showed marked effects of age with highest estimates for birth weight and decreased estimates for weights up to 6 months of age. In this study, the additive genetic effect influenced BW at an age of 84 days to a greater extent than birthweight and individual weaning weight (K rogmeier et al 1994). A greater importance of additive genetic effects in the postweaning period than in the preweaning period is in agreement with higher heritability estimates for ADG after weaning in this study and is also in agreement with results of V arewyck et al (1987), who found higher heritability estimates for ADG after weaning compared with ADG up to weaning.…”

“…Housing and feeding of the rabbits were as described by K rogmeier et al (1994). The individual live weight of the rabbits was recorded at weaning, at an age of 84 days, and before slaughter.…”