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

Abstract

Additive genetic and maternal effects were estimated for postweaning growth traits and carcass traits using a derivate-free REML procedure under animal model. The traits studied were weight at 84 days of age, age at slaughter, postweaning ADG, dressing percentage, weight of kidney and pelvic fat, and muscle pH value and electrical conductivity in the semimembranosus muscle. Heritability estimates from a total of 728 rabbits in a reciprocal crossbreeding experiment ranged from 0.15 to 0.26 for postweaning growth traits, 0.21 for dressing percentage, 0.38 for weight of kidney and pelvic fat, 0.02 for pH value, and 0.51 for electrical conductivity. Considerable maternal effects were present in postweaning growth traits and in weight of kidney and pelvic fat. Genetic correlation estimates indicated that genetic selection for postweaning daily gain would lead to lower dressing percentages (- 0.51) and leaner carcasses (- 0.34). The genetic relationships between ADG after weaning and pH value (- 0.90), and between ADG and electrical conductivity (0.58) illustrated a shifting towards a glycolytic energy metabolism of the muscle due to increased growth. Litter size at birth was found to be a significant source of variation for all postweaning growth traits (p < 0.001) and for electrical conductivity (p < 0.05). Genetic selection for litter size at birth would result in decreased growth rates, lower dressing percentage and enhanced adiposis. ZUSAMMENFASSUNG: Die Schätzung additiv-genetischer und maternaler Effekte auf Mastleistungs- und Schlachtkörpermerkmale beim Kaninchen Additiv-genetische und maternale Effekte wurden für Mastleistungsmerkmale nach dem Absetzen und für Schlachtkörpermerkmale anhand eines Tiermodells (DFREML-Methode) geschätzt. Bei den untersuchten Merkmalen handelt es sich um das 84-Tage-Gewicht, das Schlachtalter, Zunahmen nach dem Absetzen, Ausschlachtungsprozente, Nieren- und Beckenfettgewicht und um den pH-Wert und die elektrische Leitfähigkeit im M. semimembranosus. Die Heritabilitätsschätzungen an insgesamt 728 Tieren, die aus einem reziproken Kreuzungsversuch stammten, lagen bei den Wachstumsmerkmalen zwischen h(2) = 0,15 und h(2) = 0,26. Sie betrugen h(2) = 0,21 für die Ausschlachtungsprozente, h(2) = 0,38 für das Nieren- und Beckenfettgewicht, h(2) = 0,02 für den pH-Wert und h(2) = 0,51 für die Leitfähigkeitsmessung. Die Schätzung genetischer Korrelationen deutet an, daß eine genetische Selektion auf tägliche Zunahmen nach dem Absetzen zu einer verringerten Ausschlachtung (- 0,51) und zu magereren Schlachtkörpern führen würde. Die genetischen Beziehungen zwischen den Zunahmen und dem pH-Wert (- 0,90) und zwischen den Zunahmen und der elektrischen Leitfähigkeit (0,58) lassen eine Verschiebung in Richtung eines glykolytischen Muskelenergiestoffwechsels bei verstärktem Wachstum erwarten. Die Wurfgröße bei der Geburt stellt eine signifikante Variationsursache für die Mastleistungsmerkmale nach dem Absetzen (p < 0,001) una für die elektrische Leitfähigkeit (p < 0,05) dar. Bei einer Erhöhung der Wur...

Pannon breeding program in rabbit at Kaposvár University

“…Dressing out percentage showed high heritability (0.47-0.48). These estimates were very similar to the reported values of Lukefahr et al (1996) and Varewyck et al (1986) but different of those of Ferraz et al (1992a) Lukefahr et al (1992Lukefahr et al ( , 1993 Krogmeier et al (1994), who reported lower heritability values. The heritability estimate of the hind part ratio was high (0.59) and for this trait there was no available literature to compare our results.…”

Two-way selection for daily gain and feed conversion in a composite rabbit population.

“…The heritability estimates were high, especially for ADG (.48), suggesting that response to mass selection would be particularly effective for this trait. Published estimates of heritability of postweaning gain in rabbits were variable, ranging from .13 to .48 (Rochambeau et al, 1989;Moura et al, 1991;Estany et al, 1992;Ferraz and Eler, 1994;Krogmeier et al, 1994;Lukefahr et al, 1996;McNitt and Lukefahr, 1996). Variability may be due to the variety of breeds, environmental conditions, and methodology involved in these studies.…”

“…Average daily gain has been indicated as the preferred trait for selection in the postweaning period, especially in unimproved populations, because it is less affected by common litter effects than the individual weights at specific ages (Rochambeau et al, 1989;Estany et al, 1992;McNitt and Lukefahr, 1996). Previously reported heritability estimates for ADG varied in magnitude from .13 to .48 (Rochambeau et al, 1989;Moura et al, 1991;Estany et al, 1992;Ferraz and Eler, 1994;Krogmeier et al, 1994;Lukefahr et al, 1996;McNitt and Lukefahr, 1996), suggesting that mass selection could be successfully used to improve this trait. In fact, selection for ADG and slaughter weight has been effective in rabbits (Mgheni and Christensen, 1985;Rochambeau et al, 1989;Estany et al, 1992;Lukefahr et al, 1996), although in some cases the response was less than expected (Rochambeau et al, 1989;Estany et al, 1992).…”

Genetic parameters of growth and in vivo computerized tomography based carcass traits in Pannon White rabbits

“…However, the slaughter weight is fixed by the market and the carcasses are expected to have poorer carcass yield when comparing two breeds of different adult size at the same commercial weight. Accordingly, Krogmeier et al (1994) reported moderately high negative (À 0.51) correlation between ADG and DoP, which suggests that selecting for ADG would cause lower dressing percentage if the slaughter weight is fixed.…”

“…R: score of Gelman and Rubin test. et al, 1992;Lukefahr et al, 1992bLukefahr et al, , 1993Krogmeier et al, 1994) found low or negligible heritabilities for DoP.…”