Genetic analysis of meat quality traits in maternal lines of rabbit and their diallel cross

[EN] Young rabbits, the dams of which came from a full diallel cross among four maternal lines (A, V, H and LP) and the sires from a single paternal line (It), that produce sixteen genetic groups, was carried out to evaluate the genetic groups and to estimate the crossbreeding genetic parameters of meat quality. The meat quality traits were recorded by NIRS from a sample of 285 longissimus lumborum muscles. Crossbreeding parameters were estimated according to Dickerson model. No differences in protein were found. The line A had significant differences with V line for intramuscular fat, and fatty acids groups. Significant differences for these traits appeared between the crossbred AH and VV (in favor of AH). As conclusion, the significant contrasts between genetic types for chemical composition of the meat are mainly consequence of direct-maternal genetic effects, having grandmaternal and maternal heterosis effects a less relevant role.This work was supported by the Spanish project AGL2011-30170-C02-01 from the Spanish National Research Plan. C. Minguez acknowledges a Formacion de Personal Investigador (FPI) grant from the Ministerio de Economia y Competitividad (MEC), Spain.Mínguez Balaguer, C.; Sánchez Serrano, JP.; Hernández, P.; Ragab, M.; El Nagar, AGF.; Baselga Izquierdo, M. (2017). Genetic analysis of meat quality traits in maternal lines of rabbit and their diallel cross. Meat Science. 131:1-8. https://doi.org/10.1016/j.meatsci.2017.04.005S1813

Interacción genotipo x tipo de dosis de inseminación artificial para la fertilidad del macho de conejo

El objetivo de este trabajo fue estimar los parámetros genéticos de la fertilidad tras la IA con 3 tipos de dosis obtenidas de eyaculados de machos de la línea Caldes: 1) tipo 10: con 10 x 106 espermatozoides/ml y 24h de conservación en un diluyente comercial tipo A. 2) tipo 40: con 40 x 106 espermatozoides/ml y las mismas condiciones de conservación que las del tipo 10. 3) tipo X: dosis preparadas tras diluir los eyaculados con un diluyente comercial tipo B (1:5) siendo desconocida la concentración y sin periodo de conservación. Se realizaron 3,628 IA con dosis del tipo 10 sobre hembras cruzadas, 3,027 con dosis del tipo 40 y la misma población de hembras, y 5,779 con dosis del tipo X sobre hembras puras de la línea Caldes. La fertilidad tras la IA con dosis del tipo 10 (F10), 40 (F40) y X (FX) fue considerada un carácter distinto en cada caso, de tipo binario. Los datos se analizaron utilizando un modelo umbral tri-carácter. La estima de la media de la distribución marginal posterior (DMP) de F10 menos F40 fue de -0.13. Este resultado indica un claro efecto de la concentración sobre la fertilidad, que podría no ser lineal. Las medias de la DMP de F10 menos FX y F40 menos FX fueron -0.37 y -0.23, respectivamente, lo que indica que el efecto de las condiciones de conservación sobre la fertilidad podría ser más importante que el de la concentración ya que FX fue muy próxima a la fertilidad tras la MN y la concentración del tipo de dosis X sería en promedio de unos 50 x 106 espermatozoides/ml. Las heredabilidades parecen ser similares para F10 y F40 y ambas mayores que las correspondientes a la fertilidad tras la MN y a FX. La interacción del genotipo x concentración de la dosis de IA es prácticamente despreciable debido a que las varianzas genéticas fueron similares para F10 y F40 y a que su correlación genética fue próxima a 1. Sin embargo, la interacción podría ser de mayor importancia entre el genotipo y las condiciones de conservación

Genetic comparison of milk production and composition in three maternal rabbit lines

[EN] The aim of this study was to compare 3 Spanish maternal rabbit lines (A, V and LP) in terms of milk production and composition. These lines were founded on different criteria but selected for litter size at weaning. A total of 194 mature does in their third or higher parity were used. The milk yield of does was recorded at 1, 2, 3, 4, 8, 9, 10, 11, 15, 16 and 17 d post-partum (dpp). The milk production traits studied were weekly milk yield (WMY; g/wk) and milk conversion ratio (MCR; grams of litter gain per grams of milk suckled during the first 21  dpp). The milk composition traits studied were fat (%), protein  (%), ash (%), lactose (%) and total solids (%). The milk samples to be analysed were collected from each doe at 18 dpp. Data were analysed using single trait mixed and fixed models with and without covariates; the covariates were number born alive (NBA) and doe weight at kindling (DW). The overall mean of WMY, during the first 3 wk, was 1547±16 g/wk. Milk yields during the different lactation weeks were for line A 872±39, 1503±39 and 1865±39 g for first, second and third lactation weeks, respectively. In line V, the corresponding values were 919±35, 1633±35 and 2004±35  g, and in line LP, they were 1043±36, 1819±36 and 2254±36  g. Means of MCR were 0.41±0.01, 0.41±0.01 and 0.42±0.01 for A, V and LP lines, respectively. Overall means of fat, protein, ash, lactose and total solids (%) were 14.62±0.17, 11.10±0.07, 1.89±0.04, 2.67±0.12 and 30.27±0.24, respectively. The differences between lines for milk production traits were significant except for MCR, while the differences between lines for milk composition traits were not significant. NBA had significant effects on all milk yield traits but had no significant effects on milk composition traits. DW only had a significant effect on weekly milk yield. The parity order had no significant effect either for milk production traits or milk composition traits in multiparous does, except for ash %.This work was supported by the Spanish project AGL2011-30170-C02-01 from the Spanish National Research Plan. Ayman EL Nagar acknowledges a MAEC-AECID grant from The Spanish Agency for International Cooperation for Development (AECID). The authors are very grateful to Prof. Juan Jose Pascual professor of Animal Nutrition, Institute for Animal Science and Technology, Universitat Politecnica de Valencia for revising the manuscript and his fruitful comments.El Nagar, AGF.; Sánchez, JP.; Ragab, MM.; Mínguez Balaguer, C.; Baselga Izquierdo, M. (2014). Genetic comparison of milk production and composition in three maternal rabbit lines. World Rabbit Science. 22(4):261-268. doi:10.4995/wrs.2014.1917261268224Abou Khadiga G., Youssef Y.M.K., Baselga M. 2012. Characterization of reproductive performance of the APRI line of rabbits. In Proc.: 10th World Rabbit Congress, 3-6 September, 2012. Sharm El-Sheikh, Egypt. 743-747.AOAC. 1980. Official Methods of Analysis. 13th Edition, Association of Official Agricultural Chemists, Washington, D.C., USA.Case R.A., Bradley R.L., Williams R.R. 1985. Chemical and physical methods. In: Standard Methods for the examination of Dairy Products. Richardson G.H., (ed.), 15th Edition, American Public Health Association, Washington, D.C., USA. 327-402.Castellini C., Dal Bosco A., Cardinali R., Mugnai C., Sciascia E. 2004. Effect of dietary N-3 fatty acids on the composition of doe's milk and tissues of suckling rabbits. In Proc.: 8th World Rabbit Congress, 7-10 September, 2004. Puebla, Mexico. 771-777.Cowie A.T. 1968. Lactation in the rabbit. Natl. Inst. Res. Dairying, Rep 1968, 84.El-Maghawry A.M., Soliman A.M., Khalil H.H. 1993. Doe milk production as affected by some genetic and environmental factors in New Zealand White and Californian rabbits under the Egyptian conditions. Egypt. J. Rabbit Sci., 3: 141-150.Fernández-Carmona J., Blas E., Cervera C., Pascual J.J. 2004. The measure of milk rabbit. In Proc.: 8th World Rabbit Congress, 7-10 September, 2004. Puebla, Mexico. 824-828.Fortun-Lamothe L., Bolet G. 1995. Les effects de la lactation sur les performances de reproduction chez la lapine. INRA, Prod. Anim., 8: 49-56.Garreau H., Piles M., Larzul C., Baselga M., Rochambeau H de. 2004. Selection of maternal lines: last results and prospects. In Proc.: 8th World Rabbit Congress, 7-10 September, 2004. Puebla, Mexico. 14-25.Hassan N.S., El-Feel F.M.R., Sallam M.T., Ahmed M.F. 1992. Evaluation of milk production and litter milk efficiency in two and three-way crosses of three breeds of rabbits. Egypt. J. Anim. Prod., 29: 307-319.Iraqi M.M. and Youssef Y.M.K. 2006. Genetic analysis for milk production traits in New Zealand White rabbits raised in Egypt. Egypt. J. Rabbit Sci., 16: 1-13.Khalil M.H., Al-Saef A.M. 2012. Genetic groups comparison for litter and lactational traits and feeding parameters in programs of synthesizing new lines of rabbits. In Proc.: 10th World Rabbit Congress, 3-6 September, 2012. Sharm El-Sheikh, Egypt. 235-239.Khalil M.H., Mehaia M.A., Al-Homidan A.H., Al-Sobayil K.A. 2004. Genetic analysis for milk yield and components and milk conversion ratio in crossing of Saudi rabbits with V-line. In Proc.: 8th World Rabbit Congress, 7-10 September, 2004. Puebla, Mexico. 82-89.Lukefahr S., Hohenboken W.D., Cheeke P.R., Patton N.M. 1983. Characterization of straightbred and crossbred rabbits for milk production and associative traits. J. Anim. Sci., 57: 1100-1107.McNitt J.I., Lukefahr S.D. 1990. Effect of breed, parity, day of lactation and number of kits on milk production of rabbits. J. Anim. Sci., 68: 1505-1512.Pascual J.J., Cervera C., Blas E., Fernández-Carmona J. 1996. Milk yield and composition in rabbit does using high fat diets. In Proc.: 6th World Rabbit Congress, 9-12 July, 1996. Toulouse, France. 1: 259-262.Pascual J.J., Cervera C., Blas E., Fernández-Carmona J. 1999. Effect of high fat diets on the performance, milk yield and milk composition of multiparous rabbit does. Anim. Sci., 68: 151-162.Zerrouki N., Lebas F., Berchiche M., Bolet G. 2005. Evaluation of milk production of an Algerian local rabbit population raised in the Tizi-Ouzou area (Kabylia). World Rabbit Sci., 13: 39-47

A comparison of reproductive traits of four maternal lines of rabbits selected for ltter size at weaning and founded on different criteria

The objective of this study was to compare four Spanish maternal lines of rabbits (A, V. H and LP) on different criteria but selected for litter size at weaning, since their foundation until present for 39, 35, 16 and 4 generations, respectively. The comparisons among the lines were performed for litter size traits and kindling interval. The first comparison made was at the foundation time of the lines, using mixed animal models (additive and non-additive permanent effects) involving the complete data set (from June 1980 to February 2009) and the full pedigree to take into account the process of selection. A second comparison was made at fixed times and location (during the six year-seasons shared at the same farm and similar conditions for lines A, V and H involving data from March 1997 to August 1998, and A, V and LP lines from September 2007 to February 2009. The models used in the second comparison did not include the complete data set nor the additive genetic effects so that line comparisons were not dependent on the genetic model. The raw means for 47,132 parities produced from 12,639 does were 9.80, 9.07, 7.79 and 6.95 rabbits for total born, number bon alive, number weaned and number marketed per litter, respectively, demonstrating high levels of prolificacy among the lines, and with a kindling interval of 49.80 days. At their respective times of foundation, line A showed the lowest litter size with mean differences (1.39 rabbits/litter for total born, 120 for number born alive, 0.84 for number weaned and 1.06 for number marketed) among the combined means of the other lines being important Lines V and H did not show significant differences for litter size traits, but for kindling interval the contrast was 330 +/- 0.72 days, which was significant and favourable to line H. LP exceeded V by approximately one rabbit for all litter size traits. The differences between the lines for kindling interval were negligible. Some interactions between lines and farm-year-seasons were important. In comparison of lines A. V and H from March 1997 to August 1998. the pattern of the differences between the line A and the others was similar to the one observed at the origin, and the only significant difference was found between lines V and H for the kindling interval (4.62 days in favour of line V). The comparison between the lines A. V and LP from September 2007 to February 2009 showed an approximation in their reproductive performance compared to the differences at the origin. Overall, good agreement was observed between the comparisons of lines for litter size traits at fixed times, using a model without genetic effects and data recorded during the time of comparisons, and the predictions derived from the model with genetic effects. Another point is the importance of the criteria in the sample of founders of lines that were used to determine the initial or starting performance levels. Therefore, it is recommended that commercial rabbit producers utilize line populations selected for the traits of economic interest rather than on a popular breed. (C) 2010 Elsevier B.V. All rights reserved.This work was supported by the Spanish Research Projects (CICYT) AGL2008-03274 and ACOMP09/013 (Valencia Generality, Spain). The first author (Mohamed Ragab) appreciated the grant obtained from the Mediterranean Agronomic Institute of Zaragoza (CIHEAM), Spain. Thanks are given to Prof. Steven Lukefahr for his critical revision of this manuscript.Mohamed Ragab, M.; Baselga Izquierdo, M. (2011). A comparison of reproductive traits of four maternal lines of rabbits selected for ltter size at weaning and founded on different criteria. Livestock Science. 136(2-3):201-206. doi:10.1016/j.livsci.2010.09.009S2012061362-