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Crossbreeding parameters of some productive traits in meat rabbits.

July 2010
World Rabbit Science 12(3)

DOI:10.4995/wrs.2004.575

Authors:

Miriam Piles

IRTA Institute of Agrifood Research and Technology

Oriol Rafel Guarro

IRTA Institute of Agrifood Research and Technology

Javier Eduardo Ramon

Universidad Tecnica de Machala

Ernesto A Gomez

Valencian Institute for Agricultural Research

A crossbreeding experiment using animals from C and R rabbit strains was conducted. Direct and maternal additive genetic effects and direct heterosis were estimated for some productive traits during the post-weaning growing period. Growth rate, daily feed consumption, and feed conversion ratio, between 32 to 60 days of age, were recorded for 1377 young rabbits. At 66 days of age, 736 animals were weighed and slaughtered in a commercial slaughter-house. No fastening was practiced. Carcasses were weighed 30 min after slaughter and then they were chilled (4ºC, 24 hours) and weighed again. Carcass yield and drip loss percentage were computed. Model of analysis included the genetic type effect (C, CxR, RxC, R), batch effect, parity effect, litter size at birth effect, live weight at 60 days as a covariate to adjust growth, consumption and feed efficiency for differences in live weight at 60 days of age, common environmental litter effects and the additive genetic effects. Main relationships between individuals were taken into account through the relationship matrix. Crossbreeding parameters were computed from linear contrasts between levels of genetic type effect following Dickerson's model. Despite the differences between genetic types found, the difference between direct additive genetic effects was only significant for live weight at 60 days and daily feed intake. Neither heterosis nor maternal effects were significant for any of the traits analyzed.

: Number of records by genetic type (C, CxR, RxC, R), overall mean, standard deviation and coefficient of variation (CV) of the traits analyzed.

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139

WORLD

RABBIT

SCIENCE

World Rabbit Sci. 2004, 12: 139 - 148

Correspondence: M. Piles

E-mail: miriam.piles@irta.es

CROSSBREEDING PARAMETERS OF SOME PRODUCTIVE

TRAITS IN MEAT RABBITS

PILES M.1, RAFEL O.1, J. RAMON1, GÓMEZ E.A.1

Unitat de Cunicultura – IRTA, 08140 CALDES DE MONTBUÍ, Barcelona, Spain.

ABSTRACT: A crossbreeding experiment using animals from C and R rabbit strains was conducted. Direct

and maternal additive genetic effects and direct heterosis were estimated for some productive traits

during the post-weaning growing period. Growth rate, daily feed consumption, and feed conversion

ratio, between 32 to 60 days of age, were recorded for 1377 young rabbits. At 66 days of age, 736

animals were weighed and slaughtered in a commercial slaughter-house. No fastening was practiced.

Carcasses were weighed 30 min after slaughter and then they were chilled (4ºC, 24 hours) and weighed

again. Carcass yield and drip loss percentage were computed. Model of analysis included the genetic

type effect (C, CxR, RxC, R), batch effect, parity effect, litter size at birth effect, live weight at 60 days

as a covariate to adjust growth, consumption and feed efficiency for differences in live weight at 60

days of age, common environmental litter effects and the additive genetic effects. Main relationships

between individuals were taken into account through the relationship matrix. Crossbreeding parameters

were computed from linear contrasts between levels of genetic type effect following Dickerson’s model.

Despite the differences between genetic types found, the difference between direct additive genetic

effects was only significant for live weight at 60 days and daily feed intake. Neither heterosis nor

maternal effects were significant for any of the traits analyzed.

Key words: rabbit, crossbreeding parameters, growth, feed efficiency, carcass yield.

INTRODUCTION

Efficiency of meat production can be improved by taking advantage of the

diversity of rabbit breeds through crossbreeding. Genetic parameters such as additive

genetic effects and direct or maternal heterosis are generally important for maternal

performance but they are not well known for post weaning performance of growing

rabbits, especially for traits related to feed efficiency and carcass merit. Besides,

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PILES et al.

crossbreeding parameters can differ dramatically among environments and they can

also evolve with selection of the lines.

In meat rabbit production, post weaning daily weight gain or weight at the end

of the fattening period are used as selection criteria of sire lines in most breeding

programmes (ROCHAMBEAU et al., 1989; RAFEL et al. 1990; ESTANY et al, 1992). Feed

efficiency is one of the most commercially important traits because post-weaning

feeding accounts for around 40 % of total cost (ARMERO and BLASCO, 1992). This

trait is improved through the negative genetic correlation with growth rate (MOURA

et al., 1997; PILES et al., 2003) because direct selection is difficult and costly. Carcass

yield is also an important trait in Spain, because carcasses are generally graded and

the price is established according to this value in commercial slaughter- houses.

The aim of the present study was to estimate heterosis and additive genetic, direct

and maternal, effects on several post-weaning growth and feed efficiency traits using

a diallel crossbreeding design involving two sire lines of different genetic origin.

MATERIAL AND METHODS

Animals and experimental conditions

A complete diallel cross between two lines of rabbit C and R led to the production

of 4 genetic types of individuals (C, CxR, RxC and R).

Line C was set up in 1979 from five New Zealand White sources and a 6th strain

formed by California x New Zealand White animals (RAFEL et al., 1990). It was

selected for litter weight at 60 days by the independent culling levels method using

as selection criteria litter weight at weaning and individual daily weight gain between

32 and 60 days of age. Since 1993, it has been selected for individual daily weight

gain by individual selection.

Line R was created by mating animals from a California line with animals from

another synthetic line created by mating two commercial populations of crossbred

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CROSSBREEDING PARAMETERS OF PRODUCTIVE TRAITS

rabbits. It has been selected for increased post-weaning daily weight gain by

individual selection since 1980 (ESTANY et al., 1992).

At weaning age (32 days), 320 animals from lines C and R were housed in

individual wire cages in the experimental farm of the Institut de Recerca i Tecnologia

Agroalimentàries (IRTA). These animals were born in January 2001. The farm has

isolated roof and walls, controlled lighting and ventilation, and a cooling-system to

avoid high temperatures in summer. During the fattening period (32 to 60 days of

age), animals were fed ad libitum with a commercial pelleted diet (16.4% raw protein,

4% fat, 15.2% fiber). Fresh water was always supplied ad libitum. Individual weights

and feed consumption were recorded weekly. Then, 19 and 23 females and 12 and

13 males form lines C and R respectively, were allocated to reproductive wire cages

and fed with 180 g/d of another pelleted diet (16% raw protein, 4.3% fat, 17%

fiber). Does followed a semi-intensive reproductive rhythm (first mating at four

and a half months of life and reproductive cycles of 42 days). Offspring were born

between July 2001 and April 2002. After weaning, they were also housed and fed in

the same conditions as their parents during the fattening period. Individual weights

and feed consumption were also recorded weekly. Data of individuals with symptoms

of illness were excluded from the analysis. At 66 days of age, animals were weighed

and slaughtered in a commercial slaughterhouse. No fastening was practiced. Animals

were bled by cutting the jugular vein and the carotid artery after electrical stunning.

Carcasses were weighed after slaughter and then they were chilled (4ºC, 24 hours)

and weighed again.

Experimental design

A 2 x 2 diallel crossing design was applied. Bucks were randomly assigned to

does but repeated matings and matings between related individuals were avoided.

Traits

GR: growth rate between 32 and 60 days of age (g/d).

DFI: daily feed intake between 32 and 60 days of age (g/d).

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PILES et al.

FCR: Fed conversion ratio between 32 and 60 days of age.

LW: Live weight at 60 days of age (g).

SW: Slaughter weight (g).

CCW: Chilled carcass weight (g).

DoP: Dressing out percentage (%). DoP= 100 x CCW / SW.

DLP: Drip loss percentage (%). DLP=100 x (HCW-CCW)

Statistical analysis

The number of records per genetic type (C, CxR, RxC, and R) for each trait is

shown in table 1. The following mixed model was applied:

y=X

ββ

+Zu+Wp+e

where: y is the data vector,

is a vector containing the genetic type effect (4 levels),

batch effect (10 levels), parity effect (first, second and third or more), litter size at

birth effect (8 levels: less than 6, six levels from 6 to 11, and more than 11) and LW

as a covariate to adjust growth, consumption and feed efficiency for differences in

live weight at 60 days of age. p is a vector containing the environmental common

litter effects (335 levels), u is a vector containing the additive genetic effects. There

were 1625 animals in the pedigree file containing individuals, parents, and grandparents

to take into account the main relationships between individuals. X, Z and W are the

corresponding incidence matrices and e is the vector of residuals.

Crossbreeding parameters were computed from linear contrast between levels

of genetic type effect. The model of DICKERSON (1969) was chosen:

where yij is the mean performance of offspring of sire line i mated with dam line j, is

ijijj

ij ehm

y+++

δµ

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CROSSBREEDING PARAMETERS OF PRODUCTIVE TRAITS

the mean of parental lines, gi (gj) is the direct additive genetic effect of the ith sire

line (the jth dam line), mj is the maternal genetic effect of the jth dam line, hij is the

direct heterosis of the cross between lines i and j,

is 1 for crosses between lines

i≠j and 0 for lines i=j, e is the residual effect.

RESULTS AND DISCUSSION

Descriptive statistics

Table 1 shows the number of records of each genetic type (C, CxR, RxC, R),

and some descriptive statistics (overall mean, standard deviation and coefficient of

variation) of the traits analyzed. In Spain, there is a demand for light carcasses.

Live slaughter weight and chilled carcass weight averaged 2670g and 1574g

respectively. These values are high but correspond to animals that are used as sires

in terminal crosses, not as commercial fryers. Most of the traits had a coefficient of

variation around 0.14. DoP and DLP had small and large coefficient of variation

respectively (0.03 and 0.29).

Table 1: Number of records by genetic type (C, CxR, RxC, R), overall mean, standard

deviation and coefficient of variation (CV) of the traits analyzed.

Trait C CxR RxC R Mean SD CV

LW 435 295 211 436 2411 343 0.14

GR 435 295 211 436 55.6 7.5 0.13

DFI 435 295 211 436 160 30 0.19

FCR 435 295 211 436 2.87 0.36 0.13

SW 198 217 130 191 2671 362 0.14

CCW 198 217 130 191 1574 223 0.14

DoP 198 217 130 191 58.9 1.6 0.03

DLP 198 217 130 191 2.23 0.65 0.29

LW: live weight at 60 d ays of age, GR: growth rate, DF I: daily feed inta ke, FC R: feed conve rsion rate, S W: slaughter weight,

CCW: chilled carcass weight, DP: dressing percentage and DLP: drip lo ss percenta ge.

C = C line, R = R line

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PILES et al.

Breed type comparison

Table 2 shows estimated mean and standard error of levels of genetic type effect

(C, CxR, RxC, R) for all traits analyzed. Significant differences between genetic

types were observed in all of them except in GR, FCR and DLP. Kits of genetic type

C were lighter at 60 days of age, grew slower and ingested less feed than kits of

genetic type R, CxR and RxC. Slaughter weight and CCW followed the same pattern:

animals belonging to group C were lighter than animals from groups CxR and R,

being the values for the intermediate group RxC. A significant difference was also

found in DoP between genetic types CxR and R the lower value corresponding to

genetic type R and genetic types C and RxC being the intermediate between them.

No differences between the two types of crossbred animals were found for any trait.

These results agree with those reported in previous experiments for LW and CCW,

comparing the same lines of selection. RAMON et al. (1996) and GOMEZ et al. (1998)

reported differences in live weight at 60 and 63 days of age, CCW, GR and DP,

among other carcass quality traits. Animals from line R, selected exclusively for

increased growth rate, were heavier at all ages (313 g and 347 g), had a heavier

carcass (133 g), grew faster (6.4 g/d) and had a lower FCR (0.2) and DoP (2.8 %)

Table 2: Mean and standard error (in brackets) of the estimated genetic type effects (C,

CxR, RxC, R) of the traits analyzed.

Trait C CxR RxC R

LW 2331 (27) a2459 (31) b2429 (34) b2460 (27) b

GR (g/d) 55.4 (0.4) 54.9 (0.4) 55.8 (0.5) 55.8 (0.4)

DFI (g/d) 158 (1) a159 (1) ab 162 (1) b161 (1) b

FCR 2.84 (0.03) 2.89 (0.03) 2.89 (0.04) 2.90 (0.03)

SW (g) 2549 (44) a2704 (41) b2620 (45) ab 2701 (44) b

CCW (g) 1505 (27) a1595 (25) b1541 (28) ab 1579 (27) b

DoP (%) 58.9 (0.2) ab 59.0 (0.2) b58.8 (0.2) ab 58.5 (0.2) a

DLP (%) 2.2 (0.1) 2.2 (0.1) 2.2 (0.1) 2.3 (0.1)

LW: live weight at 60 days of age, GR: growth rate, DFI: daily feed intake, FCR: feed conversion rate, SW: slaughter

weight, CCW: chilled carcass weight, DP: dressing percentage and DLP: drip loss percentage.

C = C line, R = R line.

Means within a row with different superscripts differ (P<0.05).

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CROSSBREEDING PARAMETERS OF PRODUCTIVE TRAITS

with respect to animals from line C, selected for a history of litter weight. Some of

the differences between lines R and C could be partly explained by the different

origin of the lines and by the more intensive process of selection for individual

growth rate in line R, leading to heavier animals throughout all the growth period,

higher adult weight and less mature animals at slaughter weight (PILES et al., 2000;

BLASCO et al., 2003).

Additive genetic effects and direct heterotic effects

Table 3 shows mean and standard error of the estimated direct heterosis effect

(h), direct additive genetic effect (dC-dR) and maternal genetic effect (mC-mR) in

lines C and R, for all traits. Despite the differences found between genetic groups,

the difference between additive genetic effects was only significant for DFI. Neither

heterosis nor maternal effects were significant for any of the traits analyzed in

agreement with GOMEZ et al. (1999) who analyzed data of animals from line R and

two other dam lines of different genetic origin. LUKEFAHR et al. (1986) and MEDELLÍN

and LUKEFAHR (2001), in studies involving large and medium size breeds, showed

Table 3: Mean and standard error (in brackets) of the estimated direct heterosis

effect (h), direct additive effect (dC-dR) and maternal genetic effect (mC-mR) in lines

C and R, of the traits analyzed.

Trait hCR dC- dR mC- mR

LW (g) 49 (27) -99 (46) ** -29 (37)

GR (g/d) -0.3 (0.4) -1.3 (0.7) 0.9 (0.6)

DFI (g/d) 1 (1) -6 (2) ** 3 (2)

FCR 0.02 (0.03) -0.05 (0.06) 0.00 (0.05)

SW (g) 36 (33) -67 (63) -84 (46)

CCW (g) 26 (20) -19 (39) -55 (28)

DoP (%) 0.20 (0.18) 0.60 (0.33) -0.2 (0.2)

DLP (%) - 0.06 (0.08) -0.10 (0.15) 0.01 (0.11)

LW: live weight at 60 days of age, GR: growth rate, DF I: daily feed intake, FC R: feed conversion rate, SW: slaughter

weight, CCW: chilled carcass weight, DP: dressing percentage and DLP: drip loss percentage.

C = C line, R = R line.

**P<0.01

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PILES et al.

that additive genetic effects were higher in magnitude than maternal genetic effects

or direct and maternal heterotic effects on individual live weight at 56 or 70 days of

age. However, BRUN and OUHAYOUN (1989), AFFIFI et al. (1994) and ABDEL-GHANY et

al. (2000), in studies involving medium-sized breeds, found that maternal breed

effects were comparable to or higher than additive genetic effects for individual

growth. BRUN et al. (1992), EIBEN et al. (1996), SZENDRO et al. (1996) and MEDELLIN

and LUKEFAHR (2001) observed direct heterosis effect in live weight at different

ages (from 2.4 % to 6.8 %), in GR (from 4.8 % to 7.3 %) and also in DoP (from 1 %

to 2.3 %) in crosses between strains of different composition.

Non-genetic effects

Least square means of the levels of the different environmental effects were

also estimated. Batch was the most important effect. Summer had a negative effect

on feed intake because of high temperatures, leading to low values of live weights,

growth rate and carcass weight as other authors have reported (TORRES et al., 1992;

FEKI et al., 1996). Batch effect was also significant on feed efficiency and drip loss

percentage as in TORRES et al (1992), FEKI et al. (1996) and GOMEZ et al. (1998).

Parity effect was low, the higher difference between levels, with respect to the overall

mean, being for DFI (7.5 %). Litter size effect was also small, the higher difference

between levels being for CCW (23 % of the mean).

In conclusion, direct additive genetic effects, but not heterosis and maternal

genetic effects, were found for growth, consumption and carcass traits in a complete

diallel cross between two large-size lines of rabbit, both selected for growth rate

during the fattening period.

Acknowledgements: Research was supported by INIA SC00-011. The authors acknowledge the staff of the

farm at IRTA (N. Picornell, O. Perucho, N. Aloy and C. Requena) for their contribution to the experimental

work.

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Full-text available

Dec 2023

There is need for breeders and farmers to know the best mating method to employ and the breeding goals to expect in rabbit breeding programmes. However, information on which breed should be used as male or female in crossbreeding rabbit for commercial purpose is limited. This study was conducted to evaluate the effect of reciprocal crossing on body weight (BW), reproductive, morphometric and carcass characteristics of two breeds of rabbits, New Zealand White (NZW) and chinchilla (CHA) raised in tropics. Offspring from the crossing of NZW x CHA and CHA x NZW were studied for body weight (BW) and reproductive traits for twelve weeks. Reproductive traits studied were litter size at birth (LSB), litter size at weaning (LSW), Average birth weight (ABWT), Average weaning weight (AWWT), Gestation length(GSTL) and percent mortality. Morphometric traits studied were body width (BWD), body length (BL), heart girth (HG) and tail length (TL). While carcass characteristics were dressed weight, foreleg, thoracic, loin, hind and skin. The heterotic values and their percentages were calculated in the two genetic groups using the linear contrast procedure. The direct and percent heterosis for reproductive traits were all positive for the two genetic groups except in gestation length and percent mortality which showed negative heterosis (-1 and 3.2%; 3.19;10.12% for gestation length and -7.19 and -19.07; -9.36 and -24.83% for percent mortality in CHA X NZW and NZW X CHA respectively). Body weight at different ages studied, morphometric and carcass traits were also positive for NZW x CHA off springs while CHA x NZW off springs had negative values for all these parameters measured indicating that CHA sired off springs had no improvement for BW at various ages, reproductive, morphometric and carcass traits studied. It could therefore be concluded that rapid improvement in Body weight, Reproductive, morphometric and carcass could be achieved by crossbreeding involving mating of New Zealand White male and Chinchilla does. Il est nécessaire que les éleveurs et les agriculteurs connaissent la meilleure méthode d'accouplement à utiliser et les objectifs d'élevage à attendre dans les programmes d'élevage de lapins. Cependant, les informations sur la race qui doit être utilisée comme mâle ou femelle dans les croisements de lapins à des fins commerciales sont limitées. Cette étude a été menée pour évaluer l'effet du croisement réciproque sur le poids corporel (PC), les caractéristiques reproductives, morphométriques et de carcasse de deux races de lapins, le New Zealand White (NZW) et le chinchilla (CHA), élevés sous les tropiques. La progéniture issue du croisement NZW x CHA et CHA x NZW a été étudiée pour son poids corporel (PC) et ses caractéristiques de reproduction pendant douze semaines. Les caractères reproductifs étudiés étaient la taille de la portée à la naissance (TPN), la taille de la portée au sevrage (TPS), le poids moyen à la naissance (PMN), le poids moyen au sevrage (PMS), la durée de la gestation (DGS) et le pourcentage de mortalité. Les traits morphométriques étudiés étaient la largeur du corps (LC), la longueur du corps (LC), la circonférence du cœur (CC) et la longueur de la queue (LQ). Les caractéristiques des carcasses étaient le poids paré, la patte antérieure, la poitrine, la longe, l'arrière et la peau. Les valeurs hétérotiques et leurs pourcentages ont été calculés dans les deux groupes génétiques en utilisant la procédure de contraste linéaire. L'hétérosis direct et le pourcentage pour les caractères reproductifs étaient tous positifs pour les deux groupes génétiques, sauf pour la durée de gestation et le pourcentage de mortalité qui présentaient une hétérosis négative (-1 et -3,2% ; 3,19 ; 10,12 % pour la durée de gestation et -7,19 et -19,07 ; - 9,36 et -24,83 % pour le pourcentage de mortalité dans CHA X NZW et NZW X CHA respectivement). Le poids corporel à différents âges étudiés, les caractéristiques morphométriques et de carcasse étaient également positifs pour NZW x CHA hors printemps, tandis que CHA x NZW hors printemps avaient des valeurs négatives pour tous ces paramètres mesurés, indiquant que CHA engendré hors printemps n'avait aucune amélioration du poids corporel à différents âges, de la reproduction. , caractères morphométriques et carcasses étudiés. On pourrait donc conclure qu'une amélioration rapide du poids corporel, reproducteur, morphométrique et carcasse pourrait être obtenue par un croisement impliquant un accouplement de mâles blancs de Nouvelle-Zélande et de chèvres Chinchilla.

Pengaruh Kombinasi Pemberian Pakan Hijauan dan Konsentrat dengan Bentuk yang Berbeda Terhadap Performa Kelinci Jantan New Zaeland White

Article

Feb 2022

Penelitian ini bertujuan untuk mengetahui efek penggunaan kombinasi antara hijauan dan konsentrat dengan bentuk yang berbeda terhadap performa kelinci jantan new zaeland white. Materi yang digunakan pada peneltian adalah kelinci jantan new zaeland white umur 3 bulan sebanyak 32 ekor. Kelinci dikelompokan berdasarkan 4 perlakuan yang berbeda yaitu: Daun Kubis Bunga (DKB) + konsentrat bentuk pellet (T1), Daun Kubis Bunga (DKB) + konsentrat bentuk crumble (T2), Daun Kubis Bunga (DKB) + konsentrat bentuk mash (T3), Daun Kubis Bunga (DKB) + konsentrat bentuk pasta (T4). Metode yang digunakan pada peneltian adalah percobaan dengan completely random design (CRD). Data diolah menggunakan ANOVA (Analysis of variance) bila terdapat perbedaan yang sangat nyata maka dilanjutkan dengan uji Duncan Multipel range test (DMRT). Hasil dari penelitian menunjukan bahwa efek penggunaan kombinasi antara hijauan dan konsentrat dengan bentuk yang berbeda memberikan hasil berbeda nyata (P<0,01) pada konsumsi pakan dan konversi pakan, tetapi memberikan hasil yang nyata (P>0,05) pada pertambahan bobot badan. Kesimpulan dari penelitian ini bahwa efek pemberian kombinasi antara hijauan dengan bentuk konsentrat yang berbeda memberikan perbedaan hasil pada konsumsi pakan dan konversi pakan, pertambahan bobot badan, dan konversi pakan terhadap kelinci jantan new zaeland white, meskipun terdapat perbedaan pada performa tetapi pertumbuhan kelinci terlihat normal dan dalam keadaan sehat. Kata kunci: kelinci jantan new zaeland white, daun kubis bunga, perbedaan bentuk konsentrat.

Genotype by feeding regimen interactions for slaughter traits in rabbit and expected responses under restricted and full feeding

Article

Full-text available

May 2022
J ANIM BREED GENET

The interaction between the genotype and feeding regimen (G×FR) for slaughter traits was estimated from data corresponding to 2557 animals under full (FF) and 2424 with restricted feeding (RF). Expected responses to selection under different scenario regarding feeding regimen were also calculated. Body weight at slaughter (SW), carcass weight (CW) and dressing out percentage (DoP) were analysed by using linear animal models in which records obtained under different feeding regimes were treated as different traits. Animals belonged to Caldes line, selected for average daily gain (G) under ad libitum feeding. The selection process information was included in the analyses. Marginal posterior mean of heritabilities were 0.102 for G, and 0.364, 0.257 and 0.167 for SW, CW and DoP under FF feeding. The corresponding values for animals fed on RF were 0.243, 0.203 and 0.379 for SW, CW and DoP, respectively. Genetic correlations between G and CW were positive and moderate, and those between G and DoP were low. The estimated genetic correlation between SW, CW and DoP under different feeding regimens were: 0.73, 0.69 and 0.87, respectively. These correlations cannot be said to be far enough from one to generate relevant G×FR interaction variance, which were estimated to be only 11.1%, 8.6% and 5.3% of the mean of the phenotypic variance for SW, CW and DoP, respectively. This lack of G×FR interaction variance, jointly with the higher heritability of DoP under RF, explains that the genetic improvement of DoP can be done more efficiently recording traits on animals under RF, even if the interest is on the performances under FF, i.e. by indirect selection.

ASSESSMENT OF CARCASS TISSUE COMPOSITION IN GROWING RABBITS USING REAL TIME ULTRASONOGRAPHY † [EVALUACIÓN DE LA COMPOSICIÓN TISULAR DE LA CANAL EN

Article

Full-text available

Mar 2022

p> Background. Carcass yield varies depending on the relative proportions of muscle, fat and bone, therefore, the possibility of predicting its value would produce valuable information that will promote the viability and sustainability of rabbit meat production. Methodology. Thirty-eight male growing rabbits (New Zealand White × Californian) with body weights (BW) of 1329 ± 291 g and from 60 to 100 days of age were used. Real time ultrasonography (RTU) measurements were taken 12 h before slaughtering. For that, rabbits were shaved between the 6^th and 7^th lumbar vertebrae. The longissimus thoracis et lumborum muscle (LM) area (LDA) and also the maximum LM width (LDW) and the maximum depth LM (LDD) were measured. Data recorded at slaughtering included carcass and non-carcass components. After chilling at 4° C for 24 hours, carcasses were split longitudinally to obtain left and right halves that were later weighed. Thereafter, the right half carcass was weighed and manually deboned for recording weights of muscle (TCM), and bone (TCB). Results. The highest correlation (r = 0.84, P <0.001) was observed between TCM and LDD, while the lower correlation (r = 0.4, P <0.001) was observed between TCB and LDW. The BW were highly related to carcass characteristics (r>0.77≤0.97). In vivo RTU measurements explained a low to moderate amount of variation in TCB and TCM with an r²of 0.36 to 0.77 ( P < 0.001) respectively. BW explained from 49 to 92% of variation in TCB and TCM, respectively. Implications. The in vivo ultrasound measurements it is a viable tool that allows predicting carcass value of rabbits. Conclusion. Our results indicated that the use of RTU measurements could accurately predict muscle from growing rabbit's carcass.</p

Impact of crossbreeding on performance traits in two breeds of rabbit under Egyptian conditions

Article

Jun 2020

Heterotic Effect on Body Weight, Reproductive, Morphometric and Carcass Traits of Crossbred Kits of New Zealand White and Chinchilla Rabbits

Article

Feb 2024

There is need for breeders and farmers to know the best mating method to employ and the breeding goals to expect in rabbit breeding programmes. However, information on which breed should be used as male or female in crossbreeding rabbit for commercial purpose is limited. This study was conducted to evaluate the effect of reciprocal crossing on body weight (BW), reproductive, morphometric and carcass characteristics of two breeds of rabbits, New Zealand White (NZW) and chinchilla (CHA) raised in tropics. Offspring from the crossing of NZW x CHA and CHA x NZW were studied for body weight (BW) and reproductive traits for twelve weeks. Reproductive traits studied were litter size at birth (LSB), litter size at weaning (LSW), Average birth weight (ABWT), Average weaning weight (AWWT), Gestation length(GSTL) and percent mortality. Morphometric traits studied were body width (BWD), body length (BL), heart girth (HG) and tail length (TL). While carcass characteristics were dressed weight, foreleg, thoracic, loin, hind and skin. The heterotic values and their percentages were calculated in the two genetic groups using the linear contrast procedure. The direct and percent heterosis for reproductive traits were all positive for the two genetic groups except in gestation length and percent mortality which showed negative heterosis (-1 and -3.2%; 3.19;10.12% for gestation length and -7.19 and -19.07; -9.36 and -24.83% for percent mortality in CHA X NZW and NZW X CHA respectively). Body weight at different ages studied, morphometric and carcass traits were also positive for NZW x CHAoff springs while CHAx NZW off springs had negative values for all these parameters measured indicating that CHA sired off springs had no improvement for BW at various ages, reproductive, morphometric and carcass traits studied. It could therefore be concluded that rapid improvement in Body weight, Reproductive, morphometric and carcass could be achieved by crossbreeding involving mating of New Zealand White male and Chinchilla does. Il est nécessaire que les éleveurs et les agriculteurs connaissent la meilleure méthode d'accouplement à utiliser et les objectifs d'élevage à attendre dans les programmes d'élevagede lapins. Cependant, les informations sur la race qui doit être utilisée comme mâle ou femelle dans les croisements de lapins à des fins commerciales sont limitées. Cette étude a été menée pour évaluer l'effet du croisement réciproque sur le poids corporel (PC), les caractéristiques reproductives, morphométriques et de carcasse de deux races de lapins, le New Zealand White (NZW) et le chinchilla (CHA), élevés sous les tropiques. La progéniture issue du croisement NZW x CHAet CHAx NZW a été étudiée pour son poids corporel (PC) et ses caractéristiques de reproduction pendant douze semaines. Les caractères reproductifs étudiés étaient la taille de la portée à la naissance (TPN), la taille de la portée au sevrage (TPS), le poids moyen à la naissance (PMN), le poids moyen au sevrage (PMS), la durée de la gestation (DGST) et le pourcentage de mortalité. Les traits morphométriques étudiés étaient la largeur du corps (LRC), la longueur du corps (LC), la circonférence du cœur (CC) et la longueur de la queue (LQ). Les caractéristiques des carcasses étaient le poids paré, la patte antérieure, la poitrine, la longe, l'arrière et la peau. Les valeurs hétérotiques et leurs pourcentages ont été calculés dans les deux groupes génétiques en utilisant la procédure de contraste linéaire. L'hétérosis direct et le pourcentage pour les caractères reproductifs étaient tous positifs pour les deux groupes génétiques, sauf pour la durée de gestation et le pourcentage de mortalité qui présentaient une hétérosis négative (-1 et -3,2% ; 3,19 ; 10,12 % pour la durée de gestation et -7,19 et -19,07 ; - 9,36 et -24,83 % pour le pourcentage de mortalité dans CHA X NZW et NZW X CHA respectivement). Le poids corporel à différents âges étudiés, les caractéristiques morphométriques et de carcasse étaient également positifs pour NZW x CHA hors printemps, tandis que CHA x NZW hors printemps avaient des valeurs négatives pour tous ces paramètres mesurés, indiquant que CHA engendré hors printemps n'avait aucune amélioration du poids corporel à différents âges, de la reproduction. , caractères morphométriques et carcasses étudiés. On pourrait donc conclure qu'une amélioration rapide du poids corporel, reproducteur, morphométrique et carcasse pourrait être obtenue par un croisement impliquant un accouplement de mâles blancs de Nouvelle-Zélande et de chèvres Chinchilla.

Effect of crossing California with Gabali rabbits on litter weight, litter size and milk production.

Article

Aug 2023

The effect of selection for growth rate on carcass composition and meat characteristics of rabbits

Article

Full-text available

Apr 2000
MEAT SCI

The effect of selection for growth rate on carcass composition and meat quality was assessed by comparing two groups of rabbits belonging to different generations of a selection experiment. A Bayesian approach was used. Embryos belonging to generations 3 and 4 of selection were frozen and thawed to be contemporary of animals from generation 10. A control group (C), formed from offspring of these embryos, was contemporary to offspring of generations 10 and 11 of selection, chosen at random, which constituted the selected group (S). One hundred and thirty-one contemporary rabbits were slaughtered at approximately the Spanish commercial live weight of 2 kg. Carcasses were dissected and measured according to the norms of the World Rabbit Scientific Association. An animal model including effects of genetic group (C, S) and sex, and slaughter weight as a covariate was used. S animals had a higher development of liver, kidneys and of a set of organs consisting of the thymus, trachea, oesophagus, lung and heart, relative to C. For dissectible fat, S animals had less than C: −0.31 g for scapular fat, −1.62 g for perirenal fat and −2.03 g for inguinal fat. S had a lower content (−0.39%) of dissectible fat percentage in the “Reference” carcass, indicating a lower degree of maturity at slaughter. The meat to bone ratio was not affected by selection, but the meat and bone contents of the hind leg were 3.25 and 0.71 g higher, respectively, in the C group. Selected animals had a lower water holding capacity in the raw meat (−2.10%), a higher water holding capacity in the cooked meat (2.17%), a higher cooking loss (3.31%) and a lower fat percentage in the meat of a hind leg (−0.37%). Females had more fat than males: 0.26 g for scapular fat, 1.02 g for perirenal fat, 1.10 g for inguinal fat, and 0.24% for total dissectible fat percentage of the “Reference” carcass.

Selection response of growth rate in rabbits for meat production

Article

Full-text available

Jan 1992
GENET SEL EVOL

Genetic and environmental trends in 2 lines of rabbit (B and R) selected on individual weight gain (WG) from weaning (4 wk) to slaughter (11 wk) were estimated using mixed model methodology. Line B was derived from the California breed and line R was a synthetic of stock of different origin. The data were collected from a single herd and comprised 7 718 individuals in line B and 9 391 in line R, the lines having 12 and 9 generations of selection respectively. Realized responses in the 2 lines were 2.7% and 2.2% of the initial mean per year respectively and showed that selection on WG was effective but was less than expected. Selection on slaughter weight (SW) and effects of selection on other economic traits are discussed. It is concluded that selection on either WG or SW is a simple method for improving growth rate in rabbit sire line stocks. On estimé les tendances génétiques et environnementales dans 2 lignées de lapin (B et a R), sélectionnées sur le gain de poids (WG) entre le sevrage (28 jours) et l’abattage (77 j), en utilisant la méthodologie du modèle mixte. La lignée B est issue de la race californienne; la lignée R est une souche synthétique. Les données, recueillies dans un seul élevage, incluaient 7718 individus de la lignée B et9391 de la lignée R, représentant respectivement 12 et 9 générations de sélection. Les réponses à la sélection dans les 2 lignées, respectivement 2,7% et 2,2% de la moyenne par an, montrent que la sélection a été efficace, mais avec des réponses inférieures aux valeurs espérées. La sélection sur le poids d’abattage (SW) et les effets de la sélection sur d’autres caractères économiques sont discutés. On conclut que la sélection sur WG, ou sur SW, est une méthode simple pour améliorer la vitesse de croissance des souches paternelles de lapin.

Two-Way Selection for Daily Gain and Feed Conversion in a Composite Rabbit Population

Article

Full-text available

Sep 1997

We conducted a two-way selection experiment in a composite rabbit population to investigate the responses to selection for postweaning ADG and feed conversion (FC). Two generations of crossing, followed by four generations of random pair matings, preceded three generations of selection. Selection was practiced within four lines: high-feed conversion (HFC), low-feed conversion (LFC), high gain (HG), and low gain (LG). Data on 1,446 rabbits from the random mating and selection generations were fitted to an animal model to estimate heritabilities of and the genetic correlation between ADG and FC. The two-trait model included rabbit and common litter random effects and line, generation, and sex fixed effects. Estimates of heritability of ADG and FC were .48 and .29, respectively, and the genetic correlation between them was -.82. Common litter environmental effects accounted for a proportion of .11 and .13 of the phenotypic variation of the two traits, respectively. For ADG (in g/d) the regressions of mean breeding values on generation number during the selection period were 1.23 +/- .12 (P < .01) in the HG line and -.86 +/- .12 (P < .01) in the LG line; the regressions for FC (in g feed/g gain) were -.07 +/- .01 (P < .01) in the HFC line and .03 +/- .01 (P < .05) in the LFC line. Selection for ADG was effective in improving ADG and FC.

A Bayesian analysis of the effect of selection for growth rate on growth curves in rabbits Genet

Article

Full-text available

Jan 2003

Gompertz growth curves were fitted to the data of 137 rabbits from control (C) and selected (S) lines. The animals came from a synthetic rabbit line selected for an increased growth rate. The embryos from generations 3 and 4 were frozen and thawed to be contemporary of rabbits born in generation 10. Group C was the offspring of generations 3 and 4, and group S was the contemporary offspring of generation 10. The animals were weighed individually twice a week during the first four weeks of life, and once a week thereafter, until 20 weeks of age. Subsequently, the males were weighed weekly until 40 weeks of age. The random samples of the posterior distributions of the growth curve parameters were drawn by using Markov Chain Monte Carlo (MCMC) methods. As a consequence of selection, the selected animals were heavier than the C animals throughout the entire growth curve. Adult body weight, estimated as a parameter of the Gompertz curve, was 7% higher in the selected line. The other parameters of the Gompertz curve were scarcely affected by selection. When selected and control growth curves are represented in a metabolic scale, all differences disappear.

Heterosis, maternal and direct effects for postweaning growth traits and carcass performance in rabbit crosses. Journal of Animal Breeding and Genetics, 111: 138-147, Germany

Article

Jan 1994
J ANIM BREED GENET

A crossbreeding experiment was carried out in Egypt using a local breed (Baladi Red, BR) and New Zealand White (NZ) to estimate direct heterosis, maternal additive effects and direct sire effects on some growth and carcass traits in rabbits. Data of body weight (at 5, 6, 8, 10, 12 weeks) and daily gains (at intervals of 5–6, 6–8, 8–10, and 10–12 weeks) on 2153 weaned rabbits were collected. Carcass performance at 12 weeks of age (weight and percentages of carcass, giblets, head, fur, blood and viscera) on 213 male rabbits was evaluated. Estimates of coefficients of variation (CV) for most growth and carcass traits were high and ranged from 10.0 to 40.2%. Sire‐breed was of considerable importance in the variation of growth traits and some carcass traits, while dam‐breed contributed little. Sire‐breed × dam‐breed interaction affected (P<0.01 or P<0.001) most body weights and gains studied, while it contributed little to the variation of carcass traits. The purebred NZ resulted in rabbits with heavier weights and carcass and with lighter non‐edible carcass (blood and viscera) compared to the BR. Heterosis percentages for most growth traits were significant and ranged from 2.5% to 5.0% for body weights and from 0.7% to 9.5% for daily gains. Insignificant positive direct heterosis was observed for most carcass traits. Crossbred rabbits from NZ sires with BR dams were superior to from the reciprocals. Maternal‐breed effects on most weights and gains were insignificant, while sire‐breed contrasts for some weights and gains proved significant. Postweaning growth and carcass performances of BR‐mothered rabbits generally surpassed the NZ mothered, while NZ‐sired rabbits were superior at later ages. High edible carcass was observed for BR‐sired rabbits, while more non‐edible carcass wastes (blood and viscera) for NZ‐sired rabbits. Maternal‐breed effects appeared to be less important than paternal‐breed effects in influencing most weights, gains and carcass traits studied. Zusammenfassung Heterosis, maternale und direkte Wirkungen bei Wachstums‐ und Schlachtkörpermerkmalen in Kaninchenkreuzungen Der Kreuzungsversuch wurde mit lokalen ägyptischen Rassen (BR) und Neuseeland Weißen (NZ) zur Schätzung direkter Heterosis, maternaler additiver Wirkungen, direkter Vater‐Wirkung auf einige Wachstums‐ und Schlachtkörpermerkmale von Kaninchen durchgeführt. Angaben über Körpergewicht (5, 6, 8, 10, 12 Wochen) und Zuwachs (Intervalle 5 bis 6, 6 bis 8, 8 bis 10, 10 bis 12 Wochen) wurden von 2153 abgesetzten Kaninchen gewonnen. Die Schlachtkörperleistungen bei 12 Wochen Alter (Gewicht und Anteil von Schlachtkörper, Kopf, Pelz, Blut und Innereien) stammen von 213 männlichen Kaninchen. Schätzungen der Variationskoeffizenten (CV) für meiste Wachstums‐ und Schlachtkörpermerkmale waren hoch und bewegten sich zwischen 10 und 40,2%. Vaterrasse hatte erheblichen Einfluß auf Unterschiede in Wachstumsrate und einige Schlachtkörpermerkmale, während die Mutterrasse weniger beigetragen hat. Interaktion zwischen beiden beeinflußte die meisten Körpergewichts‐ und Zuwacnsleistungen, während sie wenig zur Variabilität der Schlachtkörpermerkmale beigetragen hat. Reinrassige NZ waren schwerer und hatten weniger nicht nutzbare Schlachtkörperteile (Blut und Eingeweide) verglichen mit BR. Heterosis‐Prozente für die meisten Wachstumsmerkmale waren signifikant und schwankten zwischen 2,5 und 5% für Körpergewicht, 0,7 bis 9,5% für Zuwachs. Insignifikante positive direkte Heterosis wurde für die meisten Schlachtkörpermerkmale beobachtet. Kreuzungskaninchen von NZ Vätern waren den reziproken überlegen. Maternale Wirkungen auf meiste Gewichtsmerkmale waren insignifikant, während Vaterrassenkontraste hierfür signifikant waren. Zuwachs‐ und Schlachtkörperleistung von BR gesäugten Kaninchen haben im allgemeinen die von NZ gesäugten übertroffen, während von NZ Böcken gezeugte in späteren Altersabschnitten überlegen waren. Hohe Werte für Schlachtkörper wurden für BR gesäugte Kaninchen gefunden, während mehr nicht verzehrbare Abfälle (Blut und Eingeweide) bei NZ gezeugten vorhanden war. Maternale Rassenwirkungen schienen weniger wichtig als paternale zu sein.

Study on the performance of normal hair, angora and their reciprocal crossbred rabbits: 3- growth and carcass traits.

Conference Paper

Jan 1996

Qualités bouchères de lapereaux issus d'un croisement diallèle de 3 souches : interaction du type génétique et de la taille de portée d'origine

Article

Jan 1994

Growth performance and carcass traits in three strains of rabbits and their two-way crosses

Article

Jan 1989

Comparison of growth and feed efficiency among rabbit lines selected for different objectives

Article

Jan 1996
Livest Prod Sci

An experiment has been carried out to evaluate correlated responses in feed efficiency in lines selected for postweaning daily gain and litter size, respectively. One sire line, selected for growth rate for 19 generations, and two dam lines, selected for litter size at weaning for 14 and 18 generations, have been compared for weaning weight (28 d), daily gain (28–63 d), feed intake and feed conversion. Large differences between the sire line and the dam lines are expected for the last three traits as a result of the different methods of selection. The most important estimated differences between lines during the postweaning growth period (weaning at 28 d, and slaughter at 63 d) were: The sire line grew about 9 g/d (24%) faster than the dam lines, had a greater feed consumption of 17 g/d (14%) and a lower feed conversion rate of 0.33 (11%). Selection of the sire line for growth rate is suggested as the main cause of the differences between the lines.

Breed and heterotic effects on postweaning traits in Altex and New Zealand White straightbred and crossbred rabbits

Article

May 2001

Postweaning data from 1,111 straightbred and reciprocally crossbred rabbits were analyzed to evaluate Altex and New Zealand White (NZW) breeds for individual growth and litter traits. The Altex is a recently developed sire breed, whereas the NZW is a popular commercial dam breed. Individual fryer growth traits were weaning (28 d; WW) and market (70 d; MW) weights and ADG. Litter traits included litter size (LSW) and total weight of litter at weaning (LWW), 28 to 70 d total feed intake (LFI), feed efficiency (LFE = total litter gain/LFI), survival rate, and within-litter MW uniformity. Least squares models consisted of fixed effects of sire breed, dam breed, season of weaning, doe parity, two- and three-way interactions, and random effects of sire within sire breed, litter within sire x dam breed, and(or) residual error (depending on whether an individual or a litter trait was analyzed). Crossbreeding parameters (direct breed additive, maternal breed, and individual heterosis) were estimated. Altex sires increased WW, ADG, and MW by 40 g (P < 0.10), 2.5 g/d, and 152 g (P < 0.001), respectively. Individual growth traits were not significantly influenced by the maternal breed effect. Litter size at weaning and LWW means were numerically similar for Altex and NZW dams. Direct heterosis increased ADG (1.7 g/d; P < 0.01) and MW (66 g; P < 0.10). In straightbred Altex compared to NZW fryers, ADG and MW were increased by 3.6 g/d and 216 g, respectively (P < 0.001). In Altex (sire) x NZW (dam) crossbred compared to NZW straightbred fryers, WW and MW were heavier (55 and 218 g; P < 0.10 and < 0.001) and ADG was more rapid (4.2 g/d; P < 0.001). For litter traits, Altex compared to NZW sires increased LFI by 1.28 kg (P < 0.10). Individual crossbreeding parameters did not affect (P > 0.05) other litter traits. No relationship existed between breed type of fryer and survival status (chi2 = 2.81; P > 0.25). For litter traits, straightbred Altex had significantly greater LFI by 2.45 kg and increased LFE by 0.015 units relative to NZW. Combined direct breed additive and heterosis effects increased LFI by 1.84 kg (P < 0.05) in Altex (sire) x NZW (dam) crossbreds compared to NZW straightbreds. Also, 25% more Altex (sire) x NZW (dam) crossbred fryers were marketable (body weight > or = 1.8 kg) by 63 d of age than NZW straightbred fryers. These data suggest that crossing Altex bucks to NZW enhanced breeding efficiency of fryer growth performance.