scholarly journals Comparison of degrees of maturity of rabbit lines selected for different traits

2015 ◽  
Vol 23 (3) ◽  
pp. 155 ◽  
Author(s):  
M. Pascual ◽  
E.W. Calle ◽  
A. Blasco
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Robustness Analysis ◽  
Maturity Stage ◽  
Maternal Line ◽  
Adult Weight ◽  
Paternal Line ◽  
Slaughter Age ◽  
Selection For ◽  
Degree Of Maturity

<p>The aim of this work was to study whether commercial nucleus lines of rabbits selected for different traits, and experimental lines having commercial purposes, have the same degree of maturity when compared at the same slaughter age. The study was carried out with 17897 rabbits from Universitat Politècnica de València. Rabbits came from the maternal lines A (3902 rabbits; 44<sup>th</sup> generation), V (4238 rabbits; 39<sup>th</sup> generation) and LP (6115 rabbits; 9<sup>th</sup> generation), selected for litter size at weaning; the paternal line R (2023 rabbits; 25<sup>th</sup> generation), selected for growth rate between 28 and 63 days of age; the maternal line OR (586 rabbits; 11<sup>th</sup> generation) selected for ovulation rate; and the lines High (503 rabbits; 5<sup>th</sup> generation) and Low (530 rabbits; 5<sup>th</sup>generation) lines, from a divergent selection for high and low intramuscular fat, respectively. Rabbits were weighted at 28 (W28) and 63 (W63) days of age. Rabbit does (42, 25, 39, 94, 14, 32 and 22 from lines A, V, R, LP, OR, High and Low, respectively) were weighed between 30 and 80 wk of age to determine adult weight (AW). Line R had higher W28 and W63, growth rate between 28 and 63 d of age and AW than lines A, V and LP (5802 g vs. 4410, 4222, and 4391 g for AW, respectively). No relevant differences between lines in degrees of maturity at 28 and 63 d of age and time to reach 40% of degree of maturity (percentage of weight compared to AW) were found between lines A, V, R and LP, but the degree of maturity at 2000 g and the time taken to reach that weight were lower in line R (34.7% and 55.2 d) than in lines A (45.5% and 71.1 d), V (47.4% and 69.6 d), and LP (45.8% and 68.0 d). No relevant differences were found between lines OR, High and Low in the traits analysed. A robustness analysis showed that results can be extrapolated to other commercial lines and other slaughter weights. In conclusion, comparison of lines at similar slaughter age could be considered a valid approach for comparisons at the same maturity stage.</p>

A note on growth curves of rabbit lines selected on growth rate or litter size

1993 ◽  
Vol 57 (2) ◽  
pp. 332-334 ◽  
Author(s):  
A. Blasco ◽  
E. Gómez
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Growth Curves ◽  
Live Weight ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Standard Errors ◽  
Adult Weight ◽  
Weight Growth ◽  
Using Data

Two synthetic lines of rabbits were used in the experiment. Line V, selected on litter size, and line R, selected on growth rate. Ninety-six animals were randomly collected from 48 litters, taking a male and a female each time. Richards and Gompertz growth curves were fitted. Sexual dimorphism appeared in the line V but not in the R. Values for b and k were similar in all curves. Maximum growth rate took place in weeks 7 to 8. A break due to weaning could be observed in weeks 4 to 5. Although there is a remarkable similarity of the values of all the parameters using data from the first 20 weeks only, the higher standard errors on adult weight would make 30 weeks the preferable time to take data for live-weight growth curves.

Reproductive performance of pigs selected for components of efficient lean growth

1995 ◽  
Vol 60 (2) ◽  
pp. 281-290 ◽  
Author(s):  
J. C. Kerr ◽  
N. D. Cameron
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Reproductive Performance ◽  
Selection Line ◽  
Food Conversion ◽  
Daily Food Intake ◽  
Lean Growth ◽  
Daily Food ◽  
Ad Libitum ◽  
Selection For

AbstractCorrelated responses in reproductive performance to five generations of divergent selection for daily food intake (DFI), lean food conversion (LFC), lean growth rate on ad–libitum feeding (LGA), and lean growth rate on scale feeding (LGS) were studied. Litter traits were measured on 1220 Large White gilts. Mean litter weights at birth and weaning were 12·9 kg and 63·5 kg, with average litter sizes of 10·3 and 7·9. Responses to selection in the high and low lines for litter size in the DFI and LFC selection groups were 1·9 and –1·5 (s.e.d. VI) at birth and 0·9 and –1·8 (s.e.d. 1·2) at weaning. Responses in litter birth weights were respectively positive and negative for DFI and LFC (3·0 and –2·8 (s.e.d. 1·4) kg) and the response in LGS (3 kg) was greater than in LGA (–0·1 kg). Selection line differences in litter weaning weight followed a similar pattern to birth weight for DFI and LFC (17·5 and –17·3 (s.e.d. 10·1) kg). Responses in litter weights were a result of selection line differences in both litter sizes and piglet weights. The relationships between litter size, litter weights and piglet weights at birth and weaning were essentially linear. An extra piglet at birth and weaning corresponded to an increase of 1·0 (s.e. 0·02) kg and 6·9 (s.e. 0·1) kg in litter weights. Piglet birth and weaning weights were decreased by 0·03 (s.e. 0·003) kg and 0·19 (s.e. 0·02) kg. A uterine constraint on piglet growth was implied, but there was no evidence for a limit to uterine capacity. Heritabilities for litter size, weight and piglet weight at birth of 0·06, 0·11 (s.e. 0·04) and 0·16 (s.e. 0·02) respectively were similar to those at weaning. Common environmental effects on piglet weights at birth and weaning were substantially higher than the heritabilities (0·38 and 0·45, s.e. 0·01). The study indicated that selection for lean growth on either an ad–libitum or restricted feeding regime did not significantly affect reproductive performance, but the high lean food conversion ratio and low daily food intake selection lines had impaired reproductive performance.

Correlated response to selection for litter size in pigs: II. Carcass, meat, and fat quality traits

2002 ◽  
Vol 80 (10) ◽  
pp. 2566 ◽  
Author(s):  
J. Estany ◽  
D. Villalba ◽  
M. Tor ◽  
D. Cubiló ◽  
J. L. Noguera
Keyword(s):  
Litter Size ◽  
Correlated Response ◽  
Quality Traits ◽  
Response To Selection ◽  
Fat Quality ◽  
Selection For

scholarly journals GENETIC CORRELATION BETWEEN GROWTH RATE AND LITTER SIZE IN MICE

Genetics ◽  
1966 ◽  
Vol 54 (6) ◽  
pp. 1423-1429 ◽  
Author(s):  
G W Rahnefeld ◽  
R E Comstock ◽  
Madho Singh ◽  
S R NaPuket
Keyword(s):  
Growth Rate ◽  
Genetic Correlation ◽  
Litter Size

Selection for components of efficient lean growth rate in pigs 2. Selection pressure applied and direct responses in a Landrace herd

1994 ◽  
Vol 59 (2) ◽  
pp. 263-269 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran
Keyword(s):  
Growth Rate ◽  
Genetic Correlations ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Direct Response ◽  
Lean Growth ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

AbstractResponses to divergent selection for lean growth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Landrace pigs were studied. Selection was practised for four generations with a generation interval ofl year. A total of 2642 pigs were performance tested in the high, low and control lines, with an average of 37 boars and 39 gilts performance tested per selection line in each generation. The average within-line inbreeding coefficient at generation four was equal to 0·04. There was one control line for the DFI and LFC selection groups and another control line for the LGA selection group. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively with ad-libitum feeding. The selection criteria had phenotypic s.d. of 32, 29 and 274 units, for LGA, LFC and DFI, respectively, and results are presented in phenotypic s.d.Cumulative selection differentials (CSD) were 5·1, 4·5 and 5·5 phenotypic s.d. for LGA, LFC and DFI, respectively. Direct responses to selection were 1·4,1·1 and 0·9 (s.e. 0·20) for LGA, LFC and DFI. In each of the three selection groups, the CSD and direct responses to selection were symmetric about the control lines. The correlated response in LFC (1·1, s.e. 0·19) with selection on LGA was equal to the direct response in LFC. In contrast, the direct response in LGA was greater than the correlated response (0·7, s.e. 0·18) with selection on LFC. There was a negative correlated response in DFI (-0·6, s.e. 0·18) with selection on LFC, but the response with selection on LGA was not significant (0·2, s.e. 0·16).Heritabilities for LGA, LFC and DFI ivere 0·25, 0·25 and 0·18 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·12 (s.e. 0·02). Genetic correlations for LFC with LGA and DFI were respectively positive (0·87, s.e. 0·02) and negative (-0·36, s.e. 0·09), while the genetic correlation between DFI and LGA was not statistically different from zero, 0·13 (s.e. 0·10). Selection on components of efficient lean growth has identified LGA as an effective selection objective for improving both LGA and LFC, without a reduction in DFI.

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