Selection indices for rabbit improvement

1986 ◽  
Vol 107 (3) ◽  
pp. 537-548
Author(s):  
M. H. Khalil ◽  
J. B. Owen ◽  
E. A. Afifi
Keyword(s):  
Litter Size ◽  
Genetic Gain ◽  
Genetic Improvement ◽  
Large Contribution ◽  
Litter Weight ◽  
Selection Indices ◽  
Selection For ◽  
Lower Contribution ◽  
Size At Birth

SUMMARYRecords on 884 litters and 3051 bunnies of the Bauscat (B) and Giza White (G) breeds were used to construct different selection indices.A series of selection indices and subindices were constructed for both B and G does. An index or subindex based on litter size at weaning, mean bunny weight at weaning, litter size at birth and litter weight at birth could be practically applied to improve the productivity of B and G does, under local Egytian conditions. Preweaning mortality did not contribute significantly to the different selection indices and subindices. Litter weight at birth made a large contribution to the different indices and subindices constructed. Litter size at weaning contributed little in the subindices to be used to select for mean bunny weight at weaning. Mean bunny weight at weaning made a lower contribution to the subindices to be used to select for litter size at weaning. The expected genetic gain in litter size at weaning was slight in all of the selection indices and subindices constructed because of low heritability values for this trait. Considerable genetic improvement for doe productivity of the G breed might be achieved through selection for mean bunny weight at weaning.Four selection indices and subindices were constructed for B and G rabbits. The index or subindex based on 6-week weight and 8-week weight was the best criterion for selection for the genetic improvement of 6-week weight and 12-week weight. Six- and 8-week weight contributed substantially while 12-week weight contributed little to the value of most of the selection indices and subindices constructed. The highest total genetic gain attributable to 6- and 12-week weight was obtained when the selection indices or subindices including 6-week weight and 8-week weight were used.

A note on the relationship between litter size at birth and litter weight at weaning in domesticated and feral mice

1981 ◽  
Vol 33 (2) ◽  
pp. 219-222
Author(s):  
W. R. Congleton
Keyword(s):  
Assortative Mating ◽  
Litter Size ◽  
Indirect Selection ◽  
Litter Weight ◽  
The Mean ◽  
Selection For ◽  
The Relationship ◽  
Size At Birth

ABSTRACTThe relationship between litter size at birth and litter weight at weaning is curvilinear, with an intermediate litter size resulting in the heaviest litter weight at weaning. Relative to feral mice, the mean and variation for litter size at birth was larger for domesticated mice which had been selected for fertility and crossbred. Consequently, some of the litters from the crossbred domesticated mice were larger than the litter size at birth which optimized litter weight at weaning, primarily due to increased pre-weaning mortality. If litter weight at weaning is to be optimized by indirect selection for litter size at birth, the variation around an intermediate optimum litter size at birth could be most effectively reduced by negative assortative mating.

The effect of selection for litter size and litter weight at weaning in mice maintained on two diets

1963 ◽  
Vol 5 (3) ◽  
pp. 317-326 ◽  
Author(s):  
D. C. Dalton ◽  
T. L. Bywater
Keyword(s):  
Litter Size ◽  
Genetic Improvement ◽  
Random Mating ◽  
The Other ◽  
Response To Selection ◽  
Control Groups ◽  
Litter Weight ◽  
Dietary Switch ◽  
Selection For ◽  
Time Selection

SUMMARYAn experiment was carried out with mice over 24 generations to measure the response obtained to selection for litter size and litter weight at weaning on two dietary regimes designated normal and diluted. In addition, control groups bred by random mating were maintained on each diet. The stock were maintained on the diets from generation 0–3 after which time selection for the traits started and continued up to generation 17. After generation 17 for a further 6 generations, all selection stopped and half of each group was switched on to the other diet, while the remaining half continued as before.No significant response was obtained to selection for either litter size or litter weight at weaning.The diets provided did not bring about a differential response to selection for the traits, and the response to the dietary switch was small and temporary in its effect.Due to strong maternal effects and low heritability, little genetic improvement was obtained by selection for litter size and litter weight at weaning in these mice.

scholarly journals Genetic Analysis Of Rabbit Litter Traits At Birth And Weaning

2021 ◽  
Vol 19 ◽  
pp. 64-69
Author(s):  
I. K Odubote ◽  
B. Somade
Keyword(s):  
Birth Weight ◽  
Genetic Analysis ◽  
Litter Size ◽  
Weaning Weight ◽  
Litter Weight ◽  
Phenotypic Correlations ◽  
Litter Traits ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Size At Birth

Data on 260 litters were used to provide therefore to estimate the heritability and estimates of heritability, repeatability, genetic and phenotypic correlations for litter traits at birth and at weaning. Breed, sire within breed and doe within sire effects were found to be significant, (P<0.05) for litter size at birth and at weaning and for litter weight at birth and at weaning. Heritability estimates of 0.33±0.08, 0.38±0.02, 0.03±0.02 and 0.16±0.05 were obtained for litter birth weight, litter size at birth, litter size at weaning and litter weaning weight, respectively. Repeatability estimates were found to be generally moderate to high. Genetic and phenotypic correlations were positive and significant (P<0.01). Selection for litter size at birth and litter birth weight are likely to result in improved litter size at weaning and litter weaning weight respectively.

Effect of remating interval and diet on the performance of female rabbits and their litters

1993 ◽  
Vol 56 (3) ◽  
pp. 399-405 ◽  
Author(s):  
C. Cervera ◽  
J. Fernandez-Carmona ◽  
P. Viudes ◽  
E. Blas
Keyword(s):  
Factorial Design ◽  
Energy Intake ◽  
Litter Size ◽  
Intensive Treatment ◽  
The Other ◽  
Interactive Effects ◽  
Energy Concentration ◽  
Lactation Performance ◽  
Litter Weight ◽  
Size At Birth

AbstractIn an experiment of factorial design, female rabbits were given four diets, containing 13·0, 11·4, 10·4 and 9·7 kJ digestible energy (DE) per g and subjected to two remating intervals (R) of 1 to 2 days (intensive) or 9 days (semi-intensive) from parturition. The experiment lasted for 2 years during which 352 does produced a total of 1254 litters. The only major differences due to diet were that the diet with the highest energy concentration, and which contained 35 g/kg added fat, promoted a significantly higher energy intake in lactation (111 v. an average of 94 MJ DE) than the other diets, and thereby increased litter weight at weaning at 28 days (3·48 v. 2·99 kg). Diet and R showed no major interactive effects. The intensive treatment significantly reduced parturition interval (46 v. 52 days) and increased the output of weaned rabbits per doe per year (35 v. 29). As actual R was more variable than the theoretical R imposed by the treatments, further analyses were made by dividing the does into four groups according to the actual R. In these analyses, the effects of R on current and subsequent lactation performance were assessed separately. The main difference between the groups was that litter size increased significantly with R (e.g. litter size at birth in subsequent parities was 8·0, 9·2, 9·7 and 9·0 for mean intervals of 2, 10, 16 and 37 days). However, the same pattern of differences occurred in the current parity, indicating that it was litter size that affected R, rather than the reverse (i.e. does with small litters conceived earlier than those with larger litters).

MASS SELECTION IN A PIG POPULATION. 2. THE EFFECTS OF INBREEDING WITHIN THE SELECTED POPULATIONS

1977 ◽  
Vol 57 (4) ◽  
pp. 627-634 ◽  
Author(s):  
HITOSHI MIKAMI ◽  
H. T. FREDEEN ◽  
A. P. SATHER
Keyword(s):  
Litter Size ◽  
Reproductive Performance ◽  
Degrees Of Freedom ◽  
Regression Coefficients ◽  
Longissimus Dorsi ◽  
Mass Selection ◽  
Cross Sectional ◽  
Litter Weight ◽  
Daily Gain ◽  
Size At Birth

The regression of reproductive performance of dams and post-natal performance of progeny on inbreeding was examined for a population of replicated lines subjected to mass selection over a period of nine generations. Inbreeding advanced by 2.0–2.3% per generation. Regression coefficients per 1% increase in inbreeding, based on 817 degrees of freedom for first parity sows, were −.56 ±.23 kg for dam weight at first parturition (12 mo), −.48 ±.19 kg for dam weight change from parturition to weaning, −.013 ±.034 for litter size at birth, −.103 ±.033 for litter size at weaning and −1.36 ±.36 kg for litter weight at weaning. Regressions for post-natal traits, estimated for progeny produced by second parity dams during the final three generations (638 df) were 10.3 ± 4.0 g for birth weight, 16.8 ± 32.7 g for weaned weight, −4.53 ± 1.22 g for post-weaning daily gain, −.34 ±.16 mm for backfat,.10 ±.04 cm2 for cross-sectional area of the longissimus dorsi, and.09 ±.04% for estimated yield of trimmed retail product from the carcass.

Reproductive attributes of local pig (Votho) of Nagaland, India

2016 ◽  
Author(s):  
N. Savino ◽  
Z. Chusi ◽  
A. Dhali ◽  
P. Perumal
Keyword(s):  
Mortality Rate ◽  
Litter Size ◽  
Field Survey ◽  
Gestation Length ◽  
Reproductive Parameters ◽  
Litter Weight ◽  
Significant Difference ◽  
Size At Birth ◽  
Selection Of ◽  
Age At First Farrowing

The present study was conducted to measure the reproductive attributes of Naga local pigs (Votho) in Kohima, Peren and Phek district of Nagaland. The reproductive parameters were measured through field survey and reproductive records of owner. The reproductive parameters such as age at first fertile service (AFFS), age at first farrowing (AFF), gestation length, farrowing interval, litter size at birth, litter size at weaning, litter weight at birth, litter weight at weaning, mortality rate and stillbirth rate were measured. The result revealed that there was a significant difference among the different districts of Nagaland in AFFS, AFF and litter weight at birth. Parameters such as AFFS, AFF and litter weight at birth were significantly higher and gestation length, farrowing interval, litter size at weaning, litter weight at birth, litter weight at weaning were non-significantly higher in Kohima than in Peren and Phek District. Similarly, parameters such as litter size at birth, mortality rate were non-significantly higher in Peren district and stillbirth was non- significantly higher in Phek district than other districts of Nagaland. These reproductive attributes analyses may be useful in selection of breeding stock for future parents and select the place for breeding programme for indigenous local Naga pigs.

Performance evaluation of Soviet Chinchilla and Californian White rabbit breeds in tropical climatic conditions of India

2017 ◽  
Author(s):  
Uday Kannegundla ◽  
S. Sai Reddy ◽  
M. Gnana Prakash ◽  
M. Mahenderand ◽  
P. Amareswari
Keyword(s):  
Least Squares ◽  
Litter Size ◽  
Climatic Conditions ◽  
Research Station ◽  
Productive Performance ◽  
Litter Weight ◽  
Body Weights ◽  
Genetic And Phenotypic Correlations ◽  
High Heritability ◽  
Size At Birth

Study was conducted to evaluate the performance of Soviet Chinchilla and Californian White rabbit breeds maintained in tropical environment at rabbit research station, Hyderabad, Telangana. Data generated on total of 1364 bunnies, 701 belongings to the Soviet Chinchilla born in 122 litters and 663 bunnies of Californian White born in 124 litters during the period from 2012 to 2015 were utilized to examine the various productive performance traits. The overall least-squares mean litter size and litter weight was 5.52 ± 0.16 and 264.75 ± 7.86 at birth and 3.56 ± 0.17 and 1439.67 ± 72.55 g at weaning, respectively. The overall least-squares mean pre weaning body weights were 48.39 ± 0.48, 113.65 ± 1.38, 161.50 ± 2.03, 226.15 ± 3.47, 417.89 ± 7.53g at birth, 1, 2, 3 and 4 weeks of age and the post weaning weights at 6, 8, 10, 12, 14 and 16 weeks of age were 628.75 ± 13.02, 844.11 ± 14.81, 1040.79 ± 16.42, 1225.96 ± 17.81, 1437.57 ± 20.54 and 1636.99 ± 28.87 g, respectively. Season of birth and litter size at birth showed significant (£0.01) effect on body weights while genetic group, parity of the doe and sex of the bunny had slight effects only. The low to high heritability estimates, genetic and phenotypic correlations of body weights are the indication for improvement of body weights by appropriate breeding plans.

A genetic analysis of litter traits in Bauscat and Giza White rabbits

1987 ◽  
Vol 45 (1) ◽  
pp. 123-134 ◽  
Author(s):  
M. H. Khalil ◽  
J. B. Owen ◽  
E. A. Afifi
Keyword(s):  
Genetic Analysis ◽  
Litter Size ◽  
Litter Weight ◽  
Phenotypic Correlations ◽  
Large Litter ◽  
Litter Traits ◽  
Genetic And Phenotypic Correlations ◽  
Size At Birth

AbstractAn analysis of doe productivity traits was carried out on 884 litter records including 52 sires and 210 daughters (paternal half sisters) of Bauscat (B) and Giza White (G) rabbits. Traits examined included litter size and weight at birth and at weaning, pre-weaning mortality and mean weight of young at weaning. Year-of-kindling affected most litter traits but no pattern of parity effects on litter size and pre-weaning mortality was observed. Litter weight and mean weight of young at weaning generally increased linearly as parity advanced. Litter size and weight and mean weight of young tended to increase as month of kindling advanced from October to March, and to decrease again during April and May. Pre-weaning mortality decreased as month of kindling advanced up to March and increased thereafter during April and May. The sire of the doe affected all litter traits studied, with the exception of litter size at birth and pre-weaning mortality in the B breed. Estimates of heritability for most of the litter traits were moderate or high. Genetic and phenotypic correlations among litter size traits and between litter size and litter weight traits were positive and relatively moderate or large. Litter weight traits were positively correlated both genetically and phenotypically. The genetic and phenotypic correlations between litter size traits and mean weight of young at weaning were negative and relatively moderate or large.

scholarly journals Phenotypic relationships between gestation length and preweaning litter traits in rabbits.

2021 ◽  
Vol 31 (2) ◽  
pp. 154-160
Author(s):  
O. N. Durunna ◽  
U. E. Ogundu
Keyword(s):  
Litter Size ◽  
Average Daily Gain ◽  
Gestation Length ◽  
Litter Weight ◽  
Litter Traits ◽  
Degree Of Association ◽  
High Degree ◽  
The Relationship ◽  
Daily Gain ◽  
Size At Birth

A total of 135 kittens from 22 kindlings were used to determine the relationship between gestation length (GL) and some preweaning litter traits alongside the weight of their 12 dams. Average daily gain at 21 days (ADG21), average litter weight at birth (ALWB), kindling to weaning viability (KWV), litter size at birth{L.SB), litter size at 21 days (LS21), litter weight at 21 days(LW21), litter weight at birth (LWAB), and still birth number (SBN) when subjected to multiple regression analysis revealed non-significant t-test value with GL. However, Average litter weight at 21 days (ALW21) was highly significant (P<0.01) suggesting that such can be used to predict GL. Weight of doe (WOD) was highly significant (P<0.01) showing that such parameter is important for predicting GL. A high R2 value was obtained indicating that the variability in GL is explained by the linearity of the preweaning litter traits and WOD. However the correlation coefficient R, (0.89) revealed a high degree of association between the preweaning litter traits in the rabbits and the weight of doe in a linear form. The F-value was significant at P<0.05 indicating that WOD and the preweaning litter traits in rabbits have significant contribution to the variation in GL. The correlations among traits were positive and significant for majority of the traits, which include live birth number (LBN), ADG21, ALW21, KWV, LS21, and LW21. However SBN had negative correlation with other traits.

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