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.

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.

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 THE EFFECT OF THE DOE WEIGHT ON HER REPRODUCTIVE EFFICIENY

2021 ◽  
Vol 22 (1) ◽  
pp. 131-142
Author(s):  
Mohammad Ebrahim Ahmed ◽  
Hussain Yawr Hussain
Keyword(s):  
Growth Rate ◽  
Litter Size ◽  
Conception Rate ◽  
The Other ◽  
Gestation Period ◽  
Reproductive Efficiency ◽  
Litter Weight ◽  
The Third ◽  
Other Hand

Thirty-six local dose have been used and were divided in to three groups sacording to weight, in each group twelve dose. In the first group the weights of the dose were higher than ( 2.5 kgs) and less than (3 kgs). The second groups was higher than 3 kgs) and less than (3.5 kgs). The third group was higher than (3.5 kgs) and less than (4 kgs). The aim of this study was to obtain the effect of doe weight on her reproductive efficiency (gestation period, litter size, litter weight at birth and weaning, growth rate of offspring preweaning, conception rate and preweaning mortility).  The weight of the doe had no significant effect upon the gestation period and this period was 30.9, 31.2, 31.3 days for the three groups respectively, on the other hand the litter size was affected significantly by doe weight and litter size was at birth and preaweaning (5.1 , 5.8 and 6.2), (4.5, 5.3 and 5.7) for the three groups respectively. The offspring weight at birth and weaning was affected significantly by doe weight and this weight was (40.1 , 48.2 and 53.3 gms), (203.6, 227.5 and 233.8 gms) for the three groups respectively while the conception rate was not affected by doe weight. The mortility percentage in the prewaning period was not significantly by doe weight

scholarly journals EFFECTS OF ANCESTRAL X IRRADIATION FOLLOWED BY RANDOM MATING ON BODY WEIGHT OF RATS

Genetics ◽  
1977 ◽  
Vol 86 (4) ◽  
pp. 849-860
Author(s):  
Daniel Gianola ◽  
A B Chapman ◽  
J J Rutledge
Keyword(s):  
Body Weight ◽  
Random Mating ◽  
Rapid Response ◽  
Response To Selection ◽  
Previous Evidence ◽  
Selection Responses ◽  
Inbred Rats ◽  
X Irradiation ◽  
Selection For ◽  
Variance Estimates

ABSTRACT Effects of nine generations of 450r per generation of ancestral spermatogonial X irradiation of inbred rats on body weight were examined. After six generations of random mating (avoiding inbreeding) following the termination of irradiation, descendants of irradiated males (R) were significantly lighter than their controls (C) at 3 and 6 weeks, but not at 10 weeks of age. However, differences in growth between R and C populations were small. Among-litter and within-litter variance estimates were generally larger in the R lines than in the C lines, suggesting that selection responses would be greater in R than in C lines. In conjunction with previous evidence—obtained during the irradiation phase of the experiment—this suggested that more rapid response to selection for 6-week body weight, in particular, might accrue in the R lines.

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).

The impact of racial pattern on the genetic improvement of Morada Nova sheep

2016 ◽  
Vol 58 ◽  
pp. 73-82 ◽  
Author(s):  
L. Shiotsuki ◽  
P.H.T. Silva ◽  
K.M. Silva ◽  
A.V. Landim ◽  
O.R. Morais ◽  
...  
Keyword(s):  
Birth Weight ◽  
Genetic Improvement ◽  
Coat Colour ◽  
Simulated Population ◽  
Response To Selection ◽  
Selection For ◽  
Productive Traits ◽  
Red Variety ◽  
The Impact ◽  
Selection Of

SummaryThe objective of the present study was to describe the frequency of the main racial traits of Morada Nova sheep and simulate the impact of this culling on the response to selection for birth weight. The data from sex, coat colour, hoof pigmentation, muzzle pigmentation, polled and cryptorchidism were collected individually at weaning from 385 Morada Nova sheep of the red variety, born between 2010 and 2012, which belonged to four different flocks in the state of Ceará, Brazil. To estimate the impact of culling of animals due to racial pattern on the genetic improvement of the Morada Nova population, the genetic gains in birth weight per generation were calculated considering the following different scenarios of culling due to racial pattern in a simulated population. The present results indicate that the most urgent step is flexibilization of the requirement of dark muzzles and hooves. The selection of Morada Nova sheep based on racial pattern has caused losses in the genetic gain for productive traits such as birth weight. Readaptation of the official racial pattern established for Morada Nova sheep is necessary so that the racial pattern is achieved and an adequate number of animals will be available for selection.

scholarly journals Response to selection for increased pupa weight in Tribolium castaneum as related to population structure

1977 ◽  
Vol 30 (3) ◽  
pp. 237-246 ◽  
Author(s):  
Alan J. Katz ◽  
Franklin D. Enfield
Keyword(s):  
Random Mating ◽  
Selection Response ◽  
Response To Selection ◽  
Short Term ◽  
Selection Systems ◽  
Line Selection ◽  
Selection For ◽  
Seven Generations ◽  
Generation Period ◽  
Term Response

SUMMARYThe effectiveness of selection for increased pupa weight in Tribolium was compared for three different selection systems. In all three systems the same number of breeding individuals was used each generation. Population L was a large random mating population with 24 males and 48 females selected each generation. The C4 and C8 populations were each divided into 6 subpopulations (lines) consisting of 4 males and 8 fem ales. Each of the three populations was replicated. In C4, selection for pupa weight was within lines for three generations, followed by a generation of among-line selection when the best two out of six lines were selected. These lines were then crossed to produce 6 new subpopulations, and the cycle was repeated. The C8 population was handled in exactly the same manner except that seven generations of selection within lines were practised before each generation of among-line selection. Selection response for the 42-generation period was significantly greater in the L population than in either subdivided population. No consistent differences among the selection systems were apparent when evaluating short-term response for the first 12 generations of the experiment. The results were interpreted as indicating that the influence of multiple-peak epistasis was not of major importance for this trait in determining ultimate response to selection when starting from a base population of previously unselected lines and utilizing a within- and among-line selection regime.

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.

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