scholarly journals Egg Production Traits as Correlated Responses to the Selection for Immune Responses in Chickens.

1992 ◽  
Vol 29 (5) ◽  
pp. 296-300
Author(s):  
Hisato OKABAYASHI ◽  
Yosuke KOSUGI
Keyword(s):  
Immune Responses ◽  
Egg Production ◽  
Production Traits ◽  
Correlated Responses ◽  
Selection For

Continued selection of Romney sheep for resistance or susceptibility to nematode infection: estimates of direct and correlated responses

2000 ◽  
Vol 70 (1) ◽  
pp. 17-27 ◽  
Author(s):  
C. A. Morris ◽  
A. Vlassoff ◽  
S. A. Bisset ◽  
R. L. Baker ◽  
T. G. Watson ◽  
...  
Keyword(s):  
Maximum Likelihood Estimates ◽  
Research Centre ◽  
Control Line ◽  
Production Traits ◽  
Correlated Responses ◽  
Breeding Lines ◽  
Nematode Parasites ◽  
Phenotypic Standard Deviation ◽  
Selection For ◽  
Fleece Weight

AbstractDivergent breeding lines of Romney sheep, selected as lambs for consistently high or low faecal worm egg count (FEC) following natural multi-species challenge by nematode parasites, were established in New Zealand at Wallaceville Animal Research Centre in 1979 and at Rotomahana Station in 1985. In 1988 the Rotomahana lines, including an unselected control line maintained under the same management conditions, were transferred to Tokanui Station where they remained for 4 years. In 1993 elite high and low FEC animals from Tokanui, along with the controls, were transferred to Wallaceville, where merged lines have since been managed together. Selection responses from the lines at Rotomahana and Tokanui, and from a further 5 years of divergent selection in the merged lines, are reported here. For the two most recent lamb crops (1996 and 1997 birth years), log-transformed FECs of the high and low lines were 1·27 and -1·46 phenotypic standard deviation units from the control. After back-transformation to the original scale, where the FEC for control line lambs averaged 1255 eggs per g, the means for the high and low lines were 3Ό5 and 0·27 times the control mean. Animal-model restricted maximum likelihood estimates of her it ability and repeatability for single-record FEC (following separate infections) were 0·28 (s.e. 0·02) and 0·42 (s.e. 0Ό1), respectively. Correlated responses in production traits include significantly decreased post-weaning weight gain and increased dags (breech soiling) in lambs, and decreased fleece weight in yearlings and ewes in the low FEC line, compared with those in the high line. However the low FEC line had proportionally 0·11 more lambs weaned per ewe mated than the high FEC line (F < 0·01). It is concluded firstly that selection for high or low FEC in Romney s has achieved an 11-fold difference between the divergent lines. Secondly, it will generally be necessary in a commercial environment to apply index selection for a combination of increased productivity, decreased FEC and possibly decreased dags, when potential candidates are recorded under conditions of nematode challenge.

scholarly journals Effect of Selection for Weight of Early Eggs on Egg Production Traits in Japanese Quail

2015 ◽  
Vol 9 (4) ◽  
pp. 179-190 ◽  
Author(s):  
Mohamed Bahie El- Deen ◽  
Ayman A. Nour ◽  
Waleed S. El- Tahawy ◽  
Hala A. Fouad
Keyword(s):  
Japanese Quail ◽  
Egg Production ◽  
Production Traits ◽  
Selection For

scholarly journals Effect of feathering alleles (K/k+) on laying performance, hatchability parameters and some body measurements in two lines of white plymouth rock hens

2012 ◽  
Vol 28 (3) ◽  
pp. 405-414 ◽  
Author(s):  
N. Mincheva ◽  
M. Lalev ◽  
M. Oblakova ◽  
P. Hristakieva ◽  
I. Ivanova
Keyword(s):  
Egg Production ◽  
Shape Index ◽  
Substantial Effect ◽  
Body Measurements ◽  
Production Traits ◽  
Broiler Production ◽  
Live Body Weight ◽  
Laying Performance ◽  
Lower Fertility ◽  
Selection For

The study aimed to investigate the effects of sex - linked feathering alleles on laying performance, hatchability parameters and body measurements in hens from two White Plymouth Rock lines (line L and line K) used as maternal lines in broiler production. Four groups of 18-week-old hens were formed, two of each line, with genotype K/W (slow feathering) and k+/W (rapid feathering) respectively. Groups of line L included 72 hens divided into 6 boxes with 1 rooster per 12 hens, whereas line K groups comprised 96 hens of each genotype, housed in 8 boxes with one rooster per 12 hens, totally 192 birds. The K locus alleles had no significant effect on egg production traits (p>0.05). The presence of slow feathering allele resulted in lower fertility and hatchability of set eggs in both studied lines (p<0.05). A substantial effect of feathering rate alleles was observed with respect to the egg shape index (p<0.05), eggshell thickness (p<0.001) and albumen index (p<0.05). The presence of the slow feathering allele resulted in lower live body weight of birds from line K at the age of 36 weeks (p<0.05), but in longer thighs (p<0.01) and metatarsi (p<0.001) in both lines. The selection for creation of slow feathering lines for feather sexing purposes should take into consideration the effect of the K gene on studied traits.

Sire × hatching season interaction in egg production traits within flocks of domestic fowl

1979 ◽  
Vol 30 (5) ◽  
pp. 991
Author(s):  
BH Yoo ◽  
BL Sheldon
Keyword(s):  
Domestic Fowl ◽  
Variance Component ◽  
Egg Production ◽  
Production Traits ◽  
White Leghorn ◽  
Egg Weight ◽  
Sib Families ◽  
Selection For ◽  
Efficiency Of Selection ◽  
Season Interaction

The extent of sire x hatching season interaction in egg production characters has been studied in White Leghorn, Australorp and Synthetic flocks in which half-sib families bred from the same sires were mated largely to the same dams for spring and autumn hatchings. Interaction appeared to be more important in White Leghorn and Synthetic than in Australorp. The estimate of variance component for interaction was not consistent among the three flocks, and it was important only in certain flocks for different characters: age at first egg, part-annual hen-housed production (PHP), and egg weight at 34 and 62 (EWL) weeks of age in Synthetic; and annual survivors' production and egg specific gravity at 62 weeks of age (SGL) in White Leghorn. Comparison of within-season and across-seasons heritabilities showed that the former could be on average more than 45% higher than the latter in PHP, EWL, SGL and annual hen-housed production. As the estimates of the genetic correlation coefficient between seasons tend to be below 1.0 for many characters in White Leghorn and Synthetic, the sire x hatching season interaction may need to be taken into account and investigated further to improve the efficiency of selection for egg production.

scholarly journals Direct and Correlated Responses to Long-Term Selection for Increased Body Weight and Egg Production in Turkeys

1996 ◽  
Vol 75 (10) ◽  
pp. 1180-1191 ◽  
Author(s):  
KARL E. NESTOR ◽  
D.O. NOBLE ◽  
J. ZHU ◽  
Y. MORITSU
Keyword(s):  
Body Weight ◽  
Egg Production ◽  
Correlated Responses ◽  
Term Selection ◽  
Selection For
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