scholarly journals Effect of final photoperiod and twenty-week body weight on sexual maturity and early egg production in broiler breeders

2006 ◽  
Vol 85 (3) ◽  
pp. 377-383 ◽  
Author(s):  
P.D. Lewis ◽  
R.M. Gous
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Broiler Breeders

Effect of constant photoperiods on the laying performance of broiler breeders allowed conventional or accelerated growth

2005 ◽  
Vol 143 (1) ◽  
pp. 97-108 ◽  
Author(s):  
P. D. LEWIS ◽  
D. BACKHOUSE ◽  
R. M. GOUS
Keyword(s):  
Body Weight ◽  
Sexual Development ◽  
Sexual Maturity ◽  
Egg Production ◽  
Egg Laying ◽  
Broiler Breeders ◽  
Egg Weight ◽  
Laying Performance ◽  
Body Weights ◽  
Accelerated Growth

An experiment was conducted at the University of KwaZulu–Natal to assess the effect of constant photoperiods on sexual maturity and egg-laying performance in broiler breeders given two levels of control-feeding during the rearing phase. Cobb broiler breeder females were grown to reach 2·1 kg body weight at 17 or 21 weeks, and maintained on 10, 11, 12, 13, 14 or 16-h photoperiods from 2 days to 68 weeks of age. There were no significant interactions between photoperiod and growth rate for any production parameter. The time required reaching 2·1 kg increased proportionally with photoperiod but, because of delayed sexual development, birds on longer photoperiods consumed more feed to, and were heavier at, sexual maturity than shorter daylengths. The longer-photoperiod birds also had inferior rates of lay in the first half of the cycle, but superior in the second, which, together with the photoperiodic effects on maturity, resulted in birds on 11, 13 or 14 h producing most eggs to 68 weeks, and those on 16 h fewest. It is possible that the pattern of egg production was due to some of the birds on [ges ]13-h photoperiods becoming photorefractory, having a mid-cycle pause, and then spontaneously resuming egg production in the latter half of the cycle. However, a hinge-analysis of current and other data to the more usual depletion age of 60 weeks showed that the combined effects of photoperiod on sexual maturity and egg production resulted in constant 10-h birds producing the highest number of eggs, with numbers decreasing by 3·6 eggs/h of photoperiod above the hinge and 7·8 eggs/h of photoperiod below it. Mean egg weight increased by 0·4 g/h of photoperiod, but the proportion of abnormally large and floor eggs and the incidence of mortality were unaffected by daylength. For each photoperiod, accelerated growth resulted in body weights being heavier than controls at sexual maturity, despite the mean age at maturity being 10 days earlier for the faster-growing birds. Body weights for the two growth groups were not significantly different at 68 weeks. Faster-growth birds consumed 1 kg less feed to 2·1 kg body weight, but 1·3 kg more feed to sexual maturity and 2·7 kg more to 68 weeks, and produced 6 more eggs than, but had similar patterns of egg production to, the conventionally managed controls. Mean egg weight, the proportion of floor eggs and the incidence of mortality were similar for both groups. Notwithstanding that the overall production of abnormally large eggs was low (1·1 eggs per bird); the faster-growing birds produced significantly more than the controls. Egg weight was positively influenced by age at sexual maturity, body weight at sexual maturity and photoperiod, but was unaffected by rate of growth to 2·1 kg per se.These findings show that there are differences between broiler breeders and egg-type pullets in their response to constant photoperiods. It is likely that the factors responsible for these differences, particularly in terms of sexual development, are the exhibition of photorefractoriness by, and the retardational effects of controlled feeding on, broiler breeders.

PERFORMANCE OF DWARF BROILER BREEDERS IN LAYING CAGES AND FLOOR PENS AND OF NORMAL BREEDERS IN FLOOR PENS

1975 ◽  
Vol 55 (4) ◽  
pp. 741-747 ◽  
Author(s):  
J. H. STRAIN ◽  
A. P. PILOSKI
Keyword(s):  
Body Weight ◽  
Egg Production ◽  
General Pattern ◽  
Female Offspring ◽  
Male Offspring ◽  
Production Cycle ◽  
Feed Conversion ◽  
Broiler Breeders ◽  
Feed Costs

Dwarf broiler breeders in single-bird cages (DC), in floor pens (DF) and normal broiler breeders in floor pens (NF) were compared for their own and their offspring’s performance. No differences were observed in rate of egg production at 147–329 days of age between the NF and DF birds (48 vs. 47%) whereas the DC birds laid at the rate of 40%. Hen-housed egg numbers for the same period followed the same general pattern (NF, 81; DF, 82; DC, 70 eggs/bird). DF and DC birds consumed less feed per dozen eggs than the NF birds (3.4 vs. 4.3 kg/doz). Egg weights in the early part of the production cycle were not significantly different among the groups but at 294 days of age the normal birds laid larger eggs than the dwarfs (65 vs. 62 g). Dwarfs in cages reached 50% production earlier than the DF or NF birds. Female offspring from the three groups grew at the same rate and weighed 1.7 kg at 56 days of age but there were significant differences in feed conversion (NF, 2.46; DF, 2.43; DC, 2.53 kg/kg body weight produced). Male offspring had small but not statistically significant differences in body weight at 56 days (NF, 2.16; DF, 2.12; DC, 2.09 kg) or feed conversion (NF, 2.30; DF, 2.29; DC, 2.34 kg/kg body weight). Mortality in the offspring ranged from 2.7 to 9.2% but did not differ significantly. Income over feed costs per broiler started did not differ from the three groups regardless of the meat price – feed price combination considered. However, when profit was computed on a breeder hen basis, the DF females were more profitable than either the NF or DC females.

scholarly journals DOMINANCE AND EPISTASIS IN HETEROSIS OF WHITE LEGHORN STRAIN CROSSES

1987 ◽  
Vol 67 (3) ◽  
pp. 663-680 ◽  
Author(s):  
R. W. FAIRFULL ◽  
R. S. GOWE ◽  
J. NAGAI
Keyword(s):  
Body Weight ◽  
Sexual Maturity ◽  
Egg Production ◽  
Significant Contribution ◽  
Production Traits ◽  
White Leghorn ◽  
Cross Combination ◽  
Commercial Strain ◽  
Better Than

Four unrelated pure strains of White Leghorns including a grandparent strain from industry and 12 two-strain, 24 three-strain, 24 four-strain and 12 F2 strain crosses produced contemporaneously were used to examine the role of dominance and epistasis in heterosis. A control strain and a commercial strain were also included. For egg weight, the heterosis observed closely approximated that expected due to dominance alone. For sexual maturity and body weight, dominance was the major component of heterosis, but epistasis made a significant contribution — additive by additive (A × A) genetic effects for sexual maturity and 140-d body weight, and parental epistasis for mature body weight. Both dominance and epistasis played a significant role in heterosis for egg production traits. A × A, dominance by dominance (D × D) and additive by dominance (A × D) epistasis were all important for hen-housed egg production and hen-housed egg yield. For hen-day rate of egg production, A × A epistasis was significant only early in the laying year (to 273 d), A × D and D × D were significant to 385 d and in the full year (to 497 d); however, none (A × A, A × D and D × D) was significant near the end of lay (386–497 d). Overall heterosis estimates for full year egg production measured as hen-housed egg production to 497 d or hen-day rate from housing to 497 d clearly showed that on average two-strain crosses were superior to three-strain crosses which were superior to four-strain crosses which in turn exceeded the F2 crosses. Nevertheless, several three-strain crosses had performance for egg production that was equal to or better than the two-strain cross with the highest egg production. Thus, in commerce, where the level of egg production is of great economic importance, the testing and use of a specific three-way cross combination will usually result in a better commercial product. Key words: Heterosis, egg production genetics, epistasis, stocking rate, strain cross, White Leghorn

scholarly journals GENETIC AND PHENOTYPIC ASSOCIATIONS OF JUVENILE BODY WEIGHTS AND EGG PRODUCTION TRAITS IN TWO STRAINS OF RHODE ISLAND CHICKENS

2021 ◽  
Vol 18 ◽  
pp. 66-70
Author(s):  
O. O. ONI ◽  
B. Y. ABUBAKAR ◽  
S. O. OGUNDIPE
Keyword(s):  
Body Weight ◽  
Rhode Island ◽  
Sexual Maturity ◽  
Egg Production ◽  
Genetic Parameters ◽  
Laying Hens ◽  
Genetic Correlations ◽  
Selection Criterion ◽  
Production Traits ◽  
Body Weights

Data on body weight at 16 (WT16); 20 (WT20) weeks of age and at sexual maturity (WTSM) weight of first egg (WT1st), age at sexual maturity (ASM) and 120-d egg production (EN)  were used to estimate genetic parameters in 636 hens of two strains of Rhode Island chikens. There were significant (P.01) differences between  the two strains for all traits except for WTSM.The heritability estimates obtained ranged from 0.05 to 0.41 and 0.04 to 0.30 for strains 1 and 2 respectively. The genetic correlations obtained for the various traits were medium to high for the two strains. The phenotypic correlations were generally low but followed the same trend. The results indicate that selected stocks of the two strains would show improvements in egg production and age   at sexual maturity if juvenile body weight (WT20) is employed as a selection criterion at housing for laying hens.

scholarly journals Effect of Sex-linked Feathering Genes on Body Weight, Age At Sexual Maturity, Feed Intake and Subsequent Laying Performance of Baladi Chickens

1997 ◽  
Vol 2 ◽  
pp. 37
Author(s):  
A. AI-Sobayel ◽  
A.A. AI-Mulhem
Keyword(s):  
Body Weight ◽  
Feed Intake ◽  
Sexual Maturity ◽  
Egg Production ◽  
Management Practices ◽  
Feed Conversion ◽  
Standard Management ◽  
Laying Performance ◽  
Adult Body ◽  
Adult Body Weight

A total of 320 twenty week-old slow and rapid feathering Saudi Arabian Baladi pullers were used to assess the effect of sex-linked feathering genes on body weight, age at sexual maturity, feed intake and subsequent laying performance. Similar numbers of rapid feathering Leghorns pullets were included in the study for the purpose of comparison. The experimental birds of each genotypic group were randomly divided into four replicates and subjected to standard management practices. Slow feathering Baladi pullers had higher (P<0.05) adult body weight, rate of mortality, and feed intake and a similar age at sexual maturity but showed lower (P< 0.05) hen-day, and hen-housed egg production and feed conversion compared with rapid feathering Baladi pullets. Rapid feathering Leghorns had higher (P<0.05) adult body weight. age at sexual maturity, hen-day egg production, rate of mortality and feed intake and lower feed intake/kg eggs than rapid and slow feathering Baladi. However, rapid feathering Baladi and Leghorns had similar hen-housed egg production and feed intake per dozen eggs and had better (l’<0.05') performance than slow feathering Baladi.

scholarly journals Canonical correlation analysis for studying the relationship between egg production traits and body weight, egg weight and age at sexual maturity in layers

2011 ◽  
Vol 50 (No. 4) ◽  
pp. 163-168 ◽  
Author(s):  
Y. Akbaş ◽  
Ç. Takma
Keyword(s):  
Body Weight ◽  
Correlation Analysis ◽  
Canonical Correlation Analysis ◽  
Canonical Correlation ◽  
Sexual Maturity ◽  
Egg Production ◽  
Production Traits ◽  
Egg Weight ◽  
Canonical Correlations ◽  
The Relationship

In this study, canonical correlation analysis was applied to layer data to estimate the relationships of egg production with age at sexual maturity, body weight and egg weight. For this purpose, it was designed to evaluate the relationship between two sets of variables of laying hens: egg numbers at three different periods as the first set of variables (Y) and age at sexual maturity, body weight, egg weight as the second set of variables (X) by using canonical correlation analysis. Estimated canonical correlations between the first and the second pair of canonical variates were significant (P &lt; 0.01). Canonical weights and loadings from canonical correlation analysis indicated that age at sexual maturity had the largest contribution as compared with body weight and egg weight to variation of the number of egg productions at three different periods. &nbsp;

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