Chick Hatch Weight Research Articles

Egg traits, fertility, hatchability and chick survivability of Rhode Island Red, local and crossbred chickens

SUMMARY The local chicken has profound potential for upgrading through cross breeding with improved commercial birds to increase meat and egg production. This study aimed at evaluating egg traits, hatchability, fertility, chick hatch weight, and chick survivability of commercial Rhode Island Red (RIR), local, and crossbred chickens. A total of 6752 local chicken eggs were collected to obtain breeding stock and to study egg traits. RIR breeding stock was obtained from raising 250 (50 males, 200 females) while crossbred chickens were obtained by crossing RIR layer cocks to local hens and vice versa. A total of 1382, 1523, and 1476 local, RIR, and crossbred chicken eggs respectively were assessed for egg weight, length, breadth, and volume as well as chick hatch weight. Fertility and hatchability were assessed in 3675 local chicken eggs and 3350 eggs from RIR and crossbred chicken each. There was no significant difference (p < 0.05) in egg traits and chick hatch weight between RIR and crossbred chickens but these birds had significantly higher egg weight, egg length, egg breadth, egg volume, and chick hatch weight than local chickens. There were significant (p < 0.0001) positive relationships between egg volume and egg weight, chick hatch weight and egg weight, and chick hatch weight and egg volume for all chickens. Fertility was 92.0±4.14, 91.1±4.42, and 94.5±2.21 for local, RIR, and crossbred chickens respectively. Hatchability varied significantly at p<0.05 (80.6±1.43 in crossbred, 64.0±2.16 in RIR, and 52.2±2.54 in local chickens). Survivability of local chicks was superior by 50% over RIR and crossbred chicks. It is concluded that cross breeding local chickens to RIR produces a superior breed to local ecotype in terms of egg traits, hatchability and survivability. Such superiority can be exploited to upgrade the genetic potential of local ecotype and thus improve poultry production.

The relationship among age, yolk fatty acids content, and incubation results of broiler breeders

This research was carried out to investigate the correlations among age, yolk fatty acids content, and incubation results of broiler breeders. Egg samples were obtained from Ross 308 broiler breeder parent stock at 28, 45, and 65 wk of age. A total of 1,800 eggs were used for incubation results of each age period. The mean values of hatchability of fertile eggs (H/F) were 94.04 +/- 0.42, 91.36 +/- 1.08, 85.97 +/- 0.96%, values for hatchability of total eggs (H) were 92.00 +/- 0.47, 83.61 +/- 1.23, 62.78 +/- 1.57%, and fertility ratios (F) were 97.83 +/- 0.30, 91.50 +/- 0.54, and 73.00 +/- 1.55% at 28, 45, and 65 wk of age, respectively (P < 0.01). The mean values of early embryonic mortality and hatched chick weight were 2.73 +/- 0.27, 4.01 +/- 0.56, 8.93 +/- 0.89% and 36.58 +/- 0.51, 42.47 +/- 0.48, 45.31 +/- 0.96 g, at 28, 45, and 65 wk of age, respectively (P < 0.01). Myristic acid and linoleic acid contents of yolk significantly decreased with increasing age of broiler breeder (P < 0.01). The mean yolk myristic acid contents were 0.34 +/- 0.02, 0.29 +/- 0.06, and 0.24 +/- 0.01 mg/g, and linoleic acid contents were 21.60 +/- 1.26, 16.05 +/- 3.04, and 13.87 +/- 0.49 mg/g at 28, 45, and 65 wk of age, respectively (P < 0.01). Correlations between breeder age and myristic acid and linoleic acid (r = -0.317 and -0.435, respectively) were significant when data were pooled from 28 to 65 wk of age. Significant correlations between H/F and myristic acid and linoleic acid were determined. The correlation between F and linoleic acid (r = 0.364; P < 0.05) was found to be significant with the change of breeder age. There were negative correlations between late embryonic mortality and myristic acid (r = -0.432; P < 0.05), stearic acid (r = -0.437; P < 0.05), and linoleic acid (r = -0.469; P < 0.5) at 28 to 65 wk of age. The findings from this study will contribute to the hatcheries of the poultry sector and the new studies that are going to be carried out..

Effects of electrical field on hatchability performance of eggs from a layer-type breeder

1. Eggs from a layer-type breeder flock (Baladi, King Saud University) between 50 and 63 weeks of age were used in three trials to study the effects of electrical field (EF) during incubation on albumen and yolk heights, incubation temperature, egg weight loss and hatchability traits. The effects of egg size and eggshell characteristics on hatchability traits of eggs incubated under EF were investigated. 2. Eggs were weighed and graded into three weight classes (small, medium, and large). The physical dimensions, eggshell characteristics, and conductance of eggs were examined. The incubator was divided into two compartments for the control and EF treatments. Two aluminium plates were fitted on the inside walls of the EF compartment, face to face, and connected to a step up electric transformer. Eggs were exposed constantly to the EF during the first 18 d of incubation at the level of 30 kV/m, 60 Hz. 3. Egg size influenced the physical dimensions and eggshell characteristics of eggs. Large eggs had higher egg weight, egg surface area, egg volume, eggshell conductance, and eggshell weight and lower yolk weight percentage than medium or small size eggs. Small eggs had lower egg length and higher egg density than large or medium size eggs. Large eggs had higher eggshell thickness than small size eggs. 4. EF incubation of eggs raised incubation temperature by 0·06°C, and increased the percentage of egg weight loss, hatchability, and weight of hatching chicks and reduced the early embryo deaths, and length of incubation by approximately 9·8, 19·6, 1·7, 62·1 and 2·1%, respectively. 5. There was no significant difference between the two incubation treatments in the heights of albumen and yolk of incubated eggs, percentages of late embryo deaths, and pips with live and dead embryos. Hatchability traits were not significantly influenced by egg size. 6. It was concluded that EF incubation of eggs increased hatchability, chick-hatching weight, and reduced the length of incubation of Baladi eggs. Differences in the physical dimensions and eggshell characteristics of eggs did not influence hatchability traits of eggs under EF incubation.

Effects of Electric Field During Incubation of Eggs on the Hatchability and Post-Hatch Performance of Meat Chickens

The effects of electric field (EF) during incubation of eggs on hatchability traits, and post-hatch performance, nutrient utilization and carcass characteristics of meat chickens were investigated in 2 trials. Eggs from a meat-type breeder flock were incubated under EF of 30kV/m, 60Hz during the first 18 d of incubation as compared with the control incubation treatment (C). Chicks hatched from the two incubation treatments (EF and C) were fed ad libitum and their performance was monitored. Measurements were made of hatchability, hatchability failures, chick hatching weight (CHWT), length of incubation, post-hatch performance (weight gain (WTG), feed consumption, and feed conversion ratio (FCR)), and nutrient utilization (apparent nitrogen retention and nitrogen corrected metabolizable energy of birds at 30 d of age), and carcass characteristics of sexed birds at 40 d of age. EF incubation of eggs significantly (P < 0.05) increased per cent of hatchability, per cent of hatching chicks by 468 hour of incubation, CHWT and reduced embryo deaths, pips with life embryos, length of incubation and percentage of hatched chicks at 492 plus 504 of incubation by approximately 11.0, 428, 2.4, 56, 86, 5.1 and 98%, respectively. EF birds had a higher (P < 0.05) WTG than the C birds, when they were placed with feed and water after hatching, but not when birds were held without feed and water to the end of incubation period. EF incubation of eggs did not significantly influenced feed intake, FCR, and nutrient utilization of birds. Carcass of the EF birds had higher (P < 0.01) proportion of drumstick (g/kg eviscerated carcass (EC)), and lower proportions of edible offal (liver plus heart plus gizzard, g/kg live weight (LWT) and thigh (g/kg EC) when compared with those of the C birds. Carcass of male birds had significantly (P < 0.01) higher proportion of drumstick (g/kg EC), and lower proportion of edible offal (g/kg LWT) than female birds. In the EF group, female birds had significantly (P < 0.01) higher LWT and carcass neck plus back (g/kg EC), and lower EC (g/kg LWT) and carcass breast (g/kg EC) than males birds. However in the C group, male birds had a higher LWT than female birds. Whilst, sex of birds of the C group did not significantly influence EC (g/kg LWT), and carcass breast and back plus neck (g/kg EC). It is concluded that the incubation of eggs under EF of 30kV/m, 60Hz increased hatchability of eggs, and chick hatching weight, reduced incubation time of eggs and altered carcass characteristics of birds. EF incubation of eggs increased weight gain of birds when hatched chicks were placed with feed and water after hatching. EF incubation of eggs did not altered feed efficiency, and nutrient utilization of meat chickens.

Effects of injected gluconeogenic supplementation on the performance of broilers from young breeders

Previous research has shown that administering carbohydrates to late-term embryos increases chick hatching weight and liver glycogen content and that supplementing broiler chicks from young hens at day of hatch with subcutaneously injected hydrolyzed casein and thiamine enhances their early performance. It was hypothesized that other practical and readily available gluconeogenic energy sources, including hydrolyzed casein, may similarly be given to hatchlings from immature breeder hens to increase the availability of liver glycogen reserves and augment growth. In addition to physiological saline (sham) and hydrolyzed casein treatments, 2 other treatments containing practical gluconeogenic energy sources (chicken egg crude albumin or albumin hydrolysate) were tested in the current study using hatchlings that were subsequently provided adequate brooding and nutrition. Added biotin was included in the crude albumin treatment. There were no treatment effects on mortality, BW gain, feed or water consumption, feed conversion, body temperature, hematocrit, plasma refractive index, relative liver weight, or liver glycogen content at any of the ages or age intervals examined through d 16 posthatch. These results suggest that under proper brooding conditions and timely feed provision, growth is not facilitated by injected casein hydrolysate, chicken egg crude albumin, or chicken egg albumin hydrolysate during the early transition from fat to carbohydrate-based nutrient uptake in posthatch chicks from young breeder hens.

Effect of intensity of eggshell pigment and illuminated incubation on hatchability of brown eggs

1. The effects of intensity of brown eggshell pigment (light (LBP), medium (MBP) and dark (DBP)) and light intensity during incubation (low and high, 900 to 1380 and 1430 to 2080 lux, respectively) on eggshell characteristics, embryonic growth, hatchability traits, chick hatching weight and hatching time were investigated using eggs from a meat-type breeder (Hybro) flock at 32, 36 and 41 weeks of age in three trials. 2. With eggs of similar weights the intensity of brown pigment was not associated with eggshell weight and thickness, and did not influence embryo weight and egg weight loss during incubation. 3. The shade of brown pigment of eggs laid by young hens influenced the percentage hatchability (HP) of eggs incubated under light. Illuminated incubation improved HP of LBP eggs (compared with MBP and DBP eggs) from 32- and 36-week-old hens, but had no significant effect on HP of eggs from 41-week-old hens. 4. Light intensity during incubation did not influence egg weight loss. High intensity of light during incubation reduced HP and increased early death percentage (EDP) in the LBP and MBP groups, and did not influence HP and EDP in the DBP group. 5. Brown eggshell pigment and intensity of light during incubation did not influence hatching time. 6. It is concluded that the shade of brown pigment, intensity of light during incubation and age of the breeder hens influenced the hatchability performance of embryos from brown eggs. Light during incubation improved the hatchability of embryos in light brown eggs laid by young hens and the shade of brown pigment of eggs laid by older hens did not influence hatchability under illuminated incubation. 7. High intensity of light during incubation reduced hatchability of light and medium brown eggs, but not the dark brown eggs.

Relationships among prehatch and posthatch physiological parameters in early nutrient restricted broilers hatched from eggs laid by young breeder hens

The objective of this study was to establish relationships among various physiological parameters in early (through 72 h posthatch) nutrient restricted broiler chicks from young breeder hens. Despite a 19% decrease in mean BW between 0 and 72 h posthatch, there were no chick mortalities. Liver glycogen peaked at 24 h, and peaks in rectal temperature, plasma glucose, and plasma refractive index occurred at 48 h. By 24 h, negative correlations were noted between BW and relative liver weight and between liver glycogen and both refractive index and rectal temperature. By 24 h, positive correlations were noted between relative liver weight and liver glycogen, BW and plasma glucose, rectal temperature and plasma glucose, and rectal temperature and body fat loss score. Mean daily relative egg weight loss between 0 and 19 d of incubation (RIEWL) was positively correlated with rectal temperature at 0 h but was negatively correlated with rectal temperature at 24 h and liver glycogen at 24 and 48 h. Furthermore, mean relative hatching chick weight (RHCW) had significantly positive correlations with plasma glucose at 6 h and rectal temperature at 48 and 72 h. Broilers having a greater RHCW after hatching from eggs with a lower RIEWL may maintain higher metabolic rates between 24 and 72 h posthatch despite nutrient deprivation. However, broiler chicks from eggs exhibiting a higher than optimal RIEWL may have greater dependence on gluconeogenesis, thus requiring stricter management during initial brooding.

Egg size, fertility, hatchability, and chick survivability in captive California condors (Gymnogyps californianus)

AbstractCalifornia condors are one of the most endangered species native to the mainland United States and are subject of intense effort regarding captive breeding and reintroduction. We analyzed 20 years of California condor egg records from the wild and from three captive propagation facilities for fertility, hatchability, and chick survivability, along with changes in egg size due to multiple clutching. Overall annual mean percent of fertile eggs was 80.2%, hatchability was 87.3%, and chick survivability to ≥60 days was 95.5%. One egg‐laying site had a significantly lower fertility rate (P ≤ 0.0001) than the other sites, which was probably due to pair incompatibility rather than any physiological factors. Egg volume of the first egg was significantly greater than both the second (t=6.73, P=0.0001) and third egg (t=6.62, P ≤ 0.0001) of the season, while the second egg had a significantly greater volume (t=3.20, P=0.0084) than the third egg. Chicks from the second egg (t=3.24, P=0.029) and third egg (t=7.94, P=0.0014) of the season were significantly smaller than chicks from the first egg of the season. The decrease in egg measures and chick hatch weight due to multiple clutching did not affect hatchability or chick survivability. There were significant positive relationships (P&lt;0.0001) between fresh egg weight and chick hatch weight and between egg volume and chick hatch weight, as well as between fresh egg weight and egg volume. In spite of the decrease in fresh egg weight, egg volume and chick hatch weights, due to egg removal to stimulate double and sometimes triple clutching, the captive propagation program has been successful in producing birds for the restoration of this species. Zoo Biol 23:489–500, 2004. © 2004 Wiley‐Liss, Inc.

Egg Weight Loss during Incubation and Relative Hatching Chick Weight and their Relationships to Post-Hatch Blood Glucose Concentration, Body Temperature, Visceral Changes, and Liver Glycogen Concentrations in Nutrient Restricted Broilers

Egg Weight Loss during Incubation and Relative Hatching Chick Weight and their Relationships to Post-Hatch Blood Glucose Concentration, Body Temperature, Visceral Changes, and Liver Glycogen Concentrations in Nutrient Restricted Broilers

Genetic parameters for egg-, chick- and live-weight traits recorded in farmed ostriches ( Struthio camelus)

Estimates of genetic parameters for egg weight (EGWT), hatched chick weight (CHWT) and live weights recorded at 3 (LW3), 6 (LW6), 10 (LW10) or 14 months of age (SLWT) were obtained using an animal model, with data recorded in a commercially managed pair-breeding ostrich flock. Significant systematic effects included production year and month (seasonal effects), egg position in the laying sequence, hen age and parental diet for egg and chick weights; or seasonal effects, weighing date and age at weighing for live weight traits. Estimates of heritabilities were moderate, ranging from 0.15±0.03 for CHWT to 0.28±0.10 for SLWT. The exception was live weight at 3 months, for which no significant additive variation was detected. Maternal genetic and permanent environmental effects ( m 2 and c 2) explained 25–30% each of phenotypic variation for EGWT and CHWT but were less important for juvenile live weights ( m 2 was not significant and c 2<10%). Correlations between random effects for EGWT and CHWT were very high, resulting in a phenotypic correlation ( r p) of 0.84±0.01. Genetic correlations ( r g) between EGWT and CHWT or among LW6, LW10 and SLWT were close to unity. EGWT, and to a lesser extent CHWT, were not strongly associated with the later live weights ( r g: −0.24±0.24 to 0.36±0.23; r p: 0.04±0.05 to 0.15±0.04). Parameters indicate that ostrich live-weight traits will respond to selection.

Predicting Egg Weight, Shell Weight, Shell Thickness and Hatching Chick Weight of Japanese Quails Using Various Egg Traits as Regressors

The present study was conducted on eggs of Japanese quail maintained in cages at the research unit, NWFP, Agricultural University, Peshawar, Pakistan. Five hundred eggs selected at random were broken to record data on egg weight (g), egg length (cm), egg width (cm), shell weight (g) and shell thickness (mm). Another 500 eggs were put in the incubator after discarding undesirable eggs and recording data on egg weight, egg length and egg width. Egg weight was better predictable from egg width and length. Following equations were developed to predict egg weight from egg length and width; (Equation 1) = -3.3133600 + 1.835144(X ) + 2.655127(X ), (Equation 2) = 1.970096 + 2.252730(X ) and (Equation 3) = -1.0109318 + 1 2 3 2 4 every equation separately. Following equations were developed for predicting eggshell weight from egg weight, length and width; (Equation 4) =-0.521102+0.310761(X ) +0.4074 (X ), (Equation 5) 5 6 =0.138189+0.062933(X ) +0.233078(X ) and (Equation 6) =-0.001150+0.071568(X ) +0.311496(X ). Where 7 8 9 10 7 9 weight (g), respectively. Shell thickness was predictable with sufficient accuracy from egg weight, width and length and following equations were developed to predict it; (Equation 7) = 0.154646 + 0.076448(X ) and 11 (Equation 8) = 0.154721 + 0.000694(X ) + 0.073939(X ). Where Ŷ was predicted eggshell thickness, 12 13 X and X the egg width and X the egg weight for each equation separately. Weight of egg albumin was 11 13 12 predictable from the following equations; (Equation 9) = -0.685557 + 0.460613(X ) + 0.079842(X ) + 14 15 0.412241(X ), (Equation 10) = -0.553150 + 0.468198(X ) + 0.426649(X ), (Equation 11) = 0.279557 + 16 17 18 0.468198(X ) and (Equation 12) = -2.128934 + 0.925133(X ) + 1.63522(X ). Where Ŷ was the predicted 19 0.355813(X ), (Equation 15) = 0.003214 + 1.141682(X ) and (Equation 16) = 0.050845 + 0.921437(X ). 24 25 26

Embryonic Growth, Hatching Time and Hatchability Performance of Meat Breeder Eggs Incubated under Continuous Green Light

The effects of dark-control (D) and continuous green light (GL) exposure of incubated meat-type breeder eggs (Hybro) on embryonic growth from 5 to 15 days of age, hatching time, hatchability per cent and chick hatching weight were investigated in three consecutive experiments at 33, 38, and 41 weeks of age. A total of 798 eggs were used in this study. Eggs were set in an incubator on trays either in the D or under two tubes of 20-watt green fluorescent light during the first 18 days of incubation. Eggs from both treatments were transferred to the dark hatching compartment at 19 days of incubation. The light intensity was in the range of 1,340 to 1,730 lux at the surface of the eggs. GL incubation of eggs significantly (p<0.01) increased weight (expressed as an absolute value) and daily weight gain of embryos at 11 and continued to 15 days of age, hatchability per cent by 4.8%, reduced dead embryos per cent and chick weight at hatch by 37 and 2%, respectively and accelerated hatching time by about 24 h when compared with the D-control incubation. Chicks hatched at 504 h of incubation had significantly (p<0.01) higher body weight, expressed as an absolute value or as a percentage of egg weight, than those hatched earlier at 456 h of incubation. It was concluded that the GL incubation of meat breeder eggs reduced incubation period and chick weight at hatch and increased embryonic growth and hatchability per cent. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 12 : 1702-1707)

Effects of Incubational Humidity and Hen Age on Embryo Composition in Broiler Hatching Eggs from Young Breeders ,

There is a paucity of information regarding the influence of incubational humidity on the characteristics of broiler embryos from young hens that often produce chicks of marginal quality. Therefore, the effects of broiler breeder age (26, 28, and 30 wk) in young broiler breeders and incubator humidity (43, 53, and 63% RH) on embryonic growth between 16 and 21 d of incubation, hatching chick weight, and embryo and chick body compositions were evaluated. Hatching broiler chick BW at 21 d was lower for 26-wk-old breeders compared to those at 28 and 30 wk, and the lowest RH decreased relative wet embryo weight. Embryonic growth, on wet and DM bases, was increased in eggs from the youngest hens. Embryo moisture content (EM) was lower at 16, 17, and 19 d of incubation in eggs from breeders at 26 wk when compared to those at 28 wk of age. The effects of RH on embryo crude protein and fat composition were not consistent and varied with breeder age and length of incubation. It was demonstrated that broiler breeder age affects embryogenesis and hatching chick BW. Furthermore, EM was influenced by breeder age, and changes in incubational RH between 43 and 63% affected embryogenesis without having associated effects on EM or consistent effects on embryo crude fat and protein content. Nevertheless, a depression in embryogenesis with a reduction in incubational RH to 43% may accentuate poor posthatch performance of chicks from young breeders.

Relationships between egg size, chick size at hatching, and chick survival in the Whimbrel Numenius phaeopus

The relationships between egg size, chick size at hatching and chick survival in Whimbrels Numenius phaeopus were studied over a three‐year period in the Shetland Isles. Three measurements of chick size at hatching were all positively correlated with egg volume, though the relationship was strongest with hatchling body‐weight. In two of the three years the proportion of chicks from a brood which survived to fledging increased significantly with the mean hatching weight of chicks in the brood. Within broods, a significant effect of hatching weight on survival was detectable only up to 7 days after hatching. Between years the egg volumes and hatchling weights of individual female Whimbrels showed relatively little variability, indicating that these attributes could be controlled to a large extent by inheritance.

Relationship between the weight of hatching eggs and subsequent early performance of broiler chicks

1. The effect of egg weight on the subsequent performance of individual growing chicks was studied. Eggs from commercial broiler breeder hens were collected at 52, 55 and 57 weeks of age and incubated. The chicks were reared for 18 d. 2. Egg weight and hatched chick weight were not affected by the age of the hens during the 52 to 57-week period, but there was a close correlation between egg weight and hatching weight, irrespective of the age of the hens (r = 0.89). Chick:egg weight ratio at hatching was about 0.71 and independent of hen age. One d after hatching, chick weights had decreased by about 1.5 g. 3. The initial high correlation between egg weight and chick weight decreased markedly during post-hatching growth, becoming insignificant 5 d after hatching. At 18 d of age, however, chicks from eggs of older hens tended to be heavier than those from younger birds. The greater 18-d weights appeared to be associated more with higher food intake during that period, than with greater egg weight. 4. It was concluded that, in individual broiler chicks, the advantage of the initially higher weight attributable to a larger egg diminishes rapidly after hatching, and the main factor affecting final body weight is food intake.

The Effects of Parent Age and Posthatch Treatment on Broiler Performance

The relationship between age of the parent and the quality of the day-old broiler chick were studied in two experiments by examining the loss in egg weight during incubation (percentage of egg weight loss, PEWL). Also, the efficacy of a water-soluble antibiotic and the practice of withholding feed at placement time were examined. Eggs were obtained from two sets of breeders (approximately 30 and 50 wk of age). The eggs were weighed individually and were incubated. Chicks of each parent age group were randomly assigned to one of four treatments: 1) water and feed at placement time; 2) water and Neo-Terramycin and feed at placement time; 3) water at placement time and feed 4 h later; and 4) water and Neo-Terramycin at placement time and feed 4 h later. The chicks were housed in cages for Experiment 1 and in floor pens for Experiment 2.In both experiments, breeder age significantly affected BW. Chicks from old flocks were heavier and exhibited a significantly higher growth rate than the chicks from young flocks. Significant correlations between chick hatch weight and egg weight were observed. Low correlations between PEWL and BW were noted. In Experiment 1, the chicks receiving the Neo-Terramycin were significantly heavier up to 4 days of age than the chicks in other treatments. Chicks allowed access to feed at placement time were significantly heavier at most weigh times, up to 5 wk of age. Male chicks from old flocks that received both Neo-Terramycin and feed at the time of placement had a significantly higher growth rate than did the males of any other treatment in Experiment 1. In Experiment 2, neither the administration of Neo-Terramycin nor the provision of water prior to feeding had a significant effect on BW gain. Male chicks from the young flocks provided with water prior to feed exhibited a significantly higher growth rate than did the males in any other treatment. These data suggest that parent age does influence chick weight. The use of water-soluble antibiotics and the provision of water prior to feed did not benefit chicks that are normally hydrated.

Influence of environmental manipulation and nest‐box availability on reproductive success of captive cockatiels (Nymphicus hollandicus)

AbstractEnvironmental conditions greatly influenced breeding induced by nest‐box presentation in pair‐bonded cockatiels. Thirty‐six pairs were first held under nonstimulatory environmental conditions for 13 weeks. To provide potential breeding cues, photoperiod, light intensity, ambient temperature, and humidity were then increased over a 12‐day period; millet was replaced by a nutritionally adequate, crumbled diet; and nest‐boxes were presented. Compared to previous trials performed under more constant conditions, number of pairs laying eggs, pair‐day egg production, clutch size, and chick hatch weight were significantly increased.In experiment 2, either millet or crumbled diet was fed to 36 pairs during a 9‐week nonstimulatory period. Both groups were then exposed to stimulatory environments, fed crumbled diet, and presented with nest‐boxes. Their reproductive performances were not different, indicating that diet change was not required to stimulate breeding.In experiment 3, birds were fed crumbled diet throughout the trial. Nest‐boxes were presented to 31 pairs during nonstimulatory conditions (group 1) or to 28 pairs during the transition to stimulatory conditions (group 2). Percent of pairs laying (85.7 v. 16.7), pair‐day egg production (0.279 ± 0.036 v. 0.036 ± 0.014), and clutch size (9.1 ± 1.0 v. 4.6 ± 1.2) were greater in group 2, indicating that nest‐box presentation is an insufficient stimulus to evoke maximal breeding under nonstimulatory environmental conditions.

The Effects of Dietary Palm Oil and Energy on the Performance of White Rock Breeders in Nigeria

The optimum level of palm oil supplementation of a layers’ basal diet with 17% protein (N × 6.25) and 2.74 M.E./g. (calculated) appeared not less than 5.0% for egg production of White Rock breeders in Southern Nigeria. The efficiency of conversion of feed to egg, weight gains and the Haugh unit but not size and shell thickness also improved with palm oil supplementation of the basal diet. The optimum levels of dietary palm oil supplementation for percentage fertility and for hatchability of fertile eggs appeared to be 5.0–7.5% and 2.5–7.5%, respectively. The hatching weight of chicks was not affected by dietary palm oil.

The relationship between hatching egg weight and subsequent performance of broiler chickens

Synopsis Small eggs constitute a high proportion of the eggs laid by pullets. The literature shows that chick hatching weight is strongly correlated with egg weight, but evidence on the influence of egg weight on hatchability and subsequent performance of chicks is less certain. The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship. A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex. Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability. A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes. Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age. There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks. Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality. The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight.

The Effect of Climate on the Growth Performance of Populations of Broiler Chickens

The average hatching weight of chicks was heavier during summer than during other seasons of the year. Hatching weight was found to be correlated with bodyweight at nine weeks of age. The advantage in favour of the summer hatched chicken explains in part the farming community’s opinion that the summer chicks are better than other chicks. The climate affected the growth rate of hybrid chicks only in early life; within the temperature range 55–80°F, temperature influenced the bodyweight gain only during the brooding period and after this age body size was the important factor determining succeeding weight gain. Le poids moyen des poussins qui venaient d’éclore était plus élevé pendant l’été que pendant les autres saisons de l’année. On a trouvé que ce poids à l’éclosion était en corrélation étroite avec le poids des poussins de 9 semaines. Cet avantage des poussins éclosant l’été explique en partie l’opinion des éleveurs, suivant laquelle les poussins nés en été sont meilleurs que les autres. Le climat n’affectait la croissance des poussins hybrides que juste après leur naissance; entre 55 et 80°F, la température n’influençait l’augmentation de poids que pendant la couvée des poussins et, après cette période, leur taille était le facteur déterminant pour qu’ils parviennent à peser plus. Das Durchschnittsgewicht geschlüpfter Kücken war während des Sommers etwas höher als während der anderen Jahreszeiten. Das Gewicht 9 Wochen alter Kücken entsprach dem Gewichtsverhältnis nach dem Schlüpfen. Der Vorsprung der im Sommer gebrüteten Kücken erklärt teilweise, warum die ländliche Bevölkerung der Meinung ist, dass Sommerkücken besser sind als andere. Das Klima beeinflusst die Wachstumsrate gekreuzter Kücken nur in den frühen Lebensstadien; innerhalb der Temperaturspanne von 55–80°F beeinflusste die Temperatur die Gewichtszunahme nur während der Brutperiode; später war die Körpergrösse der massgebende Faktor, der die Gewichtszunahme bestimmte. El peso medio de incubación de los pollitos fué mayor durante el verano que durante otras estaciones del año. Se observó que el peso de incubación estaba correlacionado con el peso del cuerpo a las 9 semanas de edad. Las ventajas a favor de los pollitos incubados en verano explica en parte la opinión de las comunidades granjeras de que los pollos de verano son mejores que los otros. El clima afectó el índice de crecimiento de los pollitos híbridos únicamente en sus primeras etapas de vida; dentro de una temperatura oscilante entre los 55–80°F, la temperatura sólo influenció el aumento del peso del cuerpo durante el período de empolladura, y después de esta edad, el tamaño del cuerpo fue el factor importante que determinó el aumento de peso subsiguiente.