Percent Hen-day Egg Production Research Articles

Economic Analysis, Egg Quality Characteristics and Growth Parameters of Pullets Fed Graded Levels of Recycled Vegetable Wastes

A feeding trial was conducted to evaluate the economic analysis, egg quality characteristics and growth parameters of pullets fed graded levels of recycled vegetable wastes. Sixty (60) Shika Brown pullets of 22 week - old were used for the experiment. The sixty pullets were selected from a pool of eighty (80) pullets and were randomly assigned to five (5) treatments with twelve (12) birds per treatment in a Completely Randomized Design (CRD) on the basis of vigor. Each treatment group was further replicated 4 times with three (3) birds per replicate and housed in 2m x 3m pen on a deep litter and fed water and feed ad libitum starting from 7.00 am daily for the twenty- one (21) days of the feeding trial. Five experimental diets were prepared to contain 1.0, 1.5, 2.0 and 2.5% of the homogenized vegetable meal (HVM), for treatment 1, 2, 3, 4 and 5, respectively. Treatment 1 served as control. The percentage hen-day egg production, albumen index, average feed intake, shell thickness, and yolk color index for all treatments were not significant (p>0.05). Average weight (g), Haugh unit, Yolk index and Feed conversion ratio (FCR) shows that treatments 4 and 5 were significantly better (p<0.05) than in treatments 1 to 3. Birds on treatments 4 and 5 converted feed most effectively into an egg (p<0.05). Feed cost/kg bag for treatments 3, 4 and 5 were significant (p<0.05) and more economical than treatments 1 and 2. Feed used (kg) to produce the kg of egg were significantly better (p<0.05) in treatments 4 and 5 than the rest of the treatments, with the control diet numerically poorer (2.00kg fee/kg egg produced). The cost of feed/kg egg decreased with an increase in the inclusion rate. Treatments 2, 3, 4 and 5 were significantly less expensive (p<0.05) than treatment 1.

Evaluation of economic traits of White Leghorn layers under normal and controlled heat stress conditions

Based on the egg production of IWH line of WLH (n=254) during hot-dry (36–38°C and 40%RH) and hot-humid (32–34°C and 70% RH) environmental conditions, the high egg producer designated as high thermo tolerant (HT), low egg producer as low thermo- tolerant (LT) and average egg producer (control) birds were segregated. The production parameters of these birds during pre-summer were similar but the hen day egg production (HDEP) of HT group was better than LT during hot-dry summer and hot-humid summer seasons. When the HT and LT birds were placed in a psychrometric chamber and subjected to 37°C and 60% RH (THI-90) daily for 6 hours for a period of 14 days, the percent HDEP and daily feed consumption was higher in HT birds than the LT birds, however no difference was found in their daily water intake. Surface and rectal temperature was higher in HT birds than the LT birds. There was a reduction in feed intake and HDEP in LT birds than HT birds during the heat stress. After heat stress, H/L ratio and serum corticosterone levels increased in both the groups, but T3 cholesterol and protein level decreased. There was no difference in the egg weight and other egg quality parameters except the lower albumen and yolk index, higher percent yolk and total cholesterol level in HT than LT group. Based on the above study we can conclude that high thermo-tolerant birds performed better under heat stress environment.

The effect of dietary supplementation of salts of organic acid on production performance of laying hens.

Aim:An experiment was conducted to evaluate the effect of supplementing different levels of salts of organic acid in the laying hen’s diet on their production performance and egg quality parameters during a period of 16-week.Materials and Methods:A total of 140 white leghorn laying hens at 24 weeks of age were randomly distributed to seven dietary treatment groups, i.e. T1 (control), T2 (0.5% sodium-butyrate), T3 (1.0% sodium-butyrate), T4 (1.5% sodium-butyrate), T5 (0.5% calcium-propionate), T6 (1.0% calcium-propionate) and T7 (1.5% calcium-propionate) consisting of 5 replications of 4 birds each in each treatment and housed in individual cages from 24 to 40 weeks of age. Feed intake, percent hen-day egg production, egg weight, egg mass production, feed conversion ratio (FCR), and economics of supplementation of salts of organic acids in layers’ ration were evaluated.Results:The dietary supplementation of salts of organic acids did not significantly affect the feed intake (g/day/hen) and body weight gain (g). Different levels of supplementation significantly (p<0.05) improved production performance (percent hen-day egg production and egg mass production) as compared to control group. FCR in terms of feed intake (kg) per dozen eggs was lowest (1.83±0.05) in T4 and feed intake (kg) per kg egg mass was lowest (2.87±0.05) in T5 as comparison to control (T1) group. Salts of organic acids supplementation resulted in significant (p<0.05) improvement in FCR. Egg weight was significantly (p<0.05) increased at 0.5% level of salts of organic acids in the diet. The cumulative mean values of feed cost per dozen egg production were Rs. 44.14, 42.40, 42.85, 43.26, 42.57, 43.29 and 43.56 in treatment groups T1, T2, T3, T4, T5, T6 and T7, respectively, and reduction in feed cost per kg egg mass production for Rs. 0.52 and 0.99 in groups T2 and T5, respectively, in comparison to T1 group.Conclusions:It can be concluded that supplementation of salts of organic acids may improve persistency of lay, egg weight, and FCR. From economical point of view, egg production was more profitable at 0.5% level of sodium butyrate and 0.5% level of calcium propionate which reduced the feed cost per dozen eggs and per kg egg mass production without affecting the egg quality.

Effect of feeder space during the growing and laying periods and the rate of feed increase at the onset of lay on broiler breeder female reproductive function

A study was conducted to examine how 2 feeder space allocations during the rearing period followed by 2 feeder space allocations after photostimulation and 2 female feeding to peak programs (fast or slow) affected female broiler breeder reproductive performance and mortality. Sixteen pens of 76 breeder females each were equipped with either 4 tube feeders with a 132 cm circumference pan (7.0 cm/female) or 6 feeders (10.4 cm/female) to 21 wk of age. Thereafter, 64 females were moved to breeding pens, photostimulated, and fed sex-separate from either 3 (6.2 cm/female) or 5 (10.3 cm/female) feeders with either fast or slow feeding to peak feeding programs applied to complete a 2 × 2 × 2 factorial design. Seven males that were separately reared in a similar manner were added per pen. Individual female BW was determined at 6, 20, and 32 wk of age and BW uniformity assessed. Greater feeder space during rearing increased BW at 32 wk of age, whereas greater feeder space during lay or slow feeding to peak decreased BW at 32 wk. There were no differences in BW uniformity. Hens from the 10.4 to 10.3 cm/female combination produced a significantly greater number of eggs as compared with the 7.0 to 10.3 cm/female and 10.4 to 6.2 cm/female combinations with the 7.0 to 6.2 cm/female combination intermediate. Percentage hen-day egg production of the 10.4 to 10.3 cm/female combination hens was significantly greater than all other combinations. Livability was improved in the 10.4 to 10.3 cm/female combination relative to the 7.0 to 10.3 cm/female combination with the others intermediate. The fast feeding to peak program increased yolk weight as well as yolk:albumen ratio at 28 and 30 wk of age, but egg weight did not differ. These data indicated that increased or decreased feeder space between the growing and laying periods did not affect broiler breeder female BW, uniformity, egg weight, fertility, or hatchability. The 10.3 cm/female laying feeder space exhibited the best hen-day egg production in combination with 10.4 cm/pullet rearing but not with 7.0 cm/pullet rearing space. In a similar manner, hen mortality was greater in the 7.0 to 10.3 cm/female feeder space combination that the 10.4 to 10.3 cm/female combination.

Effects of live and killed vaccines against Mycoplasma gallisepticum on the performance characteristics of commercial layer chickens

Different vaccine strains of Mycoplasma gallisepticum have been used on multiple-age commercial layer farms in an effort to protect birds against virulent field-strain infections. Use of the F-strain of M. gallisepticum (FMG), as an overlay vaccine during lay, may be necessary because of the lower level of protection afforded by M. gallisepticum vaccines of low virulence given before lay. Two replicate trials were conducted to investigate effects of live and killed M. gallisepticum vaccines administered individually and in combination before lay, in conjunction with an FMG vaccine overlay after peak egg production (EP), on the performance characteristics of commercial layers. The following treatments were utilized at 10 wk of age (woa): 1) control (no vaccinations); 2) ts11 strain M. gallisepticum (ts11MG) vaccine; 3) M. gallisepticum-Bacterin vaccine (MG-Bacterin); and 4) ts11MG and MG-Bacterin vaccines combination. At 45 woa, half of the birds were overlaid with an FMG vaccine. Hen mortality, BW, egg weight, percentage hen-day EP, egg blood spots, and egg meat spots were determined at various time periods between 18 and 52 woa. The data from each trial were pooled. Treatment did not affect performance in interval I (23 to 45 woa). However, during interval II (46 to 52 woa), the EP of control and MG-Bacterin-vaccinated birds that later received an FMG vaccine overlay was lower than that in the other treatment groups. Furthermore, treatment application reduced bird BW during interval II. Despite the effects on BW and EP, no differences were observed for egg blood or meat spots among the various treatments. It is suggested that the vaccination of commercial layers before lay with ts11MG, but not MG-Bacterin, may reduce the negative impacts of an FMG overlay vaccination given during lay. These results establish that the vaccination of pullets with ts11MG in combination with the vaccination of hens with an FMG overlay, for continual protection against field-strain M. gallisepticum infections, may be used without suppressing performance.

Production of Pure Hinai-dori with Normal Reproductive Capability from Transferred Primordial Germ Cells

The production method of germline chimeras by transfer of primordial germ cells (PGCs) can be used in gene banking of chickens. However, little is known about the reproductive capability of offspring obtained by mating of male and female germline chimeras. To cryopreserve chicken genetic resources at the cellular level in future, it is necessary to demonstrate whether offspring originating from donor-derived PGCs have normal reproductive capability. In this study, we attempted to obtain the pure Hinai-droi offspring by mating of male and female germline chimeras produced by the transplantation of Hinai-dori PGCs into the Akita White Leghorn line (WL) embryos. Hinai-dori offspring from germline chimeras were screened using the Hinai-dori-specific autosomal microsatellite marker, namely, ADL0315, which allows distinction between the Hinai-dori breed and Akita WL. After sexual maturity of the Hinai-dori offspring originating from donor-derived Hinai-dori PGCs, the reproductive capability (egg production rate, fertilization rate and hatchability) was examined. Percentage hen-day egg production was investigated between 21 and 60 wk of age, and fertilization rate and hatchability were investigated between 43 and 60 wk of age, respectively. Among the 105 progeny obtained by mating of male and female germline chimeras, a single brown-colored female hatchling was obtained. The results from molecular genotyping using the Hinai-dori-specific microsatellite marker ADL0315 were consistent with results from morphological identification, and the brown-colored female hatchling was identified as the pure Hinai-dori breed. The mean percentage hen-day egg production, fertilization rate and hatchability of the Hinai-dori hen were 36.4%, 58.1% and 53.2%, which were similar to those of normal Hinai-dori hens. These results indicated that the pure Hinai-dori offspring originating from donor-derived Hinai-dori PGCs has normal reproductive capability.

Camelina Meal Increases Egg n‐3 Fatty Acid Content Without Altering Quality or Production in Laying Hens

Camelina sativa is an oilseed plant rich in n-3 and n-6 fatty acids and extruding the seeds results in high protein meal (*40%) containing high levels of n-3 fatty acids. In this study, we examined the effects of feeding extruded defatted camelina meal to commercial laying hens, measuring egg production, quality, and fatty acid composition. Lohmann White Leghorn hens (29 weeks old) were randomly allocated to three dietary treatment groups (n = 25 per group) and data was collected over a 12 week production period. All the treatment groups were fed a corn soy based experimental diet containing 0% (control), 5, or 10% extruded camelina meal. We found no significant differences in percent hen-day egg production and feed consumed per dozen eggs. Egg shell strength was significantly higher in both camelina groups compared to the controls. Egg total n-3 fatty acid content increased 1.9- and 2.7-fold in 5 and 10% camelina groups respectively relative to the control. A similar increase in DHA content also occurred. Further camelina meal did not alter glucosinolate levels and no detectable glucosinolates or metabolic product isothiocyanates were found in the eggs from either the 5 or 10% camelina groups. These results indicate that camelina meal is a viable dietary source of n-3 fatty acids for poultry and its dietary inclusion results in eggs enriched with n-3 fatty acids.

Response of shika-brown pullet chicks and layers to home made and commercial feeds in Zaria, Kaduna state, Nigeria

Two separate experiments were conducted to test the response of Shika brown pullet chicks and layers to home-made and commercial feeds in Zaria metropolis of Kaduna state, Nigeria. In both experiments a homemade chick ration and layer ration were formulated using feed ingredients available in the locality. These were compared with two prominent commercial chick mash and layer mash feeds sold in Zaria. There were three feeds in each experiment and each feed constituted a treatment. Each of the treatments was replicated three times (making a total of 9 replicates in each study) in a complete randomised design. Two hundred and seventy chicks and layers respectively were used in each experiment, with 30 birds in each of the nine replicates. Results obtained for the chick study showed that the final weight, body weight gain, daily feed intake, feed conversion efficiency and feed cost per kilogramme gain in weight were significantly (P<0.05) better for the commercial feed A than for the other two feeds. Results obtained for the layers study showed that although birds fed commercial feed A performed significantly (P<0.05) better in terms of final weight, body weight gain, daily feed intake, feed conversion efficiency and percent henday egg production, the birds fed the homemade feed were significantly (P<0.05) better in terms of income above feed expenses, which is a measure of profitability.

Impact of Feeding Program After Light Stimulation Through Early Lay on the Reproductive Performance of Broiler Breeder Hens

Skip-a-day feed restriction is a common industry management technique that is used in rearing broiler breeder pullets. Often pullets are maintained on a skip-a-day feeding program after they have been photostimulated for reproduction, and in some cases until 5% egg production is reached. The current research examined whether providing daily nutrient intake during the critical period of ovarian development that follows photostimulation for reproduction improves subsequent egg production. Pullets and cockerels were fed on a skip-a-day basis during rearing. Pullets were weighed at 20 wk of age and then distributed into 30 laying pens such that each pen had a similar BW distribution. Each individual laying pen consisted of 35 hens and 4 roosters. At 21 wk of age, the birds were photostimulated for reproduction; 15 of the laying pens were placed on an every-day feeding schedule, whereas the other 15 pens were maintained on a skip-a-day feeding schedule until they reached 8% egg production at 26.5 wk of age. From 26.5 to 65 wk of age, all hens were fed on an every-day basis. The CV of BW did not differ between the hens of the 2 treatment groups at any point from 21 to 64 wk of age. Weekly percentage hen-day egg production was greater (P < 0.05) in the hens fed on the every-day versus skip-a-day program after photostimulation from wk 25 of age to 65 wk of age except for wk 29, 30, 35, 37, 39, 46, and 47 of age. Total hen-day egg production through 65 wk of age in the hens that were provided feed every day after photostimulation was greater (172 vs. 155 eggs/hen) than in hens fed on a skip-a-day basis until 26.5 wk of age. These results suggest that continuing skip-a-day feeding after photostimulation until reaching 8% egg production does not improve BW uniformity, but does cause lasting reproductive dysfunction in broiler breeder hens.

Effects of Increased Dosages of the Mycoplasma Gallisepticum Vaccine MYCOVAC-L® in Layer Chickens Subsequently Challenged with Virulent M. gallisepticum: Egg Production and Serologic Response

Ten-week-old Hy-Line Commercial W-36 pullets were spray-vaccinated with MYCOVAC-L at the manufacturer's recommended dosage (1x) or at 15 times that rate (15x). At 22 or 45 wk of age, subsets of 1x- and 15x-vaccinated pullets were challenged with the virulent Mycoplasma gallisepticum (MG) strain Rlow. Percent hen-day egg production was determined through week 55. Analyses for treatment effects on overall (22-56 wk) percent hen-day egg production revealed no significant differences between nonchallenged 1x and nonchallenged 15x MYCOVAC-L treatments. Among 1x MYCOVAC-L-vaccinated groups, Rlow challenge at 45 wk corresponded to significantly (P < or = 0.01) lower overall egg production compared with the unchallenged 1x-vaccinated control (70.88% vs. 79.15%, respectively). Conversely, at the 15x MYCOVAC-L dosage level, overall egg production was not significantly affected by virulent MG challenge at 45 wk compared with its unchallenged counterpart (84.09% vs. 81.03%, respectively) and could indicate increased protection from virulent MG challenge. Serologic monitoring indicated the virulent MG challenge was consistently (100%) associated with seroconversion. Comparisons among the nonchallenged experimental treatments indicated that vaccinations at the 15x MYCOVAC-L dosage rate were associated with a greater seroconversion rate at weeks 21, 27, and 44, but not at week 50.

Crossbreeding Nigeria Indigenous with the Dahlem Red chickens for improved productivity and adaptability

Abstract. In a 5-year crossbreeding experiment, specific groups of the Nigeria Indigenous chicken (NI) from two ecological zones (i.e. Fulani, Fu; Fulani dwarf, FuD from the Northern Guinea Savanna and Yoruba, Y, from the Derived Savanna) and the German Dahlem Red normal (DR) and Dahlem Red Dwarf (DRD) were used to produce four genetic groups DR x Fu, Fu x DR, DR x Y, and FuD x DRD which were evaluated for age and weight at first egg, egg weight, percent hen-day egg production, percent laying mortality and resistance to disease. A total of 505 NI growers and 584 and 48 imported day-old DR and DRD chicks, respectively, were evaluated as parent stock. Data compilation was by DBase IV. Data were analysed using the General Linear Model (GLM) procedure of Statistical Analysis System (SAS, 1986). For all the traits evaluated, there was no significant difference (P &gt; 0.05) between NI from the three ecological zones. Therefore, pooled NI means were compared with the means for the DR and the crosses between them. Mean 280-day egg weights were 55.7, 36.8 and 42.9g, respectively, for DR, NI and the crosses while DR, NI and crosses produced 103, 70 and 83 eggs, respectively, over a period of 196 days. The DR x Fu cross had a significantly higher (P &lt; 0.05) egg weight for most of the periods studied with mean egg weight of 46.1g. The 280-day egg production of DR x Fu, (148) was significantly higher (P &lt; 0.05) than that of DR x Y and Fu x DR (119) and FuD x DRD (87). At week 40, DR x Fu females were significantly heavier (p&lt;0.05) than all the females of the other groups while the FuD x DRD progeny had the least body weights at all the ages studied. Overall, DR x Fu and DR x Y were superior to Fu x DR and FuD x DRD for most of the traits studied. Results of the skin test using Skin response to Phytohaemagglutinin inoculation showed FuD x DRD, DR x Y and Fu x DR with values of 0.45mm, 0.36mm and 0.34mm, respectively. Inbred lines DR x DR and Y x Y gave values of 0.33 and 0.50, respectively.

The effects of long-term caging and molt of Single Comb White Leghorn hens on heterophil to lymphocyte ratios, corticosterone and thyroid hormones

Two commercial strains of 18-wk-old Single Comb White Leghorn (SCWL) hens, HyLine W-36 and DeKalb XL, were housed six hens per cage in layer cages at two densities (361 and 482 cm2 per bird) with two replications each per strain and density combination. The high density treatment contained 24 hens per replication, and the low density treatment contained 18 hens per replication. Egg production was measured during the first egg production cycle, a molt (fast) period, and the first 4 wk of the second lay cycle (20 to 68 wk of age). Blood samples were obtained from six hens from each replicate in each strain and density combination (total of 48) at 20, 26, 34, 43, 51, 62, 64, and 68 wk of age. In addition, blood samples were obtained in a random order from hens in each cage, and the sequence of sampling was recorded (1 to 6). Blood smears were made, from which heterophil to lymphocyte ratios (H:L) were determined. Radioimmunoassays were conducted to determine levels of plasma corticosterone (CS), 3,5,3'-triiodothyronine (T3), and thyroxine (T4). The results indicated that strain did not affect percentage hen-day egg production (%HDP). Strain and cage density did not affect H:L, T3, T4, or CS. However, these parameters were affected by bird age, which was related to the egg production cycle. Plasma CS significantly (P < or = 0.001) increased during peak %HDP at 26 wk and 64 wk during the molt (fast), and H:L significantly (P < or = 0.001) increased during the molt (fast) at 64 wk. The sequence in which blood samples were obtained, from hens within a cage in sampling order, also increased plasma CS. The CS was significantly (P < or = 0.001) elevated in the third, fifth, and sixth hens from which blood samples were drawn. Plasma T3 and T4 changed during the production cycle. The T3 was significantly (P < or = 0.0001) depressed during peak egg production at 26 wk and during the molt (fast) at 64 wk when compared with the other time periods. Plasma T4 was depressed (P < or = 0.0001) at 51 wk and was elevated (P < or = 0.0001) at 64 wk during the molt (fast). The physiological and metabolic parameters of the different hen strains and cage densities were similar during egg production. However, CS, T3, T4, and H:L changed with age in relation to the egg production cycle. In addition, the physiological demands of peak egg production and molt (fast) appeared to be similar.

Effects of Population Density on Layer Performance

Four experiments were conducted to study the effects of population density on layer performance. In each experiment, 20-wk-old White Leghorn pullets were housed in 30.5 × 50.8 cm cages at the rate of one, two, three, and four birds per cage for Treatments 1, 2, 3, and 4, respectively. In Experiment 4, there were three additional treatments: for Treatments 5,6, and 7, birds were placed into identical cages (30.5 × 50.8 cm) at the rate of three, two, and three birds per cage, respectively, at 20 wk of age. At 28 wk of age, one bird was removed from each cage in Treatment 5, and one bird was added to each cage in Treatments 6 and 7. In the first three experiments, all eggs that were collected for 2 consecutive d every 8 wk starting at 28 wk of age were used to measure egg traits. In Experiment 4, egg traits were determined once at 52 wk of age.Birds at the highest population density had the lowest percentage hen-day egg production and had one of the poorest feed efficiencies. Egg production was negatively correlated (P ≤ .01, Experiments 1, 2, 3; P ≤ .05, Experiment 4) with population density. Feed required to produce a dozen eggs was positively correlated (P ≤ .01, Experiments 1, 2; P ≤ .05, Experiment 3) with population density in three out of the four experiments. The addition or removal of a cage mate to or from a multiple-bird cage in Experiment 4 did not (P > .05) affect egg production or feed efficiency. Final BW, mortality, and egg weight were not (P > .05) affected by population density. Only in one out of the four experiments was feed consumption (Experiment 1), eggshell thickness (Experiment 2), or albumen height (Experiment 3) lowered (P ≤ .05) by having more than one bird per cage. This study showed that increasing population density decreased laying performance of the birds.

Correlated Responses to Long-Term Divergent Selection for Eight-Week Body Weight in Chickens: Growth, Sexual Maturity, and Egg Production

Thirty-six generations of divergent selection for BW at 8 wk of age (BW8) resulted in approximately an eightfold difference between the high (HWS) and low (LWS) lines for this trait. Correlated traits included BW at 4, 24, and 38 wk of age (BW4, BW24, BW38, respectively), age at first egg (AFE), and percentage hen-day egg production (HDP). Responses of BW4 followed the same pattern as that for the selected trait, with the response about five times greater during the first 18 than the last 18 generations of selection in Line HWS and less than two times greater in Line LWS. For BW24 and BW38, correlated responses were greater for LWS than for HWS females without feed restriction, suggesting changes in growth curves after selection age. Although AFE was delayed in both lines, the delay was greater in Line LWS (some individuals of which were anorexic) than in Line HWS and greater in the second half than the first half of the experiment. For pullets that commenced lay, HDP declined slightly in both lines. Correlations between BW at 4, 8, 24, and 38 wk of age were moderate to high and positive in both lines. When feed intake was restricted in Line HWS, however, there were no correlations of BW4 or BW8 with BW24 or BW38. Correlations between AFE and BW at all ages were negative in Line LWS. In Line HWS there were negative correlations of AFE with BW24 and with BW38. Relaxed lines, established periodically during the experiment, were satisfactory monitors of environmental influences for primary and correlated traits.

Effect of Feather Coverage and Temperature on Layer Performance

An experiment was conducted with 59-wk-old DeKalb XL White Leghorns to determine the effect of percentage feather coverage (FC) on performance and nutrient intake of layers housed in cold (12.8 C), thermoneutral (23.9 C), and hot (33.9 C) temperatures. At each temperature, 60 hens had 0, 50, or 100% feathers removed and were fed diets containing 2,865 kcal ME/kg. Feed intake of hens housed at 23.9 C (115 g/day for all FC groups) was 25 g/day higher (P < .05) than for hens housed at 33 C and 13 g/day lower (P < .05) than for hens at 12.8 C. The feed intake of hens (across all temperatures) with 100% FC (98 g/day) increased (P < .05) by 26 g/day as FC decreased from 100 to 0%. Percentage hen-day egg production (EP) (across feather treatments) was decreased 7.5 and 6.7% (P < .05) at 12.8 and 33.9 C, respectively, compared with 23.9 C. Total lack of feathers decreased (P < .05) EP from hens with 100% FC by 9.2 and 6.4% at 12.8 and 23.9 C, respectively. Total lack of feathers at 33.9 C increased EP 5.46% compared with 100% FC. Egg weight was reduced 1.9 g (P < .05) at 33.9 C when compared with hens at 23.9 C. Hens without feathers produced a 1.8 g heavier egg (P < .05) than hens with 100% FC. The egg mass (EM) of hens housed at 12.8 and 33.9 C was less than hens at 23.9 C across all feather treatments. Metabolizable energy efficiency (kilocalories ME per gram EM) was improved (P < .05) by the highest temperature across all feather treatments and by increasing FC to 50 or 100% compared with 0% FC. The maintenance ME requirement for hens housed at 12.8 C with 0% FC was 190.4 kcal/kg of BW, which was twice the requirement of hens housed at 33.9 C with 0% FC. Results indicate economic importance of maintaining FC for layers in cold and thermoneutral temperatures and benefits of increased EM output for hens housed in hot climates with partial or complete feather loss.

Effect of Roost Temperature on Performance of Chickens in Hot Ambient Environments

A split-plot experiment was conducted in thermally controlled chambers using Columbian Plymouth Rock chickens to determine the effect of water-cooled roosts on performance in hot ambient conditions. The birds were subjected to 25 ± 1, 35 ± 1, and 25 ± 1 C ambient temperature treatments for 2, 3, and 2 wk, respectively. Roost temperature treatments were either cool (20 ± 1 C) or air-equilibrated (25 ± 1 or 35 ± 1C). The performance parameters evaluated were percentage hen-day egg production, egg weight, feed intake, feed conversion, fertility, and hatchability. Birds subjected to the water-cooled roost treatment had consistently higher performance than birds using the air-equilibrated roost under all three ambient temperatures. Both ambient and roost temperature treatments significantly influenced percentage hen-day egg production, average daily feed intake, and percentage hatchability (P≤.05). However, the biggest differences in performance were observed during the heat-stress period. Decreases in performance during the heat-stress period from the thermoneutral control values were: 5.95 and 13.1 percentage points for hen-day egg production, 22.2 and 34.8 percentage points for average daily feed intake, and 5.17 and 15.38 percentage points for hatchability in water-cooled and air-equilibrated roost treatments, respectively. The ambient and roost temperature treatments did not significantly affect egg weight, feed conversion, or percentage fertility. The improved performance with water-cooled over air-equilibrated roost treatments, especially during heat-stress periods, indicates that the water-cooled roosts minimized the deleterious effects of heat stress through conductive heat loss from the birds to the roost.

Effects of Different Methods and Severity of Growing Period Feed Restriction on Growth and Laying Performance of White Leghorns

Two experiments were conducted to study the effects of different methods of feed restriction and severity of feed restriction during the growing period on pullet growth and laying performance of White Leghorns. In Experiment 1, ad libitum feeding of the low protein diet (supplemented with amino acids) was the only treatment among four feed restriction treatments that did not significantly (P>.05) influence growing period feed consumption and body weight gain. The smallest body weight gain was obtained among birds subjected to the daily restrictive feeding (DRF) treatment. Ad libitum feeding of the low energy diet resulted in a significantly (P<.05) poorer growing period feed efficiency than any other treatment. Both energy and protein utilization efficiencies for body weight gain were significantly (P<.05) hindered by the skip feeding treatment. Although DRF birds consistently had higher egg production from 36 to 76 weeks of age than birds in any other group, overall average percent hen-day egg production from 20 to 76 weeks of age was not significantly (P>.05) improved by the DRF treatment. Also, in Experiment 2, various levels of DRF during the growing period did not significantly (P>.05) improve average percent hen-day egg production. Laying house mortality, feed efficiency, and egg weight were not significantly (P>.05) different among treatments (Experiments 1 and 2). Results of these experiments indicate that DRF was the most effective method of controlling growth rate and that neither method of feed restriction nor severity of feed restriction during the growing period significantly (P>.05) improved laying performance.

Ahemeral Light-Dark Cycles and Egg Production Parameters of Ring-Necked Pheasants (Phasianus colchicus)

The effects of two ahemeral light-dark (L:D) cycles on ring-necked pheasant egg production were investigated in this experiment. Three groups of 36 female and 12 male 10-month-old birds were exposed to control 24-hr (14L:10D), ahemeral 22-hr (14L:8D), or ahemeral 26-hr (14L:12D) L:D cycle.Average percent hen-day egg production (HDEP) was 63.8 for hens exposed to ahemeral 26-hr L:D cycle compared with 55.6% HDEP for the controls. Although this was not significant (P<.05). It suggests a trend for pheasants exposed to ahemeral L:D cycles to improve egg production. Ahemeral L:D cycles did not significantly (P>.05) affect egg mass, shell-less eggs, cracked eggs, egg hatchability, and embryonic mortality.Shell quality, measured by specific gravity and shell thickness, was significantly (P≤.05) reduced for eggs obtained from hens exposed to ahemeral 22-hr L:D cycle. Fertility of eggs from hens kept under ahemeral 26-hr L:D cycle was significantly (P≤.05) improved compared with fertility of eggs from controls (89.3 vs. 78.4).Results of this research suggest that long ahemeral L:D cycles do play a role in the improvement of pheasant egg production and egg fertility.

Feed Restriction During the Growing Period, Forced Molt, and Egg Production

An experiment was conducted to examine postmolt laying performance of White Leghorn hens that had been subjected to feed restriction from 8 to 20 weeks of age.During the postmolt period, birds in all forced-molt (FM) groups consistently had higher percent hen-day egg production than the control birds. Within the FM groups, birds that had previously been restricted fed during the growing period at the rate of 70% of the control group's consumption (R70 -FM) consistently had higher percent hen-day egg production during most of the postmolt period than the nonrestricted fed birds (Ad lib.-FM). Significant (P<.05) improvements in albumen height and shell thickness were observed 4 weeks after the FM period. When premolt, molt, and postmolt periods were combined, R70-FM birds had the highest percent henday egg production and the best feed efficiency of any group.

Egg Characteristics and Production Efficiency of Dwarf (dw) White Leghorn Hens Divergently Selected for Body Weight

Egg characteristics, feed efficiency (egg mass/daily feed intake), and performance efficiency (egg mass/body weight) were studied in dwarf White Leghorns after four generations of selection for divergent body weight at 20 weeks of age. Sexual maturity and livability were not significantly different among high (H), low (L), or control (C) lines. Mean 20-week body weights for H, L, and C lines were 1.50 kg, .76 kg, and 1.02 kg, respectively. Daily feed intake, egg mass, egg weight, and yolk, albumen, and shell weights were significantly (P<.05) different between H and L hens and were directly related to body weight. Percent yolk was greatest and percent yolk mottling and percent albumen were lowest in eggs from L hens. Percent shell was not significantly different among the lines. Albumen quality (Haugh units) was significantly better in eggs from H and L hens than from C hens. Percent hen-day egg production was not significantly different among lines. Feed efficiency was greatest in C hens with both C and L hens significantly more efficient than H hens. Performance efficiencies of C and L hens were significantly better than H hens throughout the experiment, and L hens were significantly more efficient than C hens during peak egg production. These results suggest that there may b e minimum body weight requirements for efficient egg production.