Hen-day Egg Production Research Articles

Influence of Light Sources on the Growth and Reproduction of Large White Turkeys

The present study evaluated the effects of sodium vapor (SV), daylight fluorescent (FL), and incandescent (IN) light sources on the growth and reproduction of primary breeder turkeys. Large White turkeys (90 sire line and 324 dam line) were reared by sex under one of the three light sources from 8 to 22 wk of age. At 22 wk of age, all males and females were preconditioned under their assigned light source; but the photophase was restricted to 6 h per day at an intensity of 21.6 lx. At 33 wk of age, the males were exposed to 16 h of light per day under the same light sources in which they were reared. At 35 wk of age, the females were reassigned to the various light sources in order to achieve all possible combinations of adolescent and breeder light-source treatments. Sixteen hours of light per day were provided at an intensity of 53.8 lx during a 20-wk cycle of egg production.The body weights of males and the feed efficiencies of males and females were unaffected by the adolescent light-source treatment. The females were significantly heavier under SV than those under FL and IN lights.Hen-housed egg production was significantly higher for females exposed to SV and FL lights versus IN during the first 10-wk production period. Hen-day egg production was significantly higher for females given FL than for those provided SV and IN lights. However, total hen-housed and hen-day production was unaffected by either adolescent or breeder light-source treatments. Fertility, hatchability, days to first egg, egg weight, and egg specific gravity were also unaffected by either the adolescent or breeder light-source treatment.Economic evaluations showed that the costs for installing and operating FL, SV, and IN lights for the first year after installation were $1,180, $1,542, and $5,498, respectively. The results suggest that more-energy-efficient light sources should be used in programs for growing and breeding turkeys.

Production and Egg-Quality Responses of White Leghorn Layers to Anticoccidial Agents

Two studies were conducted to determine the effects of anticoccidial agents on the production and reproduction of White Leghorns. In Experiment 1, nicarbazin (NCZ) was fed at 0, 20, 50, and 100 ppm. Hen-day egg production, egg weight, the egg-yolk DNC (4-4′-dinitrocarbanilide) level, and egg-yolk mottling were affected by the treatments. When response was evidenced, the relationship between those variables and the level of NCZ was basically linear. Decreased egg production occurred from Days 5 and 6 of the treatment through Days 1 and 2 of withdrawal. On Days 9 and 10 of treatment, the control hens peaked at 92% hen-day production, while hens fed 20, 50, and 100 ppm of NCZ peaked late-at 90, 82, and 80%, respectively. Compared to the controls, egg weight was reduced linearly as the level of dietary NCZ increased. The egg-yolk DNC level increased from Days 3 and 4 of treatment through Days 9 and 10 of withdrawal. Egg yolk mottling generally increased along with the level and duration of feeding NCZ. If the NCZ was mistakenly fed to White Leghorn layers, ill effects would be alleviated within 10 days after drug withdrawal.In Experiment 2, halofuginone (3 ppm), maduramicin (5 ppm), monensin (100 ppm), narasin (70 ppm), nicarbazin (125 ppm), robenidine (33 ppm), and salinomycin (60 ppm) were fed to White Leghorn hens at the levels specified in parentheses. Nicarbazin reduced egg production, depressed egg weight, reduced shell thickness, and caused egg-yolk mottling; but internal egg quality, as measured by Haugh Units, was unaffected. Halofuginone, maduramicin, monensin, narasin, robenidine, and salinomycin did not have a meaningful effect on the variables measured when fed to White Leghorn layers.

Effects of Cage Shape, Age at Housing, and Types of Rearing and Layer Waterers on the Productivity of Layers

The effects of cage shape, age at housing, and types of rearing and laying waterers on the productivity and ingestive behavior of two groups of caged White Leghorn layers were studied. In Experiment 1, chicks reared in pens equipped with either dome or trigger-cup waterers were housed at 17, 18, and 19 wk of age in a four-per-deep cage or a shallow cage equipped with either nipple (NW) or trigger-cup waterers (TCW). The type of rearing waterer had no significant effect on mortality, weight gain, or feed consumption from 1 day of age to housing. Pullets housed at 17 wk of age matured 3 and 5 days earlier, laid at 1.0 and 1.9% higher rates, and gained 6.1 and 5.3% more weight than those housed at 18 and 19 wk of age, respectively. Deep-caged hens consumed more feed (127.9 versus 120.2 g per hen per day) and had poorer feed conversion (2.09 versus 1.95 kg per doz) than shallow-caged hens. Although the TCW hens consumed significantly more feed in grams per hen per day (159 versus 117) and drank significantly less water (109.9 versus 123.8) 3 days posthousing than the NW birds, no significant differences in the frequency and duration of these activities existed. In Experiment 2, the chicks were reared as in Experiment 1 and housed at 18 wk of age in deep or shallow cages with NW or TCW. Neither the cage shape nor the type of rearing waterers had a significant effect on age at sexual maturity, hen-day egg production, or mortality.

Temporary Ahemeral Lighting for Increased Egg Size in Maturing Pullets

Temporary, 28-h, ahemeral lighting (TAL) cycles were compared with conventional, 24-h, hemeral lighting (CHL) cycles in an attempt to increase initial egg size from maturing pullets without reducing performance. The parameters measured were: 1) sexual maturity [age at first egg, age at 50% production, age when egg weight (EW) ≥56.7 g (large size)]; 2) EW; 3) productivity [hen-day egg production (HDP), eggs per hen, egg mass per hen-housed]; 4) efficiency (feed per hen per day, feed per egg, g of feed per g of egg); 5) egg-shell quality (specific gravity); and 6) mortality. During Trial 1,22-wk-old New Hampshire pullets were exposed to 12 h of light (L): 16 h of dark (D) for 12 wk and then changed to a 16L:8D ratio. During the 32-wk production period, the only significant (P≤.05) difference between TAL and CHL was EW (56.1 versus 54.3 g, respectively). The TAL treatment in Trial 2 exposed 17-wk-old Leghorn pullets to 11L:17D until EW reached 56.7 g at 26 wk, when the L:D ratio was changed to 13L:13D for 1 wk, then to 15L:9D from 28 to 70 weeks of age. The TAL caused the pullets to produce large eggs 2 wk (P<.001) earlier than the CHL for the controls (15L:9D, 17 to 70 wk). During the 48-wk production cycle, TAL significantly increased EW (62.5 versus 60.9 g) and improved shell quality.In both trials, a reduction of HDP was observed during TAL; but long-term HDP was not significantly (P≤.05) affected. EW was permanently increased by TAL.

RYE AS A REPLACEMENT FOR WHEAT IN LAYING HEN DIETS

Two experiments were conducted in which rye replaced wheat as the cereal component of laying hen diets. In the first experiment laying hens were fed graded levels of Puma rye (0.0, 19.5, 39.0 and 78.0% of the diet) substituted for Glenlea wheat throughout a 280-d egg-production cycle. Rye-based diets supported comparable productive performance to wheat with respect to hen-day egg production, feed conversion, and body weight gain when the level of rye was 39.0% or less of the diet; however, performance declined at the higher rye level. For the second experiment Glenlea wheat was replaced by Gazelle rye (0.0, 23.3, 46.7 and 70.0% of the diet) when laying hens were in a latter phase of egg production, with the trial period commencing at 44 wk. Substitution of rye for wheat did not significantly affect egg production, feed consumption, egg weight, shell elasticity, or tibia ash at lower rye levels (&lt; 46.7%), although there were indications of poorer performance at high rye levels (70.0%). Increasing the nutrient concentration of diets containing high levels of rye was not an effective means of alleviating poor performance induced by feeding rye in either experiment. Key words: Rye, laying hens

Laying Performance and Fear Response of White Leghorns as Influenced by Floor Space Allowance and Group Size

Three experiments were conducted with White Leghorn pullets housed in litter-floored pens to determine the effects of floor space allowance and group size on laying performance and fear response. In Experiment 1, 17 birds were housed at a floor space allowance of .40 or .29 m2/bird. In Experiment 2, 22 or 16 birds were housed at a floor space allowance of .31 m2/bird. The following treatments were used in Experiment 3: 1) 26 birds per pen at. 19 m2/bird, 2) 36 birds per pen at. 19 m2/bird, and 3) 26 birds per pen at .26 m2/bird. The test period was from 20 to 52 wk of age in each experiment. Duration of the induced tonic immobility, measured at 52 wk of age, was used as a criterion of fearfulness.Decreasing floor space allowance per bird, increasing group size per pen or a combination of the two had no significant effect on final body weight, hen-day egg production, feed efficiency, egg weight, albumen height, or fearfulness of the bird. Decreasing floor space per bird while holding the number of birds per pen constant significantly (P<.05) increased mortality. Birds given less floor space consumed significantly (P<.05) more feed than birds given more floor space in Experiment 1. This study indicates that the birds' hen-day egg production, feed efficiency, and fearfulness are not significantly (P>.05) influenced by floor space allowance or group size and that effects of floor space allowance and those of group size are not additive.

Hammer Mill Versus Roller Mill Grinding of Corn for Commercial Egg Layers

Three trials were conducted to determine differences in particle size characteristics of corn processed with a hammer mill vs. that processed with a roller mill. The particle size (geometric mean diameter) for corn processed with the roller mill ranged from 1,343 to 1,501 μm whereas that of corn processed with the hammer mill ranged from 814 to 873 μm. The trials demonstrated that the differing particle size characteristic of feed milled with hammer mill versus roller mill did not significantly influence the performance of commercial laying hens as measured by body weight, percentage of hen-day egg production, egg weight, average daily feed consumption, feed efficiency (grams of feed per gram egg produced), egg shell breaking strength, or mortality.

Response of White Leghorn Hens to Various Dietary Levels of Cassia obtusifolia and Nutrient Fortification as a Means of Alleviating Depressed Performance

Two 28-day experiments with White Leghorn hens were conducted to determine the adverse effect level of ground Cassia obtusifolia seed (coffeeweed) in the diet and to examine the nutrient fortification required to improve depressed performance due to the presence of the seed. In both experiments, five individually caged hens were used for each of the four treatment replications. Treatments for Experiment 1 consisted of a control and six diets with ground C. obtusifolia seed substituted for a filler at levels of 2, 3, 4, 5, 6, and 7%. In Experiment 2, a series of nutritionally fortified (15 to 20% higher nutrient levels) and unfortified diets coupled with seed levels of 0, 4, 6, and 8% for a total of eight treatments was used. Average daily feed intake, hen-day egg production, egg weight, egg specific gravity, and body weight change were determined during each experiment. For Experiment 1, average daily feed consumption was measured every 24 h for the first 3 days.Egg production and feed consumption were significantly reduced by 2% seed in Experiment 1. Within the first 24 h, feed intake was decreased to 37% below that of controls by increasing to the highest seed level. Egg specific gravity dropped significantly below that of controls when hens were fed 5% seed. In Experiment 2, fortification improved feed consumption, hen-day egg production, body weight change, and egg specific gravity over that of birds fed unfortified diets with the same seed level. Finished diets contaminated with 2%, or more, C. obtusifolia seed can cause reduced performance in laying hens, but nutritionally fortifying these diets can help to alleviate depressed performance.

Influence of Slat-Litter and Litter Floors on Performance of Broiler Breeder Hens

A total of 2,000 breeder pullets and 250 cockerels were fed on a skip-a-day program and reared to body weights at 20 wk of age as recommended by the breeder. Birds were housed in the laying house in pens of four treatment groups: 1) full-slat floor of plastic-covered wire (1.5 x 1.7 cm-openings (PS); 2) two-thirds slat floor of plastic-covered wire (1.5 x 7 cm-openings) and one-third litter (PS+L); 3) two-thirds white polypropylene slat floor with openings of 1.8 x 7.3cm and one-third litter (WS+L); and 4) rice hull litter floor (L). Each treatment group was in eight replicate pens. Floor space per pullet was .171, .177, .177, and .279m2 in the FP, PP, WP and L treatments, respectively. The experimental duration was nine 28-day periods.Significant differences were observed for hens on the different floor types with L floors being the highest and PS floors being the lowest in number of eggs per hen, hen-housed egg production and hen-day egg production. No significant differences were observed for hens on the PS+L and WS+L floors for these parameters. Significantly higher mortality was found for birds on PS floors than for birds on L or WS+L floors. Significantly higher feed per dozen eggs was found for birds on the PS floors than for birds on the other three floor types, with birds on the L floors having significantly lower feed per dozen eggs than for birds on any of the other floor types. No significant differences were found among the slat-litter floor types for the return on eggs per m2 of floor space; however, hens on litter floors were significantly lower in this parameter than hens on slat-litter floors. No significant differences among the slat-litter floor types for the return on eggs per m2 of floor space; however, hens on litter floors were significantly lower in this parameter than hens on slat-litter floors. Few significant differences were found for hatch of fertile eggs, hatch of all eggs or percentage of fertile eggs for hens among the floor types for each hatch; however, mean hatch of all eggs and mean percentage of fertile eggs for hens on the WS+L floors were significantly higher than for hens on the PS floors. No foot problems were noted in males or females for birds on any of the floor types.

Egg Production and Egg Composition of Parental Lines and F1 and F2 Crosses of White Rock Chickens Selected for 56-Day Body Weight

Egg production and weights of eggs and their components were measured in body weight-selected lines and in reciprocal F1 and F2 crosses. Nonadditive genetic variation was significant for age at onset of lay; percentage of hen-day ovulations, hen-day egg production, and normal eggs produced; egg weight and shell thickness; percentage of dry yolk and total moisture; shell and yolk dry matter; and ratios of albumen to yolk (A:Y) both on a wet and dry weight basis. There was recombination loss for all of these traits except percentage of hen-day ovulations, dry yolk, and total moisture; and shell dry matter, thickness and wet A:Y ratios. Reciprocal effects were negligible except for percentage of dry albumen and A:Y ratios. Greater yolk dry matter in the high BW line was observed than in the low BW line; this was consistent with observations of lipid overproduction in fast growing populations of chickens.

Effect of Dietary Acidification and Alkalinization on Urolith Formation and Renal Function in Single Comb White Leghorn Laying Hens

One of the major causes of mortality in poultry is urolithiasis. Although two of the major causes of urolithiasis have been defined, active and preventative treatments for this disease have not been extensively field tested. Previous research demonstrated that a diet acidified with NH4 Cl was effective in preventing the formation of uroliths in 16-wk-old pullets. In the present study, experiments were designed to evaluate the effects of dietary acidification and alkalinization on preformed uroliths in mature laying hens. Urolithiasis was induced by feeding excess dietary Ca (in commercial layer ration) during pullet growout (6 to 18 wk of age) and during the early laying period (18 to 32 wk of age). At 32 wk of age birds were randomly divided into three diet treatment groups: a normal layer ration group, an acidified layer ration group (1% NH4 Cl added); and an alkalinized layer ration group (1% NaHCO3 added). Each group received the respective diets until 52 wk of age, when the experiment was terminated.Blood gas analysis at 44 wk of age demonstrated that hens fed the acidified diet had significantly higher blood H+ concentrations, lower blood bicarbonate concentrations, and lower total blood carbon dioxide levels than hens fed the alkalinized layer ration. At 52 wk of age, hens fed the acidified layer ration had higher urinary H+ concentrations, higher blood H+ concentrations, and lower blood HCO3 and total CO2 concentrations than hens fed the normal and alkalinized layer rations. The acidified layer ration group had no uroliths present in their ureters (0% urolithiasis), whereas the normal and alkalinized layer ration groups had 8.3 and 13.1% incidences of urolithiasis. Hen-day egg production was not affected by the acidified or alkalinized layer ration treatments. Egg weight and percentage shell were increased by feeding the alkalinized layer ration.

Influence of Floor Types on Performance of Broiler Breeder Hens

A total of 1,800 broiler breeder pullets and cockerels were fed on a skip-a-day program and reared to 23 wk of age to body weights recommended by the breeder. Birds were housed in the laying house in pens of four treatment groups: 1) full-slat floor of plastic-covered wire [1.5 × 1.7 cm-openings (FP)]; 2) two-thirds slat floor of plastic-covered wire (1.5 × 1.7-cm openings) and one-third litter (PP); 3) two-thirds wood slat floor and one-third litter (PW); and 4) rice hull litter floor (L). Each treatment group was in four replicate pens. Floor space per pullet was .166, .174, .174, and .273 m2 in the FP, PP, WP, and L treatments, respectively.No significant differences were observed for hens on PP, FP, or PW floors for hen-housed or hen-day egg production, mortality, fertility, hatch of fertile eggs, hatch of all eggs, or egg weight. Significantly higher hen-housed and hen-day egg production and feed per dozen eggs was found for birds on L floors than for birds on the other floor treatments. No foot problems were noted in males or females for birds on slats.

Interaction of Dietary Calcium and Chloride and the Influence of Monovalent Minerals on Eggshell Quality

Two experiments were conducted to determine the influence of dietary sodium and chloride on eggshell quality of leghorn hens. In the first, hens were fed for 4 wk diets containing three levels of calcium (2.0, 2.8, and 3.5%) and two levels of chloride (.25 and .86%) in a factorial arrangement of treatments involving four replicates of five hens/treatment. Neither chloride nor calcium significantly affected hen-day egg production or egg weight (P>.05); however, chloride decreased feed consumption and calcium increased body weight gain (P<.05). Interactions of calcium and chloride were significant for eggshell strength (P<.06) and eggshell thickness (P<.05). Chloride decreased these measures of eggshell quality only for hens receiving 2.0% calcium, and calcium improved both measures only for hens receiving .86% chloride. Chloride decreased blood bicarbonate concentration and base excess (P<.05), but did not affect blood pH and pCO2 (P>.05).The effect of dietary sodium and chloride on eggshells of hens receiving 2.0% dietary calcium was determined in a second experiment. Seven diets ranging from .18% sodium and .94% chloride to .76% sodium and .24% chloride were provided for 4 wk to five replicates of five hens/treatment. Dietary sodium and chloride levels did not affect hen-day egg production or egg weight (P>.05). Increasing the proportions of sodium relative to chloride decreased food intake but increased eggshell strength and thickness (P<.01) and increased blood pH (P<.05), bicarbonate concentration (P<.01), and base excess (P<.01). The results suggest that sodium and chloride balance affect eggshell calcification and that adverse effects of excessive dietary levels of chloride are exacerbated when dietary calcium is limiting.

Factors Affecting Broiler Breeder Performance.: 7. Effect of Varying Levels of Dietary Protein on the Development and Reproductive Performance of the Dwarf Broiler Breeder

Vedette dwarf broiler breeder female chicks were raised in floor pens and fed a standard starter ration. At 3 wk of age, 1,032 pullets were divided into four dietary treatment groups (258 bird/treatment). Birds were transferred into individual cages at 18 wk of age and at 21 wk of age assigned to one of four laying rations. Dietary treatments consisted of a 4 × 4 factorial design with four developer diets (12, 14, 16, and 18% protein) and four layer diets (12, 14, 16, and 18% protein).Body weight was determined at 6, 12, and 17 wk of age and thereafter at 4 wk intervals. Hen-day egg production was determined weekly from 21 to 58 wk of age. Specific gravity and egg weights were measured at 4-wk intervals on eggs collected over 4-day periods. Fertility and hatchability were measured at 32, 34, and 44 wk of age on the one-half of the birds in each treatment that had been artificially inseminated weekly with .05 mL of semen from Ross males. Embryonic mortality and chick weights of offspring were recorded when the breeder flock was 32 and 44 wk of age.Dietary treatment had a significant effect on body weight (P>.05) at Week 12, (12% and 14% vs. 16% and 18%) but by Week 17 differences were no longer significant. Significant differences in body and egg weights during the laying cycle were detected (P<.05), with hens receiving the higher protein (16% and 18%) laying diets exhibiting heavier body and egg weights. Significant interactions between dietary treatments were seen for age at sexual maturity, hatchability, chick weights, and progeny performance (P<.05). Fertility and hen-day egg production were not significantly different among dietary treatments (P>.05).

Effects of Feeding Deoxynivalenol (DON, Vomitoxin)-Contaminated Wheat to Female White Leghorn Chickens from Day Old Through Egg Production

White Leghorn chickens one day of age were fed starter and grower diets containing either a control (noncontaminated) wheat diet or a naturally contaminated deoxynivalenol (DON) wheat diet (18 mg DON/kg) from 1 day of age to the onset of egg production. The hens were then placed on their respective layer diets of control wheat or DON-contaminated wheat (18 mg DON/kg) for six 28-day egg production periods. Feeding the DON-contaminated diet did not significantly influence body weights during the growing or the laying phases. Overall, hen-day egg production and egg weights were significantly higher for hens receiving the DON diet. Feeding DON contaminated wheat caused no significant changes in percent shell, albumen height, percent fertility, percent hatch of fertile eggs, percent hatch of eggs set, or weight of chicks at hatch. There were slight, although significant, changes in shell weight and shell thickness and in some serum chemistry values. There were no significant differences in the hematology parameters measured or in prothrombin times. None of the eggs collected from hens fed the control and the DON-contaminated wheat diet contained detectable quantities of DON. Microscopic examination of sections of the liver, kidney, and proventriculus of control and treated hens revealed no unusual histopathology. The results indicate that feeding DON at relatively high levels beginning at 1 day of age and continuing through six egg production periods had only slight effects on the parameters measured.

Effects on Productivity and Aggressive Behavior of Laying Hens of Solid Versus Wire Cage Partitions and Bird Density

The effects of solid metal cage partitions or wire mesh cage partitions and two cage densities (5 or 7 birds/60.9 cm × 35.6-cm shallow cage) on production performance traits, aggressive behavior, and feather covering of White Leghorn layers were assessed from 20 to 60 wk of age. Type of cage partition had no significant effects on any of the traits measured. Higher cage density, however, was associated with significantly lower hen-day egg production, feed usage, final body weights, and feather covering. No differences were observed for egg weights, egg loss, mortality, or aggressive head pecking activity of birds housed in the two cage densities.

Effect of Watering Devices on Performance During Pullet-Rearing and Cage-Laying Phases of Single Comb White Leghorn Hens

An experiment was conducted to examine the effect of watering devices used during pullet-rearing and cage-laying phases on subsequent biological and production responses of hens with 960 pullets reared in floor pens for an 18-wk period. During the pullet phase, birds were placed in one of three watering regimens: start/grow trigger-cups (SGTC), bell drinkers (BD), or a combination treatment consisting of 9 wk on BD and 9 wk on SGTC (BD/SGTC). During the laying phase, birds were placed in laying units with four birds per cage. Cages were equipped with mature bird trigger-cups (TC), fount-cups (FC), vertically activated nipple drinkers (VAND), or cone-shaped cups (CC).Cage waterers had significant influences on average hen-day egg production (HD) and feed conversion of the hens. For HD production, there was no difference between hens on CC and TC or between CC and FC. Birds drinking from VAND had significantly lower HD production and poorer feed conversion than birds on the other waterer treatments. There were no significant differences in body weight for birds raised on the different drinking devices. Cumulative mortality during the cage-laying phase was nonsignificantly higher for birds drinking from VAND than for birds drinking from CC. There was no effect of waterer type on egg weight or Haugh units. Specific gravity was poorer for eggs produced by hens drinking from FC as compared with eggs from hens on CC or VAND. Kidney weights and kidney as a percentage of body weight were affected by the interaction of the pullet-rearing and cage-laying phase waterers.

Effects of Body Weight Groupings on Productivity, Feather Loss, and Nervousness of Caged Hens

Two experiments compared performance traits, feather loss, and nervousness of hens kept in contrasting homogeneous and heterogeneous body weight groupings. In addition, 15-day periods of daily uterine palpating vs nonpalpating for an egg in the uterus were compared for effects on egg production. Eighteen-wk-old pullets were weighed and characterized as light, medium, or heavy and housed in laying cages at 19 wk for a 50-wk production period. In Experiment 1, two hens were placed in each cage and there were three treatment groups: both light (L), mixed or 1 heavy and 1 light (X), and both heavy (H). In Experiment 2, three pullets were used per cage; a medium-weight group (M) was included and mixed cages included 1 heavy, 1 medium, and 1 light weight bird. In an ancillary experiment, 50-wk-old hens were also palpated or not palpated for an egg in the uterus over a single 15-day period.Results indicated that differences that were present in initial body weight groups persisted over the 50-wk period in Experiments 1 and 2 with no effect of weight grouping on body weight gain, egg production, and livability. Differences that were associated with weight groups were: age at sexual maturity, egg weight, egg mass, and nervousness score. No differences in mean feather scores were present among weight groups.Comparisons between individual hens of the same relative weight but kept in homogeneous or heterogeneous weight groups failed to indicate competitive advantages or disadvantages in egg production, feathering, and nervousness scores. No significant associations were found between nervousness scores of individual hens and other traits except for total body weight gain in Experiment 1, in which individuals that gained more were less nervous in the X groups (r = −.55).Palpating hens daily for two 15-day periods significantly increased hen-day egg production in Experiment 2 and nonsignificantly in Experiment 1, with no influence of palpation on hen-day egg production, egg weight, or egg mass in the ancillary experiment.

Effect of a High Fat Diet Fed Prior to or at Sexual Maturity on Egg Weight ,

This study compared the effects of a low fat, high carbohydrate diet with a high fat diet fed prior to or at the onset of egg production on initial egg weight. Commercial egg-type pullets were assigned to one of three dietary regimens: 1) the control (CON), a low fat, high carbohydrate diet, 2) a high fat (HF) diet containing eight parts of fat, and 3) the high carbohydrate diet provided prelay and the high fat diet during the production period (CHO-HF). The carbohydrate prelay and laying diets contained .990 and .943% fat and had a calculated metabolizable energy (ME) value of 2,831 and 2,697 kcal/kg, respectively. The high fat prelay and laying diets contained 8.959 and 8.484% fat with a calculated ME value of 3,202 and 3,032 kcal/kg, respectively. The first 60 eggs produced by each pullet were collected and weighed.At Egg 60, no significant differences were seen in body weight and abdominal adipose tissue. The CON treatment had a significantly greater liver weight, liver lipid content, and ovary weight than the HF or CHO-HF treatments. The CON and HF treatments had a similar hen-day egg production (HDP). The CHO-HF treatment was slow to adjust to the high fat diet and that may have caused the lower HDP that was seen for this treatment. No indication of a failure to adjust to the high fat diet was noted for the HF treatment. Additionally, a high fat diet resulted in higher egg weights.This study indicates that when fat was supplemented to the diet prior to the onset of egg production, pullets adjusted to the high fat diet and HDP was not adversely affected.

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.