Strains Of Hens Research Articles

Changes in plasma levels of prolactin and estradiol, nutrient intake, and time spent nesting during the incubation phase of broodiness in the Chabo hen (Japanese bantam)

The plasma concentrations of prolactin (PRL) and estradiol, time spent nesting, consumption of feed and water, body weight, and hematocrit were measured during egg layin, incubating, and brooding of the chicks in a Japanese strain of dwarf bantam hen, Chabo. Plasma levels of PRL increased before incubation, were maintained at high levels during incubation, and decreased rapidly at the onset of hatching the yound. The concentration of estradiol decreased before incubation and was maintained at low levels when circulating levels of PRL were high. During incubation, hens spent >95% of the day on the nest, reduced their daily intake of feed and water by 63 and 78%, respectively, and decreased their body weight by 19% by the end of incubation. Thus, Chabo hens show a mode of incubation behavior similar to that reported in larger chickens. The temporal changes between nutrient intake and plasma levels of PRL at the start and end of incubation behavior suggested that changes in nutrient intake may not cause changes in the concentration of PRL, whereas the association between increased levels of PRL and decreased levels of estradiol suggested that they may be causally associated. Plasma levels of PRL also appeared to be associated with time spent on the nest.

Phospholipid Content of the Chicken Shell Gland and Its Relationship to Egg Shell Strength

Egg shell strength declines during the latter part of the laying cycle. Shell gland (uterine) lipids have been postulated to be associated with this decline. A membrane-bound Ca2+-adenosine triphosphate (ATP)ase has been shown to require phospholipids for maximum activity. It is hypothesized that the age-associated decline in shell strength is the result of alterations in shell gland phospholipids. Shell strength, as assessed by shell surface density, of eggs from two commercial strains of hens in their first cycle of lay was monitored during the latter half of the laying cycle and following an induced molt.Significant differences were not detected in abdominal fat weight, oviduct weight, or total lipid concentration of the shell gland of hens that produced premolt strong egg shells (SES) and weak egg shells (WES). The SES hens had higher concentrations of shell gland phosphatidylcholine (PC) and lower concentrations of shell gland phosphatidylethanolamine (PE) than WES hens. The ratio of PC:PE was significantly lower in WES hens in the premolt than in the postmolt phase. An improvement in shell strength after the induced molt was associated with an increase in shell gland PC:PE ratio. These results indicate that the weak egg shells produced towards the end of lay are laid by hens whose shell gland contains less PC and a lower ratio of PC:PE. The differential response after an induced molt supports the hypothesis of a cause and effect relationship. These alterations could affect the function of Ca2+-ATPase and egg shell calcification.

Effects of age and diet on the lipid content and composition of gallbladder bile, liver and serum in laying strains of hen.

1. Changes in lipid content and composition of liver and bile during pre- and post-laying periods were investigated in hens of a laying strain. 2. The large increase in liver lipid concentration, particularly triacylglycerols, at the onset of laying was accompanied by the appearance of triacylglycerols in the bile. 3. Accumulation of triacylglycerol in the liver was increased by a diet containing maize and soyabean meal. This was associated with increases in the triacylglycerol concentration in both serum and bile. 4. Liver microsomal phosphatidate phosphohydrolase activity was positively correlated with liver triacylglycerol content in birds given the maize/soyabean meal diet. 5. The time course of triacylglycerol accumulation in the liver and associated changes in the bile triacylglycerol concentration in laying strain hens were different to those previously observed in broiler hens. 6. Over the lifetime of the bird, secretion of triacylglycerols into bile may play an important role in the prevention of fatty liver syndromes.

Effects of beak trimming and restraint on heart rate, food intake, body weight and egg production in hens.

1. Heart rate (measured on restrained hens in two experiments) was used as an indicator of short term fear and pain responses of light and heavy strains of hens subjected to beak trimming. 2. In the first experiment 3 mm of the upper and lower mandibles was trimmed, while in the second 0, 2, 4, 6 and 8 mm of upper and lower mandibles were removed. 3. Production responses to beak trimming were measured after trimming, for 4 weeks in experiment 1 and for 10 weeks in experiment 2. 4. In the first experiment the recovery of beak trimmed hens to normal heart rate took significantly longer than that of control hens subjected only to catching and restraint, suggesting that there was short term pain associated with beak trimming. 5. The heavier strain took about 4 min longer to return to a normal heart rate than the lighter strain, indicating a strain difference in responsiveness to beak trimming. 6. Trimming the hens' beak by 3 mm had no significant effect on rate of lay or body weight, but their mean egg weight was depressed and food intake took 9 to 10 d to recover to pre-trimming values. 7. In the second experiment a plateau was reached in recovery time of the heart rate once 4 mm of beak was removed. Removal of 4, 6 and 8 mm of beak depressed normal feeding and resulted in variable effects on production and body weight.

Significance of increased secretion of glucocorticoids in mice and rats injected with bacterial endotoxin

Injection of mice or rats with lipopolysaccharide (LPS) is associated with an increased secretion of glucocorticoids. The high level of mortality following injection of LPS that is noted in adrenalectomized rats can be reversed by dexamethasone or corticosterone. That histamine may be an endogenous mediator of the release of corticosterone caused by LPS is suggested by an attenuation of this corticosterone response by promethazine, an H 1 antihistamine. Additional support that LPS-dependent glucocorticoid secretion is mediated, in part, by histamine, is suggested by spleen cell transfer studies revealing differences in the induction of histidine decarboxylase (HDC) synthesis and corticosterone release by the C3H HeN and C3H HeJ strains of mice that are differentially sensitive to LPS effects. These and other data on increased levels of histamine and HDC during mitogen-induced lymphocyte blastogenesis, as well as experiments revealing immunomodulatory effects of histamine and histamine agonists and antagonists on lymphocyte blastogenesis, are consistent with the hypothesis that following infection with gram-negative bacteria, the histamine-induced increase in glucocorticoid secretion results in inhibition of HDC in splenocytes, a concomitant attenuation of histamine production, and a resulting return to immune homeostasis.

Occurrence of waxy-textured yolk in the egg of the domestic hen (Gallus domesticus).

An unusual yolk material (waxy yolk) was identified in some hard boiled yolks of one strain of domestic hen. Its structure was consistent with it being formed from normal yolk through disruption of the yolk spheres. These are normally stable during even long periods of storage. Formation occurs mainly after ovulation, during passage of the egg down the oviduct; only rarely could it be found in the larger follicles of the ovarian hierarchy. In the flock of birds examined the incidence of eggs with waxy yolk was 75% of all eggs laid over a 7 d period. Of the 173 birds tested, the eggs of only 17 birds were totally unaffected; all eggs of 82 birds contained this material. The results of a hatchability trial indicated this material had no apparent influence on the embryo or hatchability.

Research Note: Effect of Preincubation Storage of Hatching Eggs on Subsequent Performance of White Leghorn Hens

Eggs from three strains of White Leghorn hens were stored up to 21 days prior to incubation in 1964 and 1965. Eggs stored longer than 7 days were packaged in Cryovac2 bags with the air evacuated (1964) or flushed with nitrogen (1965) and held at about 12 C and 80% relative humidity. Each year, all eggs were set together and incubated at 37.5 C (29.5 C wet bulb). At 18 days of incubation, eggs were candled, apparently infertile eggs removed, and incubation continued at 37.0 C (32.5 C wet bulb). Hens were housed at 147 days in floor pens in 1964 and in individual cages (20 × 41 cm) in 1965.Preincubation storage reduced hatchability of apparently fertile eggs. Preincubation storage affected only housing body weight (1964), egg weight (1964, 1965), Haugh units (1964, 1965), and blood spots (1965). Effects of preincubation storage of hatching eggs on hens’ subsequent performance do not appear important enough to offset the advantage of storing hatching eggs for up to 3 weeks in experiments and breeding programs where it is advantageous to reduce hatch effects or to offset the management advantages of fewer hatches.

Effects of times of collection and different storage methods on the microflora and nitrogen content of poultry waste.

An experiment was conducted to determine the effects of times of collection and storage methods on the kinds and numbers of microflora and nitrogen content of poultry excreta (waste). Fresh waste collected in the morning had a higher mean count of viable bacteria than the evening collection in both strains of hen studied. Fresh waste samples had higher mean counts than dried ones. Escherichia coli and Proteus spp. were the predominant microflora identified in waste collected at both times from both strains. Collection time had no effect on the type of micro-organisms isolated. Bacillus spp. was least frequently isolated in fresh waste but most often in dried waste. Samples of waste collected in the morning from Babcock layers contained more nitrogen than those collected in the evening. Samples collected in the morning from Warren layers and stored under aerobic conditions had the highest nitrogen content. However, there were no significant differences in the nitrogen content of waste from Babcock layers attributable to storage method.

Effects of Calcium and Phase-Feeding Phosphorus on Production Traits and Phosphorus Retention in Two Strains of Laying Hens

Three levels of dietary Ca (3.0, 3.5, or 4.0%) were fed throughout a 336-day experiment to two strains of Single Comb White Leghorn hens in a factorial arrangement with three P feeding programs: .64% P fed continuously; .56, .49, and .39% P; or .64, .54, and .44% P fed when hens were 24 to 36, 36 to 52, and 52 to 72 weeks, respectively. In addition to production traits, measurements of P retention were made at 34, 42, 50, 62, and 72 weeks of age.No dietary effects were observed on production traits. Average P retention over the entire experiment was 104, 148, and 178 mg/day when hens were fed 3.0, 3.5, and 4.0% Ca, respectively. Most of the favorable effect of Ca on P retention occurred after 50 weeks of age. However, increasing dietary Ca had an adverse influence on P retention at 42 weeks, when ambient temperature was unusually hot and feed intake decreased markedly. Significant P effects were observed when hens were 42 and 72 weeks of age. At these times, hens fed .64% P retained the most P while those phase fed .56, .49, and .39% P retained the least. Retention of P tended to decline with increasing age of the hens. Overall, the hens were in a state of marginal to negative P balance at 42, 62, and 72 weeks of age even when P deposited in eggs was considered.

Metabolism and Ovarian Follicular Uptake of the Major Yolk Precursor in Laying Turkey Hens

The total turnover of the major yolk precursor lipoprotein (very-low-density lipoprotein from laying hens; VLDL-L) was determined in laying turkey hens (n = 21) of a single strain selected for increased egg production (egg strain). Separate calculations were made for the two major lipid fractions, the triglycerides (TG) and phospholipids (PL). No difference was found between the fractional clearance rates of VLDL-L TG and VLDL-L PL (–.00248 min−1vs. –.00245 min−1, respectively). The concentration of VLDL-L TG was greater than that of VLDL-L PL (14.03 mg·ml−1vs. 5.60 mg·m−1) and accounted for the difference in total turnover between VLDL-L TG and VLDL-L PL (12.12 g. d−1vs. 4.77 g·d−1).Multiple regressions, with total turnover of either VLDL-L TG or VLDL-L PL as the dependent variable and fractional turnover rate (k) of VLDL-L TG or PL, concentration (C) of VLDL-L TG or PL, the distribution volume (V) of VLDL-L (not measured independently for TG and PL), and body weight (B wt) were calculated. For VLDL-L TG as the dependent variable, significant contributions to R2 were made by C, V, and k with C>V>k. For VLDL-L PL, significant contributions were made by these variables with C>k>V. The percentage uptake of VLDL-L radioactivity by developing ovarian follicles was 30.3% (n = 17). When percentage uptake was the dependent variable, multiple regression analysis did not explain the variance in the data utilizing either the VLDL-L TG or VLDL-L PL data sets. Thus, follicular uptake was not associated with plasma concentration, fractional clearance rate, distribution volume, or body weight in this strain of turkey hens.

Investigation of Calcium and Available Phosphorus Requirements for Laying Hens by Response Surface Methodology

Abstract A 3 × 3 factorial experiment with 324 laying hens was conducted for 280 days to examine the effect of calcium and available phosphorus on biological responses associated with egg production. Calcium levels were 2.50, 3.75, and 5.00% and available phosphorus levels were .35, .50, and .65%. The data were analyzed quantitatively using response surface methodology. Results showed that within the range of the experimental design, there were no significant effects of the two minerals on hen-day egg production, final body weight, or average egg weight. A trend was shown for improvement in feed conversion at the 2.5 and 3.75% calcium as the available phosphorus percent was reduced. This trend was not evident at the 5% calcium level. Cumulative mortality was related to low dietary levels of calcium. Eggshell percentage was significantly affected by calcium and available phosphorus levels. A second order equation was found to describe the mineral and percent eggshell relationship with an R2 value of .77. Optimal levels of calcium and available phosphorus for the percent eggshell were calculated to be 4.73 and .48, respectively. A confidence area and interval were described for the predicted optimal response. The high calcium and available phosphorus were postulated to be associated with the strain of hen used in the experiment.

Egg Quality. 2. Albumen Quality of Eggs from Five Commercial Strains of White Leghorn Hens During One Year of Lay

Egg weight and albumen height of a sample of 160 eggs from each of five commercial strains of White Leghorn hens were measured at each of 18 sampling times between 197 and 484 days of age for a total of 14,400 eggs. Age (P<.01) and strain (P<.05) were the main factors affecting interior egg quality. Both albumen height and Haugh units decreased at an approximately constant rate over time. An electronic albumen meter was used to measure albumen height. The tip of the measuring rod had to be kept free of dried albumen to prevent measurement errors.

Influence of cottonseed meal on vanadium toxicity and 48vanadium distribution in body tissues of laying hens.

Hens of two commercial White Leghorn strains were fed diets representing a complete factorial arrangement of 0, 3, or 6 ppm vanadium (V) from dicalcium phosphate and 0 or 5% cottonseed meal (CSM). Test diets were fed for 4 consecutive weeks beginning when hens were 25, 40, 62, or 76 weeks old. After each 4-week treatment period, all hens were fed a diet containing no added V or CSM. Albumen quality (Haugh units) was determined on eggs produced on Days 6 and 7 of each week of feeding the test diets. Three ppm V caused a slight decrease in Haugh units, while 6 ppm V reduced Haugh unit score (HU) by 6 to 15 units when fed to hens 29, 44, or 80 weeks old. The relative influence of V on HU of eggs from 66-week-old hens was less pronounced. The inclusion of 5% CSM in the diet counteracted most of the adverse effects of V on egg quality, irrespective of strain of hens. Egg production and egg weight were not affected by V or CSM. In a second experiment, hens fed diets containing no V + no CSM, 6 ppm V + no CSM, no V + 5% CSM, or 6 ppm V + 5% CSM were given 110 microCi of 48V by oral capsule. Greatest concentrations of 48V were found in bone, kidney, liver, and magnum. Little 48V was detected in whites, and none was found in yolks of eggs produced 2 days after 48V dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Egg Quality. 1. Shell Strength of Eggs from Five Commercial Strains of White Leghorn Hens During Their First Laying Cycle

Eggs were collected 18 times from five strains of commercial White Leghorn hens between 197 and 484 days of age. Egg weight, specific gravity, nondestructive deformation, and quasistatic compression breaking strength were measured on all eggs. Shell weight, percent shell, and shell weight per unit surface area were available for eggs collected between 372 and 484 days of age. Shell thickness was measured at 421, 449, and 477 days of age. Age and strain (P<.01) influenced all the variables except shell thickness, which was affected only by strain (P<.05). Egg weight and deformation increased and specific gravity and compression breaking strength decreased over the experimental period. Shell weight, percent shell, and shell weight per unit surface area decreased slightly between 372 and 484 days. The variability, expressed as the standard deviation of an observation, remained relatively constant for specific gravity, egg weight, shell weight, percent shell, and shell weight per unit surface area. It increased for deformation between 197 and 484 days. The variability of compression breaking strength was not constant over the experimental period, but neither did it exhibit any simple trend. There were few interactions: strains of hens which had the highest shell quality at 197 days also had the highest at 484 days.

The Effect of Maternal Age on Broiler Performance on Litter and a Raised Perforated Floor

The effect of maternal age and floor type on the performance of broiler chicks was studied. Hatching eggs were collected and hatched from the same Cobb commercial strain of broiler breeder hens at 27, 42, and 52 weeks of age. Chicks from each group were reared separately or intermingled on commercial diets.Maternal age had a significant effect (P<.05) on live body weights of broilers reared either separately or intermingled. Weight differences found at day-old between chicks from 42- and 52-week-old dams were overcome by the age of 44 days. Chicks from the 27-week-old dams were not as heavy and consumed less feed than those from other parentage groups. Broilers on the perforated floors were heavier than their floor counterparts.Overall performance, except for body weight, was not affected by floor type or rearing condition.

Plasma sex hormone and lipid patterns in normal and restricted-ovulator chicken hens

The relationships of circulating estradiol, estrone, and progesterone levels to plasma lipid levels and ovulatory frequency were studied in sexually mature hens. New Hampshire × Columbian (NH × C) cross-bred hens, which have a relatively low frequency of ovulation, were compared with pure-bred White Leghorn (WLH) hens with a high frequency of ovulation. A mutant strain of WLH hen, exhibiting the phenotypic characteristic of restricted ovulation (RO) was also tested. It was found that NH × C hens had a basal circulating estrogen: progesterone ratio 2.7 × greater than WLH hens. Furthermore, WLH-RO hens exhibited 3 × higher basal plasma estrogen and 4 × lower progesterone than normal WLH hens, resulting in an estrogen: progesterone ratio which was 12.6 × higher. In addition, WLH-RO hens did not exhibit any diurnal variation in circulating progesterone levels, and had smaller primary sex organs and also intermittent hyperlipidemia. It is concluded that the basal circulating estrogen: progesterone ratio in sexually mature hens is a good indicator of ovulatory frequency, and that the magnitude of the ratio is determined primarily by the progesterone component.

Stimulation Lighting of Meat-Type Pullets

Meat-type pullets of two strains, housed in windowless floor pens, were subjected to two stimulation lighting treatments beginning at 140 days of age. The treatments provided increases in photoperiod from 6 to 16 hr/day by either 1) 5 increases of 2 hr/day each week or 2) increases each of 2 and 1 hr/day followed by 14 increases of .5 hr/day each week.Overall, there was no significant difference due to lighting treatment in number of hatching eggs per hen housed. However, age at 50% production was 6.3 days less; percentage hen day egg production was higher, 56.2 vs. 54.2; and egg weight was .8 g lower for hens of Treatment 1 vs. Treatment 2. For the strain with lower egg size, the number of additional eggs obtained for Treatment 1 was no greater than losses due to undersized eggs. For the strain with higher egg size, Treatment 1 prevented excess body weight gain and permitted earlier egg production.The merits of using rapid vs. slow stimulator lighting procedures for meat-type birds depend on the egg; and body weight characteristics of the strain of hen.

Influence of Genetic Increases in Egg Production on Traits Associated with Broodiness in Turkeys

Egg production, nesting frequency, and serum levels of prolactin, estradiol, and total phosphorus were monitored in relatively nonbroody (egg) and relatively broody (RBC1) strains of turkey hens during a reproductive period. In the egg strain, prolactin levels were increased in a group with a relatively high frequency of nesting in comparison to a group with a relatively low frequency of nesting. No differences between these two groups were detected for serum estradiol, total phosphorus, or egg production.In the RBC1 strain, prolactin levels did not differ between a group of hens that did not exhibit broodiness and a group that exhibited one or more bouts of broodiness. A broodiness treatment was used for the latter group. The broody group exhibited extremely variable levels of prolactin. In individual broody hens, the levels of prolactin were relatively high. After broodiness treatment, which was successful in arresting broodiness in 12 of 13 hens, the level of prolactin fell to relatively low levels. In the one hen not responding to broodiness treatment, the level of prolactin became extremely high. Nesting frequency, total serum phosphorus, and egg production were generally not different between the two groups.The level of prolactin showed seasonal changes in both strains of hens, starting low, increasing to maximal levels between 40 and 80 days of production, and then declining to low levels late in the reproductive period. Laying hens always had higher levels of prolactin than nonlaying, non-broody hens.

An Observation of Dermatitis in Caged Dwarf and Normal-Sized Single Comb White Leghorn Laying Hens

Dermatitis was observed on the feet of Single Comb White Leghorn hens. Dermatitis scores and score ranges showed lesions to be predominately on the feet of dwarf compared with normal-sized hens. Statistical analysis by log-linear models showed that the percent incidence was closely related to the strains of hen tested and, to a lesser extent, to the type of ration fed the birds.

The Performance of Four Strains of Laying Hens Subjected to Various Postrest Combinations of Calcium and Phosphorus After Forced Rest in Winter or Summer

Four strains of laying hens, including one brown egg strain, were force-rested in February at approximatey 62 weeks of age. Hens from the same four strains, which were the same age, were also force-rested under similar conditions during August of the same year. In each of the two trials, a total of 2300 hens were housed at the rate of two per 25.4 × 45.7-cm cage. The resting procedure for both studies included feed withdrawal for 9 or 10 days followed by feeding a 8.6% protein diet for 25 days. Water was supplied at all times. After the 35-day resting period, the hens were assigned to four calcium and phosphorus combinations, which varied from the duplication of a first-year pullet phase feeding program to the feeding of a final phase type diet for the entire postrest production period. Nutrient level within each dietary system was adjusted periodically based on daily feed intake.Strain performance differences were observed in both seasons. Rate of return to production and postrest production rates were similar to the patterns observed within the respective strain's performance during the pullet year. This was noted in both studies. Relative strain production performance, however, when compared to the other strains, was not consistent between the two rest seasons. There was no difference in performance due to calcium and phosphorus treatment utilized in either postrest production season. Force-rested hens fed diets designed for older hens performed comparably to those that received other dietary treatments under both winter and summer forced rest conditions.