Laying House Mortality Research Articles

Production benefits of the crossbreeding of indigenous and non-indigenous ducks—growing and laying period body weight and production performance

To evaluate different crosses and purebreds ducks in respect to various economic traits and to estimate different crossbreeding genetic parameters, a 3 x 3 complete diallel cross involving indigenous duck (DD), Khaki Campbell (KK) and White Pekin (WW) were used to produce three purebreds (DD, KK, WW) three crossbreds (DK, DW, KW) and three reciprocals (KD, WD, WK). A total of 609 ducklings produced were reared on deep litter and the females (316 in number) were evaluated for growing and laying period body weight along with the production performance traits. Different crossbreeding genetic parameters were estimated for different traits. All the traits in respect to body weight gain during growing and laying period and different production traits including laying house mortality rate showed significant (p <or= 0.05) difference between different genetic groups. In general, crossbreds perform better than the purebreds for most of the traits studied. General combining ability (GCA), specific combining ability (SCA) and reciprocal effect (RE) were significant (p <or= 0.01) for body weight and production traits. Egg weight showed significant (p <or= 0.01) difference in respect to GCA, SCA and RE for all the ages of measurement except RE for 30th week egg weight. Laying period mortality rate was only significant (p <or= 0.05) for SCA. Most of the crossbreds recorded heterosis rate in desirable direction for majority of the traits. Overall results revealed that the crossbreds perform well in respect to different traits than the purebreds and may be used to take advantage of heterosis. DW performs well in respect to majority of the traits measured and is of importance for commercial exploitation. Further, pure line selection with development of specialised sire and dam line followed by crossing may be of importance to enhance the performances in the crosses.

Effects of Imperfect Albinism (sal–s) on Egg Production in Two Lines of Chickens

Two trials were conducted with two different lines of chickens to determine whether a gene for sex-linked imperfect albinism (sal–s) affected various egg production traits. In a line with relatively good egg production, sexual maturity was delayed for albino compared with nonalbino hens, but overall egg production by albinos was higher. The increased production resulted in eggs with reduced yolk and shell weights. Albumen weights were not affected, and because the eggs from albinos were smaller, Haugh unit scores were higher. In another trial, sexual maturity of hens of a heavy line was not affected by the genotype, but these hens did not receive controlled lighting during the growing period. Egg production curves of these hens were very similar to those seen in the first trial. The laying house mortality rates were not affected by the sal–s gene, despite several periods of high environmental temperature. These trials suggest that sal–s could be used in a sex-linked cross of commercial layers or broiler breeders.

Effects of fermented cassava peel meal on the performance of layers

One hundred and ninety-two AF Bosbek commercial layers were given four experimental diets containing 0, 25, 50 and 75 g kg −1 fermented cassava peel meal (FCPM), replacing equal amounts of white maize (corn). Each treatment was replicated four times and the experiment lasted 11 weeks. Hen-day egg production declined from 63.4% for birds on the control diet to 61.2, 60.3 and 55.3% for birds on 25, 50 and 75 g kg −1 FCPM diets, respectively, the decline being significantly linear ( P < 0.05). Similarly, feed conversion efficiency and live weight gains showed significant ( P < 0.05) linear declines as the level of FCPM increased. Feed conversion efficiency declined from 2.5 for the control diet to 2.8 for the highest level of FCPM. Birds given 75 g kg −1 FCPM gained on average 1.4 g week −1, while those given no FCPM gained 30 g week −1. Differences in feed consumption, eggshell thickness, egg interior quality and laying house mortality however, were not significant.

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.

Phosphorus Requirement of Commercial Leghorn Pullets from 8 to 20 Weeks

Hisex White pullets, hatched in November, were used to study the influence of the amount of dietary phosphorus in practical grower diets during the 8 to 20-week growing period. Measurements were made on 20-week body weight, bone ash, and layer house performance. All chicks were fed a 21% protein starter diet through 8 weeks at which time they were randomized into eight treatment groups. Grower diets were changed at 8, 12, and 16 weeks at which time different dietary phosphorus percents were used. Percents of total phosphorus used were .60, .55, .50, .45, and .32 for 8 to 12 weeks and .31 for 13 to 20 weeks.Lowering the phosphorus to .32% at 8 weeks or .31% at 12 weeks significantly reduced 20-week body weight. Lowering total phosphorus to .31% at 16 weeks did not significantly affect 20-week body weight. Bone ash measured at 20 weeks was not significantly affected by feeding less phosphorus. Laying house mortality, egg production, egg weight, and egg specific gravity were not influenced by lowering phosphorus in grower diets.

Effects of Comb Dubbing on the Performance of Laying Stocks

Three studies were conducted with birds dubbed at hatch vs. dubbed and dewattled at 118 days or 255 to 260 days of age or with normal hens. In the first, involving 5928 pullets of four strains housed 1 per cage, dubbing and dewattling at 255 to 260 days caused small adverse effects on egg numbers as compared with nondubbed controls. Body size was reduced, and both egg weight (EW) and shell strength were increased slightly. In the second study, involving 8180 pullets of nine strains housed 1 per cage, dubbing and dewattling at 118 days slightly increased survivor egg production (SEP) and laying house mortality, and reduced age at first egg, 240-day EW, and 450-day Haugh units (HU), as compared with dubbing only at hatch. There were significant strain by dubbing treatment interactions for hen-day rate of lay (HDR) and SEP. In the third study, involving 1824 pullets of three strain crosses housed 2 and 3 birds per cage (three different cage sizes), there were no significant differences between birds dubbed at hatch and those not dubbed. Variation in age at 50% production, SEP, and HDR was reduced for the dubbed groups. These studies show that the older the birds are when dubbed, the greater the negative effects of dubbing. Hens dubbed at hatch exhibit no effects with the early dubbing or adverse effects in the laying house.

Inbreeding Effects on Traits with and Without Selection for Part Record Rate of Lay in Chickens

Data from inbred lines, one (D) selected for part record rate of lay and the other (C) unselected for any trait, were analyzed. After 19 generations of continuous full sib matings, the C line showed significant decreases in part record egg number, 32-week egg weight, shell thickness, full record egg number and part record rate of lay but nonsignificant decreases in hatchability, full record rate of lay, and laying house mortality. Age at first egg, Haugh unit and mature body weight showed significant increases in this line. The D line was similar to the C line in its response to the same intensity of inbreeding for all traits except full record egg number, part record rate, and fertility, each of which showed a significant decrease, and Haugh unit and full record rate of lay, which showed nonsignificant increases.Results indicated that the small advantages selection conferred on the inbred line in part record rate of lay (the selection criterion), full record egg number, and full record rate of lay were accompanied by undesirable changes in other traits, resulting in later sexual maturity, larger body weight, lower Haugh unit, fertility, and hatchability compared with the unselected line.

Effect of Step-Down and Step-Up Protein-Energy Feeding Systems on Egg-Type Pullet Growth and Laying Performance

Four egg-type pullet feeding systems were compared for the production of egg-type pullets. The dietary regimens consisted of either a step-down protein, high energy feeding program; a step-down protein, low energy program; a step-up protein, high energy program; or a step-up protein, low energy program. At 150 days of age all pullets were housed 2 birds per 25.4 × 45.7 cm laying cage and fed a standard layer diet (16% protein). The experiment utilized 2880 birds grown on the floor in a conventional growing house.At 140 days of age, birds subjected to the step-up protein feeding programs were 82 g smaller in mean body weight, had higher mortality, and consumed less feed than the birds on the step-down protein feeding programs. Body weights at 140 days of age were 1.17 and 1.09 kg for the step-down and step-up feeding programs, respectively. Energy levels fed had no significant effect on pullet weight, feed consumed, or mortality to 140 days of age.During the laying phase, hens that had been on the step-down protein feeding program reached 50% production 2.0 days earlier than birds subjected to the step-up protein feeding program. Hen-day production for the step-down and step-up pullet feeding systems based on 308 days’ records was 76.09 and 76.86%, respectively. Feed efficiency and mature body weight were not significantly affected by grower feeding programs. The largest egg size and highest laying house mortality were noted in hens grown on the step-down protein feeding program.

Curvilinear Trends in Direct and Some Correlated Responses to Nineteen Generations of Selection for Part Record Rate of Egg Production in a Randombred Line of Chickens

Direct and correlated responses to 19 generations of selection for part record rate of egg production were studied. The select line (B line) was derived from a base randombred control line (A line) which, in turn, was derived as a random sample of the Regional Cornell control population. Cumulative direct and correlated responses were computed as deviations of the generation means of the various traits from the corresponding means of the control line. Second-order polynomial regressions of the various traits reveal significant curvilinear relationships between cumulative responses and cumulated selection differentials for the selection criterion (part record rate of lay) and the correlated traits, part record egg number, full record egg number, full record rate of lay, mature body weight, 32-week egg weight, and Haugh unit.It was determined that this line attained a limit of upward selection response in the 12th generation. The genetic change in the selection criterion per generation before the attainment of the limit was 1.07% (P<.001), which gave a highly significant (P<.001) direct response of .09% per unit of selection applied. Significant negative correlated responses were obtained for 32-week egg weight and Haugh unit; a nonsignificant decrease in body weight response was observed; age at first egg, shell thickness, and laying house mortality decreased in their correlated responses to 19 generations of selection for part record rate of lay; fertility and hatchability increased .05 and .02%, respectively, although these were not significant.

Long Term Effects of Marek's Disease Vaccination with Cell-Free Herpesvirus of Turkey and Age at Debeaking on Performance and Mortality of White Leghorns

Three-hundred-sixty, day-old Single Comb White Leghorn chicks were randomly placed in 8 treatment combinations. The combinations consisted of vaccinated or nonvaccinated chicks that were either not debeaked, or debeaked at day-old, 4 weeks old, or 8 weeks old. Vaccinated birds received 6,000 plaque forming units of cell-free herpesvirus of turkey vaccine per chick at day-old. Debeaking was performed by removing approximately two-thirds of the upper beak. Data were analyzed at the 5% level of probability.During the growing period (8 to 20 weeks of age), average daily feed consumption per bird and feed efficiency for the vaccinated birds were not significantly different from those for the nonvaccinated. Regardless of the age at which debeaking was performed, the debeaked birds consumed significantly less feed and had superior feed efficiency than the nondebeaked birds. These traits were not significantly different among the various debeaked groups. Vaccination, or debeaking, or age at debeaking did not significantly influence mortality during the growing period.During the laying period (20 to 84 weeks), a significantly higher percentage of extra large eggs and a significantly lower percentage of medium eggs were collected from the vaccinated birds in comparison to those collected from the nonvaccinated. Also, average egg weight for the vaccinated birds was significantly heavier than that for the nonvaccinated. Debeaking at either 4 weeks or at 8 weeks of age caused a significant reduction in egg weight. Vaccination, or debeaking, or age at debeaking did not significantly influence hen-day egg production. Feed efficiency between the vaccinated and die nonvaccinated birds was not significantly different. Debeaking tended to improve feed efficiency. Vaccination as well as day-old debeaking significantly reduced laying house mortality. Debeaking the birds either at 4 weeks or at 8 weeks of age reduced laying house mortality numerically.

Vaccination Against Marek’s Disease: Efficacy of Cell-Associated and Lyophilized Herepesvirus of Turkeys in Nine Strains of Leghorns

Females from six strains selected for high egg production and from three unselected control strains (a total of 11,000 chicks) were pedigree hatched from dams that had been vaccinated with herpesvirus of turkeys (HVT). On the day of hatch, each family of full sisters was divided at random into two groups, one of which was vaccinated with cell-associated HVT (C-HVT) and the other with lyophilized HVT (L-HVT). The chicks were adventitiously exposed to Marek’s disease (MD) virus and were observed to 497 days of age. A third group, consisting of 413 females of one of the unselected strains, was kept with the vaccinated chicks to 139 days of age as non-vaccinated controls.Total rearing mortality of the non-vaccinated pullets was 10.4% and rearing mortality due to MD was 5.6%. A comparison with rearing mortality in the vaccinated chickens of the same strain indicated that both C-HVT and L-HVT protected the pullets against MD. However, on an overall basis, the C-HVT vaccinated groups had a lower total laying house mortality (6.8 vs. 8.5%), laying house mortality due to MD (1.4 vs. 3.0%) and higher hen-housed egg production (246 vs. 242 eggs) than the L-HVT vaccinated groups. In one of the strains tested the L-HVT vaccinated pullets had 7% higher laying house mortality and laid a dozen eggs less than the C-HVT vaccinated pullets. This observation pointed out the dangers associated with drawing general conclusions about effectiveness of vaccines from testing only a small number of genetic stocks of chickens.

Light Intensity Required for Maximum Egg Production in Hens ,

Two experiments were conducted with a medium weight, brown egg hen to investigate the effects of various intensities of illumination upon egg production, feed consumption and mortality over a 50-week production period. Intensities of 5.38, 21.53 and 53.82 lux and a treatment consisting of a three month progressive increase on each intensity with the final period utilizing 107.64 lux were tested. In each of two trials, the birds exposed to 5.38 lux had the highest egg production; but the differences in egg production between the various treatments were not statistically significant. Feed consumption per hen and laying house mortality were not significantly influenced by light intensity.

A genetic analysis of adult mortality in leghorn by heavy‐breed reciprocal crosses1

1. Genetic mechanisms of resistance to disease in 1930 pullets and 296 cockerels were investigated by using a Leghorn line (G), a heavy-breed line (H), and their reciprocal crosses G x H and H x G plus two synthetic lines, GnH and HnG which were segregating for line-intact Z chromosomes. 2. The most frequent cause of death was leukosis. 3. Gmale x Hfemale pullets had a significantly higher adult mortality (40-9%) than the reciprocal cross (27-3%). 4. A direct effect of the Z sex chromosome on the incidence of leukosis or on total adult mortality could not be demonstrated. 5. Maternal breed effects and heterosis were relatively more important than Z sex chromosome and autosomal breed effects as causes of both leukosis and total laying house mortality. 6. The heavy-breed line had higher cellular resistance to the leukosis/sarcoma virus subgroups A and B than did the Leghorn line.

A Marek’s Disease Vaccination Trial

The New Brunswick Poultry Test Station was utilized to examine the protection afforded by a Marek’s disease vaccine administered to day old chicks via the subcutaneous route. Four commercial Leghorn-type strains of chickens were used. The vaccine was equally effective in all strains in affording protection during the brooding and growing stages as shown by a test mortality of 1.1% for vaccinated birds versus 8.6% for non-vaccinated birds. In addition, the laying house mortality was 19.1% less in the vaccinated groups.

Genetic and Phenotypic Variation in Randombred White Leghorn Controls over Several Generations

IT IS A generally accepted fact that adequate controls are essential for the estimation of genetic gain in selection studies. Lerner (1950), Dickerson (1955), Goodwin et al. (1955), Gowe and Johnson (1956), King et al. (1959) and others have recognized and discussed the value of control strains for the separation of genetic and environmental effects. Gowe et al. (1959) clearly demonstrated the value of a control strain by comparing absolute trends of two selected strains with trends estimated by use of deviations from a control population. These workers also studied changes in this White Leghorn Control Population during six years by regressing annual means on generation number. No significant changes in hen-housed and survivor egg production, body weight at housing, March body weight or laying house mortality were noted. A significant increase in March egg weight and a significant decrease in sexual maturity were observed. King et al. (1963) investigated.

Relation of Pre-Incubation Factors and Post-Hatching Performance to Length of Incubation Period: 2. Relation of Length of Incubation Period to Post-Hatching Performance

FUNK (1934) recorded mortality among birds of known incubation period, finding that the last 10 percent of the hatch had an 8-week mortality rate nearly 3 times that of the earlier hatched chicks. Henderson and Champion (1948) found a significant negative correlation between speed of hatching and 8-week weight in Rhode Island Reds. Other breeds indicated the same relationship, but estimated correlations were not significant. Henderson (1944) found significant positive regressions of age at sexual maturity on speed of hatching in White Leghorns and Rhode Island Reds, but his estimates for other matings were not significant.Hays (1941 a, b) summarized observations on 4,730 Rhode Island Red chicks hatched over a 3-year period. Salient points of his conclusions were that females predominated among early hatched chicks, mortality to 6 months increased with length of incubation period, there was no relationship between speed of hatch and laying-house mortality, early hatched pullets .

The relative importance of traits reported in the first three gosford random sample tests

Synopsis An analysis was performed on the published results of the first, second and third Gosford Random Sample Tests to determine which of the various biological traits reported had the greatest influence upon the overall ranking. Ten traits were considered. It was found that regression on survivors’ average egg production and laying house mortality removed 88.1 per cent of the variation in financial return. The addition of average egg weight and daily food consumption increased this figure to 93.3 per cent. The remaining traits, number of unsaleable birds at 500 days, body weight at 500 days, age at 50 per cent production, blood spots, meat spots and shell thickness, did not produce significant reductions except in so far as they were correlated with those previously mentioned. The financial returns expected from improvements in the four important traits were: Per bird + 12 in survivors egg production 2S. 4¼d. ± 1¼d. —5 in percentage laying mortality is. 5d.± 1d. + 1 g. in average egg weight 10½d. + 1 ½d. —5 g. in food consumed per day 43/4d.± 1¼d. Laying house mortality was found to be positively correlated among the entries with survivors’ average egg production and with average egg weight.

Effect of Restricted Feeding During the Growing Period on Reproductive Performance of Large Type White Turkeys

CONSIDERABLE interest in recent years has centered around feeding systems which bring about a decrease in the plane of nutrition either through the restriction of a “complete” ration or the full feeding of an “incomplete” ration at some interval during the growing period. The value of these systems in feeding replacement chickens and their secondary effects on subsequent production and reproduction has been explored by several groups of investigators (Schneider et al., 1955; Sunde et al., 1954; Milby and Sherwood, 1956; Isaacks et al., 1960; and Hollands and Gowe, 1961). In general it has been demonstrated that the body weight of growing pullets is reduced, the onset of sexual maturity delayed from two to four weeks and laying house mortality reduced as a result of lowering total feed intake. These studies do not indicate consistent effects of restrictive feeding on final body weight, total feed consumption, total eggs produced, egg …

Restricted Feeding of Pullets: 1. The Value of Pasture and Self-Selection of Dietary Components

THE EFFECT of restricting the feed intake of growing pullets on subsequent productivity has been reviewed recently by Gowe et al. (1960). It is generally agreed among researchers that restricted feeding in any of its forms reduces body weight and delays sexual maturity to an extent dependent upon the time and severity of restriction. When sexual maturity is delayed, normal egg size is attained more rapidly without any loss of total eggs laid, resulting in a greater total weight of eggs (Sunde et al., 1954; Schneider et al., 1955; Couch and Isaaks, 1957; Bruins, 1958; Bruckner and Hill, 1959; MacIntyre and Aitken, 1959; Walter and Aitken, 1961; Hollands and Gowe, 1961).When restriction is severe, mortality is usually increased during the period of restriction with a corresponding decrease in laying house mortality (Schneider et al., 1955; Bruins, 1958; Bruckner and Hill, 1959; Ringrose, 1958; Gowe et al., 1960; Hollands and …

The Effect of Restricted and Full-Feeding During Confinement Rearing on First and Second Year Laying House Performance

GOWE et al. (1960) have reviewed recent published comparisons of the performance during the first laying year of pullets reared under a restricted and under a full-fed regime. These authors concluded that restricting the feed intake during the rearing period will (1) reduce body weight at housing, (2) delay sexual maturity, (3) increase the intensity of egg production once the delay in sexual maturity has been overcome, and generally (4) lower laying house mortality, (5) increase egg size, and (6) return more profit excluding any differences in labour costs.There is very little information available on the performance of laying birds in their second production year following a restricted feeding program during the rearing period. As far as these authors are aware only Walter and Aitken (1961) have studied the effect of restricted feeding on second year performance. They found no differences between treatments in egg number in egg number…