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PubMed1984

Influence of phase feeding available phosphorus on egg production characteristics, carcass phosphorus content, and serum inorganic phosphorus levels of three commercial layer strains.

An experiment was conducted to obtain information on the concept of progressively decreasing dietary phosphorus levels (phase feeding) on the performance of three different commercial layer strains. Dietary available phosphorus (AP) levels of .15, .30, or .45% were fed continuously from 22 to 70 weeks of age. Concurrently, a diet containing .35, .25, and .15% AP was phase-fed during age intervals of 22 to 34, 34 to 50, and 50 to 70 weeks, respectively. Dietary AP levels did not significantly affect egg production except the .15% AP level, which significantly reduced egg production when compared with the other three dietary AP treatments. Efficiency of feed utilization was significantly superior for hens phase-fed AP compared with hens fed the other AP treatments. There were no differences in egg weight or mortality due to dietary AP. Eggshells were significantly thicker when hens received .15% AP. The .15% AP and phase-fed regimen resulted in hens with significantly lower body weights at the end of the experiment. Hens fed .30% AP and phase-fed AP had significantly lower carcass ash and phosphorus levels. Serum phosphorus levels corresponded directly to dietary AP levels. There were no significant differences in egg production due to strain nor were there any strain by dietary treatment interactions that influenced production traits. Significant strain differences were noted in feed efficiency, egg weight, carcass ash, and carcass phosphorus.

Animal Feed↗
PubMed1984

Response of different commercial strains of laying hens to short total photoperiods in interrupted night experiments during days of 24 and 28 hours.

Experiments were conducted: as pilot experiments in which each experimental unit, replicated two or three times, consisted of 15 hens, as practical experiments in which each of four strains was replicated twice in two rooms containing 200 to 265 hens, and as commercial experiments in which each experimental unit consisted of 4 strains of 1000 hens but in which no replication occurred. Short total photoperiods were used in interrupted night experiments with 24-hr and 28-hr days. A light regimen of 2L:6D:2L:18D yielded similar results as 12L:16D for percent egg production, egg mass, egg shell breaking strength, and feed efficiency. Exposure to 28-hr days, in comparison with 24-hr days, resulted in a reduction of number of eggs produced but did not reduce egg mass produced. In one of four strains, the increase in egg size and reduction in number of eggs produced was significantly (P less than .05) less than in the other three strains, Under the 28-hr day regimens shell breaking strength was consistently greater (P less than .01) than under 24-hr light regimens. In an additional experiment, no relationship was found in egg breakage during transport between two populations of eggs that differed in eggshell breaking strength as a result of differences in light regimens received by the hens. Short (2L:10D:2L:10D or 2L:12D:2L:8D) and very short (2L:12D:1/4L:9 3/4D) interrupted night regimens generally yielded lower egg production than 16L:8D or 8L:10D:2L:4D light regimens. There was an indication that there might be strain differences in the response to the interrupted night regimen. Exposure to 2L:6D:2L:8D for 6 weeks at the start and 8 weeks at the end of an 11-month experimental period, with 16L:8D given during the remainder of the period, resulted in lower egg production during the last 8 weeks and no compensatory improvement in egg shell breaking strength or egg weight in comparison with continuous exposure to 16L:8D.

Animals↗
PubMed1987

Scanning electron microscopy of thin and soft shells induced by feeding calcium-deficient or vitamin D-deficient diets to laying hens.

A scanning electron microscopic study was conducted on shells from eggs laid by four groups of hens maintained on different types of diets: a) control, b) vitamin D3-deficient, c) Ca-deficient, and d) vitamin D3-deficient supplemented with 1,25-(OH)2D3. After 1 week for Ca-deficient hens and after 4 weeks for vitamin D3-deficient hens, the thickness of the shell decreased abruptly and numerous thin-shelled and soft-shelled eggs were laid. The study showed that with both Ca-deficient and vitamin D3-deficient diets, the outer layers of the shell (cuticle and spongy) were reduced or absent but the mammillary layer was present even in the thinnest soft-shelled egg. The order in which layers disappeared as treatment progressed was exactly the reverse of the order in which these layers are formed in normal eggs. No eggs were found without mammillary knobs, which suggests that the hens stop laying before Ca concentrations in blood become too low for the formation of the mammillary knobs. Uncalcified portions of the shell organic matrix were never found, suggesting that Ca deposition and matrix formation were inhibited simultaneously. The relationship between fibers of the shell membrane and mammillary knobs was preserved in all cases. The eggshells from hens on 1,25-(OH)2D3-supplemented diets were ultrastructurally indistinguishable from those of hens on diets adequate in vitamin D3.

Animals↗
PubMed1987

Pineal gland and ocular influences on turkey breeder hens. 2. Body weight, feed intake, and egg characteristics.

Yearling Large White turkey breeder hens underwent pinealectomy (PX), bilateral ocular enucleation (EX), or both and were then photo-induced into reproductive activity. During the subsequent 20-week reproductive period, data were recorded for body weight, change in body weight, feed intake, egg weight, eggshell thickness, and percent settable eggs. A significant interaction between PX and EX treatments did not occur for any of the parameters of this study. Absolute body weight, feed intake, shell thickness, and percent settable eggs were not significantly affected by PX during the study, but PX significantly increased egg weights. Feed intake was significantly reduced by EX, but other parameters were not affected. Both PX and EX reduced body weight losses typically observed in breeder hens during an in-season egg laying cycle. It was concluded that the pineal gland and the eyes can influence body weight changes, egg size, or feed intake in breeder turkey hens during a reproductive cycle.

Animals↗
PubMed1987

Evaluation of sex differences in embryonic heart rates.

Adult female chickens are known to have higher heart rates than adult males. Previous evidence suggested that sex-related differences in heart rates exist in embryos. The objective of the present study was to determine if differences in heart rate can be used for sexing chickens during embryonic development. The effects of hyper and hypothermia also were evaluated. On Day 14 of incubation, Single Comb White Leghorn embryos were candled and three surface electrodes were placed on the eggshell. The electrodes were attached to an electrocardiograph. Heart rates were recorded from Days 15 to 20 of incubation. Female embryos exhibited higher mean heart rates than males (2 to 4 beats/min) for Days 15 to 19 of incubation. Average heart rates of male and female embryos decreased and were significantly different when exposed to hypothermia (26.1 C for 2 h) on Day 15 of incubation. Hyperthermia (39.4 C for 45 min) on Day 15 of incubation increased embryonic heart rates, but male and female heart rates did not differ significantly. Extensive overlap between male and female heart rates under normal and hypothermic conditions makes this technique an industrially impractical method for determining embryonic sex.

Animals↗
PubMed1987

Influence of different phosphorus phase-feeding programs and dietary calcium level on performance and body phosphorus of laying hens.

Two nonphytate P (NPP) feeding programs (.35, -.25, -.15% NPP or .45, -.35, -.25% NPP during the age intervals of 23 to 35, 35 to 51, and 51 to 71 wk, respectively) were evaluated for White Leghorn hens in a complete factorial arrangement with 3.3 or 4.0% dietary Ca. Total P (TP) concentrations of the NPP feeding programs, as determined by analysis, were .60, -.48, and -.37 or .70, -.58, and -.46%, respectively. Egg production, feed efficiency, and egg weight over the 48-wk experiment were reduced significantly by the .35, -.25, and -.15% NPP program, irrespective of dietary Ca. Most adverse effects of the low NPP program occurred from 51 to 71 wk when hens fed .15% NPP consumed about 150 mg NPP daily as compared with NPP intake of 250 mg daily for hens fed .25% NPP. Hens fed 3.3% Ca consumed significantly more feed than did those fed 4.0% Ca, irrespective of NPP feeding program or age period. Neither NPP or Ca levels affected eggshell thickness at 71 wk nor mortality during the experiment. Dietary NPP and Ca did not significantly affect P content of the body, including feathers. Body P declined from an average of 8.6 g/hen at 23 wk of age to 7.3 g/hen at 55 and 63 wk. By 71 wk, body P returned to 8.6 g/hen. The results show that NPP intakes of 250 mg and 150 mg/hen daily from 35 to 51 and from 51 to 71 wk, respectively, were inadequate for laying hens' performance, but no adverse effects of these NPP intakes on body P were detected. It seems that utilization of dietary P was affected adversely by high ambient temperatures.

Animals↗
PubMed1988

Significance of growing photoperiod and light stimulation at various ages for Leghorn pullets subjected to regular or ahemeral photoperiods.

Leghorn pullets were cage reared to 15 or 19 wk of age in environmentally controlled rooms that provided either 8 h or 14 h of light per day. In Experiment 1, birds were moved to laying cages at 15 wk of age and subjected to either 14 h light (L): 10 h (D) dark or ahemeral 14L:14D photoperiods. Feed intake, egg weight, shell quality, and egg production were monitored to 67 wk of age. In Experiment 2, pullets were moved at 19 wk of age and subjected to 14L:10D or 17L:7D light programs. Production parameters were measured as previously described. No significant (P greater than 0.5) interactions were observed between rearing and laying photoperiods, suggesting that increase in the length of photoperiod around time of maturity is not essential for adequate performance. In Experiment 1, ahemeral lighting resulting in reduced egg production, whereas egg shell quality and egg weight were improved (P less than .05). In both experiments, the 14-h rearing program resulted in improved egg size together with improved eggshell quality (P less than .05). Whereas increased egg size may relate to body weight, no explanation is apparent for the consistent pattern with respect to shell quality. In Experiment 2, poorer shell quality was observed with 17 vs. 14 h light per day. It is concluded that light stimulation at maturity has little effect on overall egg production. Improved shell quality observed with birds reared under 14 h light vs. those reared under 8 h per day may relate to a less rapid attainment of peak egg production.

Aging↗
PubMed1989

Effects of lighting program during the growing period and dietary fat during the laying period on broiler breeder performance.

In two experiments, broiler breeders were grown in either of two lighting regimens, fed diets without added fat, and then fed diets with or without 5% added poultry fat during the subsequent laying period. In Experiment 1 half the birds were subjected to decreasing daylength using daylight (800 lx) and half were subjected to 9 h of incandescent light (20 lx) to 20 wk of age. In Experiment 2 the lighting regimen was either an 8-h photoperiod supplied by daylight (800 lx) or an 8-h photoperiod supplied by incandescent light (20 lx) to 20 wk of age. Added dietary fat produced significantly higher egg weight (Experiments 1 and 2), egg production (Experiment 2), and significantly lower fertility and hatchability of fertile eggs (Experiments 1 and 2). Short photoperiods (8 or 9 h) provided by incandescent light produced significantly higher fertility (Experiments 1 and 2) and hatchability of fertile eggs (Experiment 2), and significantly lower egg specific gravity, shell percentage (Experiment 1), egg weight, and eggshell weight (Experiment 2). Effects on fertility may be related to higher female body weight during lay due to daylight rearing or added fat, or relative changes in light intensity at photostimulation.

Analysis of Variance↗
PubMed1990

Effect of feeding diets containing corn treated with a commercial mold inhibitor (Myco Curb) on broiler-breeder performance.

Corn purchased from commercial sources was split at delivery and was left untreated or treated with a commercial mold inhibitor. Feed was prepared from these two lots of corn from within 1 wk to as much as 20 wk after delivery over the course of two experiments. There was evidence of reduced mold growth due to the mold inhibitor, particularly in the second experiment where initial mold populations were higher. Mycotoxins were evident in feed samples, regardless of the corn treatment. There was no significant effect from the treatment of corn on growth, livability, egg production, feed conversion, egg weight, or the eggshell quality of broiler breeders. Treatment of corn with a mold inhibitor significantly increased hatchability of fertile eggs in both experiments. Fertility was also significantly improved in the second experiment. These data suggest that using corn treated with a mold inhibitor results in significantly better hatchability in broiler breeders than untreated corn, although there were no observed differences in the incidence of mycotoxins in the samples taken.

Animal Feed↗
PubMed1990

Accumulation and distribution of ions of group-IIIA elements in the tissues and eggs of the Japanese quail.

Solutions of salts of the five Group-IIIA elements were given, intravenously, to mature Japanese quail. By 18 h, the accumulation maxima in the major tissues were: leg bones, 20% for Ga+3 (67Ga label) in estradiol-treated males; liver, 51% for Al+3 (26Al label) in control males; kidneys, 32% for In+3 (114mIn label) in estradiol-treated males; and growing oocytes plus ova, 37% for In. Accumulations of Tl+1 (202Tl label) were 6 times those for Ga or In in the brain and muscles, and .1 times in plasma. The cumulative maxima in egg components over 8 (B; Tl) or 10 (Al; Ga; In) days were B, 23% in albumen; Al, 38%, Ga 27%, In, 43% in yolks; Tl, 12% in shells. The accumulation of thallium in the eggshells markedly exceeded (P less than .001) the deposits of the other IIIA elements in shells, Al being the next highest at .54%.

Aluminum↗
PubMed1990

Some observations on the influence of vitamin D metabolites when added to the diet of commercial laying hens.

Three experiments were conducted to study the influence of two vitamin D3 metabolites on the performance of commercial laying hens. In Experiment 1, adding of .75, 1.50, 3.00, and 4.50 micrograms of 1 alpha-hydroxycholecalciferol (1 alpha-OHD3) or of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] per kg to the diet containing 2,200 ICU of vitamin D3 from 55 micrograms of cholecalciferol per kg of diet resulted in increased plasma calcium (Ca) and phosphorus (P). The response was greater from the 1,25-(OH)2D3 metabolite than from the 1 alpha-OHD3 metabolite. Neither metabolite affected tibia breaking strength (TBS), egg production (EP), egg weight (EW), feed consumption (FC), feed conversion, eggshell quality (ESQ), fertility, or the hatchability of eggs or the tibia ash (TA) of the day-old chick. In Experiment 2, the EP, EW, FC, ESQ and TA of the hens were not affected when 1.5 micrograms of 1,25-(OH)2D3 were added to each kilogram of a corn-soybean meal diet containing either .38 or .43% P with adequate vitamin D3. Adding the 1,25(OH)2D3 metabolite to the low-P diet reduced plasma Ca and increased TBS. However, adding 1,25-(OH)2D3 to the high-P diet increased plasma Ca and P. In Experiment 3, the EP, ESQ, FC, and TA of the hens were significantly lower when the diet contained 2.04% Ca rather than 3.04% Ca. Plasma Ca and P, EW, or TBS were not affected by the dietary Ca. Neither the plasma Ca and P, EP, EW, ESQ nor the TBS and TA were influenced by adding the 1,25-(OH)2D3 metabolite to either diet.

Animal Feed↗
PubMed1991

Response of laying hens to supplemental niacin.

Two experiments were conducted to investigate the effect of supplemental niacin on laying hen performance and liver fat and egg cholesterol content. In Experiment 1, 16 replicate groups of four adjacently caged birds were fed corn and soybean meal diets calculated to contain 22, 44, 66, or 132 mg supplemental niacin/kg (23.2, 38.7, 57.0, and 143 mg/kg niacin by analysis). Egg production, egg weight, feed intake, and eggshell quality were assessed each 28 days through a 364-day trial period. After 280 days, cholesterol content on three eggs per replicate was measured. At the end of the study, one bird per replicate was killed for subjective scoring of liver fat content. In Experiment 2, 24 birds from the control treatment (22 mg/kg supplemental niacin) of Experiment 1 were retained and fed for a subsequent 28-day period. Over this time, eight birds were each fed diets containing 22, 522, or 1,022 mg/kg supplemental niacin. Egg cholesterol content was measured in eggs collected on the last 3 days of the study. In Experiment 1, birds fed 66 or 132 mg/kg supplemental niacin/kg produced more eggs (P less than .05) than birds fed 22mg/kg. Niacin supplementation affected shell quality (P less than .05). Dietary niacin level had no effect on egg cholesterol content of liver lipid evaluation. In Experiment 2, supplementary niacin levels up to 1,022 mg/kg, which more closely stimulates therapeutic levels used for humans, again failed to affect egg cholesterol content.

Animal Feed↗
PubMed1991

The effects of various dietary phosphorus levels on the circadian patterns of plasma 1,25-dihydroxycholecalciferol, total calcium, ionized calcium, and phosphorus in laying hens.

Six hundred and sixty 75-wk-old Hy-line W36 hens were allocated to one of three dietary levels of total phosphorus, .30, .60, or .90%. Birds were fed the diets for 3 days following which blood samples were collected at six different times, 2, 6, 10, 14, 18, and 22 h postoviposition (POP), and analyzed for 1,25-dihydroxycholecalciferol [1,25-(OH)2 D3], total calcium (TCa), ionized calcium (Ca++), percentage Ca++ to TCa (%Ca++/TCa), and phosphorus (P). Plasma TCa and P significantly (P less than .001 and .025, respectively) peaked at 10 to 14 h POP. The Ca++ and %Ca++/TCa significantly (P less than .001) decreased during eggshell formation and following completion of the shell (22 h POP) levels returned to resting concentrations. Plasma 1,25-(OH)2D3 results confirmed the existence and time of a circadian rhythm in laying hens. Peak concentrations of the metabolite occurred at 10 to 14 h POP, which resulted in a quadratic relationship (P less than .001). Plasma P decreased with decreasing dietary P and plasma 1,25-(OH)2D3 increased (P less than .025). Feeding low dietary P significantly (P less than .001) increased Ca++ and %Ca++/TCa. Results of feeding various levels of dietary P to laying hens indicate that low P stimulates an increase in plasma 1,25-(OH)2D3 as well as Ca++ and %Ca++/TCa, but high P actually suppressed this response.

Animals↗
PubMed1991

Effectiveness of zinc bacitracin on production traits and energy metabolism of heat-stressed hens compared with hens kept under moderate temperature.

Two experiments with a total of 100 White Leghorn hens (26 to 59 wk of age) and 120 Rhode Island Red chickens (4 to 12 wk of age) were conducted to study the effect of 100 mg zinc bacitracin (ZBA)/kg of feed on hens and chickens acclimatized to 20 or 34 C environments. Layers were provided ad libitum access to a diet containing 11.12 MJ ME/kg (1 MJ = .239 Mcal) and 174 g CP/kg supplemented with 0 and 100 mg ZBA/kg. Body weight gain, egg number, total egg mass, and feed efficiency of ZBA-treated hens kept at a moderate temperature (20 C) were not significantly improved by 3.5, 2.6, 3.3, and 3.1%, respectively. However ZBA supplementation induced a more pronounced increase in performance in heat-stressed hens. The respective traits were significantly improved by 66.3, 15.4, 16.9, and 5.9%. Additionally, treated hens maintained at 34 C consumed significantly more feed than untreated hens. Eggshell breaking strength of treated hens held under normal conditions was not significantly improved. Feeding ZBA to heat-stressed hens led to a statistically higher breaking strength. Supplementation with ZBA for hens acclimatized to 20 and 34 C reduced fasting heat production by 4.1 and 7.6%, respectively. However, in the 20 C environment the differences were significant at only one of seven ages. The upper critical temperature (UCT) of ZBA-treated hens increased significantly at both temperatures from 34 to 42 wk of age relative to the control group. No significant effects of ZBA on UCT were observed at 24 to 32 wk and 40 to 52 wk of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Genetic variation in the incidence of pipped eggs in turkeys selected for low and high semen ejaculate volume.

Genetic variation in embryonic mortality, expressed as embryos that pip their eggshell but do not hatch, was investigated in turkeys selected for low and high semen ejaculate volume (SEV). Through five generations (Generations 10 to 14, inclusive) mean heritability estimates for pipped eggs were .21 and .08 in the low- and high-SEV lines, respectively. Estimates of sire, dam, and within-hatch components of variance suggest greater environmental and maternal effects than genetic influences on the incidence of pipped eggs in turkeys.

Animals↗
PubMed1991

Effect of dietary sodium zeolite A and graded levels of calcium on growth, plasma, and tibia characteristics of chicks.

Sodium zeolite A (SZA), a synthetic sodium aluminosilicate having high ion-exchange capacity, has been shown to increase eggshell specific gravity in laying hens and to improve Ca utilization in chickens. A 4 x 2 factorial arrangement of treatments was used to investigate the effect of dietary Ca (.6, .8, 1.0, and 1.2%) and SZA (0 and .75%) on growth, plasma, and tibia characteristics of chicks from 5 to 15 days of age. Increasing dietary Ca linearly increased (P less than .05) Ca and alkaline phosphatase (AP) in plasma and increased tibia shearing force and percentage ash, Ca, and P in tibiae. However, dietary Ca linearly decreased (P less than .05) inorganic P and Mg in plasma and Mg and Mn in tibiae. Sodium zeolite A decreased (P less than .05) plasma P and AP and tibia Mg but increased (P less than .05) tibia Ca, Zn, Al, and Mn concentrations. Tibia ash and shearing force were increased in chicks fed SZA receiving inadequate dietary Ca, but they were decreased in chicks fed SZA and excess Ca (Ca by SZA interaction, P less than .05). Tibia density showed a similar trend, but the effect was not significant (Ca by SZA interaction, P less than .12). The addition of SZA enhanced tibia ash, density, and shearing force when dietary Ca was low; however, when added to diets containing 1.2% Ca, SZA reduced many bone mineralization indices with the exception of tibia Ca.

Aluminum↗
PubMed1991

Iodine toxicity in large white turkey breeder hens.

Iodine was fed to turkey breeder hens during a 20-wk laying cycle to determine the appropriate dietary level to support reproduction and avoid toxicity. A basal diet that contained by analysis. 7 ppm iodine supported good hatchability of Large White turkey eggs. Supplementing 35 or 350 ppm iodine to the basal diet resulted in toxic effects (P less than or equal to .05) on hatchability. Feeding 350 ppm also depressed (P less than or equal to .05) egg weights, egg production, and eggshell water vapor conductance. Embryonic mortality data indicated that toxic effects of iodine on embryos occur principally during the 1st wk of incubation and immediately prior to and during pipping. It was concluded that iodine toxicity may occur in Large White turkey breeder hens when 350 ppm are fed in the diet.

Animals↗
PubMed1992

Effect of duration of fasting on postmolt laying hen performance.

Two experiments were conducted to examine the effects of varying length of feed withdrawal on postmolt laying hen performance. Commercial laying hens (65 wk of age) were fed continuously or fasted for 4 or 10 days in Experiment 1 and fed continuously or fasted for 4, 7, or 14 days in Experiment 2. Egg production performance was evaluated for 35 wk of production following initiation of fasting. Hen-day egg production (Weeks 1 to 35) and egg weight (Weeks 5 to 35) did not differ between treatments in Experiment 1; however, in Experiment 2, egg production was depressed for the 14-day fasted hens compared with the fed hens. Lower egg weight also occurred for the 14-day fasted hens compared with the fed, 4-, or 7-day fasted hens in Experiment 2. Egg yield (grams of egg per hen per day) for Weeks 5 to 35 was lower for fed hens versus the 4- or 10-day fasted groups in Experiment 1, but no treatment differences occurred in Experiment 2. Feed efficiency (grams of egg per gram of feed) for Weeks 5 to 13 was not affected by length of fasting in Experiment 1, but feed efficiency of hens fasted for 14 days was lower (P less than .05) than that of hens on other treatments in Experiment 2. Egg specific gravity was highest for hens fasted for 10 or 14 days and was lowest for fed hens, with egg specific gravity for hens fasted for 4 or 7 days being intermediate (P less than or equal to .05). The results indicated that fasting periods of less than 10 days may yield satisfactory egg production and egg weight but that eggshell quality may be enhanced by using fasting periods of 10 days or longer.

Animals↗