The efficacy of using prelay and early-lay rations for brown-egg pullets.

Experiments were conducted using two brown-egg strains to determine whether additional calcium or CP is required by these pullets prior to sexual maturity (prelay) and whether increased CP during the early part of production (early lay) would improve overall performance. In Experiment 1, the prelay treatments were arranged at a 2 x 3 factorial arrangement with two levels of CP (15 or 17%) and three levels of calcium (.9, 1.8, or 3.5%) and given to the pullets from 18 to 20 wk of age. From 20 to 26 wk of age, pullets were given either a 17 or 19% CP ration with 3.5% calcium, resulting in a total of 12 treatments. There were no significant effects of the prelay or early-lay rations on eggs per hen housed, hen-day percentage production (HDP), or feed efficiency. Egg weight was significantly improved using the 17% prelay ration at 26, 28, and 31 wk of age, but adversely affected by the higher levels of CP in the early-lay ration at 28 and 31 wk of age. Increasing calcium in the prelay ration had only minimal effects on egg size distribution. Experiment 2 consisted of a 3 x 2 factorial arrangement of treatments with three levels of prelay CP (15, 17, or 19%) and two levels of early-lay CP (17 or 19%) and given to the pullets from 18 to 20 to 41 wk of age, respectively. There was a significant improvement in HDP from 30 to 41 wk of age using the 19% CP prelay ration. Egg size distribution was not significantly affected by either the prelay or the early-lay rations at 35 wk of age.

Research note: influence of ahemeral light:dark cycles on egg traits in brown egg pullets.

Brown egg pullets (DeKalb Sex-Sal) were subjected to an ahemeral lighting program to determine their response in terms of egg traits. All birds were reared on a conventional lighting program of 10 h light (L):14 h dark (D) to 16 wk. At 16 wk, all birds received a schedule of 11L:13D followed by a weekly 1-h increase in photoperiod to 14L:10D at 19 wk. Control treatment (CON) birds were continued on this schedule. Ahemeral treatment (AHM) birds were given a 28-h schedule 14L:14D at 23 wk that was continued to 28 wk, then returned to a 24-h cycle of 14L:10D. Shell weight responded quickly to the ahemeral treatment and showed a significant (P less than .05) increase during the 2nd 28-h cycle. Shell thickness and total egg weight showed significant increases on the 3rd cycle; albumen weight showed an increase on Cycle 4, and yolk weight increased significantly only on the 8th cycle. When AHM treatment birds were returned to a conventional cycle (14L:10D) at 28 wk, the total weight remained significantly higher (P less than .05) as late as Cycle 6.

Effect of ahemeral light:dark cycles on egg production in early photostimulated brown-egg pullets.

A laying trial was conducted to determine the effect of an ahemeral lighting program on early photostimulated brown-egg pullets (DeKalb Sex-Sal). All birds received 24 h of light/day (24L:0D) to 3 days of age followed by 8 h of light (8L:16D) to 8 wk of age. From 8 to 16 wk the birds received 10 h of light daily. At 16 wk, the control group (CON) received 11 h of light and 13 h of darkness (11L:13D) followed by a weekly 1-h increase in photoperiod to 14L:10D at 19 wk, which was maintained for the duration of the trial (59 wk of age). Birds on the ahemeral (AHM) schedule were exposed to a 26-h schedule of 11L:15D at 16 wk with a weekly 1-h increase in the photoperiod to 14L:12D at 19 wk. The AHM schedule (14L:12D) was maintained from Weeks 19 to 30 at which time birds were returned to a 24-h cycle of 14L:10D and kept on this schedule for the remainder of the trial. Egg weight was significantly increased by the AHM treatment for 27 to 30 wk; however, there was no cumulative (Weeks 19 to 59) effect on egg weight. Percentages of eggs per hen per day (%HDP) were significantly reduced by the AHM treatment for the periods 23 to 26 wk and 31 to 34 wk. This reduction caused a significant cumulative effect on %HDP (68.9 for CON versus 66.2 for AHM).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vitamin E and synthetic antioxidants on the survival rate of mercury-poisoned Japanese quail.

The effect of vitamin E and the synthetic antioxidants, 6-ethyoxy,1,2-dihydro 2,2,4-trimethylquinoline (ethoxyquin), 2,6 bis(1,1 dimethyethyl)-4-methylphenol (BHT), N,N-diphenyl-p-phenylene diamine (DPPD), bis-(diethyl thiocarbamoyl) disulfide (Antabuse), and 2 tertiary-butyl-4-methoxyphenol (BHA) on organic mercury-induced mortality was investigated in Japanese quail. When the synthetic antioxidants, ethoxyquin, BHT, and Antabuse were fed at 1% of the diet, they induced mortality. Ethoxyquin was less toxic in combination with mercury (Hg) than when it or mercury was given alone. Of the antioxidants tested at .5% of the diet, only Antabuse was toxic as shown by increased mortality. At .5% of the diet, both ethoxyquin and DPPD reduced mortality associated with organic Hg poisoning. Neither BHA nor BHT had any effect in reducing Hg toxicity. In fact, mortality from organic Hg was greater when organic Hg was given in combination with .5% BHT than when given alone. Vitamin E was equal or superior to all synthetic antioxidants tested in alleviating the toxicity of organic Hg poisoning. The cause of observed antioxidant protection during organic Hg stress is not known but the protection may result from the ability to scavenge free radicals generated by induction of in vivo peroxidation by the Hg compound.

Effects of early maturation of brown egg-type pullets, flock uniformity, layer protein level, and cage design on egg production, egg size, and egg quality.

Eight-week-old Harco Sex-Link pullets were assigned to four growing regimens. Feed was restricted to Group 1. The birds reached an average weight of 1.52 kg at 20 weeks of age and were then light stimulated. Group 2 received the same ration ad lib and reached an average weight of 1.64 kg at 16 weeks. At this age they were light stimulated. Birds in Groups 3 and 4 were separated into two weight classes at 8 weeks of age. Those below the median weight received an 18% protein grower ration and those above the median weight a 16% ration. Group 3 birds were grown similarly to Group 1; Group 4 birds were grown similarly to Group 2. At housing, each group was equally divided and given either a 17 or 19% protein layer ration. Two cage designs (standard and reverse) were used and each treatment combination was equally represented. Ad lib-fed, early-housed pullets reached 1.64 kg at 16 weeks of age, but they did not come into production until 19.4 weeks of age. Hen-day percent production (HDP) was significantly less than for the late-housed pullets. Feed per dozen eggs was not affected by the early housing, but early-housed pullets laid significantly smaller eggs and feed per gram egg was significantly increased. Hens in reverse cages on a 19% protein layer ration laid the largest eggs in weight and size. Although early housing had a detrimental effect on average egg weight, it appeared possible to manipulate egg weight and size distribution through a combination of cage design and layer protein. Birds grouped by body weight at 8 weeks had higher uniformity, but this trait was not correlated with egg numbers or size. Moreover, housing body weights were not significantly correlated with egg size, suggesting factors other than body weight were responsible for the smaller eggs from early-housed pullets.

The effect of pelleting the layer ration on egg size in early-housed brown-egg-type layers.

Harco Sex-Link pullets (n = 360) were reared in cages and given a 15% protein grower ration. At 17 weeks of age, half the birds were transferred to laying cages and the photoperiod was increased to 13 hr for the first week and to 15 hr thereafter. The remaining birds were continued in the growing facility on 8 hr of light until 19 weeks when lights were increased to 13 hr daily. These birds were transferred to the laying cages at 20 weeks of age where they received 15 hr of light. At 2% production, all birds were fed a 17% protein layer diet in either a mash or pelleted form. Neither egg production nor feed efficiency was affected by age at housing or the physical form of the ration. Early-lighted pullets produced a greater percentage of small and medium-sized eggs. Egg size distribution was not affected by the physical form of the ration

Effects of early maturation, layer protein level, and methionine concentration on production performance of brown-egg-type pullets.

Three hundred and sixty 17-week-old Harco Sex Link pullets were transferred to laying cages and received 13 hr of light daily for the first week followed by 15 hr the second and subsequent weeks. A second group of 360 pullets remained in the growing facility on 8 hr of light until 19 weeks of age when the light was increased to 13 hr. At 20 weeks these birds were transferred to the laying facility where they received 15 hr of light daily for the duration of the experiment. A 15% protein grower ration was fed until daily production of each group reached 2%, at which time the diets were changed to either a 17 or 19% protein layer ration, each supplemented with DL-methionine so as to contain .3 or .4% total methionine. Early housed pullets averaged 140.4 days at first egg whereas late housed reached sexual maturity at 149 days. The initial increase in egg production by the early housed pullets was followed by a more rapid decline and overall, from housing to 66 weeks, equivalent egg numbers were produced. The early housed pullets were less efficient than the late housed birds due in part to their larger body mass. The greater percentage of small and medium-sized eggs produced by the early housed birds was not influenced by increasing the concentration of protein or methionine in the layer ration.

The effect of mercury and vitamin E on tissue glutathione peroxidase activity and thiobarbituric acid values.

The effects of methyl mercuric chloride (CH3 HgCl) and mercuric chloride (HgCl2) on red blood cell (RBC), plasma, and liver glutathione peroxidase (GSH-Px) activities were determined in Japanese quail fed a semipurified diet with 1 ppm added selenium (Se). The RBC GSH-Px activity was significantly increased by 5 ppm mercury (Hg) as CH3 HgCl. Plasma GSH-Px activity was significantly depressed only in th 20 ppm Hg group. Liver GSH-Px activity was not affected. The RBC GSH-Px activity was significantly lower at all levels of HgCl2 compared to the Ch3 HgCl-treated birds. Plasma and liver GSH-Px activity of the HgCl2 -treated birds were not significantly different from control values. In a second experiment, GSH-Px activity and estimates of peroxidation via the thiobarbituric acid (TBA) test were determined on quail fed diets containing .07 ppm added Se to which either 10 ppm Hg as CH3 HgCl or 150 ppm Hg as HgCl2 were added with or without the supplementation of vitamin E. Plasma and kidney GSH-Px activities were unaffected by CH3 HgCl, whereas RBC GSH-Px was significantly elevated. Kidney GSH-Px was significantly depressed by HgCl2-Vitamin E had no effect on GSH-Px activities. Vitamin E protected the liver, kidney, and brain from peroxidation; however, peroxidation was not induced by either of the mercurials.

Vitamin E deficiency in the Japanese quail.

Japanese quail were maintained on a low vitamin E soybean meal diet for 35 weeks. Percent fertile eggs was significantly decreased after 20 weeks and hatchability was severely depressed. Free tocopherol in the plasma of both sexes was markedly reduced in the deficient birds. Plasma creatine phosphokinase was unaffected by the low vitamin E treatment. Although no other clinical symptoms were observed, dietary vitamin E (2 IU/kg diet) was inadequate to support normal reproduction.

Mercury metabolism in Japanese quail. I. The effect of dietary mercury and selenium on their tissue distribution.

Immature and adult coturnix quail were fed isolated soybean protein diets to which methylmercuric chloride or mercuric chloride were added with or without supplemental selenium for seven days. Samples of brain, blood, liver, and kidney were analyzed for total mercury and selenium via atomic absorption spectrophotometry. Selenium addition had no effect on the mercury concentration in kidney, brain, or blood but did tend to increase the concentration of mercury in the livers of the methylmercuric chloride-treated birds. Selenium in the presence of methylmercury increased the selenium concentration of liver and kidney but had little effect on the selenium concentration of brain or blood. Methylmercuric chloride supplementation resulted in increased selenium concentration in the blood of the selenium supplemented group. All other tissue selenium levels were unaffected by the addition of mercury.