جستجوی مقالات مرتبط با کلیدواژه « molting » در نشریات گروه « علوم دام »

Stress increases the need for antioxidants, decreases eggs production and weakens immune system of laying hens. Since there is insufficient knowledge about overcoming natural stress conditions with minimal cost and side effects in old laying hens, the medicinal herb contained flavonoid and polyphenolic compounds are concerned. Apart from estrogenic, antibacterial effects and cholesterol reduction property that will result to lower cholesterol deposition in poultry products and where calyx and leaf of Hibiscus sabdariffa
are known as potent antioxidant. Therefore, these experiments were designed to investigate the effect of Hibiscus sabdariffa extract as natural antioxidants on the immune system, blood biochemical parameters, plasma antioxidant status and the antioxidant balance of laying hens during molting and post-molting periods, also, laying performance and egg yolk cholesterol in the second phase of laying hen egg production.

In these experiments, aqueous-alcoholic extract of calyx and leaf of Hibiscus sabdariffa were prepared and sprayed on feed at levels of 300 and 700 mg/kg. One liter of %96
ethanol/distilled water mixture (30:70) were used to infuse 100 g each of the plant material (calyx or leaf) for 24 h. During the pre-experimental stage, minerals composition and antioxidant properties of Hibiscus sabdariffa were measured. Each of the main experiments, were conducted with 200 laying hens in a completely randomized design. In both experiments, five treatments consisted of control diet (basal diet), basal diet with 300 and 700 mg/kg of leaf extract of Hibiscus sabdariffa and basal diet with 300 and 700 mg/kg Hibiscus sabdariffa calyx extract. In both experiments, the blood cholesterol, total protein, triglyceride, LDL, HDL, glucose and malondialdehyde were evaluated by Spectrophotometer auto analyzer. In the end of each experiment, immune system and plasma antioxidant status for 2 samples from each replicate were determined. The egg production, egg weight, egg mass, feed intake and feed conversion ratio were recorded weekly. The egg malondialdehyde was determined during post molting period. In order to measure the level of yolk cholesterol and triglyceride, in the end of the experimental period, 2 samples were randomly taken from each replicate and after separating the yolks and mixing them, were analyzed by Spectrophotometer auto-analyzer with enzymatic method. The data were statistically analyzed with the general linear model by SAS software. The
mean differences between treatments were studied by Tukey's test.

Although there was more vitamin C in the leaf compared to calyx, the antioxidant activity including total antioxidants, phenols and anthocyanins in calyx were higher than
leaf. In both experiments, plasma antioxidant status of laying hens in a dose-independent manner were improved. During post molt period, attempt to increase oxidative stability of plasma and egg yolk also, improving plasma antioxidant status by dietary supplementation of Hibiscus sabdariffa extract was not significant, however, the Hibiscus sabdariffa calyx at 300 and 700 mg/kg levels, significantly affected plasma MDA and total antioxidant capability during molting period. In both experiments, the relative increase in antibody titers and the ratio of heterophil to lymphocyte were observed by all treatments as compared to the Control treatments. Hibiscus sabdariffa showed to have no significant effect on performance parameters. Probably, the negative effect of polyphenol compounds found in Hibiscus sabdariffa on digestive enzymes decreased lipid, protein and carbohydrates digestibility, thus reduced feed intake, egg weight and total blood protein, insignificantly, blood glucose and cholesterol, significantly. Also, the Hibiscus sabdariffa, especially leaf, decreased the yolk cholesterol and triglyceride. On the other hand, supplementation of Hibiscus sabdariffa at 700 mg/kg, improved production performance following feed conversion ratio compared with Control treatment that's probably due to quercetin and daidzein phytoestrogens found in Hibiscus sabdariffa. It seems that some compounds in Hibiscus sabdariffa, including phytoestrogens and organic acids that has been reduced the negative effect of other Hibiscus sabdariffa components on the performance of laying hens.

It can be concluded that Hibiscus sabdariffa, especially its leaves, which are discarded in most countries, including Iran, have the significant beneficial effects, such as anti-lipid effects, improvement of total plasma antioxidant and oxidative balance of old laying hens, with minimal cost and no significant negative effect on functional and immune parameters. It seems that finding of effective dose of Hibiscus sabdariffa is important to achieve layer hens’ maximum efficacy according to the test conditions and can economically be extended the range of its usage.

CLA is a mixture of several geometrical and positional conjugated isomers of linoleic acid (C 18:2 cis-9, cis-12). Ruminant products, such as milk, meat, and cheese, are major CLA sources in human diets, but foods obtained from non-ruminants, contain much less CLA. Some reports showed positive effects of CLA on production performance of layer hens. Egg internal quality traits may be depressed during storage, but incorporation of CLA, may increase the permeability of the yolk membrane due to the cis-trans arrangements of CLA, therefore ion movement between the yolks and albumen through the yolk membrane, restrict some changes in egg internal quality traits, therefore an experiment was conducted to evaluate the effects of different levels of CLA in post-molting phase of laying hens on production performance and egg quality in different storage times and temperatures.
Material and In this experiment, sixty W-36 White leghorn laying hens in post-molting phase (78 week) were assigned to 3 treatments with 5 replications and 4 birds each based on completely randomized design. The purity of CLA source used in this study was above 90% with mixture of 50% c9-t11 and 50% c10- t12 isomers. Experimental diets were 1) Control diet (basal diet containing 0% CLA), 2) basal diet+0. 25% pure CLA and 3) basal diet+0.5% pure CLA and after adaptation period, diets were fed for 4 weeks. During the experiment, hens were provided feed and water ad-libitum. Egg production, egg weight, feed consumption, egg mass and feed conversion ratio were recorded weekly and reported as total period. Every two weeks, internal and external quality traits such as albumen percent, yolk percent, albumen pH, yolk pH, Haugh unit, yolk height, yolk Roche scale, yolk index, egg size, egg surface, specific gravity, shell strength, shell percent and thickness were evaluated. The eggs from treatments having best production performance (0.5 %) collected and stored in different temperatures (4 and 27° C) and duration times (1 day, 1 week and 1 month after production) then evaluated their internal quality. Results showed that egg production performance and egg mass of birds fed 0.5 % CLA was significantly higher than control or those fed 0.25 % during whole experimental period, but egg weight and feed consumption were not affected significantly by dietary CLA level and feed conversion ratio of birds fed 0.5 % CLA was significantly (P<0.05) lower than control or those fed 0.25 %. In the end of experiment, the internal egg quality traits such as albumen percent, yolk percent, albumen pH, yolk pH, Haugh unit, yolk height, yolk Roche scale, yolk index were not affected by dietary CLA levels (P>0.05). Also the external egg quality traits such as egg size, egg surface, specific gravity, shell strength, shell percent and thickness were not affected significantly. Results of egg quality traits during different times and temperatures showed that main effects of CLA levels, storage times and storage temperatures were significant (P<0.05) on most important egg internal quality traits such as Haugh unit and pH of albumen. Interaction effects of CLA levels with storage times and temperatures were significant (P<0.05) and in eggs kept within higher temperatures and longer times, albumen pH of eggs for birds fed 0.5 % CLA, were lower compared to albumen pH of eggs for birds fed control diet containing 0 % CLA. These results indicate that ion movement between the yolks and albumen through the yolk membrane in eggs from hens fed 0.5 % CLA was greater than that in the control eggs and caused to restrict pH increase during storage. It is speculated that the incorporation of CLA, most of which was in the trans form, could have increased the permeability of yolk membrane because of the cis-trans arrangements of CLA, which would have increased membrane fluidity and sizes of space between the fatty acid chains of phospholipids that constitute the membrane bilayer. It is concluded that use of 0.5 % CLA in post-molting diet of laying hens improved egg production performance of birds and restricted luctuations in pH and Haugh unit changes of eggs keep during high storage temperatures and duration times, therefore it is suggested to adding 0.5 % pure CLA in post-molted laying hen diets.

An experiment was conducted to evaluate effects of different levels of grape pomace in diets of laying hens on egg production performance and egg internal quality traits during different times and temperatures. One hundred and sixty Leghorn laying hens in post-molting phase were assigned to four treatments with five replications and eight birds each based on completely randomized design. The birds fed experimental diets containing zero, 1.5, 3 and 4.5% of grape pomace for eight weeks. Egg samples from treatment 4 were selected and stored in different temperatures (4 and 27° C) and duration times (1 day, 1 week and 1 month after production) at the end of experiment, then their internal quality traits were evaluated. Results showed that with the use of 4.5% grape pomace, the egg production rate, egg weight, egg mass and feed conversion ratio of birds were not affected, but feed intake decreased (P

The objective of this experiment was to studythe effects of fiber-rich molting diets as alternative to the conventional feed withdrawal method, on performance, gastro intestinal fermentation and microbial activity of laying hens. One hundred eighty Hy-line (W36) laying hens were used in a completely randomized design with 5 treatments and 6 replicates by 12 birds in each replication during 12 days. Treatments were: 1- control group (hens fed with a layer diet), 2- feed withdrawal group, 3- laying hen diet containing 20000 mg zinc oxide/kg, 4- laying hen diet diluted by adding 90% alfalfa meal, 5- laying hen diet diluted by adding 90% palm kernel meal. Egg production of hen was monitored for 12 weeks during post molting period. Results show that lactobacilli and Escherichia coli bacteria population was significantly greater (P

Introduction The commercial egg industry commonly uses induced molt procedures to rejuvenate flocks for a second or third laying cycle. Molting may be induced by feed withdrawal for up to 10 days (7), water withdrawal for 2 days (19), or both, along with a reduction of day length (14). Such programs cause concern about animal welfare because it is thought that they may be harmful to hens (28). Given the concerns for potential bird stress, various methods of nutrient restriction that would avoid long term feed withdrawal have been investigated (20, 24). One of the alternative methods for molt induction is high-dietary Zn (4).
Materials and Methods In this study, a total of 30 Hy-line W-36 leghorn hens (at 50 wk old) (1400 ± 150 g), were randomly assigned to 5 replicate. Ten cages (3 hens in each cage) on both the upper and lower tiers were considered to observe behavior patterns. Data recording of predetermined behavioral patterns were carried out using five Camera Digital Video Recorder Multiplexer System. Behavior recording began at 9:00 h each day and ended at 11:00 h and a second observation starting at 16:00 p.m and ended at 18:00 p.m. Total of ten cages (containing 3 hens/ cage (30 hens total)) were used to collect 5 behaviors (feeding, drinking, nonnutritive pecking, preening and aggression pecking) and one posture (sitting). The following ethogram was adopted from Webster (27) feeding defined as pecking behavior directed toward the feed trough or toward a neighboring feed trough. Drinking was defined as the appearance of ingesting water from the nipple at the near of the cage. Nonnutritive pecking was defined as non aggressive pecking at anything other than feed, which included cage pecking, feather pecking, bill pecking and air pecking. Preening behavior involved the manipulation of the plumage with the beak. Aggressive was the sum of pecks that occurred within a cage or between neighboring cages. Sitting was defined as a crouched posture with shanks or breast in contact with the cage floor.
Results and Discussion Percentage of observation of all behaviors except for non-nutritive pecking was significantly affected by high dietary zinc (P

This experiment was conducted to evaluation effect of molting program by single feed on performance، plasma metabolites، and supply organs weight and egg quality in laying hens. Treatment groups were feed deprivation، ad libitum access to corn، alfalfa meal and alfalfa leaf meal programs vs. full fed layer ration (Control). Results shown that Alfalfa group resulted in total cessation of egg production sooner than other groups in molting period. At the end of molting period، plasma phosphorus levels of alfalfa and alfalfa leaf groups and plasma calcium levels of Control group were exhibited higher concentrations than other groups. Ovary، oviduct and liver weight of molted groups were lower than Control group. Also proventriculus+gizzard Alfalfa and Alfalfa leaf groups were higher weight than other groups. Intestinal weight and plasma glucose concentration was not differing significantly between groups. In postmolt period، hens fed by corn reentered and reach to 10% and 50% hen-day egg production significantly faster than other hens، but feed deprivation group showed adverse effete. Post molt egg production، egg weight and egg mass (wk 3 to 9) for the alfalfa leaf group were generally higher and feed intake and FCR for feed deprivation group lower than for other groups. At wk 4 of post molting، albumen percentage of control group was significantly heavier and yolk percentage lighter than other group. Shell percentage and shell thickness of corn group were highest. Egg of hens molted by alfalfa or alfalfa leaf has higher albumen and yolk height and Haugh units than other molting programs. The results of current study suggested that molting with alfalfa and alfalfa leaf were used in replace to feed deprivation molting program.