Molting Layers—Alternative Methods and Their Effectiveness

Effects of non-fasting molting on performance, oxidative stress, intestinal morphology, and liver health of laying hens

Animal welfare concerns in laying-hen production facilities have necessitated research on alternative strategies for improving egg production and hen health. At present, most laying-hen facilities in China use the fasting method, but with international emphasis on animal welfare, scholars have begun to find ways to improve production efficiency while ensuring animal welfare standards are adhered to. Therefore, this study investigated the effects of non-fasting molting on production performance, oxidative stress, intestinal morphology, and liver health of laying hens. A total of 180 healthy 90-week-old Dawu Jinfeng laying hens with similar body weights and laying rates (76 ± 2%) were randomly divided into three groups, with five replicates per group and 12 hens per replicate. The hens in the experimental group (NF) were molted using the non-fasting method, the negative control group (C) was not treated with centralized molting, and the positive control group (F) was molted using the fasting method. The results showed that: (1) During the molting period, the laying rate in the NF group (10.58%) decreased and was significantly lower than that in the other two groups (P < 0.05). During the secondary laying peak period, the laying rate in the NF group was highest (89.71%); significantly higher than that in the C group (P < 0.05). (2) During the molting period, compared to the C group, the NF group showed a significant decrease and increase in the total antioxidant capacity (T-AOC) and superoxide dismutase (T-SOD) activity, respectively (P < 0.05). During the secondary laying peak period, the T-SOD activity of the NF group was significantly lower than that of the C group (P < 0.05). (3) During the molting period, the villus height (VH) and the ratios of VH to crypt depth (V/C) of the duodenum, jejunum, and ileum in the NF group were significantly lower than those in the C group (P < 0.05). At the secondary laying peak period, the jejunum V/C was significantly higher than that in the C group (P < 0.05), whereas in the duodenum and ileum it increased but not significantly (P > 0.05). (4) During the molting period, serum glutathione transaminase (AST) and glutathione alanine transaminase (ALT) activities were significantly higher (P < 0.05), and very low-density lipoprotein (VLDL) content and liver weight were significantly lower (P < 0.05) in the non-fasted and fasted groups. However, there was a low degree of liver injury (cell boundary still visible) in the NF group. At the secondary laying peak period, there was no significant difference (P > 0.05) in the indices among the three groups and the liver returned to normal. In summary, non-fasting molting can improve the production performance of laying hens in the later stages, ensure the welfare and health of animals, and provide a theoretical basis for the efficient production of laying hens.

Evaluation of different non-fasting molting methods on laying performance and egg quality during molting and post molting periods

The study evaluated different molt-inducing methods to achieve the main goal of molting in commercial layers during molting and post-molting periods. A total of 400 60-week-old Lohmann Brown layers were randomly divided into five groups (eight replicates of 10 birds for each group). Laying hens in the fasting control group received no diet from day 1 to day 10. The second group received a molt-inducing diet recommended by the breeding company. The third group received a wheat bran-based diet. The fourth group received a commercial layer diet with 8,000 ppm zinc (as zinc oxide, ZnO). The fifth group received an induced molting diet given to the second group with 8,000 ppm zinc, respectively. Egg production in the fasting control group and groups fed a diet with ZnO were significantly lower (p < 0.001) than those in groups fed the molt-inducing and wheat bran-based diets without ZnO during molting. Egg laying in the fasting control group was rapidly reduced and stopped on the 5.9th day of molting. In both groups having molt treatment with ZnO, egg production was similarly reduced and ceased on the 6.9th day and 7.0th day of molting, respectively, none of them differed significantly from the control. Layers fed molt-inducing diet or wheat bran-based diet did not reach the cessation of laying even on the 28th d of molting period. Relative weights of the ovary and growing oocytes of layers subjected to fasting or fed diets with ZnO were significantly lower than those of other groups. During the first two weeks of post molting, layers fed molt-inducing diet with ZnO showed higher egg production than the other two groups (p < 0.01). The eggshell strength in the group fed the commercial diet with ZnO was significantly higher than those fed the molt-inducing diet or wheat bran-based diets at 6 weeks of post molting (p < 0.05). These results suggest that the non-feed withdrawal molting using ZnO is more effective in inducing molting and increasing post-molt egg production and egg quality than other methods using a molt-inducing diet alone or wheat bran-based diet without ZnO.

Practices and issues of moulting programs for laying hen: A review

1. Moulting is a natural physiological process in birds when they shed their old feathers and replace them with new ones, and is followed by reproductive quiescence resulting in reduced egg production. Different birds undergo moulting at different points in their life. Some birds have seasonal moulting while some moult at the end of their breeding cycle. This review will mainly focus on moulting practices associated with commercial layer birds because, in all other bird types, this is not managed.2. Commercial farms commonly analyse the cost-benefit ratio to decide the time and method to adopt for moulting. Commercial layer farms adopt different practices to force birds out of moult and restart the production cycle. Animal welfare groups consider this as stressful and against animal welfare, raising questions about the ethics of this practice.3. Many studies have been conducted using complete or partial feed withdrawal and non-feed withdrawal programs to measure their effectiveness in maintaining animal welfare, economy, and post-moult performance in mind.4. Animal welfare should not be compromised during moulting. The United States Egg Producers and other such groups from the United Kingdom and Europe have decided to sell eggs produced only through a non-feed withdrawal moulting programs.

Welfare issues associated with moulting of laying hens

A practice that is used to extend the period of lay of hens is induced moulting. It involves restriction of nutrients, and sometimes manipulation of lighting, with the consequent loss of bodyweight and feathers, regression of the reproductive tract and cessation of egg lay. When the period of moulting is completed, the reproductive tract will regenerate and egg production will resume, thereby extending the overall period of lay. Towards the end of the laying cycle of hens, the production and quality of eggs decline. At this point, some egg farmers will induce a moult in the flocks to reduce bird-replacement costs and improve profitability. In the Australian egg industry, less than 10% of layers are moulted. There are implications for the welfare of hens that are induced to moult, particularly due to loss of bodyweight and feathers. Histopathological studies have shown the extent to which loss of feathers may affect welfare from a physical perspective, and it terms of pain. It is apparent that induced moulting can lead to an increase in aggression and injurious pecking, and birds with poor feather cover are vulnerable to damage from this pecking. Induced moulting can increase stress, although the implications of this for the welfare of hens is not well understood. The endocrine events associated with induced moulting are reasonably well known and it is possible to manipulate the endocrine system to extend the lay of hens without the need to moult. Nevertheless, these approaches are unlikely to be adopted into practice. More importantly, hens should always have feed and water available and are in good condition before undergoing a moult. This is essential from the perspective of ensuring adequate standards of welfare of birds.

Increased serum levels of advanced glycation end products due to induced molting in hen layers trigger a proinflammatory response by peripheral blood leukocytes

Induced molting (IM), a severe detriment to animal welfare, is still used in the poultry industry in some countries to increase or rejuvenate egg production and is responsible for several physiological perturbations, possibly including reactive oxidative stress, a form of metabolic stress. Because metabolic stress has been shown to induce a proinflammatory response involved in attempts to restore homeostasis, we hypothesized that similar responses followed IM. To confirm this hypothesis, we initially confirmed the establishment of oxidative stress during IM in 75-wk-old layers by demonstrating increased production of advanced glycation end products (AGE). Concomitant with increased oxidative metabolites, cellular stress was demonstrated in peripheral blood leukocytes (PBL) by increased levels of stress gene products (the glucocorticoid receptor, sirtuin-1, and heat shock protein 70 mRNA). Increased expression of stress proteins in PBL was followed by a proinflammatory response as demonstrated by increased levels of proinflammatory gene products (IL-6 and IL-1β mRNA); increased expression of these gene products was also demonstrated in direct response to AGE in vitro, thus establishing a direct link between oxidative and cellular stress. To establish a possible pathway for inducing a proinflammatory response by PBL, we showed that AGE increased a time dependent expression of galactin-3, Toll-like receptor-4, and nuclear factor - κB, all involved in the proinflammatory activation pathway. In vivo, AGE formed complexes with increased levels of circulating acute phase proteins (lysozyme and transferrin), products of a proinflammatory immune response, thereby demonstrating an effector response to cope with the consequences of oxidative stress. Thus, the harmful consequences of IM for animal welfare are extended here by demonstrating the activation of a resource-demanding proinflammatory response.

A biphasic curve for modeling, classifying, and predicting egg production in single cycle and molted flocks

Egg production on a flock level can be summarized into several phases determined by biology of individual birds: rapid increase in production reflecting achieving sexual maturity, peak production related to maximum laying potential, followed by gradual decrease in the rate of lay as the birds age. In 1989 Yang et al. proposed a mathematical model (modified compartmental model) to describe this process. In this study a biphasic modified compartmental model was proposed for modeling, classifying, and predicting egg production in single cycle and molted flocks. Goodness-of-fit was high for both single cycle (average R² = 0.99) and molted flocks (average R² = 0.97), suggesting that the model could be used for benchmarking molted flocks. The difference in R² between the biphasic model and the model used by Yang et al in 1989 can be used to differentiate between single cycle and molted flocks. The biphasic model was shown to predict future records well up to 8 wk in advance, but as with any regression model, caution is recommended when predicting records outside of the observed age range.

Reproductive management of poultry

Based on data from the UN's Food and Agricultural Organization, about 120 million metric tons of poultry meat were produced globally in 2016. In addition, about 82 million metric tons of eggs were produced. One of the bases for this production is the reproductive efficiency of today's poultry. This, in turn, is due to their inherent reproductive physiology, intensive genetic selection and advances in husbandry/management. The system of reproduction in males in largely similar to that in mammals except that there is no descent of testes. In females, there are marked differences with there being a single ovary and oviduct; the latter being the name of the differentiated entire Müllerian duct. Moreover, females produce eggs with a yolky oocyte surrounded by albumen, membranes and shell. Among the most successful reproductive management techniques are optimizing photoperiod, light intensity and nutrition. Widespread employment of these has allowed maximizing production. Laying hens can be re-cycled toward the end egg production. Other aspects of reproductive management in poultry include the following: artificial insemination (almost exclusively employed in turkeys) and approaches to reduce broodiness together with cage free (colony), conventional, enriched and free-range systems.

Evaluation of molt induction using cassava meal varying the length of feeding period in older (90 week) laying hens

Physiological changes during molt and postmolt egg production variables were compared among hens induced to molt by using cassava meal varying the length of the feeding period. Hens were randomly assigned to 3 treatments of 72 birds each: 1) molted by full feeding with cassava meal for 4 wk (CAS4); 2) molted by full feeding with cassava meal for 5 wk (CAS5); and 3) molted by full feeding with cassava meal for 6 wk (CAS6). All groups were fed a pullet developer diet for 2 wk following treatment. During the molt period, the birds were exposed to an 8L:16D photoperiod and had access to drinking water at all times. Thereafter, all hens were fed a layer diet (17.71% CP), and exposed to a 16L:8D photoperiod, and production performance was measured for 16 wk. The molt treatments resulted in total cessation of egg production in all treatments within 2 wk following feeding of the molt diet. BW loss of birds in the CAS6 treatment was approximately 41.81%, which was significantly higher (P < 0.05) than those in the CAS5 (37.63%) and CAS4 (31.89%) treatments. The CAS5 and CAS6 hens had significantly lower (P < 0.05) ovarian and oviducal weights than the CAS4 hens. No consistent differences were observed for concentrations of plasma estradiol and progesterone, bone quality, or mortality among the treatments. Postmolt feed consumption, egg weight, and mortality were not different (P > 0.05) as a result of molt induction method. However, the CAS4 hens had significantly higher (P < 0.05) cumulative egg production and lower feed conversion ratio than hens in the CAS6 treatment. Significant differences were found among treatments for Haugh units and shell thickness in some periods of the postmolt. It was concluded that cassava meal could be used to induce molt in laying hens effectively, feeding the molt diet for 4 wk produced optimum body weight loss and postmolt performance.

Comparative histomorphological and ultrastructural study of the luminal epithelium of the isthmus in laying and moulting domestic fowls (Gallus domesticus)

This study describes ciliated, nonciliated and mitochondrial luminal epithelial cells of the isthmus in laying and moulting domestic fowls using histological and ultrastructural techniques. The ciliated cells were nonsecretory, while numerous electron-dense secretory granules were present in the nonciliated cells of laying birds. Mitochondrial cells, occurring in two morphologically distinct forms, constituted the third type of epithelial cell present in the isthmus. The SEM study showed that the luminal epithelium was dominated by ciliated cells, the cilia of which partially obscured adjacent nonciliated cells. The involution of the luminal epithelium in moulting birds occurred via autophagy, apoptosis and necrosis. Autophagic inclusions, which included autophagosomes and autolysosomes, were present in the early degenerative phases of ciliated, nonciliated and mitochondrial cells. Nonciliated cells underwent degeneration via apoptosis, which was characterized by nuclear and cytoplasmic condensation. Apoptotic and necrotic ciliated cells were evident during the intermediate and advanced stages of regression. The presence of apoptotic cell death was confirmed using the TUNEL assay. Loss of cilia via the formation of cilia packets was observed using TEM and SEM. Necrotic cell death occurred in mitochondrial cells during the intermediate and late stages of degeneration. In conclusion, the findings of the study on isthmus involution in moulting birds suggest that autophagy is a process confined to the early stages of degeneration, while apoptosis and/or necrosis occur in the terminal stages of regression.

Alternative induced molting methods for feed withdrawal and their effect on post molt egg quality parameters of White Leghorn hens

Forced molting were practiced using the flock of hens by promoting a second laying cycle. In the present study, the effectiveness of induced molting method was studied in comparison to conventional feed withdrawal in terms of egg quality parameters. Layer chicken (160), 72–week-old were divided into 4 groups and were subjected to induce molting for a period of 14 days. The first group that received ad lib. water with complete feed withdrawal served as a control. The birds of the second group received ad lib. layer ration without calcium fortified with organic zinc (20,000 ppm) along with organic copper (600 ppm/kg of feed). The third group was provided with organic zinc (20,000 ppm) along with organic cobalt (150 ppm/kg of feed). The fourth group was provided with organic zinc (20,000 ppm) with organic chromium (500 ppm/kg of feed). Egg and shell weight were significantly different among different treatments; whereas, in shell thickness, egg production and body weight reduction, no significant difference was observed. The feed withdrawal treatment resulted in lower egg weight than other treatments. In conclusion, mineral supplemented methods could be substituted for conventional feed withdrawal method of induced molting.

An appraisal of moulting on post-moult egg production and egg weight distribution in white layer hens; meta-analysis

1. The aim of this study was to establish how different moulting methods and body weight losses influenced post-moult performance and USDA egg weight distribution. 2. Data on 5 laying flocks (#34-38) of the North Carolina Layer Performance and Management Test were used in this meta-analysis. 3. The moulting methods were non-fasted moulted (NF), short feed restricted (SF), 13-d feed restricted (FR), non-anorexic moult programme (NA), non-anorexic moult programme with low sodium (NALS) as well as non-moulting programme as control treatment. The percentages of targeted body weight loss during the moulting period were 20, 24, 25 and 30% of body weight at the end of the first egg production cycle. 4. Post-moult egg production and egg mass were influenced by all moulting methods. Maximum increase in post-moult egg production rate and egg mass occurred with FR and NF programmes, respectively, at 30% of body weight loss, compared to non-moulted hens. Non-fasting methods reduced mortality rate more effectively than fasting methods. 5. Moulting resulted in increases in percentage of grade A and decreases in percentage of grade B eggs. Non-fasting methods increased percentage of grade A eggs more effectively than fasting methods. Percentage of cracked eggs decreased in moulted rather than non-moulted hens and the lowest rate was associated with the NA programme. 6. Post-moult egg weight was not significantly influenced by moulting methods. However, percentage of body weight reduction affected egg weight. The optimum increment in egg weight was achieved by 24% body weight reduction. 7. Overall, non-fasting methods resulted in similar egg production compared with fasting methods. Considering post-moult mortality and USDA egg weight distribution, non-fasting methods, especially NF and NA programmes, performed much better than fasting methods, indicating that non-fasting moulting methods, which are better for animal welfare, are effective alternatives to fasting methods.

Animal welfare and society concerns finding the missing link

Young adults in developed countries are distanced from agriculture and the meat industry needs to do a better job of communicating with them. A major welfare concern is slaughter without stunning. Other concerns, such as poor stunning or high levels of bruising, can be easily corrected by management who is committed to maintaining high standards. Another concern is biological system overload, occurring when animals are bred for more productivity. Researchers and industry need to determine optimum production levels instead of maximums. Retailers are major drivers of animal welfare standards enforcement and they respond to pressure from both activists and consumers.

Applying the principles of welfare and quality of production in the organic farm of the laying hens

European Union  banned with Council Directive No. 74/1999/EC use of the conventional battery cages for laying hens in European Union with effect from January 1, 2012. By this time much attention was paid to the assessment of laying hens welfare in the modified breeding system,namely from aspect of behavior and expression fyziological stress. At present are used the enriched cages,   which device is defined by the Code of laying hens living conditions. Quantification of intensity and sequence of the events in different behaviour and a time regime can contribute to knowledge of time spending of the laying hens  in the breeding area and to determining of prioritizing their behavior.The aim of our research was assessment an application of principles laying hens welfare in the farm, their production and egg quality. An object of investigation was ecological farm of laying hens. In the experiment were observed thehousing conditions and nutrition of laying hens in farm, egg production, egg weight at laying hens old 42 weeks and selected indicators of chemical formation of the eggs. In the farm were reared laying hens ISA Brown, which are high-productive and the most   the most widely used in EU. The informations and data on farm, laying hen hall, breeding facility, breeding conditions, the behavior of the laying hens, nutrition, feeding and egg production were obtained by personal visit an organic farm and informations which  the farmer records and stores. The informations about the behavior of laying hens were obtained by observing and comparing with the knowledge and data of the Slovak Government regulation on December 11, 2002, which   minimum standards determine for the protection of laying hens.The informations on feed were obtained  directly from an organic farm and   feed company that followed by accordance  the minimum content of nutrients and energy in accordance with the needs of the laying hens. Egg production was monitored on the base of  collecting eggs two and several times a day, which was recorded daily on an organic farm. Chemical analyzes of samples of eggs were conducted according to the methodology for analytical laboratories (2009). In the farm were application welfare principles.  The laying hens had unlimited access to feed and water, ad libitum, free movement in the stable hall on the litter and perches. The laying hens rummaged and ashed in the free-range are of clay. In the free-range area of grassland where was a shelter, they free ranged and explorated environment. The microclimatic conditions, a construction of the perches, nests in the hall and location of the feedersand drinkers in the hall and in the free-range were solution in the accordance with the needs of improved living conditions of the laying hens. The laying hens achieved an intensity of egg-laying 84.60% in the all laying cycle. An egg weight was 62.30 g at laying hens old 42 weeks. The average dry mater contents was in the table eggs 26.21 g per 100 g of egg mass, the proteins 12.34 g per 100 g of egg mass, a fat 11.63 g per 100 g of egg mass and a cholesterol 1.27 g per 100 g of egg yolk. On the base of achivied the results, further research was recommended in the field the welfare of the laying hens intendent for the production of the table eggs.