Effect of removing trace minerals from the diet of hens laying eggs with heavy or light shell weight

The Role of Zinc in Poultry Breeder and Hen Nutrition: an Update

Zinc (Zn) is an essential trace mineral in breeder hen diets and functions in diverse physiological processes, including reproduction, immunity, antioxidant ability, and epigenetic processes. In this paper, five main aspects of Zn nutrition in poultry breeder birds and hens, including semen quality, molting, egg production and egg quality, hatchability and embryonic development, and offspring performance, are reviewed. Zn deficiency in poultry breeder birds led to lower semen quality (reducing around 10% sperm motility) and egg production (lowering 3-10 g/day/bird egg mass) as well as poor offspring development and growth performance (increasing 9-10% weak chick ratio and 10% mortality of progeny). Adequate maternal or higher Zn supplementation was adopted not only to induce molting with a greater postmolt performance (rising 4-7% laying rate) but also to enhance progeny immune response and antioxidant ability via epigenetic mechanisms. Therefore, it is necessary to reevaluate the optimal Zn requirement for egg production as well as the embryonic development and offspring chick performance of breeder hens. In the last 10 years, greater attention has been focused on the effectiveness of organic Zn for improving the reproductive performance of breeders and progeny viability and immune status. In fact, organic Zn sources are not always beneficial to the above aspects. So far, it has been very important to know the exact mechanisms of greater bioavailability and the epigenetic role of organic Zn sources in the augmentation of immune status and antioxidant abilities in poultry breeder birds and offspring. Therefore, a comprehensive analysis of these key points will not only aid in maintaining the beneficial effects of Zn nutrition for breeders and their progeny under stable conditions but will also support birds under stressful conditions such as disease as well as provide a better understanding of the integrated nutrition of breeder-offspring.

Dietary manganese supplementation influences the expression of transporters involved in iron metabolism in chickens

To investigate the effects of dietary manganese (Mn) supplementation on iron (Fe) metabolism, a total of 480 50-week-old hens were fed the basal diet (control, 24.35 mg Mn/kg) without Mn supplementation for 6 weeks to reduce Mn storage in the body. Hens were then randomly assigned to one of three treatments, which included the control and control added with 60 or 300 mg Mn/kg diet (M-Mn or H-Mn). Duodenum, heart, liver, and tibia were collected in hens after 12-week feeding period. No significant differences were observed in egg production, feed/egg ratio, shell breaking strength, and shell thickness among different treatments. Compared with control or M-Mn, H-Mn decreased (P < 0.05) serum Fe concentration, while increased (P < 0.05) total Fe-binding capacity (TIBC). The Fe concentration decreased (P < 0.05) in duodenum, and tended to reduce (P < 0.10) in liver from control to M-Mn and to H-Mn; whereas, dietary Mn supplementation did not influence (P > 0.10) Fe concentration in the heart and tibia. In conjunction with reduced Fe retention, DMT1 mRNA expression decreased (P < 0.05) with dietary Mn concentration increasing in the duodenum and liver. Duodenal FPN1 mRNA level was higher (P < 0.05) in H-Mn group than that in control or M-Mn group, while hepatic FPN1 mRNA expression was lower (P < 0.05) in M-Mn or H-Mn group when compared with control. The results demonstrated that dietary Mn supplementation decreased Fe concentration in duodenum and liver of hens, which may be related to the alteration of DMT1 and FPN1 expression in these tissues.

Supplementation of poultry feeds with dietary zinc and other minerals and compounds to mitigate nitrogen emissions--a review

One of the environmental challenges that the poultry industry has been faced with is ammonia emission from manure. One way to reduce nitrogen excretion and emissions is supplementing dietary trace minerals to inhibit the activity of microbial uricase, a key enzyme converting nitrogen compounds in the manure into ammonia. Several dietary minerals are commercially available as economic alternatives for reducing ammonia emissions in poultry. In this review, we discuss different mineral elements including zinc as feed amendment minerals that could be used to reduce ammonia emission. Issues discussed include potential for inhibiting microbial uricase, dietary supplementation levels, growth performance, toxicity, their influence on manure nitrogen emission, and potential mineral accumulation in soil. In addition, we discuss other minerals and compounds that have the potential to reduce ammonia volatilization by inhibiting microbial uricase and growth of uric acid-utilizing microorganisms.

A combination of zinc and pyridoxine supplementation to the diet of laying hens improves performance and egg quality

The objective of this study was to investigate whether zinc, along with pyridoxine, is effective in improving performance and egg quality of laying hens. One hundred and twenty, 28-week-old Hy-Line laying hens were assigned to four treatment groups, 30 hens each. The birds were fed a basal diet or the basal diet supplemented with either 30 mg of zinc/kg of diet, 8 mg of pyridoxine/kg of diet, or 30 mg of zinc plus 8 mg of pyridoxine/kg of diet. Feed conversion (P < 0.01) and egg production (P < 0.01) improved most when both zinc and pyridoxine were supplemented to the diet. Eggshell weights were also greatest (P < 0.01) when the diet was supplemented with both pyridoxine and zinc. Egg-shape index was, however, greatest with zinc-supplemented diet (P < 0.004). Haugh unit was greatest in eggs of hens fed a diet supplemented with both zinc and pyridoxine (P < 0.01). Dietary zinc and pyridoxine supplementations together increased plasma calcium and phosphorous concentrations (P < 0.002). The results of the present study suggested that zinc (30 ppm) and pyridoxine (8 ppm) supplements, when used together, are recommended in terms of a better performance and egg quality in laying hens.

Supplementation of a corn-soybean meal diet with manganese, copper, and zinc from organic or inorganic sources improves eggshell quality in aged laying hens

An experiment was conducted to evaluate the effects on eggshell quality of supplementing the diet of laying hens with a combination of Zn, Mn, and Cu from organic or inorganic sources. Three groups of hens, aged 32, 60, and 69 wk were fed a corn-soybean basal diet containing 32.6 mg/kg Zn, 24.7 mg/kg Mn, and 4.95 mg/kg Cu or a basal diet supplemented with 30-30-5 and 60-60-10 mg/kg of Zn, Mn, and Cu, respectively. Addition of Zn, Mn, and Cu in combination increased their concentrations in egg yolk and slightly decreased egg weight during some sampling from aged hens. The Zn, Cu, and Mn dietary supplementation did not affect the following measures of eggshell quality: percentage eggshell, eggshell index (shell weight per unit surface area), and eggshell stiffness. However, there was a small increase in elastic modulus of the eggs from one group of the older hens due to supplementation with Zn, Mn, and Cu. More consistently we observed improved breaking strength and fracture toughness (resistance to fracture) in the two oldest groups of hens at 1, 5, and 9 wk after introduction of the experimental diets. The effect was observed regardless of the source of trace elements.

Effects of maternal nutrition on hatchability

The effects of dietary factors on the development and viability of avian embryos have been extensively documented. A good nutritional status of the parent birds is crucial to the transfer to the egg of an adequate, balanced supply of nutrients required for normal development of the embryo. The consequences to the embryo may be lethal if the egg contains either inadequate, excessive, or imbalanced levels of nutrients. As nutritional deficiencies or excesses occur, it is common for the effects on the embryo to also become more severe and to occur at earlier stages of development. The type of nutritional stress signs visible in the embryo often depend upon the severity of the maternal nutritional stress. Diseases, parasitic infections, toxins, poisons, or drugs may also cause nutritional or pseudonutritional problems with hatchability.