Afrikaans 
Effect of Dietary Supplementation with Diatomaceous Earth on Egg Quality Traits in Hens Raised on Deep Litter
An excerpt from:
Abstract – The study was conducted to investigate the effect of dietary diatomaceous earth (DE) on egg quality traits in deep litter hens. A total of 280 Lohmann Brown pullets were at 20 weeks of age divided into 4 groups.
Three groups were fed on one of the three experimental diets supplements with 2%, 3%, or 4% DE, while the fourth group was fed on a control diet without DE supplementation. Each group had seven replicates of 10 birds. One egg was collected randomly per replicate (for a total of 7 eggs per group), weighted, and determined for: yolk weight, albumen weight, eggshell weight, eggshell thickness, specific gravity, albumen height, yolk height, yolk colour and Haugh unit. Findings showed that DE supplementation resulted in a significant (p<0.05) increase in eggshell weight and yolk height. Dietary supplementation with DE in the current study was, however, not effective on other egg quality parameters such as on eggshell weight percentage, egg specific gravity, yolk colour and Haugh unit. However, results of the study also showed that DE supplementation improved significantly (p<0.05) egg quality especially by improving viscosity as flocks grew older as compared to younger flocks. Further research should focus on the effect of dietary DE on eggshell and bone strength of layer birds. Research should also explore the interactions among the minerals found in DE (e.g., calcium, phosphorus and magnesium) and how these interactions affect egg quality in laying hens.
1. Introduction
Diatomaceous earth (DE) is the fossilized remains of diatom shells. The benefits of DE in animal production are numerous and include but not limited to health improvement; controlling internal and external parasites; and growth enhancement among other benefits. Diatomaceous earth has also found use as a feed additive where it serves as an anticaking agent as well as controlling mycotoxins. The demand for safe and ethical production of food is increasing each day. This has prompted producer’s animal products including organic poultry eggs and other poultry products. In organic farming, the routine use of prophylactic medications is not allowed. Natural products that are organic in nature such as DE need to be prompted to avoid the hazard resulting from the use of synthetic drugs in animal production that lead to residues in animal products posing a health hazard to consumers. Diatomaceous earth has been recently emphasized as an alternative to synthetic drugs in treatment of livestock diseases.
The economic losses due to cracked and damaged eggs account for 6 to 8% of the total egg production/ a weak, damaged or cracked eggshell can be a quick pathway for microorganisms to reach the inside of the egg leading to deterioration of its quality (ibid). High breaking strength of eggshell and absence of shell defects are paramount in safeguarding eggs against penetration of pathogenic bacteria such as Salmonella sp. On the other hand, eggshell quality attributes play a key role since only eggs having intact shells are taken for hatching or for table use. Nutritional factors for example mineral balance are crucial in maintaining good quality eggshell, so supplementation with bioavailable minerals responsible for the formation of eggshell can be a key strategy. Eggshell quality, therefore, is one of the most important aspects in the poultry industry since it has a big influence on the economics, especially profitability of egg production and hatchability. Therefore, ensuring eggshell quality is the surest way of increasing the number of eggs produced from each hen. Eggshell thickness is hence, one of the major egg quality parameters to consider. Egg shell quality decreases as the hen grows older. This is due to an increase in egg weight without an increase in the amount of calcium carbonate deposited in the shells. This usually leads to high incidences of cracked eggs towards the end of the laying period which could even exceed 20%. Consumers consider colour and viscosity of egg yolk among the key indicates when evaluating egg quality. The egg yolk is made up of 35% lipids; 16% proteins; and approx. 0.2% lipophilic pigments which include carotenoids. The egg yolk components combine to make up the final colour. The diet given to laying hens has a big influence on colour tones which range from light yellow to dark orange. Egg yolk colour is also influenced by carotenoids especially zeaxanthin, lutein and xanthophyl and these have antioxidant effects.
Discussion
Although not significant (p>0.05) at weeks 24 and 40 of age, the higher eggshell thickness observed in hens in intervention groups as compared to control groups in this study could be an indication that calcium absorption and utilization was higher in birds fed on DE supplemented diets. Eggs having thick and strong shells usually command a higher market elsewhere as compared to those with thin shells. This trait is of high economic importance since thick shells protect the eggs from breakage. The higher shell weight observed in weeks 32 and 40 of age might be attributed to the fact that mineralized eggshell is formed of calcium carbonate (96%); the remaining components include organic matrix (2%), magnesium, phosphorus, and a variety of trace elements. On the other hand, diatomaceous earth (diatomite) contains many minerals which include calcium, phosphorus, magnesium, silicone and many others as well as a range of trace elements which include iron, zinc, cobalt, potassium, manganese, molybdenum and sulphur. Therefore, DE supplemented diet in this study provided more calcium and other trace elements required in eggshell formation. The yolk height of intervention groups was higher (p<0.05) than in control group. A significant (p<0.05) increase in yolk height was observed throughout the entire duration of this study. This increase in yolk height might as a result of the mineral and trace elements present in DE (ibid).
Published on November 30, 2020
