Cracked Eggs and Role of Calcium – Trouble Shooting
Calcium in Eggs: Eggshell which weighs about 5 to 6 grams contains around 2g pure calcium. Eggshell is made of mainly calcium carbonate and some protein. Calcium carbonate is about 94% of the total shell mass. Imbalance calcium feeding is often associated with eggshell problems in which cracked shells are a major quality issue and responsible for market egg rejection. There are certain points which needs to kept in mind while troubleshooting cracked egg reasons.
Calcium Partitioning: The reproductive system of hen is a luxury system which works properly only when all nutrients are available in abundance. The body never diverts basic nutrients towards egg production, which are required to sustain a life of hen. It means first of all body completes its basic needs of survival than produces eggs. Calcium is no exception to this. When calcium deficiency arises in feed it will first reduce and then cease ovulation in order to protect a hen’s bone integrity.
Cracked Eggs: The very first and often rapid response of calcium deficiency is the production of cracked eggs or thin-shelled eggs. Under such circumstances, we must carry out the comprehensive drill to evaluate calcium feeding. Following points could be helpful to reduce shell related losses when such problems arise.
Source of Calcium: Major source of calcium in feed is calcium carbonate which is commonly available as limestone powder or LSP. Recommended particle size is usually 50% 1mm and 50% 2-5mm. As the hen ages its ratio get increases by up to 65 %: 35%.
Concentration in Feed: Calcium concentration in feed is around 4% and this should be adjusted as per the amount of feed consumption and hen’s age. In general, hen requires 4g calcium each day in initial days of laying which increases up to 4.5g as hen ages.
Role of Organic Acids: In the last days of laying cycle addition of organic acid increases calcium solubility and bioavailability in the intestine, therefore, the inclusion of organic acids is beneficial sometimes especially when hen ages.
Chloride Imbalance: Higher chloride feeding seems to be the finest example of metabolic mineral antagonism. Chloride is antagonistic to calcium and chloride feeding more than 0.24% increases calcium deficiency especially in summer months. Excess chloride feeding reduces carbonate production in hen which is required for the formation of calcium carbonate in during egg calcification.
Watch out Chloride Sources: One should also account for chloride coming from lysine hydrochloride and choline chloride. If chloride content is higher than required than any deficiency of sodium should be corrected with sodium bicarbonate or sodium sulphate.
Saline Water: Saline water contributes to excess salt intake in which chloride again become a problem. While calculating total sodium and chloride intake salinity of water must be taken into account.
Oyster Shell could Improve Calcification: Oyster shell is expensive than limestone powder but considered as a superior calcium source. When cracked egg problem surfaces oyster shell usually respond positively in correcting shell issues. Although LSP and oyster shell used interchangeably in layer feed and LSP is preferable due to its low cost and abundant availability. Oyster supplementation in evening time in addition to normal calcium feeding in feed is recommended.
Timing of Calcium Feeding: In continuation of the above point, the timing of calcium feeding is very important and for that calcium cycle of laying hens should be understood properly. Ovulation occurs in the morning and than albumin deposition occurs. Calcium requirements increase in the late afternoon as calcium deposition is started in the late afternoon. But feeding is decreased in the evening and consequently, calcium availability for shell deposition becomes reduced. So feeding calcium in the evening in large particle size proves to be very fruitful and helps in reducing eggshell cracks.
Phosphorus Antagonism to Calcium: Excess phosphorus is antagonistic to calcium absorption in the intestine which could aggravate calcium deficiency. Available phosphorus must not be greater than 0.4% in finished feed.
Excess Mineral Supplementation: An unnecessary large amount of mineral supplementation is also caused a problem because most of the minerals like magnesium, potash, manganese, zinc, copper etc are antagonistic to calcium.
Egg Size: As the hen ages size of egg increases while ovulation frequency decreases. When the egg gets more time in reproductive passage more amount of albumin deposited but calcium deposition is not increased. A larger egg does not contain more calcium carbonate than a smaller one. So, a similar amount of calcium has to a larger surface. A hen deposits around 2 grams of calcium per egg regardless of size. As a result, larger eggs will invariably have thinner eggshells. This problem cannot be resolved by increasing calcium intake. But in this case, increasing ovulation frequency could resolve the problem up to some extent, increasing frequency with the help of egg production stimulator products is quite a good option.
Vitamin D Inclusion: Vitamin D is essential for calcium absorption and adequate levels should be added to the feed. Adding at least 3,000-4,000 units per kg of finished feed should be adequate for most situations. Vitamin D3 (VD3), also known as cholecalciferol, is the inactive form of vitamin D that can be ingested through dietary intake while adding 25-OH-D3 (calcidiol), the first internal metabolite of vitamin D, has been shown to increase calcium retention in hens. Vitamin feed premixes for poultry are rich in cholecalciferol, but levels higher than the requirement of vitamin D3 generally have no beneficial effect on performance, or the eggshell and bone calcification process. However, the occurrence of signs of rickets and dyschondroplasia in chickens fed D3-rich
practical diets may suggest that transformation of cholecalciferol in the liver and kidney is insufficient. This results also in poor eggshell quality and leg problems – as often observed in modern intensively producing laying hens flocks. Inclusion of the active form of Vitamin D in hen’s diet is an important strategy to correct eggshell problems.
Mycotoxin Zearalenone: Certain mycotoxins (zearalenone) are known to bind vitamin D in the feed. Water administration of vitamin D is recommended in acute phases of mycotoxin contamination. Vitamin C has been shown to be an effective antidote to zearalenone. Inclusion of vitamin C at the rate of 200g per ton of feed is quite effective. Increasing vit D in the diet has no apparent benefits.