Four failed clutches from Funkie and Fatina earlier this year had jolted me out of my complacency to re-examine certain areas regarding nutrition for breeding birds. Infertile and thin shelled eggs as well as the occurences of fits just cannot be ignored anymore and there was an urgent need for some serious thoughts on the inadequacy of the diet used for my breeding birds. They were fed with a diet of full live food which can be quite deficient in some nutrients.
Due to the risk of overdosing, I do not advocate heavy supplementations with vitamins and minerals and had instead, decided to switch the breeding birds from a full live food diet to feeding on mainly chicken feed until the eggs are hatched. Insects were used only as a supplementation for their valuable protein. This I feel, will take care of most of the deficiencies caused by the solely live food diet, except for the calcium inadequacy, which is the likely cause of thin shelled eggs. The starter formula for broilers that I had chosen to use, although will have sufficient calcium at the level to support maintenance, will be insufficient to provide the female birds for the high calcium requirements for egg shell formation during the days of egg laying. The option of supplementations with fishes and frogs will provide for a safer source of calcium supply but had seemed to me to be unpredictable at best. Previous observations of their use had not been totally without occurences of thin shelled eggs. Fishes were also being used during the period of the four failed clutches but had obviously failed to serve their purpose.
Using liquid calcium supplements may seem to be another option for me. Liquid calcium is quickly absorbed. This fast acting feature, I think can be best put to use during an acute deficiency to quickly restore normal muscular contractions. It can also be of good use as a supplement when needed, to prevent bone calcium depletion due to its deficiency in the diet. However, the risk of oversupplementing with liquid calcium cannot be ignored and at the least, that will interfere with the absorption of other nutrients. Just as in deficiency of this mineral, excess calcium will also affect the egg shell quality. Moreover, the solubility and fast acting properties of liquid calcium will render it to be not an ideal source for egg shell formation. I will try to explain this below.
The calcification of the egg shell at the last stage of the egg formation before it is laid, will take up to many hours (in chicken, the egg enters the shell gland of the oviduct about 19 hours prior to oviposition and calcium deposition is most rapid during the last 10 hours). Female shamas lay their eggs in the morning, hence most of the egg shell calcification will take place during the non-feeding hours at night. Calcium for the egg shell comes from the circulating calcium and when the circulating calcium is depleted, bone calcium will be mobilized. Studies in chicken have shown that when calcium is mobilized from the bones for egg shell formation, the egg shell quality is poorer. In contrast, a constant supply of this mineral from the digestive tract throughout the non-feeding hours at night, will yield better egg shell qualities. Hence, liquid calcium which will not be retained in the gut for a prolonged period, will not serve this purpose well. A slow release form of calcium may be required if I were to see improvements in my situation of thin shelled eggs being laid.
Several other studies in chicken have also indicated that using a less soluble and larger particle sized calcium supply in the form of crushed oyster shells can improve the quality of egg shells because they remain in the gut longer and will act to provide a slow release form of calcium supply during the non-feeding hours. The remaining question in my mind then was whether the female shama will consume crushed shells. Shamas are not like the seed-eaters that will consume grit as part of the diet. Will the instinct to seek out nutrients in times of need be able to drive her to consume something most of us would have assumed to be not her natural source for nutrients?
My previous experiments had indicated to me that female shamas will consume small trumpet snails when these are provided during the egg laying period. However, they will only consume baby snails about the size of sand grains and will leave out the larger ones. On several occasions, I had also witnessed female shamas consuming the egg shells of their own eggs after they had hatched. From these observations, there could be a possibility that they will also take to crushed sea shells and egg shells if these are provided. I proceeded to crush some egg shells and Yap(dance4rain), my good friend and shama breeding partner, provided me with some crushed 'lala' shells (lala is a popular shell fish consumed here, usually fried with sambal). These were mixed together and offered on a shallow dish. In order to have a clearer picture of the result, fishes were excluded from their diet (I don't feed frogs because they are not available here) and no other calcium supplements were provided. During the laying of the next clutch, the female shama was observed to eagerly feed on this mixture of crushed shells daily during the few days of egg laying but stopped as soon as the last egg was laid. The result was a clutch of 4 eggs and 3 of them hatched successfully. The remaining infertile egg was also observed to have good shell quality. I had continued to supplement calcium this way and she is now sitting on another clutch of 4 good sized eggs.
It may be too early to tell if other females will likewise be as eager to feed on crushed shells during the egg laying period. However, the current situation so far is encouraging enough for me to decide that I will also try this form of calcium supplementation with my other females when they are ready to be bred.
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