Influence of Dietary Calcium on Bone Calcium Utilization

At about 16 mg, zinc per 100 gm of diet feed consumed by laying hens increased until a level of 2.0% dietary calcium. Increasing the dietary calcium to 2.0% also stimulated more egg production. When less than 2.0% dietary calcium was fed more feed was required to produce a dozen egg and the eggs were of small sizes. The egg shell strength and the bone calcium were improved when at least 2.0% dietary calcium was given to the laying hen. These results were correlated with tissue accumulation of zinc thus establishing that for profitable egg production in the tropics 2.0% dietary calcium is required when 16 mg zinc per 100 grains of feed is given

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Circadian variations in contributions of bone and intestine to plasma calcium in dogs

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1984.246.5.r688 ◽

1984 ◽

Vol 246 (5) ◽

pp. R688-R692 ◽

Cited By ~ 2

Author(s):

K. M. Wong ◽

L. Klein

Keyword(s):

Sole Source ◽

Dietary Calcium ◽

Normal Diet ◽

Plasma Calcium ◽

Dietary Calcium Intake ◽

Circadian Variations ◽

Calcium Diet ◽

Low Calcium Diet ◽

Bone Calcium ◽

Calcium Pool

Young euparathyroid dogs, prelabeled with radiocalcium and fed a normal-calcium diet exhibited circadian variations in the amount of bone calcium contributed to the plasma calcium pool, as evaluated by changes in plasma calcium-45 radioactivity. When these dogs were fed a low-calcium diet or fasted, the contribution of bone calcium to plasma calcium rose to the point where bone constituted nearly the sole source of plasma calcium, and plasma calcium-45 no longer varied. In thyroparathyroidectomized (TPTX) dogs fed a normal diet, the fraction of plasma calcium due to bone contribution was reduced and plasma calcium-45 did not vary. When dietary calcium in TPTX dogs was increased by supplementation with calcium lactate pills, total plasma calcium rose, but the contribution of bone calcium to the plasma calcium pool remained unchanged. Thus the ability of normal young dogs to modulate bone calcium mobilization in response to dietary calcium intake appears to be hormonally regulated in a circadian manner.

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Eggshell quality and calcium utilization in feed of hens in repeated laying cycles

Czech Journal of Animal Science ◽

10.17221/90/2009-cjas ◽

2010 ◽

Vol 55 (No. 2) ◽

pp. 66-74 ◽

Cited By ~ 6

Author(s):

H. Arpášová ◽

M. Halaj ◽

P. Halaj

Keyword(s):

Shell Thickness ◽

Dietary Calcium ◽

Shell Formation ◽

Shell Deformation ◽

Eggshell Quality ◽

Opposite Trend ◽

Number Of Cycles ◽

Advanced Cycles ◽

Calcium Utilization

Hens of the laying hybrid Shaver Starcross 288 were used in two consequential experiments. The first experiment (for 10 months) was conducted on hens at the age from 18 to 60 weeks (1st cycle; n = 50) and moulted hens after 10 months laying from 70 to 110 weeks of age (2nd cycle; n = 50). For the second experiment (for 8 months) in the 1st cycle 18 weeks old hens were bought (n = 60) and hens from the first experiment after moulting were used in the 2nd and 3rd cycle (n = 32 and n = 28). During the experiments eggshell qualitative parameters and calcium utilisation (%) were determined. The results indicate that the percentage of eggshell decreased with the increasing number of cycles. The significant correlation of the eggshell proportion and the age of hens was higher in long, advanced cycles (P < 0.05). The shell strength in both experiments decreased slightly in relation to the age of hens and repeated laying cycles. The shell deformation had an opposite trend to the shell strength, i.e. it increased with the increasing laying. The average shell thickness showed a decrease in the repeated laying cycles, more significant in shorter cycles (P < 0.01). The specific shell gravity maintained balanced values both in cycles and by the age of hens. The shell density in all cycles in both experiments showed a decreasing tendency in relation to the age of hens. In dietary calcium utilization for the shell formation a significant decrease was recorded in the second cycles after moulting (P < 0.05).

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