Effects of dietary calcium levels and limestone particicle size on the performance, tibia and blood of laying hens

Dietary supplementation with protected calcium effects production and egg quality of Hy-line brown laying hens

Context Currently, the commonly used dietary calcium sources are not sufficiently bioavailable to be used for eggshell formation or bone health in laying hens. Protected calcium, a blend of calcium and medium-chain fatty acids with matrix coating, may exert an effective absorption and metabolism ability for calcium consumption in the laying hen. Aims The present study was conducted to evaluate the effects of protected-calcium supplementation on egg production, egg quality, and serum calcium and phosphorus concentrations in laying hens. Methods In total, 144 Hy-line brown laying hens (25 weeks old) were randomly allotted to three treatments (8 replicates with 6 hens, 1 hen per cage) in a 10-week trial. Treatments consisted of corn–wheat–soybean meal-based basal diet with limestone (coarse limestone:fine limestone = 50:50) as a calcium source (CON) or basal diet supplemented with 0.5% (P1) or 1% (P2) protected calcium in substitution for an equal quantity of coarse limestone. Data were statistically analysed using linear and quadratic contrast with the GLM procedure of SAS. Probability values of <0.05 indicate significance. Key results At Weeks 31–33 and 35, the cracked-egg rates were lower in the P1 and P2 groups than in the CON group (P < 0.05; linear, P < 0.05) and, at Weeks 29 and 34, the cracked-egg rates in the P2 group were also significantly (P < 0.05) decreased. At Weeks 26, 30 and 32, the Haugh units in the P2 group were significantly (P < 0.05) higher than those in the CON group. In addition, eggshell strength was increased significantly (P < 0.05) in the P2 group at Weeks 26, 27 and 31–35. The serum calcium concentration of the P2 group was significantly (P < 0.05) greater than that of the CON group in the morning. Conclusions In conclusion, a replacement of limestone with 1% protected calcium can increase eggshell quality. Implications Protected-calcium supplementation can be used in practice for decreasing the breakage of eggs.

Effects of Different Dietary Calcium Levels on the Performance, Egg Quality, and Albumen Transparency of Laying Pigeons

Simple Summary

The transparency of pigeon egg albumen is a special phenotypic trait that different from other poultry eggs, and calcium is one of the main factors. This experiment aimed to study the effects of added dietary Ca on production performance, egg quality, and albumen transparency. It will guide producers on how to feed their laying pigeons and provide a scientific basis for special feed research and the development of laying pigeons with transparent eggs.

Abstract

In order to confirm the dietary calcium (Ca) requirement to keep a balance of the production performance and the albumen transparency, the study examined the effects of different dietary Ca levels on the production performance, egg quality, and albumen transparency of laying pigeons. 1080 pigeon pairs were randomly allocated into six treatment groups, each consisting of six replicates of 30 pigeon pairs per treatment. Ca levels of 0.60, 0.90, 1.20, 1.80, 2.40, and 3.00% were fed. The results showed that the laying rate, average egg weight, and feed to egg ratio were significantly influenced by Ca levels (p < 0.05). Albumen percentage, albumen height, Haugh unit, and eggshell thickness at 8 w and 16 w were significantly influenced by Ca levels (p < 0.05). The L*, a*, b*, and c* values of cooked albumen at 8 w and 16 w were all significantly influenced by Ca levels (p < 0.05). After 16 w of feeding different Ca levels, the percentage of transparent eggs had an early increasing and later decreasing trend. In conclusion, taking the transparency of pigeon eggs as an assessment index and considering production performance secondly, the optimal level of dietary Ca for laying White King pigeons is 0.90%.

Effects of different limestone particle sizes in the diet of broiler breeders post molting on their performance, egg quality, incubation results, and pre-starter performance of their progeny

An experiment was conducted to test the hypothesis that a coarse limestone diet improves productivity, reproductive performance and the calcium utilization of molted broiler breeders. In total, 640 broiler breeder females, 73-week-old and sixty-four 27-week-old cockerels, Cobb 500, were evaluated during 10 weeks, according to a randomized block design composed of 4 treatments with 8 replicates each. Treatments consisted of diets with the inclusion of 100% fine limestone-fine PS (0.2 mm GMD-geometric mean diameter); PS1: 30% fine limestone+70% limestone with 1.0 mm GMD; PS2: 30% fine limestone+70% limestone with 2.0 mm GMD; and PS3: 30% fine limestone+70% limestone with 3.0 mm GMD. Calcium retention in the gizzard of the breeders, bone characteristics, and breeder performance, egg characteristics, eggshell quality, incubation performance, chick quality and yield, chick pre-starter live performance, and chick bone characteristics were determined. There was no significant difference (P>0.05) in the rate of lay, percentage of non-settable eggs, egg weight, egg shape index, egg specific gravity, eggshell weight, thickness, and percentage hatchability and egg weight loss of broiler breeders fed with diets with different limestone particle sizes. The chick quality and yield, chick pre-starter live performance, and chick bone characteristics were not affected (P>0.05) by any of the limestone particle sizes. It was concluded that live and reproductive performance parameters of broiler breeders post molting is not affected by limestone particle size in the feed.

Effects of dietary energy and calcium levels on performance, egg shell quality and bone metabolism in hens

This study investigated the effects of dietary energy and calcium levels on laying performance, eggshell quality and bone metabolism of layers. One hundred and sixty-two 19-week-old Hy-Line brown laying hens in 54 battery cages were allocated to one of nine dietary treatments with control, middle and high levels of energy (11.50, 12.68 and 13.37 MJ/kg, respectively) and low, control and high levels of calcium (2.62%, 3.7% and 4.4%, respectively) for 60 days, using a 3 × 3 factorial arrangement. Compared with the control energy diet, high- and middle-energy diets increased fat deposition and egg weight, decreased feed intake and bone quality and had no effects on eggshell quality. The high-energy diet reduced the serum phosphate concentration and elevated osteocalcin mRNA expression in the keel bone without increasing osteocalcin protein. Dietary calcium intake did not affect fat deposition, feed intake or egg weight. Low dietary calcium resulted in weaker eggshells and poorer bone quality than that from hens fed the control diet. High dietary calcium increased serum calcium concentration, osteoprotegerin mRNA and osteocalcin protein and inhibited serum alkaline phosphatase activity and decreased its mRNA compared with low or control dietary calcium. The high-energy and high-calcium diet significantly reduced egg production. Compared with the control energy diet, high- and middle-energy diets increased fat deposition but had negative effects on bone metabolic homeostasis. Dietary calcium did not influence fat deposition but a high-calcium diet benefited bone homeostasis, while a low-calcium diet was associated with poorer eggshell quality and bone homeostasis.