Dietary non-phytate phosphorus requirements for optimal productive and reproductive performance, and egg and tibial quality in egg-type duck breeders

Optimal dietary non-phytate phosphorus (NPP) is essential in poultry to maximise productive and reproductive performance, along with indices of egg and bone quality. This study aimed to establish the NPP requirements of egg-type duck breeders aged from 54 to 80 weeks on the following traits: egg production, egg incubation, egg quality, tibial characteristics, reproductive organ, plasma indices, and the expression of genes related to phosphorus absorption. Longyan duck breeders aged 54 weeks (n = 300) were randomly allotted to five treatments, each containing six replicates of 10 individually caged birds. Birds were fed corn-soybean meal-based diets containing 0.18, 0.25, 0.32, 0.38, and 0.45% NPP/kg for 27 weeks. The tested dietary NPP levels did not affect egg production or egg quality indices. The hatchling weight of ducklings increased (quadratic, P < 0.01) as dietary NPP level increased, and the highest value occurred with 0.25% NPP. The number of large yellow follicles (LYF), and the relative weights of LYF and ovary showed linear and quadratic responses to dietary NPP levels; the lowest number and relative weight of LYF occurred with 0.38% NPP, and the lowest ovarian weight was obtained with 0.25% NPP. There were no differences in tibial length, breaking strength, and mineral density in response to dietary NPP levels. In contrast, tibial content of Ca increased (linear, P < 0.01) with dietary NPP levels increasing from 0.18 to 0.45%, and the tibial content of P increased at 0.32% NPP and the higher dietary NPP levels. Plasma concentration of P showed a quadratic (P < 0.05) response to the dietary NPP levels, where the highest value was seen at 0.38% NPP. In conclusion, dietary NPP levels from 0.18 to 0.45% had no effects on egg production, and egg and tibial quality of duck breeders. The duck breeders fed a diet with 0.25% NPP showed the highest hatchling weight of their offspring, while those fed 0.38% NPP had the lowest number and relative weight of LYF. These results indicated that the diet with 0.25% NPP can be used in egg-type duck breeders to improve the hatchling weight of their offspring, without adverse effects on their productivity. The regression model indicated that the maximal hatchling weight of ducklings was obtained from duck breeders fed the diet with 0.30% NPP.

Effects and interaction of dietary calcium and non-phytate phosphorus for slow-growing yellow-feathered broilers during the starter phase

Calcium (Ca) and non-phytate phosphorus (NPP) are fundamental minerals for bone formation and growth, and optimizing their level is required in broiler production. This experiment was conducted to investigate the effect and interaction of dietary Ca and NPP on growth performance, tibial characteristics and biochemical variables for slow-growing yellow-feathered broilers during 1-28 d (the starter phase). Seven hundred and twenty hatchling female broilers were randomly divided into nine groups, which received three levels of Ca (0.80%, 0.90%, 1.00%) each with three levels of NPP (0.40%, 0.45%, 0.50%). The results showed: (1) Dietary Ca level influenced (P < 0.05) the feed to gain ratio (F:G) and average daily feed intake (ADFI). Compared with broilers provided 1.00% Ca, ADFI of birds provided with 0.80% or 0.90% Ca and F:G of those with 0.90% Ca were decreased (P < 0.05). Dietary NPP level did not affect (P > 0.05) growth performance of broilers. (2) Dietary Ca affected (P < 0.05) tibial length. Compared with birds provided with 0.80% Ca, the length of tibia was decreased (P < 0.05) in birds received 1.00% Ca. Interactions between dietary Ca and NPP were observed (P < 0.05) on ash content, breaking strength and bone density of tibia. These three characteristics were better when birds received 0.90% Ca and 0.40% NPP or 1.00% Ca and 0.45% NPP. (3) Dietary Ca significantly affected (P < 0.05) the activity of alkaline phosphatase (ALP) in serum with decreased activity in birds fed 0.80% or 0.90% Ca. The dietary NPP influenced (P < 0.05) the contents of Ca in serum. Serum Ca was increased when birds were provided 0.40% NPP compared with other levels (P < 0.05). Again, there was interaction between Ca and NPP in diet on the contents of phosphorus (P) in serum (P < 0.05). In conclusion, interactions occurred between dietary Ca and NPP level on tibial breaking strength, density, ash content, and the content of P in the serum of young yellow-feathered broilers. Furthermore, dietary Ca affected ADFI, F:G and serum ALP activity, and dietary NPP also affected the P content in serum. Considering all indicators, 0.90% Ca and 0.40% NPP are optimal for slow-growing yellow-feathered broilers during 1-28 d of age.