Efficacy of dietary supplementation with 1α-hydroxycholecalciferol on performance, eggshell quality, serum metabolites, jejunal morphology and bone characteristics of laying hens at the late stage of production

Abstract

The present study evaluated the effects of 1α-hydroxycholecalciferol (1αOHD ₃) supplementation on performance, egg quality, gut morphology, serum metabolites, and bone characteristics of Lohman LSL-Lite laying hens. A total of 180 birds (110 weeks of age) were allocated according to a completely randomized design with five treatments. Each treatment had six replicates containing six hens each. The treatments consisted of basal diet with 2000 IU/kg vitamin D ₃, basal diet supplemented with 1.5, 3, 4.5, and 6 μg/kg of 1αOHD ₃. Results showed that dietary supplementation with 1αOHD ₃ increased the egg production (linear P = 0.002 and quadratic P = 0.009) and gross revenue (linear P = 0.042) whilst it decreased the abnormal eggs (linear P = 0.004 and quadratic P = 0.009) in aged laying hens. Similarly, it linearly and quadratically increased the shell thickness and eggshell strength (P < 0.001). Egg mass (linear P = 0.075) showed a tendency to increase with increasing dietary 1αOHD ₃ supplementation levels. The egg quality parameters, including Haugh unit, relative weight of albumen, yolk and eggshell were not affected by the treatments (P > 0.05). Furthermore, 1αOHD ₃ supplementation increased the serum levels of calcium (linear P = 0.003 and quadratic P = 0.011), albumin (linear P = 0.016 and quadratic P = 0.033), vitamin D (linear and quadratic P < 0.001), alanine aminotransferase activity (linear P = 0.02) whilst the addition of 1αOHD ₃ decreased alkaline phosphatase activity (linear P = 0.003 and quadratic P = 0.011), without affecting the serum levels of phosphorus and aspartate aminotransferase activity (P > 0.05) in laying hens. In addition, the linear tendency to increase was observed (linear P = 0.062) in total protein. Dietary supplementation of 1αOHD ₃ increased the tibia diameter (linear P = 0.053), tibia calcium (linear P = 0.004 and quadratic P = 0.014) and tibia strength (linear and quadratic P < 0.001). The addition of 1αOHD ₃ did not affect the phosphorus and ash of the tibia (P > 0.05). Linear and quadratic responses were found for crypt depth (linear and quadratic P = 0.001) and villus height to crypt depth ratio (linear P = 0.004 and quadratic P = 0.010). The experimental treatments did not affect the jejunal villus height, villus width and villus surface area in aged laying hens (P > 0.05). Our findings suggest that the inclusion of 1αOHD ₃ is beneficial, as it enhances egg production, profitability, eggshell thickness, and tibia quality while reducing the incidence of abnormal eggs during the later phase of egg production.