Yaojun Liu1, Rainer Mosenthin1,2, Lihong Zhao1, Jianyun Zhang1, Cheng Ji1, Qiugang Ma3. 1. State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. 2. Institute of Animal Science, University of Hohenheim, 70593, Stuttgart, Germany. 3. State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, China. maqiugang@cau.edu.cn.
Abstract
BACKGROUND: The present study aimed at evaluating the effect of vitamin K (VK) supplementation on bone health of laying hens challenged by Salmonella Enteritidis. METHODS: A total of 80 32-week-old double negative salmonella-free brown-egg laying hens were randomly assigned to 4 treatments with 20 replicates each (1 bird per replicate) according to a 2 × 2 factorial design with 2 dietary VK supplementation levels [0 mg/kg (VK0) vs 2 mg/kg VK (VK2) and 2 challenge treatments [Salmonella Enteritidis (SE) vs physiological saline solution (PS)]. During the last 3 days of week 43 of age, birds of both VK treatments were either orally challenged with 1.0 mL suspension of 109 cfu/mL S. Enteritidis daily or received the same volume of PS. RESULTS: The laying rate, daily egg mass, tibia strength, CT, cOC and cOC/(cOC + ucOC) of VK2 treatment increased (P < 0.05) in contrast to VK0, however, the medullary area and ucOC of VK2 treatment decreased (P < 0.05) in contrast to VK0. Mortality, medullary area, serum Ca content of SE treatments increased (P < 0.05) in contrast to PS treatments. In both SE treatments, the decrease (P < 0.05) in birds' tibia strength was associated with higher (P < 0.05) Ca levels in serum. There is an interaction (P < 0.05) between SE challenge and VK levels with regard to tibia strength and serum Ca levels. At week 42, serum CT was positively correlated with cOC (R = 0.99, P = 0.009); at week 44, tibia strength was positively correlated with BMD (R = 0.95, P = 0.045), but negatively correlated with medullary area (R = - 0.98, P = 0.018). CONCLUSIONS: VK (2 mg/kg) supplementation to diets of laying hens can enhance bone strength under challenge situations with Salmonella Enteritidis. Medullary area has proven to be a sensitive biomarker for bone calcium loss caused by SE infection.
BACKGROUND: The present study aimed at evaluating the effect of vitamin K (VK) supplementation on bone health of laying hens challenged by Salmonella Enteritidis. METHODS: A total of 80 32-week-old double negative salmonella-free brown-egg laying hens were randomly assigned to 4 treatments with 20 replicates each (1 bird per replicate) according to a 2 × 2 factorial design with 2 dietary VK supplementation levels [0 mg/kg (VK0) vs 2 mg/kg VK (VK2) and 2 challenge treatments [Salmonella Enteritidis (SE) vs physiological saline solution (PS)]. During the last 3 days of week 43 of age, birds of both VK treatments were either orally challenged with 1.0 mL suspension of 109 cfu/mL S. Enteritidis daily or received the same volume of PS. RESULTS: The laying rate, daily egg mass, tibia strength, CT, cOC and cOC/(cOC + ucOC) of VK2 treatment increased (P < 0.05) in contrast to VK0, however, the medullary area and ucOC of VK2 treatment decreased (P < 0.05) in contrast to VK0. Mortality, medullary area, serum Ca content of SE treatments increased (P < 0.05) in contrast to PS treatments. In both SE treatments, the decrease (P < 0.05) in birds' tibia strength was associated with higher (P < 0.05) Ca levels in serum. There is an interaction (P < 0.05) between SE challenge and VK levels with regard to tibia strength and serum Ca levels. At week 42, serum CT was positively correlated with cOC (R = 0.99, P = 0.009); at week 44, tibia strength was positively correlated with BMD (R = 0.95, P = 0.045), but negatively correlated with medullary area (R = - 0.98, P = 0.018). CONCLUSIONS: VK (2 mg/kg) supplementation to diets of laying hens can enhance bone strength under challenge situations with Salmonella Enteritidis. Medullary area has proven to be a sensitive biomarker for bone calcium loss caused by SE infection.