Development of a light-initiated chemiluminescence assay for the quantitative detection of cow's milk allergen-specific IgE.

BACKGROUND: Cow's milk allergy is a common food allergy in children. Clinically, cow's milk-specific IgE (CM-sIgE) antibody test is often used to diagnose milk allergy. An inexpensive light-initiated chemiluminescence assay (LICA), with fast detection speed and small sample volume demand, has application prospects in the field of quantitative detection of CM-sIgE. METHODS: Chemibeads coated with five major milk allergens, serum samples, biotinylated anti-human IgE antibodies, and streptavidin-coated sensibeads constitute a system to establish a LICA method for the quantitative detection of CM-sIgE. A series of experiments were performed to optimize its reaction conditions and evaluated its performance. RESULTS: The optimal conditions for LICA were 10:4 mass ratio of chemibeads to milk allergen, 20 µg/mL chemibeads, 1.0 µg/mL biotinylated anti-human IgE antibodies and a 1/10 dilution of serum for 30-min incubation. The limit of Quantitation (LoQ) was 0.22 kUA/L. For repeatability, the CV ranged from 3.71% to 8.11%. For intermediate precision, the CV ranged from 4.08% to 14.71%. It was linear within 0.20-18.20 kUA/L. This method did not interfere with common interfering substances and total IgE in serum, and there was no obvious cross-reaction with milk-specific IgG and non-milk-specific IgE. CONCLUSION: We have established a method to quantitatively detect CM-sIgE based on light-initiated chemiluminescence assay, which has good analytical performance and could meet the needs of clinical laboratories.

Phosphorus equivalency of phytase with various evaluation indicators of meat duck.

The objective of the present experiment was to determine the efficacy and the phosphorus (P) equivalency of phytase in the corn-soybean meal-rapeseed meal diets of Cherry Valley ducks from 1 to 35 d of age. 320 ducks were randomly divided into 8 blocks of 5 cages with 8 ducks per cage. This experiment included eight treatments diets. The available P levels of I to IV treatments were respectively 0.25%, 0.32%, 0.39%, 0.46% (d 1-14) and 0.20%, 0.27%, 0.34%, 0.41% (d 15-35). And 4 levels of phytase added to low-P basal diet (treatment I) with 300, 600, 900, and 1,200 U/kg (treatment V to VIII). Among them, treatment IV was a P-adequate positive control, treatment I was a low-P negative control. The ratio of calcium (Ca) to P was 1.3:1 for all diets. The other nutritional indexes in all diets were basically the same. Ducks were provided ad libitum access to water and experimental diets. The negative control diet reduced (P < 0.05) body weight, carcase weight, eviscerated weigh, breast muscle weight, leg muscle weight, bone ash, tibia Ca and tibia P, and increasing levels of available P and supplementary phytase significantly (P < 0.05) improved the growth performance and slaughtering performance of meat ducks. Phytase supplementation at a dose of 900 U/kg in the low-P basal diet increased the growth performance of ducks to a level comparable to that of a P-adequate diet. The available P level of 0.39% (1-14 d) and 0.34% (15-35 d) could meet the nutritional needs of meat ducks for P, and the apparent P utilization rate was high, and the effective utilization effect of P was the best. In addition, with the evaluation indexes of feed intake, body weight gain, tibia ash, tibia Ca, tibia P, content of blood Ca and P, the addition of 500 U/kg phytase could release available P of 0.02%, 0.02%, 0.02%, 0.02%, 0.01%, 0.04%, and 0.03%, respectively. In the same way, the addition of 1,000 U/kg phytase could release available phosphorus of 0.14%, 0.04%, 0.04%, 0.05%, 0.02%, 0.12%, and 0.01%, respectively.

Relationships among bedding materials, bedding bacterial composition and lameness in dairy cows.

OBJECTIVE: Bedding materials directly contact hooves of dairy cows and they may serve as environmental sources of lameness-associated pathogen. However, the specific composition of bacteria hidden in bedding materials is still not clear. The aim of this study was to determine the effect bedding material and its bacterial composition has on lameness of Holstein heifers. METHODS: Forty-eight Holstein heifers with similar body weights were randomly assigned into three groups including sand bedding (SB), concrete floor (CF), and compost bedding (CB). Hock injuries severity and gait performance of dairy cows were scored individually once a week. Blood samples were collected at the end of the experiment and bedding material samples were collected once a week for Illumina sequencing. RESULTS: The CF increased visible hock injuries severity and serum biomarkers of joint damage in comparison to SB and CB groups. Besides, Illumina sequencing and analysis showed that the bacterial community of CB samples had higher similarity to that of SB samples than CF samples. Bacteria in three bedding materials were dominated by gastrointestinal bacteria and organic matter-degrading bacteria, such as Actinobacteria, Firmicutes, and norank JG30-KF-cM45. Lameness-associated Spirochaetaceae and Treponeme were only detected in SB and CB samples with a very low relative abundance (0% to 0.08%). CONCLUSION: The bacterial communities differed among bedding materials. However, the treponemes pathogens involved in the pathogenesis of lameness may not be a part of microbiota in bedding materials of dairy cows.