The objective of this study is to evaluate if Omnigen-AF® supplementation can improve immune function and energy status of transiiton and early lactation dairy cows. Forty multiparous crossbred Holstein/Gir pregnant non-lactating cows will be classified according to body weight (BW) and body condiiton score (BCS)30 days previous to the expected calving date and assingned to one of two treatments: 1)diet formulated to meet maintenance and lactation requirements with Omnigen-AF® supplementation (56g/animal/day); or 2) diet formulated to meet maintenance and lactation requirements with caolin (ruminal inert product) supplementation (56g/animal/day). Animals will be kept in drylot pens with natural shade and ad libitum water and corn silage. Concentrate and supplementation (Omnigen-AF® or caolin) will be fed individually in headlock system during all the experimental period. BW will be recorded weekly and BCS every fifteen days. Blood samples will be collected every 5 days from d-30 to d-5 (relative to expected calving date) and from d22 to d46 (relative to actual calving date) and daily from d0 (calving date) to d21 for plasma concentrations of haptoglobin, ceruloplasmin, L-selectin, TNF-±, IL-6, cortisol, NEFA, BHBA, IGF-1, glucose and insulin. Milk production will be recorded daily for each animal and a milk sample will be collected for SCC and composition. Every fifteen days a individual milk sample will be collected for microbiologic culture. Metricheck® will be performed on d7, d30 and d46 and uterine cytology will be performed on d30 and d46 for uterine health evaluation. On d56±10 of experiment cows will be challenged with E. coli lipopolysaccharide for immune and inflamatory response evaluation. Data will be analyzed using SAS MIXED procedure. Haptoglobin, ceruloplasmin, L-selectin, TNF-±, IL-6, cortisol, NEFA, BHBA, IGF-1, glucose and insulin data wil be analyzed as repeated measures.
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