The farm enrolled in this study conducted pre-calving plasma NEFA analyses every 2 weeks for monitoring transition cow health. For this, ten primiparous and ten multiparous cows were randomly selected (www.graphpad.com/quickcalcs/randomSelect1/ ) for blood collection among all cows expected to calve in the following 7 to 14 d. Blood samples were collected at the time of daily delivery of fresh total mixed ration. Samples were obtained via puncture of coccygeal vessels using EDTA vacuum tubes (Monoject EDTA K3; Covidien, Minneapolis, MN). Immediately after collection, samples were centrifuged at 2,000 x g for 10 min. Plasma was removed and placed into 2-mL microcentrifuge tubes (Fisher Scientific, Waltham, MA). All samples were refrigerated, and plasma NEFA concentration was determined within 24 h by Central Star Cooperative (Grand Ledge, MI) using a 96-well plate protocol validated for cattle (14 (link)). The test has a sensitivity (95%CI) of 88.9% (67.2–96.9%) and a specificity (95% CI) of 100.0% (97.1–100.0%) for the identification of excessive lipid mobilization pre-calving (14 (link)). A convenience sample size that included the results from all the cows sampled between September 2015 and March 2020 whose actual calving date was between 4 and 14 days [mean (SD) = 7.4 (2.1) days] after sampling (n = 1,532) were included in the study. The details regarding calving date, calf identification, calf health, and calf performance were extracted from the farm record system (DairyComp 305, Valley Agricultural Software, Tulare CA).
Free full text: Click here
