Behavioral and metabolic observations of dairy cows in the transition period.

摘要

This dissertation is about the epidemiology of (1) periparturient ketosis, and (2) parturition behavior and stillbirth in dairy cattle.; First, three ketosis cowside tests were evaluated. The KetoCheck powder in milk had a moderately low sensitivity (41%) but a high specificity (99%) at detecting serum betahydroxybutyrate (BHBA) above 1400 mumol/L. The sensitivity and specificity of the Ketostix strip on urine were 78 and 96% at the "small" cutpoint. The KetoTest strip on milk had a similar accuracy at the 100 mumol/L cutpoint.; Second, blood was collected and milk production measured repeatedly for 161 cows in their first 2 weeks of lactation. Serum was analyzed for BHBA, non esterified fatty acids (NEFA), glucose and total calcium concentrations. Cows were stratified by peak BHBA concentration: low, moderate and high. Metabolite levels and milk production differed between peak BHBA groups. The short drops in calcium and glucose surrounding the time of peak BHBA in the high group could be related to drops in feed intake.; Finally, a daily urine screening program was evaluated using the previous dataset. At the Ketostix cutpoint of "small", 64% of cows with a 2-week average serum BHBA greater than 1000 mumol/L were detected. The specificity was 95%.; For the parturition topic, 464 cows were moved to individual calving pens when calving was imminent and were videotaped. The stage of calving at pen move was associated with restless behaviors, with cows moved at earlier stages spending more time standing in their 1st hour in the pen and needing more time to lie down.; Stage was closely associated with calving duration, with a median of 4, 2 and 1 h for cows moved with mucus only, envelopes or visible calf feet, respectively. Restless behaviors were associated with longer calvings, especially with the total time standing.; Finally, stillbirth was defined as death within 24 h of parturition. Adjusting for dystocia, parity and calf weight, longer calvings had higher odds of stillbirth (OR = 1.3 per hour). Because the increased risk was specifically due to longer down time (OR = 2.1 per hour), restless behaviors were not closely related to stillbirth.