ABSTRACT
The objective of this study was to describe early postpartum estrous behavior and ovulation in lactating dairy cows using radiotelemetry. Cows (n=50) were continuously monitored for behavioral estrus with a radiotelemetric system, HeatWatch II (CowChips LLC, Manalapan, NJ), from d 14 to approximately d 49 postpartum. Blood collection for analysis of progesterone and ovarian ultrasonography were performed once weekly starting on d 14. First ovulation was associated with behavioral estrus in 5 cows and occurred at 28.2±10.8 d (mean±SD; range 17 to 40 d). The average duration of estrus was 6.0±4.9 h (range 3 to 12.2 h), and the mean number of standing events was 18.4±8.9 (range 4 to 26). Based on progesterone concentrations of ≥1 ng/mL, estimated first postpartum ovulation occurred at 25.1±10.4 d (range 10 to 49 d) for 38 animals without evidence of behavioral estrus. The interval to estimated first ovulation without behavioral estrus was not different from the interval to first ovulation associated with behavioral estrus. Level of milk production and body condition score loss did not affect the interval to estimated first ovulation without estrus or first ovulation associated with estrus. Six animals did not show evidence of ovulation based on progesterone concentration, whereas 1 cow showed evidence of estrous behavior on the day before removal from the study. The majority of first postpartum ovulations (38/43; 88.4%) were not associated with behavioral estrus.
Subject(s)
Cattle/physiology , Estrus/physiology , Lactation/physiology , Ovulation/physiology , Postpartum Period/physiology , Telemetry/veterinary , Animals , Behavior, Animal/physiology , Cattle/psychology , Female , Ovulation/psychology , Postpartum Period/psychology , Posture , Progesterone/blood , Telemetry/methodsABSTRACT
The effects of alkalinizing agents, administered prior to feeding colostrum, on blood-gas and acid-base values and on absorption of IgG1 were determined in 40 newborn Holstein calves. Two treatments, sodium bicarbonate (3 mEq/kg of body weight, IV) and doxapram HCl (2 mg/kg, IV), were evaluated, using a randomized complete-block experimental design. These treatments resulted in significant (P less than 0.01) alteration of blood-gas and acid-base values, generally in the direction of normal values for adult cattle. Significant least squares mean effects were detected for sodium bicarbonate treatment on blood pH (+ 0.04 units, P less than 0.01), PCO2 (+ 4.1 mm of Hg, P less than 0.01), and HCO3 concentration (+ 4.4 mEq/L, P less than 0.01). Significant least squares mean effects were detected for doxapram HCl treatment on blood pH (+ 0.06 pH units, P less than 0.01) and PCO2 (-5.2 mm of Hg, P less than 0.01). Absorption of colostral IgG1 was not affected by the treatments given or by the altered blood-gas and/or acid-base status.
