Heat stress (HS) in dairy cows can be classified into short-term heat stress (STHS) and long-term heat stress (LTHS) according to the number of consecutive days in HS. The comparative study of these 2 types of HS is limited in terms of their effects on the production and energy metabolism of cows. In this study, 4 lactating Holstein cows (102.5 ± 12 days in milk, 605 ± 22 kg of body weight, second parity) fitted with rumen fistulae were randomly assigned to 1 of 2 groups in a 2 × 2 crossover design and allocated to 1 of 2 climate-controlled chambers. This study contained 2 periods, each with a control phase and a HS phase. There was a recovery phase between 2 periods. The HS phase comprised either STHS (3 d) or LTHS (7 d) treatments. Data collected from the 3 d of STHS and the last 3 d of LTHS were compared. The chambers were set at thermal neutral conditions (20°C, 50% humidity) during the control and recovery phases or cyclical HS conditions (26-38°C, 50% humidity) during the HS phase. Compared with STHS, LTHS decreased milk yield by 17.2% and dry matter intake by 12.6%, indicating that LTHS caused a more severe decline in milk production and feed intake. In addition, LTHS decreased milk protein concentration by 6.8% and milk protein yield by 22.4%. In comparison with STHS, LTHS decreased rumen liquor volatile fatty acid (29.7%), blood glucose (11.6%), and nonesterified fatty acid (13.6%) concentrations, but increased milk urea nitrogen by 15.1%, blood urea nitrogen by 8.6%, and creatine concentrations by 15.4%. Our results suggest that although reduced feed intake may be mainly responsible for reduced milk production during STHS, impaired rumen metabolism and suppressed mobilization of adipose tissue could be the main reasons for further reduction in milk yield during LTHS.

Spinal anesthesia-induced hypotension (SAIH) is a common complication during cesarean delivery and is closely associated with maternal intravascular volume

Background: Although altered grip strength is a recognized predictor of various central nervous system disorders, large‐scale clinical evidence linking it to delirium and postoperative delirium (POD) remains scarce. Using data from the UK Biobank (UKB), this study investigated the association between baseline grip strength and the future risk of incident delirium. Methods: We analyzed 452,711 UKB participants without delirium at baseline. Grip strength was measured at study entry. Incident delirium was identified from hospital records using ICD‐10 code F05. POD was defined by the occurrence of surgery before delirium diagnosis, using postoperative windows of 3 and 7 days. Accelerated failure time (AFT) were used in the primary analyses to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). The proportional hazards assumption was assessed using Schoenfeld residual tests. Because sex modified the associations of interest, sex‐stratified analyses were performed. Restricted cubic spline analyses and Kaplan–Meier curves were used to characterize dose‐response patterns and cumulative incidence. Results: Over a median follow‐up of 14.9 years, 7695 incident delirium events were identified. Lower baseline grip strength was associated with higher risks of incident delirium and POD. Sex modified these associations, particularly for incident delirium and POD defined within 3 days after surgery. In both males and females, restricted cubic spline analyses supported inverse associations between grip strength and the risks of incident delirium, POD within 3 days, and POD within 7 days. Kaplan–Meier curves showed higher cumulative incidence across decreasing grip strength tertiles. In fully adjusted models, lower grip strength remained associated with higher risks across outcomes in both sexes. The lowest grip strength tertile consistently showed the highest risk. In females, however, the intermediate tertile was associated with incident delirium but not with POD. Conclusion: Lower baseline grip strength was independently associated with higher risks of incident delirium and POD, with modest sex‐related differences in the strength of association. Grip strength measurement may offer a simple, noninvasive means of identifying individuals at increased risk of delirium‐related outcomes.