This study investigates the effects of heat stress in a climate chamber from day 0 to 28 days of life on physiological responses, intake, nutrient digestibility, immunity, and performance in neonatal Holstein calves. Thirty-four calves (nineteen females, fifteen males) were randomly assigned to a control group (CON, temperature–humidity index [THI] 66, with 22 °C and 65% humidity for 24 h, n = 17) or a heat-stressed (HS) group, which was exposed to a THI of 82, 32 °C, and 65% humidity for 9 h, followed by a THI of 66, 22 °C, and 65% humidity for 15 h. The HS calves exhibited increased respiratory rates and rectal temperatures (p < 0.001), particularly during heat exposure periods, as well as a 59.5% increase in water intake compared to CON. While milk and solid feed intake, average daily gain, and feed efficiency were similar between groups, HS calves had reduced ether extract digestibility and altered ruminal fermentation, including lower acetate and lower propionate concentrations. The blood cytokine analysis showed elevated interleukin-4 and reduced interleukin-8 and IP-10 levels in heat-stressed calves, indicating a shift toward an anti-inflammatory immune profile. Despite no major performance impairments, heat stress has induced clear physiological, digestive, and immunological changes. These results underscore the importance of implementing thermal mitigation strategies during early life to safeguard calf health and development in increasingly warmer climates.

This study aimed to characterize the response mechanisms and evaluate the resistance of Megathyrsus maximus hybrids to water deficit and waterlogging. The experiment was conducted in a greenhouse using a randomized block design with an 8 × 3 × 2 factorial arrangement. Treatments were a combination of eight genotypes of M. maximus, three water conditions (control, waterlogging, and water deficit), and two harvest times (20 days of water stress and 12 days post-recovery). Productive and morphological traits were evaluated [...] ABSTRACT This study aimed to characterize the response mechanisms and evaluate the resistance of Megathyrsus maximus hybrids to water deficit and waterlogging. The experiment was conducted in a greenhouse using a randomized block design with an 8 × 3 × 2 factorial arrangement. Treatments were a combination of eight genotypes of M. maximus, three water conditions (control, waterlogging, and water deficit), and two harvest times (20 days of water stress and 12 days post-recovery). Productive and morphological traits were evaluated

Forage planning is essential to overcome the seasonality of forage production, and pasture stockpiling is one of the available strategies. The cultivar BRS Paiaguás (Urochloa brizantha) has been considered to have the best drought tolerance among cultivars of this species. The objective of this study was to evaluate the effects of three stockpiling dates and three pasture stubble heights (SHs) on the yield and quality of stockpiled BRS Paiaguás forage. The experiment was conducted at the Embrapa Dairy Cattle Experimental Field using 3 × 2 m plots arranged in a randomized block design with three replicates in a factorial arrangement over two years of evaluation. Three stockpiling dates were evaluated: March 15 (early), March 30 (intermediate), and April 15 (late). For each stockpiling date, three pasture SHs at the beginning of the stockpiling period were evaluated (10, 20, and 30 cm). The stockpiling period was 70 days for all treatments. The interaction between SH and stockpiling date affected only the percentage of stems in the forage dry weight, whereas the studied factors had no effect on in vitro dry matter digestibility (663.1 g kg-1) or crude protein (67.9 g kg-1). Stubble height influenced the structure and dry matter yield of the BRS Paiaguás pasture. The 10 cm SH resulted in the greatest forage dry weight after 70 days (3,800 kg ha-1 above the SH), but also in higher percentages of stems and neutral detergent fiber. The 30 cm SH resulted in a better leaf-to-stem ratio. Early stockpiling resulted in greater ground cover and green weight (3,800 kg ha-1 vs. 3,012 and 2,468 kg ha-1), whereas late stockpiling (April 15) increased the percentage of senescent forage by 13.5 percentage points compared with the average of the other stockpiling dates. The results indicate that a 20 cm SH combined with early or intermediate stockpiling provides the best balance between productivity and quality.