Heat stress is a major concern for lactating dairy cows. This study evaluated the effects of heat stress on six Holstein-Friesian crossbred dairy cows exposed to three thermal conditions represented by the Temperature-Humidity Index (THI). These conditions included a baseline pre-treatment phase at THI-72, a heat stress treatment phase at THI-75 and THI-80, and a post-treatment recovery phase at THI-72. The duration of the heat stress treatment phase was 24 h. A total of four trials, each involving three cows, were conducted in an IoT-based climatic chamber to assess various physiological, hematological, biochemical, and production parameters across these phases. Compared to the baseline (THI-72), cows showed significant increases (p < 0.05) in rectal temperature (RT), heart rate (HR), respiration rate (RR), and water intake (WI) at both THI-75 and THI-80, with the highest elevations observed at THI-80 (RT: 5.1%, HR: 8.6%, RR: 23.5%, and WI: 19.1%). Feed intake declined significantly (p < 0.05) by 6.5% and 14.0%, and milk yield dropped by 5.3% and 14.7% at THI-75 and THI-80, respectively; milk fat and protein percentages decreased by 1.1-fold and 1.2-fold. Hemoglobin, platelet, and lymphocyte counts, along with biochemical parameters (excluding serum creatinine) also decreased significantly (p < 0.05). The different levels of THI influenced pairwise correlation patterns, with THI-75 showing intense interactions and THI-80 exhibiting greater variability. The findings highlight that Holstein-Friesian crossbred dairy cows are particularly vulnerable to heat stress, even with short-term exposure. This vulnerability can lead to economic losses for Bangladeshi dairy farmers rearing Holstein-Friesian crossbred cows.

Ionophores are naturally occurring polyether antibiotics that disrupt ion balance in bacterial cells by selectively transporting metal ions across lipid membranes, primarily affecting Gram-positive bacteria in the rumen. The use of ionophores as a feed additive in sustainable beef cattle production offers a promising and innovative solution to key challenges in livestock farming, such as enhancing feed efficiency, lowering methane emissions, and promoting animal health. However, their use is surrounded by several misconceptions, which can lead to confusion among consumers, policymakers, and even within the agricultural industry. This review aims to assess the advantages, disadvantages, and safety aspects of ionophore use in beef cattle production. Published literature related to ionophores in cattle diets and their effects was collected from PubMed, ScientificGate, Google Scholar, ResearchGate and Academia. Ionophores have been reported to reduce rumen disorders like bloat and acidosis. Ionophores reduce methane emissions by altering ruminal fermentation to favor propionate production over acetate and butyrate. Ionophores may exert varying effects depending on the animal, diet, and type and dose of ionophore administered. Studies suggest limited cross-resistance to medically important antibiotics. As ionophores are metabolized and excreted rapidly, it is expected to have minimal adverse effects on human health.Overall, ionophores are promising feed additives that may play a significant role in sustainable beef cattle production, offering producers the opportunity to improve profitability while reducing environmental risks.

Ruminants significantly contribute to global methane (CH₄) emissions, necessitating the development of dietary mitigation strategies. This study evaluated five Bangladeshi seaweeds (brown, red, and green types) from Saint Martin Island for their anti-methanogenic potential through phenotypic identification, proximate analysis, and in vitro fermentation assessment. Significant interspecies variation was (p < 0.001) observed in dry matter (DM: 82.1–99.9%), acid detergent fiber (ADF: 17.4–24.9%), neutral detergent fiber (NDF: 29.6–43.6%), and dry matter degradability (DMD: 43.9–58.7%), while crude protein (CP) remained consistent (p = 0.574). After 48 h of fermentation, total gas (1.3–22.1 mL/g DM) and CH₄ yield (0.04–1.6 mL/g DM) varied markedly (p < 0.01). DMD was strongly correlated with total gas and CH₄ production. Crucially, both ADF and NDF showed a positive correlation with total gas and CH₄ production. However, NDF displayed a weak positive correlation with DMD. These findings suggest atypical fiber fraction dynamics, contrasting with terrestrial forages. Supplementation effects of two red seaweeds, SW-4 (Gracilaria parvispora) and SW-5 (Asparagopsis taxiformis), on Napier grass were assessed at 5% and 10% inclusion levels. SW-5 reduced CH₄ by 52.7% when co-fermented with Napier grass at a 10% inclusion level for 48 h, whereas SW-4 showed no significant effect. These results highlight SW-5 as a promising dietary supplement to reduce enteric CH₄ in ruminants, suggesting further in vivo validation for optimal use.