Sumpun Thammacharoen

Open access peer-reviewed chapter

Background and Aim: High ambient temperature (HTa) associated with climate change poses challenges to livestock production and exacerbates greenhouse gas (GHG) emissions in a self-perpetuating cycle. While HTa influences ruminal fermentation and enteric methane (CH₄) emissions in dairy cows, data on long-term seasonal HTa effects in heat-adapted tropical dairy goats under natural conditions remain limited. This study aimed to evaluate seasonal HTa effects on ruminal fermentation patterns, physiological responses, and daily CO₂ and CH₄ emissions in non-lactating crossbred Saanen goats using respiratory chamber measurements. The research gap addressed includes the scarcity of studies decoupling long-term acclimatization from short-term diurnal HTa using paired ambient and cooled chamber conditions in small ruminants under true tropical environments. Materials and Methods: Twelve nulliparous crossbred Saanen × Bach Thao goats were used in a completely randomized design with two seasonal periods (winter: December–February; summer: March–May) and six replicates. Goats were housed individually and fed a total mixed ration (80% corn silage, 20% concentrate). Ambient conditions, dry matter intake (DMI), water intake (WI), rectal temperature (Tr), respiratory rate (RR), plasma cortisol, and ruminal volatile fatty acids (VFAs) were measured. Daily CO₂ and CH₄ emissions were quantified over 24 h in respiratory chambers under ambient and 25°C air-conditioned conditions at mid-experiment points. Data were analyzed using linear mixed-effects models with season, chamber, and their interaction as fixed effects. Results: Summer daytime temperature–humidity index exceeded 80, with a seasonal ΔTa of 3.0°C. Long-term HTa increased total ruminal VFA concentration (53.2 ± 0.7 vs. 57.8 ± 1.0 mM, p < 0.05) and acetate:propionate ratio (2.3 ± 0.2 vs. 3.3 ± 0.4, p < 0.05) while decreasing NH₃-N (30.1 ± 1.0 vs. 26.1 ± 0.1 mg/dL, p < 0.05), without affecting DMI or WI. Daily CO₂ (378 ± 40 vs. 407 ± 32 g/day) and CH₄ (7.2 ± 1.7 vs. 9.2 ± 1.0 g/day) emissions did not differ between seasons (p > 0.05). However, attenuating daytime HTa to 25°C reduced nighttime CO₂ emissions (188 ± 12 vs. 160 ± 5 g/day, p < 0.05), linked to altered drinking behavior. Conclusion: Seasonal HTa under tropical conditions altered ruminal fermentation without changing daily enteric CO₂ or CH₄ emissions in crossbred dairy goats, highlighting their superior adaptability. Short-term HTa attenuation revealed subtle effects on nighttime CO₂ via drinking behavior. These findings provide baseline data for species-specific GHG mitigation and challenge cattle-centric models in warming regions. Keywords: crossbred Saanen goats, enteric methane emissions, greenhouse gas emissions, high ambient temperature, respiratory chamber, ruminal fermentation, seasonal heat stress, tropical conditions.

The study aimed to evaluate the effects of cooling and rbST supplementation on milk production in crossbred Holstein Friesians and to elucidate the physiological mechanisms regulating mammary (intra-mammary) and extra-mammary functions across different stages of lactation. Ambient temperature and THI were higher in normal shade (NS) barns, while relative humidity was higher in mist-fan cooling (MFC) barns. Non-cooled cows showed higher respiration rates and rectal temperatures regardless of rbST. The rbST supplementation increased milk yield, feed intake, and efficiency, with peak responses in early lactation followed by a decline. It also enhanced mammary blood flow, expanded body fluid compartments, and increased water turnover without altering osmolality or hematological indices. The hormonal profile was characterized by increased IGF-I and decreased leptin concentrations, minor variations in insulin and thyroxine, and unchanged cortisol levels. It elevated free fatty acids as key metabolic markers. Renal hemodynamics remained stable; however, increased electrolyte retention contributed to fluid expansion via enhanced tubular reabsorption mediated by aldosterone and IGF-I. Cooling and rbST improved feed intake and digesta passage without affecting digestibility, while rumen fermentation products increased. Glucose metabolism and metabolic pathway studies using radiolabeled glucose showed that rbST did not alter glucose turnover or plasma glucose levels but enhanced mammary glucose uptake and partitioning toward lactose synthesis and the pentose phosphate pathway, increasing NADPH for fatty acid synthesis, particularly in early–mid lactation. As lactation advanced, glucose utilization shifted toward glycolysis and the TCA cycle, contributing to declining milk yield, while milk electrolytes and plasma osmolality remained unchanged.

Background and Aim: High ambient temperature (HTa) is a major environmental challenge affecting the welfare, physiological stability, and productivity of dairy ruminants raised in tropical and subtropical regions. Heat stress caused by HTa compromises feed intake, acid–base balance, water metabolism, thermoregulation, and milk production. This review summarizes the physiological, behavioral, and endocrinological responses of dairy goats and cows exposed to HTa conditions and highlights the potential role of high dietary cation–anion difference (hDCAD) supplementation as a nutritional strategy to mitigate heat stress. Under HTa conditions, dairy ruminants increase respiratory rate and panting to enhance evaporative heat dissipation, which may induce respiratory hypocapnia and alter electrolyte balance. The reviewed evidence demonstrates that hDCAD supplementation improves heat dissipation efficiency by increasing nocturnal water intake, expanding body water compartments, and supporting hydration status, thereby reducing rectal temperature increments during daytime heat exposure. In addition, hDCAD positively influences ruminal fermentation, nutrient digestibility, eating behavior, and dry matter intake. Long-term supplementation also promotes renal compensatory responses that help restore acid–base equilibrium. The concept of hDCAD as a “biological coolant” is proposed based on its ability to support physiological cooling mechanisms rather than solely improving feed intake or buffering capacity. This nutritional approach may improve animal comfort and productivity under tropical HTa conditions and could complement existing environmental heat mitigation strategies in dairy production systems. Further investigations in dairy goats and cows under practical farming conditions are required to strengthen the application of hDCAD as a sustainable heat stress management strategy. Keywords: acid-base balance, dairy goats, dietary cation-anion difference, evaporative heat dissipation, heat stress, livestock welfare, thermoregulation, tropical climate.

Background and Aim: Saline water use in livestock production is increasingly common in coastal and delta regions due to freshwater scarcity, but prolonged intake may compromise productivity, physiological balance, and immune function in small ruminants. Excessive intake of sodium (Na) and chloride (Cl) can induce osmotic and oxidative stress, which may disrupt hematological homeostasis and growth performance. Antioxidant nutrients such as vitamin E (VitE) and selenium (Se) can enhance cellular protection and immune resilience under environmental stress. This study aimed to evaluate the effects of dietary VitE and Se supplementation on productivity, hematological responses, and selected biochemical parameters in growing goats consuming diluted seawater (DSW) under tropical conditions. Materials and Methods: Ten crossbred Boer male goats (6 months old; body weight [BW] 16.66 ± 0.52 kg) were allocated to a completely randomized design with two treatments and five replicates per group over a 5-week experimental period. Goats in the control group received no supplementation, whereas goats in the treatment group received a daily premix providing 60 mg VitE and 0.9 mg Se per head. All goats consumed fresh water during period 1 (P1), followed by 1% DSW during period 2 (P2) and 2% DSW during periods 3 and 4 (P3–P4), before returning to fresh water in period 5 (P5). Dry matter intake (DMI) and water intake (WI) were recorded daily, whereas BW, plasma electrolytes, liver and kidney function indicators, and hematological parameters were measured weekly. Data were analyzed using linear mixed-effects models including treatment, period, and their interaction. Results: DMI was not significantly affected by DSW concentration or VitE–Se supplementation. WI increased at 1% DSW but declined at 2% DSW, with the supplemented group maintaining higher WI than the control group. BW change decreased in the control group during exposure to 2% DSW, whereas BW remained stable in the supplemented group. DSW increased plasma Na and Cl concentrations and elevated liver enzyme activities, while supplementation attenuated Cl accumulation and moderated Na elevation. Hematological analysis indicated greater leukocyte responses in the control group as DSW salinity increased, whereas the supplemented group maintained more stable hematological profiles. Renal and hepatic indicators remained within physiological reference ranges in both groups. Conclusion: Dietary VitE and Se supplementation mitigated DSW-associated hematological disturbances and supported WI and BW maintenance in growing goats, suggesting a practical nutritional strategy for saline water–affected production systems. Keywords: antioxidant supplementation, body weight, diluted seawater, goats, hematological responses, saline water, selenium, vitamin E.

Colostrum composition, including lactose concentration in relation to metabolomic profiles on kids’ growth performance of Black Bengal goats, has not yet been elucidated. Macronutrients, including lactose and metabolomic profiles, were determined in 37 colostrum samples using MilkoScan and 1H-nuclear magnetic resonance technique, respectively. Kids’ growth performance, including birth weight, average daily gain at 0–4 weeks (ADG0-4W), 4–8 weeks (ADG4-8W), and wean weight were determined. A total of 51 metabolites were detected in the colostrum. From the general linear model for univariate analysis, kids born from multiple litter sizes showed lower ADG during the first month postpartum (P = 0.004). The ADG0-4W was correlated positively with lactose (r = 0.434, P < 0.001), betaine (r = 0.263, P < 0.05), glycine (r = 0.303, P < 0.05), and trimethylamine N-oxide (r = 0.372, P < 0.01) but negatively with most metabolites. By using a generalized linear mixed model procedure when kid growth performances were regarded as dependent variables, and the damID was considered as a random effect with birth weight, parity number, and litter size as covariates, kids consumed colostrum with high lactose (P < 0.001) but lower protein, fumarate, malonate, glucose, myo-inositol, vitamin B2, and vitamin B7 (P < 0.05) had higher ADG0-4W. Therefore, growth performance 1 month postpartum was enhanced in kids consuming high lactose with low metabolite contents, which reflects not only the lactose is the main source of energy but also its possible role on the osmotic water-pulling effect on colostrum yield.

High ambient temperature (HTa) in tropical conditions leads to evaporative heat dissipation by panting in lactating dairy goats. This panting causes respiratory hypocapnia, which increases the renal excretion of buffer molecules including sodium, potassium, and bicarbonate. In response, renal acid excretion decreases to preserve acidity. Besides hypocapnia, lactation and HTa could further deplete buffer molecules, enhancing acid preservation. This current study restored buffer molecules using high dietary cation and anion difference (DCAD) regimen and hypothesized that renal acid excretion during acute acid load would be increased in dairy goats fed high DCAD under HTa. To investigate this, 12 early‐lactating dairy goats were randomly assigned to two groups: control and DCAD, which were fed control and high‐DCAD diets, respectively, for 8 weeks. Acute acid loading during HTa was induced by high‐dose ascorbic acid (AA) supplementation. During Weeks 4 and 8, the vehicle and AA were supplemented on the last two consecutive days of each week. The results showed that the renal acid excretion in DCAD group was higher than control group during high‐dose AA supplementation. Together with high renal buffer excretion by DCAD, an increased renal acid excretion may be partially mediated by an increase in buffer reserve.

Background: Temperature regulation is essentially important for survival of poikilotherms such as snakes. Body temperature is regulated by snakes through behavioral and physiological responses. The global-warming crisis, combined with the need to house large population of snakes in limited spaces, increases the likelihood of exposing snakes to high ambient temperature (HTa), requiring it reliance on physiological responses. This study aimed to study the effect of HTa exposure on physiological responses and venom production, which have rarely been studied.

Background and Aim: In tropical regions, the intrusion of saline from seawater (SW) due to global warming and sea level rise in recent years is an important natural factor influencing goat well-being. This study aimed to determine the effects of diluted SW in drinking water on the physiological responses and eating and drinking patterns of crossbred dairy goats under tropical conditions. Materials and Methods: Twenty dairy goats were divided into four groups (five animals each) based on body weight and milk yield. Animals received either fresh drinking water (SW0.0, control) or diluted SW at concentrations of 0.5% (SW0.5, low salinity), 1% (SW1.0, moderate salinity), and 1.5% (SW1.5, high salinity). The experiment was performed for 49 days (1st–7th week). Throughout this period, daily food and water intake were measured every day. In addition, blood collection was performed on day 25. Total urine and feces were collected from days 25 to 29. Meal and drinking patterns were determined on days 31 and 32. Results: Salinity did not influence dry matter intake throughout the experiment (p > 0.05). However, SW had a significant effect on eating patterns. The effect of SW on water intake (WI) was pronounced from the 2nd to 7th weeks of this experiment (p < 0.05). The water balance decreased and plasma antidiuretic hormone levels increased from SW1.5 to SW2.5 compared to the other treatments. Rectal temperature and respiration rate increased from 15:00 to 17:00 in SW1.5 patients. The concentrations of plasma electrolyte, creatinine, and heat shock protein 70 did not differ between treatments (p > 0.05). The urinary excretion of Na+ from SW1.5 and K+ and Cl- from SW1.0 was higher than that from SW0.0 and SW0.5 (p < 0.01). Conclusion: Lactating crossbred goats adapted to low and moderate SW by increasing urine volume and urinary electrolyte excretion (Uex), whereas animals responded to high SW by either increasing Uex or altering drinking patterns to minimize salt stress. Keywords: antidiuretic hormone, dairy goat, kidney, saline water, water balance.