ABSTRACT The present study investigated whether the same temperature-humidity index (THI) values under different conditions of air temperature and relative humidity (RH) would affect the thermoregulatory, nutritional, and behavioral responses of laying hens. One hundred twenty Hy-Line Brown laying hens (60-weeks-old) were divided equally in two environmental chambers: 26 °C with 70% RH (hRH75) and 30 °C with 30% RH (hT75) for 28 days. The two ambient environments (hRH75 and hT75) had an identical THI value of 75, calculated using an empirical formula for laying hens. Neither hRH75 nor hT75 affected rectal and body-surface temperatures and heart and respiratory rates. The concentration of volatile fatty acids in fecal excreta were altered by the thermal treatments. hT75 vs. hRH75 decreased the proportion of acetate and increased the proportion of propionate in fecal samples. hT75 vs. hRH75 lowered the digestibility of dry matter, crude protein, and neutral detergent fiber at 14 days. Thermal treatments did not affect heat stress-associated behavioral responses including feeding, drinking, panting, and wing elevation at any stage. Laying hens exposed to the same THI at different temperatures and RH exhibit equal physiological responses including rectal and body-surface temperatures, heart and respiratory rates, and behavioral responses. Nonetheless, high-temperature treatment (hT75; 30 °C and 30% RH) vs. low temperature treatment (hRH75; 26 °C and 70% RH) affects nutrient digestibility and gut metabolites, suggesting that there are negligible but discernable responses to temperature in the gut physiology.

ABSTRACT The present study aimed to investigate the kinetics of acute phase proteins and cytokines in the serum of immunized or naive pigs following infection with a field isolate of foot-and-mouth disease (FMD) virus. Five-month-old SPF pigs were intramuscularly immunized with or without the 146S antigen (7.5 μg per head) purified from FMD virus (O/Andong/SKR/2010) and were subsequently challenged 30 days post-vaccination (dpv) with FMD virus on each footpad. Serum samples were obtained at 28 dpv and on days 1, 3, and 5 post-infection (dpi). At 28 dpv, the serum concentrations of C-reactive protein and tumor necrosis factor alpha (TNF-α) were higher in the immunized pigs compared with the non-immunized control pigs. Upon challenge, the levels of all measured acute phase proteins (i.e., C-reactive protein, major acute phase protein, S-amyloid A, and haptoglobin) plateaued at 1 dpi in the immunized pigs whereas they gradually increased up to 5 dpi in the non-immunized control pigs. Levels of serum TNF-α remained higher in the immunized challenged pigs compared with the non-immunized challenged pigs. The serum concentration of interleukin (IL)-6 in the immunized challenged pigs was undetectable at all time points, but moderately increased upon challenge in the non-immunized challenged pigs. IL-1β was not detected in any of the pigs at any of the observed time points. Collectively, these findings show that the immunized pigs exhibit a rapid serum acute phase protein response following subsequent challenge with the field FMD virus compared with the non-immunized pigs.

ABSTRACT This study was conducted to investigate the effects of dietary fats (tallow [TO] or linseed oil [LO]) or conjugated linoleic acid (CLA), singly or in combination, on laying performance, yolk lipids, and fatty acid composition of egg yolks. Three hundred 50-week-old laying hens were given one of five diets containing 2% TO; 1% TO + 1% CLA (TO/CLA); 2% LO; 1% LO + 1% CLA (LO/CLA); and 2% CLA (CLA). Laying performance, egg lipids, and serum parameters were not altered by dietary treatments. Alpha-linolenic acid or long-chain ω-3 fatty acids including eicosapentaenoic and docosahexaenoic acids were elevated in eggs of laying hens fed diets containing LO (i.e., LO or LO/CLA groups) compared with those of hens fed TO-added diets. Dietary CLA, alone or when mixed with different fat sources (i.e., TO or LO), increased the amounts of CLA in egg yolks, being the highest in the CLA-treated group. The supplementation of an equal portion of CLA and LO into the diet of laying hens (i.e., LO/CLA group) increase both CLA and ω-3 fatty acid contents in the chicken eggs.