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Objective: Light is a significant component of housing environment in commercial poultry industry. This study was conducted to investigate whether Pekin ducks perform better under monochromatic lights than under white light with respect to their growth performance, carcass quality, eyeball development, oxidation resistance, and cecal bacterial communities.Methods: A total of 320 one-day-old male Pekin ducklings were randomly distributed into five rooms with different light treatments, white, red, yellow, green, and blue light. Each room consisted of 4 replicated pens with 16 ducklings per pen.Results: Blue light significantly decreased fat deposition by decreasing abdominal fat. Long wavelength light, such as red, green, and yellow light, considerably increased the back-to-front eyeball diameter and the red light potentially enlarged the side-to-side eyeball diameter. Besides, the blue light had adverse effects on the oxidation resistance status in terms of increasing the product malonaldehyde of lipid oxidation and decreasing the plasma concentration of total superoxide dismutase. The phyla of Firmicutes had the greatest abundance in the green and blue treatments, while Bacteroidetes in blue treatment was the least. The genus of Faecalibacterium was significantly lower under the red light.Conclusion: The high risk of cecal health status and decreased anti-oxidation activity were observed under blue light. Red, yellow, and green light might increase the risk of oversized eyeball and cecal illness. Therefore, monochromatic lights compared to white light did not show advantages on the performance of housing ducks, it turns out that the white light is the best light condition for grow-out ducks.

The insulin-like activity of insulin-like growth factor-1 (IGF-1) is heavily blunted by IGF binding proteins (IGFBPs, including IGFBP-1 and IGFBP-3). The effects of heat stress (HS) on the IGF-1 and IGFBPs in growing pigs are still not clear. This study aimed to investigate the alterations of IGF-1 and IGFBPs under chronic HS in growing pigs. Twenty-seven growing large white barrows with similar body weight were collected from nine litters and were assigned into three treatments. The litter effect is balanced in all treatments. Treatments were: 1) thermal-neutral (TN) group (23 °C), 2) chronic HS group (33 °C), and 3) pair-fed in TN condition (PFTN). The experiment lasted for 21 days. Compared with TN controls, decreased FI, lower average body weight gain, higher rectal temperature and increased respiration rates were observed in HS pigs. On D7, increased plasma insulin concentration and insulin:glucose ratio were observed in HS pigs compared to TN controls. A overall elevation of plasma IGF-1:IGFBP-3 ratio was detected in HS pigs compared with PFTN and TN counterparts. Besides, hepatic IGF-1 gene expression of HS pigs was 50% higher than TN counterparts. PFTN pigs, however, had no differences in plasma IGF-1:IGFBP-3 ratio and hepatic IGF-1 gene expression, compared with TN pigs. PFTN pigs increased plasma IGFBPs concentration and hepatic IGFBPs gene expression, compared with TN controls. However, no differences in plasma IGFBPs concentration and hepatic IGFBPs gene expression were observed between TN and HS group. Liver IRS-1 gene and protein expressions of HS pigs tended to be increased compared with TN controls, while PFTN pigs still kept liver IRS-1 gene and protein expressions in normal level. High temperature (33 °C), independent of feed intake reduction, increased IGF-1 but did not affect IGFBPs levels in growing pigs.

Heat stress can greatly influence metabolic activities in pigs. In heat-stressed pigs, lipid metabolism was altered in a way which is distinct from animals experiencing the same level of feed restriction at thermoneutrality. Besides stress hormones, damaged intestinal barrier functions in heat-stressed pigs can alter insulin sensitivity by inducing systemic inflammation. This study was conducted to investigate the impacts of long-term exposure to an environmental temperature of 33 °C on lipid metabolism, tissue damages and cytokine productions in growing pigs. Twenty-seven Large White pigs (40.8 ± 2.7 kg) were randomly allocated to the control (CON, n = 9; kept at 23 °C and fed ad libitum), heat-stressed (HS, n = 9; kept at 33 °C and fed ad libitum) and pair-fed groups (PF, n = 9; kept at 23 °C and fed the same amount as the HS group) for 21 days. Serum parameters were determined on d3, 7, 14, 21. Cholesterol and expression of genes associated with its metabolism were quantified in the liver on d21. The results showed serum biomarkers for liver functions, such as aspartate aminotransferase (AST, P = 0.514), lactate dehydrogenase (LDH, P = 0.792), total protein (TP, P = 0.379), and blood urea nitrogen (BUN, P = 0.997), did not differ among all treatments. But activities of serum alanine aminotransferase (ALT, P °C can influence cholesterol metabolism in growing pigs without causing severe tissue damages. Reduced feed intake did not completely explain those changes in the cholesterol metabolism during long-term heat exposure.