This study aimed to assess the impact of seasonal thermal stress on oxidative stress, immune response, and stress hormones of lactating dairy cows in subtropical regions with different levels of temperature-humidity index (THI). A total of 32 healthy lactating Holstein dairy cows experienced 4 seasons (8 cows/season). The physiological parameters were categorized into low THI (LTHI, THI = 42.97 ± 0.95) in winter, moderate THI (MTHI, THI = 61.84 ± 0.42) in spring and autumn, and high THI period (HTHI, THI = 86.09 ± 0.23) in summer. The blood samples were collected twice in each season to measure oxidative stress, inflammatory and hormonal parameters. Our results showed THI had a positive correlation with the rectal temperature ( R 2 = 0.821, P < 0.001) and respiratory rate ( R 2 = 0.816, P < 0.001). Dry matter intake, milk yield and fat percentage also significantly differed among groups ( P < 0.05). Compared with the MTHI group, the LTHI group exhibited a significant increase in malondialdehyde (MDA) level ( P < 0.001), and the HTHI group displayed a significant increase in levels of cortisol, interleukin (IL)-10, IL-1β and tumor necrosis factor-α ( P < 0.001). Opposite changes in serum endotoxin and immunoglobulin G levels were observed with the increasing THI ( P < 0.001). LTHI notably increased the triiodothyronine level, although the thyroxine level was reduced by LTHI and HTHI compared with the MTHI group. In conclusion, LTHI and HTHI conditions may induce different degrees of oxidative stress, inflammation response, and stress hormone imbalances on lactating dairy cows, therefore environmental management is necessary for the health of dairy cows in extreme weather conditions.

The present study was conducted to evaluate the effect of chemical composition of wheat by-products on the TME value to ducks and to establish the prediction models estimating TME. Seven representative samples were selected from 23 wheat by-products millings samples based on the neutral detergent fiber (NDF) content. According to the Sibbald method, male Cherry Valley ducks were chosen to assay the TME of 7 representative samples. Stepwise regression analysis was performed to establish the prediction equations of TME using CP, ether extract (EE), NDF, acid detergent fiber, crude fiber, and gross energy (GE) as independent variables. The NDF, CP, and DM of 23 samples of wheat by-product averaged to be 33.39 +/- 11.04%, 19.2 +/- 3.25%, 87.17 +/- 0.95%, respectively. The TME values of 7 representative samples averaged 12.02 MJ/kg, with much larger CV than GE (17.72 vs. 2.82%). The crude fiber, NDF, acid detergent fiber were highly but negatively correlated with TME (P < 0.01), in which the greatest correlation coefficient (r = -0.969) was observed between NDF and TME. No significant correlation of CP, EE, ash, and GE to TME was found among the 7 representative samples. The optimal equation in terms of R(2) from using a single chemical analysis was obtained in the total group: TME = -0.1564NDF + 17.4696 (R(2) = 0.94, P = 0.0003), and the TME prediction equation was improved by the addition of the EE and CP content to sequential analysis: TME = -0.17NDF + 0.98EE - 0.27CP + 19.31 (R(2) = 0.99, residual SD = 0.35, P < 0.01). The results of present study suggest that NDF could be used as an effective indicator for the prediction of the TME value of wheat by-products for ducks.

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An in vitro and a feeding trial was conducted to investigate the effect of fibre-degrading enzymes A (xylanase + β-glucanase), B (xylanase) and C (xylanase + cellulase) on the nutritive value of broiler diets containing either hulled (22.5% and 23.5% for 4–21 days and 22–42 days of age, respectively) or dehulled (20% and 21.5%) Chinese double-low rapeseed meals (DLRM). Overall, in vitro digestibility of dry matter (DM) or neutral digestibility fibre (NDF) did not differ (p > 0.05) because of meal types; both crude protein (CP) and NDF digestibility was improved (p < 0.05) because of addition of enzymes B or C either to hulled or dehulled DLRM diets. Birds fed dehulled DLRM diets had a higher (p < 0.05) growth rate, feed efficiency and lower (p < 0.05) feed intake than those fed hulled DLRM diets during the overall phase. Enzyme C addition to dehulled DLRM diets resulted in improved (p < 0.05) growth rate and feed efficiency during 4–21 days of age. Enzymes A and B addition elicited a positive response in feed intake and weight gain (p < 0.05), respectively, but did not affect (p > 0.05) feed efficiency. It would appear that the nutritive value of broiler diets containing Chinese DLRM could be improved by appropriate xylanase-based enzymes. Responses of broilers to fibre-degrading enzymes could be highlighted by hull removal of fed DLRM.

SummaryThe aim of this study was to examine the effects of different sources and levels of | INTRODUCTIONBirds were vulnerable to high temperatures during summer because of the insufficient heat dissipation after a meal, especially possible for waterfowl (e.g., duck). Heat stress (HS) badly effects on both immune function and production (Humphrey, 2006). Further, HS results in negative effects on growth performance and the relevant mechanisms were explored to mitigate the negative effects (Quinteirofilho et al., 2010;Quinteiro-Filho et al., 2012;Sandhu, Mirza, Afzal, & Mukhtar, 2012;Song et al., 2013). On the cellular level, high temperature promotes proteolysis and induces the production of excessive free radicals which caused oxidative stress damaging different organs of the body (Del Vesco et al., 2015), such as the liver and intestine. | MATERIALS AND METHODSThe study was conducted in a research farm (Hebei, China), and all procedures described here were approved by the Institutional Animal Care and Use Committee of the China Agricultural University (Beijing, China). | Animals and dietsA total of 720 four-day-old Peking ducks were randomly allotted to Table 1. And, the highest, the lowest and the comfortable temperature during study are shown in Table 2. In addition, mortality was recorded daily during the entire trial. And, mortality was almost no. | Sample collectionSix birds per treatment were randomly selected at 16 and 35 day age and euthanized by CO 2 inhalation and decapitation. Liver samples (~2 g) were collected and separated into two portions. Tissue samples were snap frozen immediately in liquid nitrogen and then stored at −80°C and −40°C until further qRT-PCR and protein carbonylation content analyses respectively. Tissue samples (~5-8 mm) were taken