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1. Effect of relative humidity at chronic temperature on growth performance, glucose consumption, and mitochondrial ATP production of broilers

ZHOU ying, ZHANG Min-hong, FENG Jing-hai, DIAO Hua-jie

Journal of Integrative Agriculture 2019, 18 (6): 1321-1328. DOI: 10.1016/S2095-3119(19)62584-0

摘要（205）

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An experiment was conducted to investigate the effect of relative humidity (RH) at chronic temperature on growth performance, glucose consumption, and mitochondrial adenosine triphosphate (ATP) production of broilers. A total of 180 28-day-old Arbor Acres broilers (half males and half females) were randomly allocated to three treatments, each containing six replicates of 10 birds per treatment, using a completely randomized design. Birds were reared at 35, 60 or 85% RH at 32°C for 15 days (temperature increased by 3°C every 3 days from 20 to 32°C within 15 days: 20–23–26–29–32°C). RH affected (P<0.05) average daily feed intake (ADFI), average daily gain (ADG), average daily water consumption (ADWC), blood glucose concentrations, muscle glycogen levels, avian uncoupling protein (av UCP) mRNA expression, and cytochrome c oxidase (CCO) activity in liver of broilers at 42 days of age. The 85% RH decreased (P<0.05) ADFI, ADG and ADWC; 35% RH decreased (P<0.02) ADG. Both 85 and 35% RH increased (P<0.01) blood glucose and decreased (P<0.05) muscle glycogen. Both 85 and 35% RH increased (P<0.05) av UCP mRNA expression. 35% RH decreased (P<0.05) CCO activity. In conclusion, both high and low RH inceased glucose consumption and reduced mitochondrial ATP poduction, leading to a decline in growth rate.

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2. Effect of relative humidity at either acute or chronic moderate temperature on growth performance and droppings’ corticosterone metabolites of broilers

ZHOU ying, LI Xiu-mei, ZHANG Min-hong, FENG Jing-hai

Journal of Integrative Agriculture 2019, 18 (1): 152-159. DOI: 10.1016/S2095-3119(18)62049-0

摘要（284）

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The present study aimed to investigate the effect of relative humidity (RH) at either acute or chronic moderate ambient temperature (Ta) on growth performance and droppings’ corticosterone metabolites of broilers. Two experiments were conducted: effect of RH (35, 60 or 85%) on average daily feed intake (ADFI) and droppings’ corticosterone metabolites at acute (1 d: 20–26 or 31–20°C, 26 or 31°C for 6 h d^–1 at 10:00–16:00) moderate Ta (experiment 1) and effect of RH (35, 60 or 85%) on growth performance and droppings’ corticosterone metabolites at chronic (step-wisely increasing temperature by 3°C every 3 d from 20 to 32°C within 15 d: 20–23–26–29–32°C) moderate Ta (experiment 2). Droppings were collected at the 2, 4, 6, 8, and 22 h after Ta-RH controlled in experiment 1 and at the 2, 4, 6, and 22 h after Ta controlled to 32°C in experiment 2. The results showed that: 1) In experiment 1, 85% RH increased (P<0.05) the droppings’ corticosterone metabolites at the 2, 6, 8, and 22 h and 35% RH increased (P<0.05) it at the 2 and 22 h compared to the 60% RH. Moreover, 85% RH further increased (P<0.05) it compared to the 35% RH, however, no difference (P>0.05) was found in ADFI among the three RH groups at acute moderate 26°C; 35 and 85% RH increased (P<0.05) droppings’ corticosterone metabolites at the 2, 6, 8 and 22 h and decreased (P<0.05) ADFI compared to the 60% RH, moreover, 85% RH further increased (P<0.05) droppings’ corticosterone metabolites and further decreased (P<0.05) ADFI compared to the 35% RH at acute moderate 31°C; and the average of droppings’ corticosterone metabolites in the whole period had a negative correlation (P<0.02) with the ADFI. 2) In experiment 2, 85% RH increased (P<0.01) droppings’ corticosterone metabolites only at the 2 h and decreased (P<0.02) ADFI and average daily gain (ADG) compared to the 60% RH, no difference (P>0.05) in droppings’ corticosterone metabolites was found between the 35 and 60% RH, however, 35% RH decreased (P<0.01) ADG compared to the 60% RH, and the average of droppings’ corticosterone metabolites in the whole period also had a negative correlation (P<0.02) with ADFI and ADG. In conclusion, droppings’ corticosterone metabolites could be used as a RH stress index and low and high RH, especially high RH, reduced growth performance possibly through inducing RH stress at moderate temperature.

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3. Effects of high ambient temperature on lipid metabolism in finishing pigs

WU Xin, LI Ze-yang, JIA An-feng, SU Hong-guang, HU Chun-hong, ZHANG Min-hong, FENG Jing-hai

Journal of Integrative Agriculture 2016, 15 (2): 391-396. DOI: 10.1016/S2095-3119(15)61061-9

摘要（1801）

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In this study, we investigated the effects of high ambient temperature on lipid metabolism in finishing pigs. Sixteen pigs ((79.6±1.2) kg) were randomly assigned to two groups: (1) ambient temperature of 30°C with ad libitum access to feed (HT; n=8) and (2) ambient temperature of 22°C and fed the average amount consumed by eight pigs in HT group on the previous day (PF; n=8). After 21 days of constant exposure to different environmental conditions, all the pigs were euthanized, and blood and tissue samples were obtained. High ambient temperature increased the proportion of backfat (P=0.04, +21.6%) and flare fat (P<0.01, +43.3%). Compared with pair-fed pigs, the activities of fatty acid synthase (FAS) and malic enzyme in backfat and flare fat were lower (P<0.05) in heat-stressed pigs, as were the amounts of acetyl-CoA-carboxylase and FAS in the longissimus muscle (LM), the amount of FAS in backfat (P<0.01), and FAS activity in the liver (P<0.01). Ambient temperature did not affect the amount of hormone-sensitive lipase in different tissues. The amount of lipoprotein lipase in flare fat tended to be higher (P=0.09, +28.3%), and the activities of β-hydroxyacyl coenzyme A dehydrogenase in front and back of LM were lower (P<0.01, –48.3 and –49.8%, respectively) at 30°C than at 22°C. The plasma concentration of high-density lipoprotein tended to be lower (P=0.08), but the plasma concentrations of very low-density lipoprotein (VLDL) (P=0.09, +50.0%) and nonestesterified fatty acid (NEFA) (P=0.04, +44.2%) were higher in heat-stressed pigs. We concluded that high ambient temperature depressed de novo fatty acid synthesis in both adipose tissues and the liver. However, β-oxidation of fatty acid in skeletal muscles was also inhibited in the high-temperature environment. As a result, more plasma NEFAs were used to synthesize VLDLs in the liver and were absorbed by adipose tissues. This may be one reason that high ambient temperature enhances the accumulation of backfat and flare fat in finishing pigs.

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4. Effects of sustained cold and heat stress on energy intake, growth and mitochondrial function of broiler chickens

ZHANG Shao-shuai, SU Hong-guang, ZHOU Ying, LI Xiu-mei, FENG Jing-hai, ZHANG Min-hong

Journal of Integrative Agriculture 2016, 15 (10): 2336-2342. DOI: 10.1016/S2095-3119(15)61314-4

摘要（1637）

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To study the correlation of broiler chickens with energy intake, growth and mitochondrial function which exposed to sustained cold and heat stress and to find out the comfortable temperature, 288 broiler chickens (21-day with (748±26) g, 144 males and 144 females) were divided randomly into six temperature-controlled chambers. Each chamber contained six cages including eight AA broilers per cage, each cage as a repeat. After acclimation for one week (temperature, 21°C; relative humidity, 60%), the temperature of each chamber was adjusted (finished within 1 h) respectively to 10, 14, 18, 22, 26, or 30°C (RH, 60%) for a 14-day experimental period. After treatment, gross energy intake (GEI), metabolizable energy intake (MEI), the ratio of MEI/BW, metabolizability, average daily gain (ADG), the concentration of liver mitochondria protein and cytochrome c oxidase (CCO) were measured respectively. Our results confirmed that when the temperature over 26°C for 14 days, GEI, MEI and CCO activities were decreased significantly (P<0.05), but the concentration of liver mitochondria protein was increased and metabolizability of broilers was not influenced (P>0.05). Compared with treatment for 14 days, the ratio of MEI/body weight (BW) were also decreased when the temperature over 26°C after temperature stress for 7 days (P<0.05), meanwhile mitochondrial protein concentration was increased at 10°C and CCO activity was not affected (P>0.05). Additionally at 22°C, the ADG reached the maximal value. When kept in uncomfortable temperatures for a long time, the ADG and CCO activities of broiler were reduced, which was accompanied by mitochondrial hyperplasia. In summary, our study focused on the performance of broilers during sustained cold and heat environmental temperatures ranging from 10 to 30°C. From the point of view of energy utilization, moreover, 22 to 26°C is comfortable for 28–42 days broilers. And these could provide the theoretical basis on the high efficient production.

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5. Effect of feeding transgenic cry1Ab/cry1Ac rice on indices of immune function in broilers

LIU Ran-ran, ZHAO Gui-ping, ZHENG Mai-qing, LIU Jie, ZHANG Jing-jing, LI Peng, LI Qing-he, FENG Jing-hai, ZHANG Min-hong, WEN Jie

Journal of Integrative Agriculture 2016, 15 (06): 1355-1363. DOI: 10.1016/S2095-3119(15)61281-3

摘要（1869）

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The safety of feeding transgenic cry1Ab/cry1Ac rice (a genetically modified (GM) rice variety) to broilers was examined from an immunological perspective. Hatchling Arbor Acres chickens (240) were assigned to two dietary treatments (diets containing GM or non-GM rice) with 12 replicates per group and 10 birds per replicate. Traits were measured on one randomly selected bird from each replicate at d 21 and 42. The 42-d feeding trial revealed that cry1Ab/cry1Ac rice had no significant effect relative to non-GM rice on body weight and the immune organ indices. No significant pathological lesion in the spleen and bursa of Fabricius was found in the GM rice group. There were no significant differences in serum concentrations of immunoglobulin Y (IgY), IgM, interleukin 4 (IL-4) and IL-6 between the two groups at d 21 or 42, except for IL-6 being higher (P<0.05) in the GM-fed chickens at d 42. There were no differences in the T and B lymphocyte transformation rate and CD4+/CD8+ ratio between the two groups at d 42. Additionally, there was no significant difference between the two diets in expression of relevant genes viz. the major histocompatibility complex class II beta chain (BLB2), interferon beta 1 (IFNβ), tumour necrosis factor alpha-like (TNFα) and toll-like receptor 4 (TLR4) in the spleen and bursa of Fabricius. All the data demonstrated that transgenic cry1Ab/cry1Ac rice had no adverse effect on these aspects of immune function of broilers during 42-d feeding trial. Transgenic rice was therefore indistinguishable from non-GM rice in terms of short-term feeding in chickens.

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