Abstract: 【Objective】The objective of this study was to study the effects of ambient temperature on feeding and intestinal development of poultry, and to supplement the absent temperature parameters for laying hens rearing, and to provide a certain scientific basis for the correct feeding of laying hens.【Method】A total of 360 Issa brown laying hens aged 11 weeks were selected and divided into 5 treatment groups with 6 replicates per group and 12 hens per replicate. The experimental laying hens were transferred to 5 intelligent environmental control chicken houses for 1 week of pre-trial and 8 weeks of formal experiment, and 3 chickens per cage. The relative humidity in the chicken house was kept at 60%, and the light was kept for 8 h (9:00-17:00) every day during the prelay period. The temperature of the control group was kept unchanged at 22℃, and four treatment groups were carried

out in a manner of daily intermittent, that is, 24℃ or 26℃ or 28℃ or 30℃ at 10:00-18:00 every day, and changed to the base temperature 22℃ for the rest of the time, the heating and cooling time are within 1 h. The experiment lasted for 8 weeks. The experimental laying hens were free to eat and drink, the feed intake was counted weekly, and the samples were collected once every two weeks. Twelve hens in each group were randomly selected and weighed, and then killed by neck cutting. The weight of glandular stomach, the weight and length of duodenum, jejunum and ileum were weighed. Hypothalamus, glandular stomach and duodenum samples were frozen in liquid nitrogen and stored at -80℃. Feed intake was calculated in heat treatment period and non-heat treatment period for 3 days before the end of experiment.【Result】The results showed that compared with T22 group, the feed intake in T30 group was significantly decreased at 13-16 wk (P < 0.05); the feed intake in T24 group was significantly higher than that in T28 and T30 groups at 17-20 wk (P < 0.05) . During the heat treatment period, the feed intake of T30 group was significantly lower than that in T22 and T24 groups (P < 0.05). The feed intake of T30 group was significantly lower than that in T22, T24 and T26 groups during the non-heat treatment period (P < 0.05). The feed intake in the heat treatment period was significantly lower than that in the non-heat treatment period (P < 0.05), and the highest feed intake was maintained in T24 group and the lowest in T30 group. Compared with T22 group, the glandular gastric index was significantly increased at 16wk (P < 0.01). At 18wk, compared with T22 group, jejunum index in T30 group was significantly lower than that in other groups (P < 0.05). At 20wk, compared with T22 group, the glandular stomach index, jejunum index and ileum index in T24 group were significantly increased (P < 0.05), and jejunum index was significantly higher than that in T30 group (P < 0.05). Compared with T22 group, the expression of NPY (Neuropeptide Y) in hypothalamus of all treatment groups was significantly increased at 14wk (P < 0.05). The expression of AgRP (Agouti-related protein) in hypothalamus of T30 group was significantly decreased (P < 0.05), and the expression of CCK (Cholecystokinin) in duodenum of T30 group was significantly increased (P < 0.05). At 20wk, compared with T22 group, the expression of CART (amphetamine-regulated transcript) in hypothalamus of T24 group was significantly decreased (P < 0.05), and the expression of ghrelin in glandular stomach of T24 group was significantly decreased (P < 0.05).【Conclusion】These results indicate that ambient temperature at 24℃ during the growing period can promote the development of gastrointestinal tract, increase the expression of NPY in hypothalamus, and inhibit the expression of CART and ghrelin in hypothalamus, which is beneficial to the growth and development of laying hens. However, high temperature treatment at 30℃ can damage the intestinal tract of laying hens, inhibit the expression of hypothalamus feeding promoting factor AgRP, and promote the expression of duodenal feeding inhibiting factor CCK, thus inhibiting feeding intake and reducing feed intake of laying hens.

Key words: laying hens, feed intake, temperature, prelay period, intestine, hypothalamus