No copper supplementation in a corn-soybean basal diet has no adverse effects on late-phase laying hens under normal and cyclic high temperatures

Abstract

Over supplementation of copper (Cu) in animal diets may cause serious pollution in soil, water and harvested crops. To minimize the potential pollution, the effects of corn-soybean basal diet with or without supplementation of 8 mg Cu/kg on laying performance, plasma biochemical metabolic indices, and antioxidant status in laying hens were evaluated under normal and cyclic high temperatures. A total of 240 Hy-Line Brown laying hens were randomly allotted to 4 treatments with 6 replicates of 10 hens per replicate according to factorial design involved in 2 temperatures [normal temperature (NT) vs. cyclic high temperature (CHT)] and 2 dietary Cu addition amount [Cu0 (0 mg/kg) vs. Cu8 (8 mg/kg in the form of CuSO4·5H2O)]. The experimental period included 1-week adaptation, 2-week heat stress and 2-week convalescence. The temperatures of NT groups in the same period or any groups during other periods were kept at 26 ± 2°C except that of CHT groups were 26 ± 2°C∼33 ± 2°C cyclically during heat stress period. CHT groups increased (P < 0.05) the rectal temperature and plasma glucose content under heat stress, but decreased (P < 0.01) the egg yield at the second week of heat stress and the first week of convalescence, and the plasma triglyceride, uric acid, and triiodothyronine levels under heat stress. Cu8 groups increased (P < 0.05) egg weight at the first week of convalescence, and plasma thyroxin level during the whole convalescence. Interactions between temperature and Cu content existed (P < 0.05) in the laying rate at the first week of convalescence, and the plasma lactic dehydrogenase level under heat stress. Conclusively, the CHT impaired laying performance. The Cu content (10.3 mg/kg) in corn-soybean basal diet might be sufficient for meeting the maintenance and production requirements of late-phase laying hens, and no Cu supplementation had no adverse effects on egg production and antioxidant indices under cyclic high (26 ± 2°C∼33 ± 2°C) or normal (26 ± 2°C) temperatures.

Effects of Different Selenium Sources on the Laying Performance, Egg Quality, Antioxidant, and Immune Responses of Laying Hens under Normal and Cyclic High Temperatures

“…During the 4-week normal feeding period (weeks 45-48), the house temperature was maintained at 26 ± 2 • C. Then, during the 2-week heat stress period (weeks 49-50), the house temperature was maintained at 33 ± 2 • C from 09:00 to 18:00, then cooled to 26 ± 2 • C, and maintained until 07:00 the next day, with ventilation for 2 min every 100 min. During the two-week convalescence (weeks 51-52), the house temperature was maintained at 26 ± 2 • C. NT groups keep the temperature at 26 ± 2 • C [4] during these three stages. A corn-soybean-meal diet was formulated as a basal diet according to Chicken Feeding Standards (except selenium) (NY/T33-2004).…”

“…During the two-week convalescence (weeks 51-52), the house temperature was maintained at 26 ± 2 °C. NT groups keep the temperature at 26 ± 2 °C [4] during these three stages. A corn-soybean-meal diet was formulated as a basal diet according to Chicken Feeding Standards (except selenium) (NY/T33-2004).…”

“…The letter W means week and D means day; for example, W49D1 means week 49 day 1. 4 Except for the selenium content, all others are calculated values.…”

“…With the global climate crisis, the frequency of high temperature weather has increased, and heat stress has become one of the important factors restricting the production of laying hens [1,2]. The high temperature environment will cause changes in the physiological functions of laying hens such as White Leghorn hens and Hy-Line Brown, and reduce their egg production, egg weight, eggshell thickness, and reproductive performance, while Animals 2022, 12, 1006 2 of 19 also altering the immunity of laying hens [3][4][5]. Thus, it is more urgent to develop new strategies to diminish negative effects of heat stress caused by high temperature and lighten economic loss caused by heat stress.…”

Changes in Production Parameters, Egg Qualities, Fecal Volatile Fatty Acids, Nutrient Digestibility, and Plasma Parameters in Laying Hens Exposed to Ambient Temperature

“…Although the effect of HS, either acute or chronic, or direct or indirect, on laying hens has been reported ( 8 , 9 ), there have been no HS reports, to our knowledge, that investigated time-dependent changes in productive and physiological responses over the course of HS. In addition, environment humidity, which is a triggering factor to HS ( 8 ), is often disregarded in many HS studies ( 8 , 10 ) which prompted us to design different ambient temperatures with constant humidity in this study. Therefore, the main objective of the present study was aimed to reveal the effects of HS on the changes in production parameters, egg qualities, fecal volatile fatty acids, and plasma parameters during the course of HS treatment.…”