Abstract
Heat stress (HS) adversely affects growth performance and inflicts heavy economic losses to the poultry industry. There is, therefore, a critical need to identify new alternative strategies to alleviate the negative effects induced by HS. The tropic medicinal plant, Morinda citrifolia (Noni), is being used in livestock nutrition, however the literature is limited and conflicting for its impact on growth performance. The present study aimed to determine the effect of Noni on feeding and drinking behavior as well as on the hypothalamic expression of stress- and metabolic-related genes in broiler chickens exposed to acute HS. A total of 480 1 day-old male broiler chicks were randomly assigned to 12 controlled environmental chambers. Birds were subjected to two environmental conditions (TN, 25°C vs. HS, 35°C for 2 h) and fed two diets (control vs. 0.2% Noni) in a 2 × 2 factorial design. Feed intake and core body temperature (BT) were recorded during HS period. Blood was collected and hypothalamic tissues were harvested for target gene and protein analyses. Acute HS-broilers exhibited higher BT (~1°C), spent less time eating with a significant decrease in feed intake, and spent more time drinking along with higher drinking frequency compared to those maintained under TN conditions. Although Noni supplementation did not improve feed intake, it significantly delayed (~30 min) and reduced the BT-induced by HS. At molecular levels and under HS conditions, Noni supplementation down regulated the hypothalamic expression of HSP90 and its related transcription factors HSF1, 2, and 4, increased orexin mRNA levels, and decreased the phosphorylation levels of AMPKα1/2Thr172 and mTORSer2481. Together, these data indicated that Noni supplementation might modulate HS response in broilers through central orexin-AMPK-mTOR pathways.
Highlights
Livestock production, including poultry is facing substantial challenges from steep projected increases in global demand for animal proteins due to predicted increases in world human population on one hand, and the need to adapt to extreme environmental conditions due to climate change on the other hand
Voluntary feed consumption was negatively affected by acute Heat stress (HS) (P < 0.05, Figure 1C) in both control and Noni-fed groups, body weight did not differ between all groups (Figure 1D)
Feeding frequency did not differ between the experimental groups (Figure 2C), acute heat stressed chickens spent less time eating compared to TN group (Figure 2A) which may explain the reduction of feed intake
Summary
Livestock production, including poultry is facing substantial challenges from steep projected increases in global demand for animal proteins due to predicted increases in world human population on one hand, and the need to adapt to extreme environmental conditions due to climate change on the other hand. Environmental HS impacts every aspect of animal lives and their very existence (Chen et al, 2011). It can result in heat-related discomfort, illness, multiple organ damage, and under extreme conditions can cause spiraling hyperthermia leading to death. In broiler chickens, which play a key role in worldwide meat production, the strong negative effects of HS on feed intake, growth, feed efficiency, meat yield, and mortality leading to dramatic economic losses are well-documented (Dale and Fuller, 1980; Cahaner and Leenstra, 1992; Geraert et al, 1996; Deeb and Cahaner, 2002) Such effects will take a heavy toll during the decades as the distribution of heat anomalies continues to rise
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