Heat stress and feeding strategies in meat-type chickens

Heat stress (HS) causes molecular dysfunction that adversely affects chicken performance and increases mortality. The responses of chickens to HS are extremely complex. Thus, the aim of this study was to evaluate the influence of acute and chronic exposure to HS on the expression of thioredoxin–peroxiredoxin system genes and DNA methylation in chickens. Chickens at 14 d of age were divided into two groups and reared under either constant normal temperature (25 °C) or high temperature (35 °C) in individual cages for 12 days. Five birds per group at one and 12 days post-HS were euthanized and livers were sampled for gene expression. The liver and Pectoralis major muscle were sampled for cellular analysis. mRNA expression of thioredoxin and peroxiredoxins (Prdx) 1, 3, and 4 in the liver were down-regulated at 12 days post-HS compared to controls. The liver activity of thioredoxin reductase (TXNRD) and levels of peroxiredoxin1 (Prdx1) at 12 days post-HS were significantly decreased. The results reveal that there was a significant decrease in DNA methylation at 12 days post HS in liver tissues. In conclusion, pathway of thioredoxin system under HS may provide clues to nutritional strategies to mitigate the effect of HS in meat-type chicken.

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46 The impact of heat stress on feedlot operations; nutritional and breeding options to reduce its impact

Journal of Animal Science ◽

10.1093/jas/skz258.075 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 37-38

Author(s):

Jenny Jennings

Keyword(s):

Heat Stress ◽

Management Strategies ◽

Past Research ◽

Mitigation Strategies ◽

Economic Losses ◽

Feeding Strategies ◽

Wind Speeds ◽

Diet Formulation ◽

Low Wind Speeds ◽

The Impact

Abstract Heat stress can and always will be an issue in the feedlot industry. Heat stress can decrease performance in feedlot animals leading to substantial economic losses. High environmental temperatures, relative humidity, solar radiation, and low wind speeds can be life-threatening to beef cattle when these conditions occur simultaneously. Management strategies to decrease or alleviate heat stress-related production losses have been a focus of research for a long period of time. There is a plethora of research completed on the additions of shades, sprinklers, air circulation of covered pens, as well as the physiological changes cattle experience. The physiological discoveries have revealed a lot about how the animal copes with certain stressors and has aided in potential mitigation strategies. The use of sprinklers and shades are the most popular additions to feedlots; however, certain nutritional management strategies and breed selection can be viable options as well. My objectives to address those management strategies were to compile and review past research that specifically addresses bunk management, diet formulation, feeding strategies, and breed characteristics as well as incorporate current information available on the cattle we feed today.

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197 Body temperature of pigs exposed to heat stress conditions: effect of dietary protein level

Journal of Animal Science ◽

10.1093/jas/skz122.197 ◽

2019 ◽

Vol 97 (Supplement_2) ◽

pp. 111-112

Author(s):

Adriana Morales ◽

Miguel J Cervantes ◽

Alan Valle-Fimbres ◽

Duckens Antoine ◽

Ernesto Avelar ◽

...

Keyword(s):

Heat Stress ◽

Body Temperature ◽

Protein Content ◽

Dietary Protein ◽

Protein Level ◽

Thermal Load ◽

Feeding Strategies ◽

Dietary Protein Level ◽

Amino Acid Intake ◽

Body Heat

Abstract Heat stress (HS) reduces feed intake and increases body temperature (BT) in pigs. Increased dietary protein content may correct HS-related reduced amino acid intake, but it may further increase BT. The effect of dietary protein level on BT of HS pigs was analyzed with 9-ileal cannulated pigs (61.7 ± 2.7 kg BW). A thermometer set to register BT at 5-min intervals was implanted into the ileum. There were two treatments: low-protein (10.8%) wheat-free Lys-Thr diet (LP); high-protein (21.6%), wheat-soybean meal diet. The study was conducted in two-10 d periods; d1-d7 for diet adaptation and d8 to d10 for BT data analysis. Pigs were fed at 0600 (morning), 1400 (midday), and 2200-h (evening), same amount each time. Ambient temperature (AT) and relative humidity ranged from 30.1 to 35.4 °C and from 50 to 84%, respectively. Both AT and BT followed a similar pattern; BT did not differ between LP and HP pigs (P > 0.05). Postprandial midday and evening BT was higher than postprandial morning BT (P < 0.05). The BT increment after the midday meal was larger and longer (P < 0.05) than that after the morning and evening meals. The postprandial morning and evening BT increments were longer in the HP pigs. Apparently, the capacity of pigs to dissipate postprandial body heat depends on the accumulated thermal load received before their meals; the thermal load before the morning meal was lower than that before the evening meal. In conclusion, these data show that the dietary protein level has a small effect on the BT of HS pigs, confirm that the effect of AT on BT of HS pigs is stronger than that of dietary protein content, and suggest that the capacity of pigs to dissipate body heat increases under HS conditions. This information may be useful to design better feeding strategies for pigs exposed to HS conditions.

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43 Nutritional management for tropical-subtropical-adapted cattle receiving high-concentrate diets

Journal of Animal Science ◽

10.1093/jas/skz258.066 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 33-34

Author(s):

Madeline Rivera ◽

Jordan Adams ◽

Luis O Tedeschi

Keyword(s):

Heat Stress ◽

Dry Matter ◽

Management Practices ◽

Animal Health ◽

Bos Indicus ◽

Physiological Adaptation ◽

Feeding Strategies ◽

Net Energy ◽

Feed Composition ◽

Diet Formulation

Abstract Contemporary nutritional research investigates the effects of diet formulation and feeding strategies on animal performance and global sustainability under different climates. Functional nutrition models have incorporated the effects of heat stress on net energy for maintenance requirements, dry matter intake (DMI), and milk production when accounting for animal and the environmental factors. It is commonly assumed that growing Bos indicus breeds receiving feedlot-type diets in tropical and subtropical regions have exhibited lower maintenance energy requirements than Bos taurus breeds. However, the ability to predict supplies of energy, protein, and minerals available to meet animal requirements depends on the accuracy and consistency of feed composition values obtained through digestibility trials and chemical analyses. Empirical observations indicate that feedstuffs grown in high temperatures affect cell wall lignification and metabolic activity rates, requiring special procedures for digestion trials. Similarly, physiological adaptation mechanisms in cattle in response to heat stress conditions include evapotranspiration, sweating, and drooling. Heat stress studies have reported a correlation between reduced DMI and increased dry matter digestibility for all breeds of cattle exposed to temperatures that exceed the upper critical temperatures. For that reason, diet formulation with integrated mathematical nutrition modeling can account for nutrient and animal variability, to improve total digestible nutrient values. Furthermore, the water requirement is influenced by stage and type of production, activity, diet composition, feed intake and environmental temperature. Adjustments in management practices could potentially result in reduced production losses caused by thermal heat stress. The utilization of region-specific facilities that accommodate cattle and ensure the availability and quality of drinking water will improve overall animal health and production. Cattle receiving high-concentrate diets in tropical and subtropical regions require adjustments in management and nutrition to mitigate challenges induced by heat stress environments, but improvements are warranted for required energy and water for Bos indicus breeds.

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