Techniques to Minimize the Effects of Acute Heat Stress or Chronic in Broilers

Abstract

High environmental temperature is limiting factor in broiler production. In order to minimize the undesirable consequences of acute or chronic heat stress, the techniques of fixed dietary electrolyte balance and early heat conditioning were evaluated. The objective of this study was to evaluate the possible interactions and effects of dietary electrolyte balance and early heat conditioning on feed intake, body weight, feed conversion ratio, mortality, energy bioeconomic index, fecal moisture, abdominal fat, and breast meat color (L*a*b*) of broilers submitted to chronic or acute heat stress. In total, 1280 chicks, were equally divided in experiment I (chronic heat stress, 6h/day at 32ºC from 35 to 39 d of age) and II (acute heat stress, 36 ºC for 6h at 38 days of age). The data of both experiments were combined and analyzed according to a 2x2x2 factorial arrangement (early heat conditioning (ETC) or not; fixed dietary electrolyte balance (EB) or not; and exposure to acute or chronic heat stress). ETC consisted of exposing 5-d-old birds to 36.0 °C for 24 hours. No interaction among the evaluated factors was detected. Birds exposed to acute heat stress presented significantly higher compared with chronic heat stress. Fixed dietary EB resulted in significantly higher fecal moisture. Lower abdominal fat percentage was obtained in birds exposed to chronic relative to acute heat stress. Higher breast meat L* and b* values were observed in birds exposed to acute heat stress than those submitted to chronic heat stress, indicating worse meat quality.

Impact of Dietary or Drinking Water Ruminococcus sp. Supplementation and/or Heat Stress on Growth, Histopathology, and Bursal Gene Expression of Broilers

“…The results of the clinical signs in the HS group are compatible with the results of Li et al ( 33 ) who reported that heat stress significantly affects the daily behavior of broilers, including feeding, drinking, lying, standing, and walking. Moreover, Rodrigues et al ( 34 ) recorded a high percentage of fecal moisture as a result of heat stress. Moreover, the results of the growth were significantly affected by heat stress.…”

Research Note: Effects of high barn temperature on group-level dispersion and individual activity in broiler chickens

“…The difference in the effect of on activity between light and dark periods may be caused by several factors. First, birds may display compensatory behavior: during the hottest part of the day, birds may eat less ( Rodrigues et al, 2019 ), and they need to compensate for this when the temperature drops in subsequent periods. This compensatory behavior is reflected in the shift of activity from the light to the dark periods in the current study.…”

“…This was surprising, because we expected that birds would move less with higher temperatures to reduce heat production. A possible explanation for this result is that although the birds are prone to move less, they are also motivated to drink more ( Li et al 2015 ; Rodrigues et al, 2019 ; Kim et al 2022 ; Cartoni Mancinelli et al, 2023 ). As a result, they may move to and away from the drinkers more often.…”

Acute thermal stress promotes morphological and molecular changes in the heart of broiler chickens

“…Our results showed an increase in mRNA levels of the ACE gene due to acute thermal stress. Although this seems beneficial at first, it is necessary to consider the fact that thermal stress severely alters the hydroelectrolytic balance (Rodrigues et al, 2019). Thus, inadequate Research, Society and Development, v. 9, n. 8, e63985059, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i8.5059 20 ACE increase followed by increased production of angiotensin II may favor the onset of hypertension and increased cardiovascular morbidity and mortality.…”