Heat Stress and feeding strategies in meat-type chickens
Syafwan, W. ; Kwakkel, R.P. ; Verstegen, M.W.A. - \ 2011
Worlds Poultry Science Journal 67 (2011)4. - ISSN 0043-9339 - p. 653 - 674.
high ambient-temperature - male broiler-chickens - dietary-protein - environmental-temperature - water-consumption - whole-wheat - tropical climate - early age - physiological stress - energy-expenditure
Heat stress can induce hyperthermia in poultry. A reduction in heat load can be achieved by increasing the possibilities for dissipation, decreasing the level of heat production or by changing the thermal production pattern within a day. Strategies to reduce the negative effects of heat stress can be based on a specific feeding strategy, such as restricted feeding. Feed that is offered long enough before a hot period can ameliorate the harmful effects of high temperature. Another strategy may be to use choice feeding from different feed ingredients, rich in protein or in energy. With such self-selection, the chicken may adjust its intake of individual components, allowing the bird to optimise the heat load associated with the metabolism of the ingested nutrients. Additional promising strategies involve offering a choice between feeds with a different feed particle size or structure. A large particle size contributes to the development of the gastro-intestinal tract (GIT), especially the gizzard and the caeca. A large gizzard will maximize the grinding process and potentially ease digestion down the GIT, thereby reducing heat production associated with digestive processing. Also wet feeding may be profitable under heat stress conditions as well. Feeding wet diets may facilitate an increased water intake and larger particle sizes can limit water excretion in droppings, resulting in more water being available for evaporation during panting, hence cooling the bird. In conclusion, these feeding strategies may help to reduce heat production peaks, facilitate evaporative activity and/or decreases the heat load, resulting in beneficial effects on performance and health of the bird kept in more tropical areas worldwide.
Effects of early life thermal conditioning and immune challenge on thermotolerance and humoral immune competence in adult laying hens
Star, L. ; Juul-Madsen, H.R. ; Decuypere, E. ; Nieuwland, M.G.B. ; Vries Reilingh, G. de; Brand, H. van den; Kemp, B. ; Parmentier, H.K. - \ 2009
Poultry Science 88 (2009)11. - ISSN 0032-5791 - p. 2253 - 2261.
mannan-binding lectin - 4 layer lines - male broiler-chickens - hygienic stress - early-age - molecular-patterns - heat-stress - temperature - performance - responses
Effects of early life experience with climatic (heat) and hygienic [lipopolysaccharide (LPS)] stress on adaptability to the same stressors in later life were studied in laying hens. Chicks were exposed to 37°C for 24 h at d 5 of age (n = 12) or were i.v.-administered once with 1 mg/kg of BW of LPS at 6 wk of age (n = 12), whereas a control group was reared under standard conditions receiving a placebo treatment of PBS (n = 36). At 24 wk of age, hens treated in early life were reexposed to the same stressor. Early life control hens were exposed to heat stress (n = 12), i.v.-administered with LPS (n = 12), or not exposed (n = 12). To evaluate improvement of adaptability, effects of climatic and hygienic stress on performance, humoral immune competence, and endocrine responsiveness were investigated in hens with early life experience to the stressors and hens only exposed to the stressors in later life. Early life heat exposure did not affect performance, immune, and endocrine parameters. Treatment x time interactions were found for level of antibody (Ab) binding to LPS and keyhole limpet hemocyanin (KLH) after LPS administration, indicating that hens with early life LPS experience differed in response level (Ab binding to LPS) and response pattern (Ab binding to LPS and KLH) compared with hens administered with LPS only at adult age. Our data suggest that early life heat stress exposure did not affect adaptability of laying hens to heat stress in later life. However, early life LPS exposure affected kinetics and magnitude of Ab levels binding to LPS and KLH, indicating that early life LPS exposure can enhance the status of immune reactivity or induce a higher sensitivity to LPS
Effect of Single or Combined Climatic and Hygienic Stress in Four Layer Lines: 1. Performance
Star, L. ; Kemp, B. ; Anker, I. van den; Parmentier, H.K. - \ 2008
Poultry Science 87 (2008)6. - ISSN 0032-5791 - p. 1022 - 1030.
multiple-hen cages - male broiler-chickens - laying hens - heat-stress - group selection - immune response - early-age - adaptation - lipopolysaccharide - thermotolerance
Effects of long-term climatic stress (heat exposure), short-term hygienic stress [lipopolysaccharide (LPS)], or a combination of both challenges on performance of 4 layer lines were investigated. The lines were earlier characterized by natural humoral immune competence and survival rate. At 22 wk of age, 80 hens per line were randomly divided over 2 identical climate chambers and exposed to a constant high temperature (32°C) or a control temperature (21°C) for 23 d. Half of the hens housed in each chamber were i.v. injected with LPS at d 1 after the start of the heat stress period. The effect of heat, LPS, or a combined challenge on feed intake, BW, hen-day egg production, egg weight, and egg shell thickness were investigated. Feed intake, BW, hen-day egg production, egg weight, and egg shell thickness were significantly reduced by heat stress. Administration of LPS significantly reduced feed intake, BW (LPS x time interaction), hen-day egg production, and egg weight (LPS x time interaction). Hens were able to recover from LPS administration but did not completely adapt to heat stress. Hens still lost weight, had a lower feed intake and hen-day egg production after 23 d of continuous exposure to heat stress. These data suggest a different nature of short-term LPS exposure versus long-term heat exposure affecting performance parameters of laying hens, and different adaptation mechanisms of hens toward these stressors. Neither natural humoral immune competence nor survival rate, for which the lines had been earlier characterized, were indicative of the response to different stressors. However, significant line x heat interactions were found for feed intake and hen-day egg production, and a line x heat x time interaction for BW, whereas a line x LPS interaction was found for hen-day egg production and a line x LPS x time interaction for BW. The lines had similar response patterns, but differed in response levels, suggesting that some lines were better able to adapt to stressors than others
Ontogeny of avian thermoregulation from a neural point of view
Baarendse, P.J.J. ; Debonne, M. ; Decuypere, M.P. ; Kemp, B. ; Brand, H. van den - \ 2007
Worlds Poultry Science Journal 63 (2007). - ISSN 0043-9339 - p. 267 - 276.
brain temperature regulation - neuronal hypothalamic thermosensitivity - gallus-gallus-domesticus - early postnatal-period - male broiler-chickens - early-age - thermal manipulations - anas-platyrhynchos - precocial birds - muscovy duck
The ontogeny of thermoregulation differs among (avian) species, but in all species both neural and endocrinological processes are involved. In this review the neural processes in ontogeny of thermoregulation during the prenatal and early postnatal phase are discussed. Only in a few avian species (chicken, ducklings) the ontogeny of some important neural structures are described. In the early post hatching phase, peripheral and deep-body thermoreceptors are present and functional, even in altricial species, in which the thermoregulation is still immature at hatch. It is suggested that the development of peripheral and deep-body thermoreceptors is not responsible for the inability to maintain a stable body temperature at cold ambient temperatures during early postnatal phase, although studies examined the ontogeny of thermoreception only in an indirect manner. Thus, other factors, such as volume to surface ratio and rate of insulation are important. Studies regarding the ontogeny of hypothalamic cold- and warm-sensitivity neurons in precocial species demonstrate that maturation of the hypothalamic temperature sensitivity takes place during the late prenatal and early postnatal period, with a relatively high cold sensitivity of the hypothalamus during the transition from poikilotherm to homeotherm. In addition, incubation temperatures are demonstrated to influence postnatal hypothalamic thermosensitivity. Brain temperature regulation is found to maturate during avian ontogeny as well and is demonstrated to coincide with the ontogenic pattern of general thermoregulation in several avian species. Relevant information of the ontogeny of the spinal cord and effector pathways related to the development of avian thermoregulation is lacking. We concluded that both prenatal and early postnatal temperature affects hypothalamic thermosensitivity and consequently condition thermoregulation in later life.