Effect of early feed restriction on physiological responses, performance and ascites incidence in broiler chickens raised in normal or cold environment

Abstract

Intensive selection of broilers for faster growth and better feed efficiency resulted in greater susceptibility to metabolic disorders such as ascites syndrome, which is one of the major causes of mortality and economic loss in broiler industry. Whereas cool temperature is one of the primary triggers for ascites, early feed restriction (FDR) significantly alleviates its incidence and mortality. However, little is known about effects of FDR, cold environmental temperature and their interaction on physiological responses in broiler chickens. For this purpose, 320 one-day-old male broilers were divided into two treatment groups of Ad libitum (Ad) and feed restricted (FR) with eight pen replicates each. Chickens in FR group underwent feed access limitation from days 7 to 14 of age. On day 21 half of the birds (four pens) in each group exposed to the cold temperature (CT) and the other half (four pens) continued at normal temperature (NT). Average daily feed intake, average daily weight gain and feed conversion ratio (FCR) were measured at days 7, 14, 21, 28 and 42. At 39 and 46 days of age two chicks with a BW around the pen average were selected from each pen and slaughtered after collecting blood samples. Then, relative weight of internal organs and right ventricle weight per total ventricle weight (RV : TV) ratio were calculated. Compared with NT group, CT birds had higher daily feed intake and FCR (P < 0.05) from day 28 to 42. Cumulative ascites mortality in CT chickens was higher (P < 0.001) than NT chicks. Within the CT group, ascites mortality in FR chickens was reduced (P < 0.001) to 1.25% compared with 8.75% in Ad chicks. Birds in CT group had significantly (P < 0.05) thicker right ventricle and greater relative weight of heart, hematocrit and triiodothyronine concentration. However, none of these parameters were affected by FDR. Under cold stress conditions, FDR reduced activity of alanine aminotransferase and aspartate aminotransferase (P < 0.05). Serum triglyceride, cholesterol, high-density lipoprotein and total protein were not influenced by either temperature or feeding regimen. In conclusion, these findings suggest that FDR reduces ascites incidence mainly by allowing better development of internal organs, which helps them to cope with the high metabolic pressure and suffer less damage.

Effects of N-acetylcysteine on the energy status and antioxidant capacity in heart and liver of cold-stressed broilers

“…Broilers are sensitive to temperature variations and their metabolic rate will rise to adapt to colder conditions [18], and thereby leading to the growth inhibition and even death [3]. Low ambient temperature is reported to induce hypoxia and ascites in broilers due to the increase of oxygen demands for both fast growth and heat production [3]. Several managements including nutritional and medicinal strategies are taken to minimize the loss in broilers due to the exposure to cold stress.…”

“…1.13 1.00 Threonine (%) 4) 0.88 0.75 Calcium (%) 3) 1.00 0.90 Total phosphorus (%) 4) 0.75 0.65 Avaiable phosphorus (%) 3) 0.54 0.45 1) The contents of crude protein in the ingredients. stress treatment) was reduced to 10°C±1°C on d 15 of age and kept constant until the end of the experiment [2,7].…”

Effect of feeding regime on the performance and blood parameters of male and female broiler chickens

“…A larger heart size in restricted animals may lead to myocyte hypertrophy and is assumed to be an adaptive response (Santos et al, 2018). Mohammadalipour et al (2017) stated that the growing heart mass elevated HC to satisfy the oxygen demand of the increased metabolic rate. However, in the present study, HC was lower numerically in restricted males and might be associated with the lack of compensatory growth.…”

“…Blood measurements give information about animal health and metabolism, though Zhan et al (2007) and Mohammadalipour et al (2017) did not find effects of feed restriction on blood biochemical parameters. Effects of feed restriction on performance, carcass composition and physiological conditions are affected by the commencement, intensity and duration of feed restriction.…”

“…Feed restriction has been shown to reduce the high mortality generally observed in commercial broiler operations (Tůmová et al, 2002). Lower mortality of restricted chickens is due to a decreased incidence of SDS and ascites (Lippens et al, 2000;Mohammadalipour et al, 2017) and leg problems (Lippens et al, 2000). Carcass composition may be negatively affected by feed restriction (Lippens et al, 2000;Zhan et al, 2007).…”