Periodic usage of low-protein methionine-fortified diets in broiler chickens under high ambient temperature conditions: effects on performance, slaughter traits, leukocyte profiles and antibody response

Abstract

This study was performed to evaluate the effects of adding methionine supplements to low-protein diets and subsequent re-feeding with a normal diet on the productive performance, slaughter parameters, leukocyte profiles and antibody response in broiler chickens reared under heat stress conditions.During the whole experimental period (6-49 days), the birds were raised in battery cages located in high ambient temperature in an open-sided housing system. A total of 360 6-day-old male chickens were divided into six treatments in six replicates with ten chicks each. Six isoenergetic diets, with similar total sulfur amino acids levels, were formulated to provide 100 and 100 (control), 85 and 100 (85S), 70 and 100 (70S), 85 and 85 (85SG), 70 and 85 (70S85G), and 70 and 70% (70SG) of National Research Council recommended levels for crude protein during the starter (6-21 day) and grower (22-42 day) periods, respectively. Subsequently, all groups received a diet containing the same nutrients during the finisher period (43-49 day). The results showed that, under heat stress conditions, average daily gain and feed conversion ratio and performance index from day 6 to 49, breast and thigh yields and antibody titer against Newcastle disease in the birds fed diets 85S, 70S and 85SG were similar to those of birds fed control diet, whereas feeding diets 70S85G and 70SG significantly decreased the values of above-mentioned parameters. Additionally, diets 85S, 70S and 85SG significantly decreased mortality rate and heterophil:lymphocyte ratio compared with the control diet. In conclusion, the results indicate that supplementation of methionine to diets 85S, 70S and 85SG, and then re-feeding with a conventional diet is an effective tool to maintain productive performance and to improve health indices and heat resistance in broilers under high ambient temperature conditions.

Achyranthes Japonica Nakai root extract supplementation improves apparent nutrient digestibility, caecum microbiota, and excreta gas emission in broiler chicks

“…On the other hand, the increase of feed intake means enhancing the energy intake in animals. Excessive energy intake will lead to an increase in heat production and/or fat deposition (Swennen et al 2007), thereby increasing the relative weight of liver and abdominal fat (Ghasemi et al 2014). Therefore, the relative weight of abdominal fat did not increase, because the addition of AJN root extract in the diet of broiler chicks had no effects on the feed intake and the relative weight of liver (Richards et al, 2003;Hada et al 2013).…”

Threonine Requirements in Dietary Low Crude Protein for Laying Hens under High-Temperature Environmental Climate

“…In addition, diets that contain a high content of dietary crude protein (CP) will increase internal heat production by the elevated heat increment in a high-temperature climate [2]. Therefore, low levels of CP with supplementing limiting amino acids can overcome the bad effects of heat stress [3,4] and enhance protein utilization [5,6]. Recently, it has been reported that laying performance was equal among 14%, 15%, and 16% dietary CP [7].…”