Probiotic bacteria maintain normal growth mechanisms of heat stressed broiler chickens.

Probiotics have growth promoting effects even under periods of heat stress challenge. More information is needed to understand the mechanisms by which probiotics maintain the growth performance. The aim of this study was to evaluate the effect of a probiotic based on Bacillus subtilis bacteria on growth related mechanisms of broilers under heat stress conditions. Specifically, growth performance, skeletal bone characteristics, skeletal muscles size, intestinal villus-crypt structure, intestinal bacteria, growth hormone (GH), insulin-like growth factor-1 (IGF-1), cholesterol, and glucose. A total of 1200 one day old Ross 308 male broilers were randomly distributed into 4 treatments, with 12 replicates per treatment and 25 birds per replicate. A 2 × 2 factorial arrangement was used; the main factors were environmental temperature (thermoneutral or heat stress) and diet (control or control + B. subtilis; 3 × 107 cfu/kg of feed). From d 22 to 35 of age, birds were either exposed to thermoneutral conditions (21 °C) or chronic heat stress (30 °C). During the same period, each group was divided into 2 subgroups and fed either the control diet or the B. subtilis supplemented diet. The results demonstrated that B. subtilis had positive effects (P < 0.05) on the body weight gain, feed conversion ratio, villus height, crypt depth, villus surface area, absorptive epithelial cell area and viable counts of intestinal beneficial bacteria. B. subtilis increased (P < 0.05) serum GH, IGF-1 and maintain normal levels of cholesterol and glucose under heat stress conditions. In addition, broilers fed B. subtilis under heat stress conditions exhibited higher (P < 0.05) skeletal muscles size and improved (P < 0.05) tibia traits and lower (P < 0.05) abdominal fat pads deposition compared with the controls. B. subtilis had no effect on rectal temperature under thermoneutral or heat stress conditions. It is concluded that B. subtilis can be used as growth promoters in broilers, particularly during the periods of heat stress conditions.

Effects of organic zinc on the performance and gut integrity of broilers under heat stress conditions.

Heat stress (HS) has negative impacts on farm animals. Many studies have been conducted in order to ameliorate the effects of heat stress in farm animals. The current project investigated the effects of organic zinc supplementation under thermoneutral and heat stress conditions on the production, physiological, and histological parameters in broiler chickens. Three-hundred and sixty chicks in the current project were assigned randomly to six different treatments ( n = 60 chicks per treatment). The treatments were (1) a basal diet containing 40 mg kg - 1 of Zn from an organic source and rearing under thermoneutral (TN) conditions (Ctrl); (2) a diet containing the amount of Zn from the basal diet + 50  % of the Zn level (from the basal diet) and rearing under TN conditions (50 TN); (3) a diet containing the amount of Zn from the basal diet + 100  % of the Zn level (from the basal diet) and rearing under TN conditions (100 TN); (4) a basal diet containing 40 mg kg - 1 of Zn from an organic source and exposure to 3 d of cyclical HS at the age of 35 d (CHS); (5) a diet containing the amount of Zn from the basal diet + 50  % of the Zn level (from the basal diet) and exposure to 3 d of cyclical HS at the age of 35 d (50 HS); and (6) a diet containing the amount of Zn from the basal diet + 100  % of the Zn level (from the basal diet) and exposure to 3 d of cyclical HS at the age of 35 d (100 HS). Our results indicated that HS has decreased final body weight (fBW), average daily gain (ADG), and feed conversion ratio (FCR) relative to TN chicks. However, organic zinc had little or no effects on the production parameters measures in the current project. Overall, intestinal histological measurements were negatively altered under HS relative to TN chicks. Organic zinc inclusion in the diet had improved villus height in the duodenum and jejunum relative to the Ctrl and CHS chicks. Blood calcium and glucose levels were decreased and increased, respectively, in HS relative to TN chicks. In summary, the results discussed in the current project revealed that the inclusion rates of organic zinc used here had little or no effects on the productive parameters. However, it improved the morphological characteristics of the intestines which might maximized the intestinal efficiency in nutrient absorption under HS conditions.

The effect of subclinical mastitis on the concentration of immunoglobulins A, G, and M, total antioxidant capacity, zinc, iron, total proteins, and calcium in she-camel blood in relation with pathogens present in the udder.

The present study aims to evaluate the amount of immunoglobulins A, G, and M in she-camel blood serum in relation with the presence of pathogens in the udder, and to compare the antioxidative capacity and the concentration of zinc, iron, total proteins, and calcium. Milk and blood samples from she-camels from south Jordan were taken; according to milk bacteriological examination, the animals were divided into two groups: (Gm) which contained samples of milk contaminated with bacteria and (Gh) which contained uncontaminated milk samples. Milk and blood were sampled from 30 females and examined for the concentration of immunoglobulins A, G, and M and for the presence of pathogens in milk. Total antioxidant capacity, zinc, iron, total proteins, and calcium concentrations in blood were determined. Milk samples were checked for the presence of pathogens. She-camels for the study were of similar age and productivity in the middle stage of lactation. It was determined that the presence of pathogenic bacteria infecting the udder quarters had considerably influenced the values of immunoglobulins G, A, and M, total antioxidant capacity, and zinc and total protein concentration (p < 0.05) in blood serum; no significant difference in iron and calcium concentration was determined. Subclinical mastitis has a crucial role in increasing the concentration of immunoglobulins in serum; some parameters measured in blood (zinc, total antioxidant capacity, total proteins) could be indicative for the presence of inflammation in she-camels.