Бройлери

Chelating agents can be used to improve the nutritional availability of trace minerals within the gastrointestinal tract. This study was conducted to determine the effect of a novel chelating agents, L-glutamic acid N,N-diacetic acid (GLDA), a biodegradable alternative to ethylenediaminetetraacetic acid on the nutritional bioavailability of zinc in broilers. Twelve dietary treatments were allocated to 96 pens in a randomized block design. Pens contained 10 Ross 308 male broilers in a factorial design with 6 incremental zinc levels (40, 45, 50, 60, 80, and 120 ppm of total Zn), with and without inclusion of GLDA (0 and 100 ppm) as respective factors. Experimental diets were supplied from day 7 to 21/22 and serum, liver and tibia Zn content were determined in 3 birds per pen. Growth performance and liver characteristics were not affected by dietary treatments, but both supplemental Zn and GLDA enhanced tibia and serum zinc concentration. The positive effect of GLDA was observed at all levels of the dietary Zn addition. The amount of zinc needed to reach 95% of the asymptotic Zn response was determined using nonlinear regression. When GLDA was included in the diet, based on tibia Zn, the same Zn status was achieved with a 19 ppm smaller Zn dose while based on serum Zn this was 27 ppm less Zn. Dietary GLDA reduces supplemental Zn needs to fulfill nutritional demands as defined by tibia Zn and serum Zn response. Considering the positive effect on the nutritional availability of Zn in broilers, GLDA presents an opportunity as biodegradable additive, to reduce Zn supplementation to livestock and thereby reducing Zn excretion into the environment, while fulfilling the nutrition Zn needs of farmed animals.

Heat stress is a major problem in the poultry industry, especially during summer months and when birds are raised under high-density conditions. Previous studies have reported that vitamin C or electrolyte supplementation could palliate the effects of heat stress in broiler chickens. The present study evaluated the effect of a mineral and vitamin mix (AHS) added to drinking water on the performance of broiler chickens. In total, 1,824 one-day-old birds were randomly allocated to 48 pens. Maximum animal density was 26.5 kg/m2. The control group received no additive; AHS-1 and -2 groups received the AHS mix at a concentration of 1 and 2 kg/1,000 L in drinking water, respectively; and the Vit-C group received vitamin C in drinking water at 200 g/1,000 L. All birds were fed the same diets based on a 3-phase feeding program; feed and water were given on ad libitum basis. To mimic heat stress conditions, temperature in the barn was raised to 35 C from 08:00 to 14:00 h each day. For the overall growing period (0 to 35 D), adding AHS to drinking water increased final BW, ADG, and ADFI linearly (PLinear < 0.05); FCR was decreased linearly with AHS supplementation (PLinear < 0.05). Final BW, ADG, and FCR for the Vit-C group were intermediate between AHS-2 and the control groups (P > 0.10). No significant effect on mortality were found (8.77%; P > 0.10). Relative to control, all the treatments tested reduced (P < 0.05) corticosterone concentration in blood serum. In conclusion, the combined use of supplementary levels of minerals and vitamins could alleviate the effects of heat stress on broilers chickens.

Feed additives that promote gastrointestinal health may complement coccidiosis vaccination programs in antibiotic-free broiler production systems. This study examined the effects of a commercial feed additive blend (FA) on intestinal histomorphology and inflammatory biomarkers in vaccinated Ross 708 cockerels (N = 2,160). The study was a randomized complete block design (12 blocks) with 3 dietary treatments: CON (negative control), AGP (positive control: 55 ppm of bacitracin methylene disalicylate), and FA (1.5 kg/MT in starter; 1.0 kg/MT in grower; and 0.5 kg/MT in finisher). Birds were reared on re-used litter and fed a 3-phase feeding program (starter, 0 to 14 D; grower, 15 to 28 D; finisher, 29 to 36 D). One master batch of basal feed for each feeding phase was prepared and final experimental diets were manufactured by mixing the basal feed with the respective test ingredient prior to pelleting. Growth measurements, including pen body weight and feed intakes, and fresh fecal samples were taken throughout the study. On day 20, samples of intestinal tissue were collected from a subset of birds (n = 72, 1 block) for histomorphology and mRNA expression of tight junction and inflammatory genes. In the duodenum, the ratio of villi length to crypt depth was significantly lower in FA (and AGP) fed birds than those consuming the CON diet. Relative mRNA expressions of iNOS, IFNƔ, and claudin-1 were upregulated in the jejunum of FA and AGP treatment groups compared to those in the CON group; the response in the FA was of lesser magnitude than AGP. Together, these results demonstrated that the FA treatment altered the microstructure of the duodenum and affected the expression of inflammatory genes in the jejunum. The timing of these changes coincided with peak oocyte shedding in feces and an observed reduction in feed efficiency in all dietary treatment groups.