Growth performance and gut response of broiler chickens fed diets supplemented with grape (Vitis vinifera L.) seed extract

To evaluate the effects of the dietary supplementation with a grape seeds extract (GSE) on growth performance, gut morphology and immune response, and meat quality, 800 chickens (8 pens/group) were fed a control diet or the same diet added with 0.1%, 0.2%, or 0.4% GSE from hatching to 42 d of age. Growth performance did not differ among dietary treatments: final live weight averaged at 3,179 g, which corresponded to a daily growth rate of 76.1 g/d; feed intake averaged 113 g/d, for a feed conversion ratio at 1.49. On average of samplings at 14 d and 28 d of age, the density of CD45þ cells in the jejunal mucosa was higher (2,497 vs. 1,931 cells/ 10,000 lm2; p < .001) in chickens fed diet 0.2% GSE compared to chickens fed the other diets; jejunum villi height tended to be lower in chickens fed diet 0.2% GSE compared to those fed the other diets (965 lm vs. 1,054 lm; p ¼ .07). Slaughter results and carcase traits, occurrence of myopathies at breast and meat quality after 24 h or 11 d of refrigerated storage were not affected by GSE inclusion or level. Under the conditions of the present study, no relevant effect of the dietary inclusion of GSE was observed on performance and health, but a pro-inflammatory immune response at the level of jejunum, based on which a positive response of chickens fed GSE can be expected under challenging conditions.