An experiment was conducted to compare the effect of a supplementary mixture of essential oils, with and without exogenous xylanase, on performance, carcass composition, dietary nitrogen (N)-corrected apparent metabolizable energy (AMEn), dry matter retention (DMR), N retention (NR), fat digestibility (FD) coefficients, and endogenous mucin losses (measured as sialic acid, SA) when fed to broiler chickens. Three hundred male Ross 308 broilers in total were reared in floor pens from 0 to 21 d of age. Birds were fed 1 of 3 wheat-based diets: basal diet (215 g/kg CP, 12.12 MJ/kg AME) with either no additive (control diet; C) or 100 g/tonne of a standardized combination of 5% carvacrol, 3% cinnamaldehyde, and 2% capsicum oleoresin (diet XT); or a combination of XT and commercial xylanase enzyme at a rate of 100 g of XT and 2,000 units (U) of xylanase/kg (diet XYL), respectively. Each diet was randomly allocated to 10 pens with 10 birds. Feeding XT and XYL diets improved birds' growth performance (P<0.05). Birds fed XT and XYL diets had an improved caloric conversion ratio (P<0.05) and consumed 1.3 MJ less AMEn per kilogram of growth compared to birds fed the control diet only. Feeding XT improved only the dietary FD coefficient (P<0.05) compared to control-fed birds, but the dietary FD coefficient did not differ for XYL diet (P>0.05). Birds fed XYL diet excreted 35% less endogenous mucin compared to control-fed birds (P<0.05). Birds fed XT alone gained more carcass protein than the control-fed birds (P<0.05) but did not differ from the birds fed XYL diet (P>0.05). There was no indication of a negative interaction between dietary essential oils and xylanase.
Experimental comparisons of the nutritional value of different wheat cultivars commonly use feeds in meal form even though the largescale broiler producers use steam pelleted feeds. The aim of this experiment was to examine the effect of steam pelleting on the performance, dietary N-corrected apparent metabolisable energy (AMEn), total tract dry matter retention (DMR), nitrogen retention (NR) and fat digestibility (FD) coefficients, and digestive tract development of broilers fed four different wheat samples in complete diets. Four European wheat samples, with different chemical composition and endosperm characteristics, were used in a broiler experiment. The wheat samples were milled through a 5 mm screen and four basal feeds containing 670 g/kg of each selected wheat sample were mixed. The basal feeds were then split into two batches and one of them was steam pelleted resulting in eight experimental diets. Each diet was fed ad libitum to eight pens of two male Ross 308 broilers from 10 to 24 days of age. Feeding pelleted diets improved ( P < 0.001) feed intake and weight gain, and daily water intake of the birds. Pelleting also improved dietary AMEn and FD ( P < 0.001) and DMR ( P < 0.05). An interaction ( P < 0.05) was observed between wheat samples and steam pelleting for NR. Steam pelleting improved ( P < 0.05) NR in the wheat sample with high starch and protein and hard endosperm but not in the rest of the wheat samples. Similar interactions ( P < 0.05) were also observed between wheat sample and steam pelleting for gain to feed (G : F) and water to feed (W : F) ratios. Pelleting improved G : F ratio the greatest in the wheat sample with high starch and protein and hard endosperm. Feeding the same wheat sample also decreased ( P < 0.05) W : F but only in the mash diets. Regardless of the wheat sample the values of dietary AMEn did not differ ( P > 0.05). Feeding different wheat types and pelleting did not ( P > 0.05) change the development of the gastrointestinal tract of the birds. The study showed that there were differences between four wheat samples when they were fed in pelleted complete feed, but no differences were observed when fed in mash form complete diets. Research on the interaction between pelleting and wheat chemical and quality characteristics is warranted.
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