Interactions between dietary fat type and xylanase supplementation when rye‐based diets are fed to broiler chickens 2. Performance, nutrient digestibility and the fat‐soluble vitamin status of livers

Abstract

1. The interactions between dietary fat type and xylanase supplementation of rye-based diets were investigated using a 2 x 2 factorial design in which a rye-based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with or without xylanase supplementation at 3000 IU/kg, and fed to 1-d-old male broilers for 35 d. Growth, nutrient digestibility and AMEN values were determined and the vitamin status of livers assessed at various ages. 2. There were significant interactions between crude fat and xylanase supplementation on the faecal digestibility of crude fat and crude protein. Fat digestibility was improved by xylanase in both fat type groups but to a greater extent for the tallow diets. However, the effects were found to be significant only for oleic, linoleic and linolenic acids. Similarly, protein digestibility and AMEN values were significantly improved by xylanase, but only for the tallow diet. 3. Ileal digestibility of nitrogen and amino acids also were affected by enzyme for both fat type diets, the effect generally being more pronounced for the tallow diet. 4. The deposition of the fat soluble vitamins A and E in livers was significantly increased by xylanase supplementation and was also better for soya oil than for tallow. 5. Xylanase supplementation increased the digestibility of insoluble pentosans whereas for the soluble pentosans the opposite effect was noted. 6. Without xylanase supplementation the tallow-based diet caused high mortality. Liveweight gain and the efficiency of food utilisation were greatest in the soya oil-based, xylanase-supplemented diet, followed by the unsupplemented soya oil-, supplemented tallow- and unsupplemented tallow-based diets.

Effect of fat source, energy level and enzyme supplementation and their interactions on broiler performance

“…The improvement in BWG of broilers that received TOM supplemented diets could be ascribed to increases in protein and energy retention. Dänicke et al (1997b) found that fat digestibility in broilers was improved by enzymes in two fat sources (soybean oil and beef tallow) but protein digestibility and AME N values were significantly improved by enzymes only in a tallow diet. It was reported that enzymes reduce the negative effects of NSPs and improve the digestion of nutrients in poultry diets.…”

“…Water-soluble NSPs fed to young chicks interfere with the digestion and absorption of other nutrients by increasing the viscosity of digesta in the gut (Ward & Marquardt, 1983). Xylanase supplementation was noted to increase the digestibility of insoluble pentosans (Dänicke et al, 1997b).…”

“…Several studies have been conducted to examine the effect of fat type on broiler performance. Dänicke et al (1997b) reported a significant effect of fat source (soybean oil vs. tallow) on bodyweight gain (BWG) and feed conversion ratio (FCR) in broilers that received soybean oil-based diets. Conversely, Preston et al (2001) reported no significant effects of fat source (tallow, soy oil, a tallow : soy oil (2 : 1) blend) on bird performance.…”

Influence of Fat Source and Xylanase Supplementation on Performance, Utilisation of Energy and Fat, and Caecal Microbiota Counts in Broiler Starters Fed Wheat-Based Diets

“…The finding that xylanase addition did not influence fat digestion suggests that viscosity was likely to be low. The effect of the xylanase on weight gain and particularly feed per gain was somewhat low compared with other studies where tallow and soy oil have been compared (Smulikowska and Mieczkowska, 1996;Danicke et al, 1997). A possible reason for this low response may lie in the use of mash diets, instead of pelleted diets.…”

“…Soybean oil is better utilised by poultry due to their high contents of unsaturated fatty acids, whereas tallow contains long chain saturated fatty acids, which are nonpolar and difficult to digest and absorb (Krogdahl, 1985). Some reports suggest that high concentrations of NSP in wheat influence the digestion and absorption of lipids in poultry, and that this effect is more evident when animal fats are used as the lipid source (Smulikowska and Mieczkowska, 1996;Danicke et al, 1997Danicke et al, , 1999aPreston et al, 2001). In the current work, therefore, the hypothesis that the influence of exogenous xylanase on bird performance and nutrient utilisation will be more pronounced in tallow-supplemented wheat-based diets compared to those supplemented with soybean oil was tested.…”