1. A total of 72 H&N Brown Nick laying hens, 76 weeks of age (moulted at 60 weeks of age), were randomly assigned into a 3 × 3 factorial arrangement with three limestone particle sizes and three dietary Ca concentrations (30, 36 and 42 g/kg Ca); with 8 replicates per treatments, and one hen (individual) per experimental unit. 2. Particle sizes of the limestone were: distributions smaller than 2 mm (Fine), between 2 to 5 mm (Medium), and larger than 5 mm (Large). The fine, medium and large limestone particles were all obtained from the same source, and sieve sizes used had screen sizes 2 mm and 5 mm. 3. The different concentrations of dietary Ca, particle size or interactions had no significant effect on egg production, egg weight, egg mass, feed intake or feed conversion ratio. 4. The concentrations of dietary Ca and particle sizes had no significant effect on egg breaking strength, eggshell as % by weight of whole egg or eggshell thickness. The interactions between Ca concentrations and particle sizes had a significant effect on eggshell breaking strength, but not on other parameters. 5. Different dietary particle sizes had no significant effect on the Ca, P and Mg mineral contents of eggshell. While the different concentrations of Ca in diets had a significant effect on the P content of eggshell, they had no significant effect on Ca and Mg contents. 6. Different dietary concentrations of Ca had a significant effect on shear stress, and Ca and Mg contents of tibiae, but not other parameters. Also, dietary particle sizes had a significant effect on shear stress and Ca contents of tibiae. The interaction between Ca concentrations and particle sizes had a significant effect on tibia shear force and Ca content. 7. According to the results of this study, moulted brown laying hens should be fed 36 g/kg Ca and a medium limestone particle size (2-5 mm) in the diet to maintain performance, eggshell and bone quality.
O. 2010. Effects of xylanase enzyme supplementation to corn/wheat-based diets on performance and egg quality in laying hens. Can. J. Anim. Sci. 90: 207Á212. This study was conducted to determine the effects of xylanase supplementation of corn/wheat-based diets on the performance and egg quality of laying hens. At 52 wk of age, 180 White Leghorn LSL laying hens were fed 15 diets, consisting of five corn:wheat ratios and three levels of enzyme. None of the treatments affected performance or egg quality, except for egg yolk index and egg yolk color. The egg yolk color was improved by the increase in dietary corn level. It is concluded that wheat can be used instead of corn as an energy feedstuff in laying hen diets. Aucun traitement n'a affecte´le rendement ni la qualite´des oeufs, hormis la couleur et l'indice du jaune. La couleur du jaune s'ame´liore avec la proportion de maı¨s dans la ration. On en conclu qu'on pourrait remplacer le maı¨s par du ble´comme source d'e´nergie dans la ration des pondeuses. Mots clé s: Qualite´des oeufs, pondeuse, rendement, xylanaseIn the poultry industry, to formulate a balanced leastcost diet, both accurate nutrient composition of feedstuffs and requirements of the birds must be defined. It is important to have accurate energy values for feed ingredients because dietary energy is a major cost in formulating a least-cost ration. Corn and wheat have been used in many countries as major ingredients for poultry rations because of their high energy content.Wheat is an excellent replacement for corn in poultry feeds, but dietary modifications need to be made because of its anti-nutritive fraction, non-starch polysaccharide (NSP). Wheat contains a relatively high level of NSP as a structural carbohydrate (Annison 1990; Ward 1995;Jaroni et al. 1999). The majority of the carbohydrate fraction is derived from b-glucan and arabinoxylan in the grain cell wall (Annison and Choct 1991;Classen and Bedford 1991). Xylans are the main NSP of wheat, and high levels of wheat in poultry diets can increase the viscosity of the gut contents, which impedes the circulation and absorption of nutrients, causing reduced feed intake, body weight gain, and feed efficiency (Annison and Choct 1991). The anti-nutritive effects of NSP are probably mediated by a number of mechanisms, including increased digesta viscosity complexing of NSP with digestive enzymes, binding of bile salts, thus reducing lipid solubilization and absorption (Ebihara and Schneeman 1989) and increasing fermentation in the small intestine with subsequent decrease in nutrient digestion (Choct et al. 1996).The use of enzymes in commercial layer diets has become more common in recent years (Lazaro et al. 2003;Mathlouthi et al. 2003; Ç iftci et al. 2003;Rafuse et al. 2004). Enzymes may be targeted at carbohydrates, proteins or lipids (Leeson and Summers 1997). In poultry diets, enzymes are responsible for increasing the digestibility of feed ingredients and reducing the incidence of wet droppings, which may result from the presence of NSP (Cho...
In this study was evaluated the effects of rosemary (Rosmarinus officinalis) essential oil on performance and eggshell quality parameters of laying hens. In experiment, a total of 192 twenty four-week-old NOVOgen White laying hens were assigned to the basal control diet supplemented with 50, 100, 150, 200 and 250 mg/kg of rosemary essential oil (6 treatment diets, 8 replicates, each replicate consists of 4 hens). Hens were fed with experimental diets from 24 to 36 weeks of age. Water and feed were supplied ad libitum throughout the experiment. The results of study indicated that there were no differences in egg production, feed intake, feed conversion ratio, egg weight, egg mass as performance parameters among the treatment groups. The eggshell weight had no significantly affected by the dietary treatments. However, eggshell thickness and eggshell breaking strength were significantly affected by the treatments (P< 0.05). The eggshell thickness was significantly increased fed with 250 mg/kg rosemary essential oil supplemented of group when compared to the control group. The breaking strength was increased by the addition of dietary rosemary essential oil. The results of this study demonstrated that performance parameters were not significantly influenced with rosemary oil addition in laying hens diet. But, rosemary oil addition in laying hens diet significantly increased to eggshell breaking strength. It may be said that the dietary addition of 50 mg/kg of rosemary essential oil would be beneficial to improve the egg shell quality in laying hens.
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