Pasture-flock-raised poultry are becoming an increasingly popular product, but only limited options are currently available for maintaining gut health. For these producers, prebiotics are an attractive option because they are generally recognized as safe (GRAS) and can be mixed into the feed and thus do not require adjustments to production protocols. However, if prebiotic treatments reduce production performance, they would not be useful to producers. Thus, the objective of this study was to measure performance of pasture-raised broilers fed 1 of 3 prebiotic treatments. For these trials, 2 breeds of birds were used: Naked Neck slow-growing breeds and Cornish White Rock cross fast-growing breeds. The experimental design was replicated for each breed. A total of 340 birds were split into 4 groups, each group fed one feed additive: 1) galactoligosaccharides (2% wt/wt), 2) fructooligosaccharides (1% wt/wt), 3) plum fibers (1% wt/wt), or 4) no additives. During the 8-wk rearing period, 10 birds from each group were collected and euthanized to take small intestine samples. Histological preparations were made from the small intestine tissue, and 4 measurements of villi height and crypt depth from each cross section were taken. Throughout the study, mortality was monitored and BW measurements were taken at 2-wk intervals. For the Cornish White Rock cross, the group receiving the feed supplemented with fructooligosaccharides had higher (P < 0.05) 8-wk BW than those fed Plum; control and birds fed galactoligosaccharides were intermediate. For the Naked Neck breed, the group receiving the plum fibers had the highest final BW. It appears that all 3 feed supplements offered some protective effect for alterations in villi length and crypt depth due to feed withdrawal, but only for the Naked Neck breed. The data indicate the 3 prebiotics utilized in this study could be used without risk of decreasing production performance, but only for Naked Neck breeds.

SummaryThe mineralization kinetics of nitrogen in acid soils, and their modification by the addition of an organic fertilizer (cattle slurry), were studied by incubating a humic cambisol for 36 weeks using a method based on that of Keeney & Bremner (1967). The cumulative curve of the quantity of nitrogen mineralized in soil not given fertilizer departs significantly from Stanford's theoretical model, which predicts linear dependence of nitrogen mineralized upon √t. The observed kinetics are interpreted as due to the superposition of two mineralization processes involving different substrates.The cumulative mineralized nitrogen curves for soil samples enriched with the various slurry fractions likewise reflect complex kinetics involving at least two main substrates. Consideration of the net mineralized nitrogen shows that F,, the solid fraction with the highest C/N ratio, clearly induced immobilization of nitrogen during the first 130 days of incubation, and analysis of the NO3/NH4 ratio suggests that this immobilization was probably at the expense of nitrate. F3, the liquid fraction, first induced a brief period of mineralization and then stabilized nitrogen levels, giving rise to a reduction in net mineralized nitrogen. The addition to the soil of F2, the semi-liquid fraction, produced results intermediate between those of the other two fractions.In conclusion, the increase in organic nitrogen in the soil after addition of cattle slurry depends in the short term on the liquid and semi-liquid fractions, whereas long-term effects involve both the stable residues of these fractions and the more solid fraction. The labile fraction of the pool of mineralizable N benefits more than the recalcitrant fraction, and the time constants of the mineralization process are reduced.

-The body composition of thirty-eight Granadina goat kids was measured. Six animals were slaughtered at birth while the remainder were kept individually at an environmental temperature of 24k2" and a relative humidity of 60 & 5 YO. They were given goat's milk or a milk-substitute at two planes of nutrition until 15 or 30 d of age and then slaughtered. The goat's milk and milk-substitute contained 2604 and 222.0 g digestible protein/kg and 23.23 and 20.85 MJ metabolizable energylkg respectively. Voluntary feed intake as metabolizable energy was a function of metabolic body-weight (kg W0775), equivalent to 2.42 and 2.44 times the energy requirement for maintenance for goat's milk-and milk-substitute-fed animals respectively. There was a high degree of correlation between the empty-body concentration of dry matter, fat and energy and empty-body-weight (P < 0001) or animal age (P < O.OOl), and between body-weight and animal age (P < 0.001). The relationships between empty-body composition and emptybody-weight were independent of type of milk or plane of nutrition. In contrast relationships between empty-body composition or empty-body-weight and animal age were affected by the type of milk and, over all, by the plane of nutrition. All these results show that in these animals any body-weight will have a similar composition, but it will be reached earlier or later depending on dietary regimen and always with the limitation of voluntary intake.

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SummaryThe characteristics of three fractions obtained by physical separation from each of 19 cattle slurries are reported, with the aim of investigating their behaviour in the soil. The fraction retained on a 1 mm sieve (F1) was the poorest in nutrient content. The fraction passing through a 1 mm sieve but retained in Richard's apparatus on a cellulose membrane of 2·4 nm pore radius (F2) contains most of the slurry's organic N and Pand most divalent cations (Ca2+ and Mg2+). F3, which passes through the cellulose membrane, contains most of the slurry's inorganic N and most monovalent cations.The individual fractions are both chemically and physically much more homogeneous than the slurry as a whole, and their relative proportions are well correlated with the slurry's density and dry-matter content (P < 0·001), so that this kind of fractionation may confidently be expected to provide an analytical scheme facilitating research on the behaviour of slurry after its application to soil.