Fiber-related digestive processes in three different breeds of pigs.

The hypothesis examined in this experiment was that, because of intensive selection for greater daily BW gains and efficient utilization of concentrated low-fiber diets, modern pig breeds differ from old local breeds in their physiological ability to respond to soluble dietary fiber. Thus, the old local breeds, Schwaebisch Haellisches Schwein (SH) and Bunte Bentheimer (BB), and a modern crossbred pig (CB) were used in metabolism trials to study fiber-related digestion, including microbial hindgut fermentation, by applying a colon simulation technique (Cositec) and measuring intestinal glucose transport in Ussing chambers. A basal diet or basal plus 20% dried sugar beet pulp (SBP) as a soluble fiber source was fed to 6 pigs/breed in a 2 x 3 factorial arrangement of treatments. Four pigs of each breed per treatment were used for intestinal anatomical measurements at the end of the metabolism trials. The pigs had an initial average BW of 33.9 +/- 3.7 kg. The basal diet was formulated to meet 80% of energy and 100% of nutrient requirements for pigs with 700 g of ADG. Feeding the SBP diet reduced total intestinal tract, but it increased colon length, water-holding capacity of the digesta, and fecal bulk (P < 0.01). The digestibility of OM, CP, and ether extract decreased, whereas that of NDF and ADF increased, by SBP (P = 0.001). Pigs receiving SBP excreted less urinary N and retained more N (P = 0.001). The fecal proportions of undigested dietary and water soluble N increased and those of bacterial and endogenous debris N decreased (P < 0.05) in SBP-fed pigs. The SH pigs had lighter empty cecum weight, shorter colons, and less NDF digestibility than BB and CB pigs (P < 0.05). Fecal N excretion did not differ (P = 0.659) among breeds, but SH pigs excreted more urinary N (P = 0.001) than the other breeds. In Cositec, OM, NDF, and ADF disappearance rates from cecal chyme of SBP-fed pigs increased (P < 0.05) irrespective of pig breed. Cecal chyme of SBP-fed BB pigs produced more VFA with a smaller proportion of propionate and a larger acetate to propionate ratio than chyme of SBP-fed SH and CB pigs. The intestinal epithelial glucose transport was greater for ileal than for jejunal tissues (P < 0.001) but was not influenced by diet and pig breed. In conclusion, the modern and intensely selected pig breed can utilize SBP fiber as efficiently as the old pig breeds under the present experimental conditions.

Improving estimates of trophic shift in Nile tilapia, Oreochromis niloticus (L.), using measurements of lipogenic enzyme activities in the liver.

To test whether the measurement of selected enzyme activities could be used to estimate more precisely the trophic shift of C isotopes, Nile tilapia (Oreochromis niloticus) were fed semi-synthetic diets differing in their lipid contents (1.7%, 5.0%, 10.8% and 20.0%). The diets were formulated to contain the same amount of nitrogen and metabolizable energy and were made from casein, wheat starch, corn germ oil supplemented with vitamins, minerals and L-arginine. The influence of the different diets on the activity of two lipogenic enzymes, ATP-citrate lyase and malic enzyme, on delta13C values in the whole fish, the liver and their correlation was investigated. There was a strong positive correlation between delta13C values in the lipids of whole fish and those of their livers. The activities of lipogenic enzymes increased significantly with increasing trophic shift of C isotopes (Deltadelta13Cdiet-fish values) in the lipids. If the relationship between trophic shift and enzyme activity can be confirmed in situations where feed quantity and quality are not known, the determination of enzyme activities would enable better estimates of the trophic shift to be made thus significantly improving back-calculation of diets from stable isotope data.

Relationships between intracellular calcium and afterhyperpolarizations in neocortical pyramidal neurons.

We examined the effects of recent discharge activity on [Ca2+]i in neocortical pyramidal cells. Our data confirm and extend the observation that there is a linear relationship between plateau [Ca2+]i and firing frequency in soma and proximal apical dendrites. The rise in [Ca2+] activates K+ channels underlying the afterhyperpolarization (AHP), which consists of 2 Ca(2+)-dependent components: the medium AHP (mAHP) and the slow AHP (sAHP). The mAHP is blocked by apamin, indicating involvement of SK-type Ca(2+)-dependent K+ channels. The identity of the apamin-insensitive sAHP channel is unknown. We compared the sAHP and the mAHP with regard to: 1) number and frequency of spikes versus AHP amplitude; 2) number and frequency of spikes versus [Ca2+]i; 3) IAHP versus [Ca2+]i. Our data suggest that sAHP channels require an elevation of [Ca2+]i in the cytoplasm, rather than at the membrane, consistent with a role for a cytoplasmic intermediate between Ca2+ and the K+ channels. The mAHP channels appear to respond to a restricted Ca2+ domain.

Feeding level and diet quality influence trophic shift of C and N isotopes in Nile tilapia (Oreochromis niloticus (L.)).

Many scientists use naturally occurring stable isotopes to reconstruct the diets of animals. However, isotopic ratios may be affected not only by the composition of the diet but also by the amount of food consumed. Thus, an experiment using tilapia (Oreochromis niloticus) was carried out to test the influence of feeding level on delta13C and delta15N of fish given a semi-synthetic wheat gluten/wheat starch based diet. In addition, the effect of diet quality was tested by comparing tilapia given this feed with tilapia fed a fish meal/wheat meal based diet. Forty-four tilapia were reared individually. After a prefeeding phase, fish were randomly assigned to five groups, four on the semi-synthetic diet at different feeding levels and one group on the fish meal/wheat meal based diet fed at the equivalent of the highest level of the semi-synthetic diet. The experiment lasted eight weeks. Proximate composition, gross energy content and delta13C and delta15N values were determined in feed and fish, for delta13C separately in the lipids and the lipid-free matter. Delta13C in the lipids and the lipid-free matter and delta15N of tilapia fed the semi-synthetic diet decreased significantly with increasing feeding rate. The absolute values of the trophic shift in fish fed the semi-synthetic wheat based diet were significantly higher than in fish fed the fish meal/wheat meal based diet. The different delta13C and delta15N values in tilapia fed the same diet at different feeding levels and the influence of feed quality on the trophic shift add to the uncertainty involved in the use of stable isotopes in ecological research.

Consequences of the ban of by-products from terrestrial animals in livestock feeding in Germany and the European Union: alternatives, nutrient and energy cycles, plant production, and economic aspects.

Consequences of the ban of meat and bone meal (MBM) and animal fat with regard to livestock feeding, cropping, ecology and economy where investigated with an inter-disciplinary approach for Germany and the European Union. Calculations were made for different production systems with pigs and poultry on the basis of statistical data for the production and for the feed markets as well as from requirement data for the respective species and production system. (1.) The ban of MBM from feeding caused a need for alternative protein sources. If all the amount of protein from MBM is to be replaced by soybean meal, in Germany and the EU about 0.30 and 2.30 x 10(6) t would be needed each year (supplementary amino acids not considered). Alternatively, doubling the grain legume acreage in Germany to about 420,000 ha would supply a similar amount of protein. A wider application of phase feeding with adjusted dietary amino acid concentrations, however, would allow for saving protein to an extent which is similar to the amount of protein that was contributed by MBM in recent years. Thus, the ban is a minor problem in terms of ensuring amino acid supply. (2.) However, alternative plant ingredients cannot compensate for the gap in P supply that is caused by the ban. An additional demand for inorganic feed phosphates of about 14,000 and 110,000 t per year is given in Germany and the EU, respectively. So far, this gap is filled almost completely by increased mining of rock phosphates. Alternatively, a general application of microbial phytase to all diets would largely fill this gap. Until the ban, MBM contributed to 57% of the supplementation of P that was needed for pigs and poultry. The ban of MBM makes large amounts of P irreversibly disappearing from the food chain. (3.) Energy from slaughter offal and cadavers can be utilized in different technologies, in the course of which the efficiency of energy utilisation depends on the technology applied. It is efficient in the cement work or rotation furnace if heat is the main energy required. In contrast, the energetic efficiency of fermentation is low. (4.) Incineration or co-incineration of MBM and other by-products causes pollution gas emissions amounting to about 1.4 kg CO2 and 0.2 kg NOx per kg. The CO2 production as such is hardly disadvantageous, because heat and electrical energy can be generated by the combustion process. The prevention of dangerous gaseous emissions from MBM burning is current standard in the incineration plants in Germany and does not affect the environment inadmissibly. (5.) The effects of the MBM ban on the price for compound feed is not very significant. Obviously, substitution possibilities between different feed ingredients helped to exchange MBM without large price distortions. However, with each kg MBM not used in pig and poultry feeding economic losses of about 0.14 [symbol: see text] have to considered. In conclusion, the by far highest proportion of raw materials for MBM comes as by-products from the slaughter process. Coming this way, and assuring that further treatment is safe from the hygienic point of view, MBM and animal fat can be regarded as valuable sources of amino acids, minerals and energy in feeding pigs and poultry. Using them as feedstuffs could considerably contribute to the goal of keeping limited nutrients, phosphorus in particular, within the nutrient cycle and dealing responsible with limited resources.

[The feed value in growing pigs of a new cultivar of field beans (Vicia faba L.) supplemented with DL-methionine or DL-methionine-hydroxyanalog]. / Untersuchungen an wachsenden Schweinen zum Futterwert einer neuen Ackerbohnensorte (Vicia faba L.) bei Ergänzung mit DL-Methionin oder DL-Methionin-Hydroxyanalog.

A basal control mixture of barley, soy bean meal and soy bean oil was replaced by 25% of the new field bean-cultivar 'Divine' and the resulting two mixtures were supplemented with minerals, trace elements, vitamins and amino acids according to the ideal protein concept. The control diet was adjusted with DL-methionine (DL-Met), the field bean mixture either with DL-Met or DL-methionine-hydroxyanalogue (DL-MHA) assuming biological equivalence on a molar basis for both supplements. The three experimental diets were fed to growing pigs (35-40 kg bwt.). Spontaneous urine samples were analysed separately for determining parameters that characterize the acid-base status of the pigs. There were no significant differences between experimental groups in nutrient digestibilities. The level of bacterially fermentable substances was increased in the diets containing field beans. The field beans contained 14 mg ME/kg DM. There were no significant (p < 0,05) differences in N- and mineral-retentions (Ca, P, Na, K) between the treatments. The stronger alkalinity found in urine after feeding the field bean mixtures resulted from a higher electrolyte balance of the diet.