Nutrient digestibility and nitrogen utilization in lactating cows under restricted protein supply and subsequent refeeding

The effects of a 17% deficiency of crude protein for four weeks on nutrient digestibility and parameters of N metabolism were investigated using four pairs of monozygotic twin cows. During a period of realimentation of three weeks with slight nutrient oversupply and a further period of three weeks with nutrient supply adjusted to the lactation trend it was examined if residual effects remain. Protein restriction enhanced the excretion of fecal dry matter by 7.7%. Total fecal nitrogen was a high in the restricted group as in the control group. Apparent digestion coefficients for dry matter, organic matter and N-free extracts were lowered by 2 to 3 percent points with deficient protein nutrition. Crude fiber and nitrogen digestibilities declined by 4.5 and 9.8 percent points, respectively. The reduction of urine nitrogen excretion amounted to 47% as consequence of a drastically diminished nitrogen content of urine. Total nitrogen retention (milk-N and body-N) was lowered by 14%. The sum of the relative nitrogen losses via faeces and urine was not different between the protein-deficient and the normal diet. The utilization of feed nitrogen for milk nitrogen excretion was 28.2% in protein deficiency and 25.9% in control feeding. After realimentation no relevant residual effects of the previous protein deficiency were found neither with respect to nutrient digestibility nor to parameters of the nitrogen balance. So far the observed permanent effect in reduced milk yield by 6% of the expected performance can not be explained with changes in digestibility or nitrogen balance.     

Migration and growth of Neostrongylus linearis (Marotel, 1913) Gebauer, 1932 in sheep

In order to establish the mammalian parasitic cycle of the nematode Neostrongylus linearis 18 lambs were infected with 5000 third-stage larvae obtained from the snail Cernuella (Xeromagna) cespitum arigonis. In the subsequent days, larvae were found in the walls of the caecum and colon, in the liver and the lungs, suggesting that the bloodstream is the main migratory route. The presence of low numbers of migrating larvae in the mesenteric lymph nodes indicates that this route is probably secondary. The first still sexually undifferentiated, fourth-stage larvae were found in the lungs on the 8th day post-infection (p.i.) and the first sexually differentiated fifth-stage larvae, on the 10th day. Also described are the macroscopic changes of the parasitized organs.     

Secondary amyloidosis in white Peking ducks

In a research institute numerous cases of amyloidosis were observed in 12 of 70 white Peking ducks kept in cages with wire bottoms. All 12 ducks also suffered from chronic inflammed alterations in the sole of foot zone (bumble-foot). A second flock of 40 white Peking ducks supplied with equivalent feed but kept outdoors showed neither signs of bumble foot nor amyloidosis. Likewise, after the healing of the bumble feet per adjustment of the wire bottoms (installing a wider footing area) no new cases of amyloidosis were noticed among the ducks kept in cages. Histologically deposits of amyloid were found in the liver, which was highly affected, the kidney, spleen, stomach, small and large intestines as well as pancreas. The fact that amyloidosis only appeared under certain circumstances indicates the presence of a secondary form of this illness.     

Bird assemblages in forest fragments within Mediterranean mosaics created by wild fires

The role of habitat heterogeneity as a key factor in determining species pools in habitat mosaics has been acknowledged, but we still know little on the relative importance of the different ecological processes acting within such complex landscapes. We compared species richness and distribution in forest fragments imbedded in shrub-lands to those in continuous forests or in continuous shrublands. We examined the consistency of our data with the predictions of two hypotheses: 1) the Habitat fragmentation hypothesis which states that fragmentation has negative effects on the species from the original continuous habitat; 2) the Habitat supplementation /complementation hypothesis which stipulates that the presence of a matrix habitat around the fragments will mitigate negative effects on the species from the original habitat (supplementation) or allow the presence of species that depend on the presence of both the fragment and matrix habitats (complementation). We show that: 1) species richness in forest fragments did not differ from species richness in segments of continuous forests of equal area; 2) the bird community of forest fragments got impoverished in some forest species but a higher proportion of species common in continuous forests were not affected by fragmentation; 3) fragment communities had a significant proportion of common species that were scarce in, or absent from both continuous forests and shrublands. While, a few forest species supported predictions from the fragmentation hypothesis, occurrence patterns observed in several other species were consistent with either the supplementation or the complementation hypotheses. Our results suggest that there is no single hypothesis that properly captures the consequences of a shift from continuous forests to a mosaic of forest fragments and shrublands and that different ecological mechanisms act in conjunction to determine species pools in habitat mosaics. Habitat heterogeneity at a local scale appears a key factor in maintaining bird diversity in fire driven Mediterranean landscapes.     

Ovicidal and nymphicidal effects of some fungicides on the greenhouse whitefly<Emphasis Type="Italic">Trialeurodes vaporariorum</Emphasis>

Eggs and L1 nymphs of the greenhouse whiteflyTrialeurodes vaporariorum (Westwood) (Hem.: Aleyrodidae) on bean leaves were directly sprayed with the fungicides maneb and mancozeb at recommended rates for practical use. Strong ovicidal and nymphicidal effects were observed. These fungicides may prove to have practical use for integration in IPM programs for whitefly control, as they also exert low or no toxicity to the whitefly parasitoidEncarsia formosa. http://www.phytoparasitica.org posting April, 30, 2004.     

Host-parasite relationships in tobacco plants infected with a root-knot nematode (<Emphasis Type="Italic">Meloidogyne incognita</Emphasis>) population from the Azores

During a nematode survey, severe infections of tobacco feeder roots and heavy soil infestations byMeloidogyne incognita race 1 were found in S. Miguel (Azores islands, Portugal). This is the first record ofM. incognita infection of tobacco in Azores. Morphology of various life stages, analysis of the esterase electrophoretic pattern and differential host tests were used for nematode characterization and identification. Nematode-induced mature galls were spherical and/or ellipsoidal and usually contained more than one female, males and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density and growth of tobacco plants was tested in a glasshouse experiment in which inoculum levels varied from 0 to 512 eggs and juveniles (J₂) cm⁻³ of soil. Seinhorst’s model was fitted to height and top fresh weight data of the inoculated and control plants. Tolerance limits with respect to plant height and fresh top weight of tobacco cv. ‘Erzegovina’ plants toM. incognita race 1 were estimated as 1.25 eggs and J₂ cm⁻³ of soil. The maximum nematode reproduction rate was 404.7 at an initial population density of 4 eggs and J₂ cm⁻³ of soil. http://www.phytoparasitica.org posting March 2, 2004.