The influence of variable precipitation patterns on simulations of pesticide mobility

The behaviour of pesticides in the soil is governed by a variety of complex processes including the climatic conditions. To investigate the influence of these specific factors, a Monte-Carlo Method was used to generate sequences of daily precipitation and temperature data representing natural weather behaviour. Simulations of the leaching process were performed for different compounds with these sequences while all other environmental parameters were held constant. The results indicated that the use of stochastic variables yields new insight into the leaching process. It is shown that the naturally occurring variability of the weather pattern has a crucial influence on the leaching of pesticides.     

Short-term effect of dietary yeast nucleotide supplementation on small intestinal enzyme activities, bacterial populations and metabolites and ileal nutrient digestibilities in newly weaned pigs

In previous studies, dietary nucleotides have been shown to improve performance in single-stomached animals by promoting the renewal of small intestine epithelial cells and by influencing the activity and composition of the microbial community in the digestive tract. The present experiment was carried out with 12 barrows weaned at the age of 18 days and fitted with a simple T-cannula at the distal ileum. To determine short-term effects of dietary yeast nucleotides, the piglets received a grain-soybean meal-based basal diet with or without supplementation of 1 g/kg of a dried yeast product containing free nucleotides. Dietary supplementation with yeast did not affect bacterial numbers in the ileum as well as ileal concentrations of individual short-chain fatty acids (SCFA), total SCFA and total lactic acid (p > 0.05). Moreover, there was no effect of supplemental yeast nucleotides on ileal α-amylase, leucine amino peptidase, maltase and lactase activities (p > 0.05), as well as on ileal dry matter, crude protein and crude fibre digestibilities (p > 0.05). In conclusion, short-term supplementation with dietary yeast nucleotides did not affect microbial metabolite concentrations, bacterial numbers and enzyme activities in the ileal digesta as well as ileal nutrient digestibilities of newly weaned pigs.     

Effect of protein restriction and refeeding on the nitrogen balance in piglets

In balance trials the effect of a 50% protein restriction with subsequent realimentation on N balance, endogenous N excretion, digestible and metabolisable energy was tested using 36 piglets. The dietary protein content during the restriction period from 5-12 kg live weight was 22.9 (control) and 12.4% of the dry matter and during the realimentation period from 12-18 kg live weight in both groups 17.2%. Protein quality and energy supply were not changed between the groups. Restricted protein supply proportionally reduced N retention with slightly improved efficiency of digestible N from 67 to 70%. During realimentation the previously reduced N supply did not influence N retention but increased the apparent N digestibility by 2% units. The endogenous N losses as well as digestible and metabolisable energy were not different between the groups. It was concluded that compensatory responses of the N metabolism might require a stronger dietary restriction and respectively or a longer restriction period.     

In vitro lymphocyte proliferative responses and gamma-interferon production as measures of cell-mediated immunity of cattle exposed to Pasteurella haemolytica.

Cell-mediated immune mechanisms may play a role in the pathogenesis and prevention of pneumonia in cattle caused by Pasteurella haemolytica serotype A1. To determine the circumstances required to stimulate and identify cell-mediated immune responses, calves were vaccinated with a commercial P. haemolytica bacterin or a live commercial P. haemolytica vaccine, or were infected intratracheally with virulent P. haemolytica. All calves were challenge-exposed intratracheally with P. haemolytica 31 d after vaccination or prior infection. Peripheral blood mononuclear cells and mediastinal and superficial cervical lymph node cells were stimulated with antigens prepared from P. haemolytica to evaluate in vitro proliferative responses and gamma-interferon production as measures of cell-mediated immunity. Strong proliferative responses and gamma-interferon production were detected in lymph node cells from calves vaccinated with the live vaccine and from infected calves, especially in response to stimulation with an outer membrane protein preparation from P. haemolytica. Greater proliferative responses and gamma-interferon production were associated with the lymph node nearer the site of bacterin administration (superficial cervical lymph node) or the site of infection (mediastinal lymph node), whereas greater proliferative responses and gamma-interferon production were associated with the more distant lymph node (mediastinal lymph node) in calves vaccinated with the live vaccine. Neither proliferative responses nor gamma-interferon production were detected in peripheral blood mononuclear cells from calves that were vaccinated for or infected with P. haemolytica. Antileukotoxin antibody titers were determined by a serum neutralization assay, and protection against pneumonic lesions was more closely correlated with antileukotoxin antibody responses than with lymphocyte proliferation or gamma-interferon responses.     

Einfluß von Zinkmangel auf den Zink-, Protein-, Fett- und Energieansatz von zwangsernährten Ratten

Uber eine Schlundsonde wurden junge männliche Ratten (110 ± 5 g) bei zwei unterschiedlichen Futterniveaus entweder mit einer Basisdiät (103 ppm Zn) oder einer Zn-Mangeldiät (1,3 ppm Zn) 4 mal täglich zwangsernährt. Gruppe 1 und 2 erhielten die Basis- bzw. Zn-Mangeldiät in einer Menge von 11,6 g/Tag und Tier (? hohes Futterniveau). Bei Gruppe 3 und 4 wurde die verabreichte Basis- bzw. Mangeldiät auf 8,7 g/Tag und Tier begrenzt (? niedriges Futterniveau). Nach 12 Versuchstagen wurde der Ansatz an Trockensubstanz, Asche, Zink, Rohprotein, Fett und Energie bestimmt. Der Ansatz an Zink, Trockensubstanz, Asche, Rohprotein, Fett und Energie war bei den Ratten neben der Zinkversorgung auch teilweise vom Futterniveau abhängig. Zinkmangel reduzierte den Ansatz an Trockensubstanz und Asche um 38 bzw. 24%, während für Zink sich ein negativer Wert errechnete, was bedeutet, daß mehr Zink ausgeschieden als aus der Nahrung absorbiert wurde. Mangelnde Zinkzufuhr erniedrigte im Durchschnitt den Energie- und Proteinansatz um 40 bzw. 43 %, während der Fettansatz nur bei niedrigem Futterniveau signifikant um 76% reduziert war.     

Requirement of true ileal digestible threonine of growing and finishing pigs

Ninety-six crossbred barrows and gilts were used to investigate the optimum supply of true ileal digestible threonine for growing (approximately 35-65 kg body weight) and finishing (approximately 65-110 kg body weight) pigs. For this purpose, according to a bifactorial arrangement in the grower as well as in the finisher phase four dietary threonine levels were combined with two dietary levels of lysine. Measurement criteria were body weight gain, feed intake, feed conversion rate and carcass characteristics. In the grower stage at the lower lysine level daily gain increased numerically (p < 0.1) and the feed to gain ratio decreased significantly with an increasing dietary true ileal digestible threonine concentration. Increasing the true ileal digestible lysine concentration of the diet from 7.8 to 9.2 g/kg increased average daily gain in the grower stage significantly from 815 to 855 g and decreased the feed to gain ratio significantly. In finishing pigs, daily gain and feed to gain ratio were significantly improved by an increasing dietary true ileal digestible threonine concentration from 821 to 902 g and from 3.14 to 2.94 kg/kg, respectively, but not by the differing lysine supply. As in the grower stage, barrows consumed more feed than gilts at similar growth rates and this resulted in a significantly reduced feed to gain ratio in gilts compared with barrows. The requirements of true ileal digestible threonine for optimize both, daily gain and feed to gain ratio, as derived by the broken-line model were 10.3 g/animal and day for growing and 10.7 g/animal and day for finishing pigs respectively.