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Open access

P. Gajewczyk, D. Korniewicz, R. Kołacz, Z. Dobrzański and A. Korniewicz

Response of pregnant and lactating sows to reduced protein content in complete compound feed

The experimental material consisted of 42 sows divided into 3 feeding groups, each containing 14 sows fed complete compound feed varying in protein content. Protein and amino acid content of the feed fed to the control group was in compliance with Polish standards. Protein content in the experimental groups was reduced by 10% and 20%, respectively. At the same time, lysine, methionine, threonine and tryptophane content was supplemented to the level of the control group. All pregnant and lactating sows were fed individually. The condition of the sows was determined by measuring the thickness of backfat at the P2 position on days 30 and 105 of pregnancy and on day 25 of lactation. The data analyzed in the study included: the total number of piglets born, their body weight gain, milk composition, weaning-to-estrus interval and the farrowing rate. Protein content of the compound feed did not have a significant impact on the increment in backfat during pregnancy and losses during lactation. The sows fed compound feed with reduced protein content gave birth to 0.7 and 0.6 less piglets per litter than the control animals. However, due to lower losses, they bred 0.3 and 0.4 more piglets than the control sows. Average body weight of a piglet on day 21 was 0.5 kg lower in the experimental than in the control group. Dry matter, protein, fat and lactose content of the sow's milk did not depend on protein content of the feed. The weaning-to-estrus interval in the experimental groups was one day longer than in the control group. The reproductive rate accounted for 86% and was comparable in all the groups.

Open access

M. Woch, M. Lis, D. Kołacz, M. Kamińska and M. Staszewski

Abstract

The paper presents the study on manufacturing of nickel and cobalt powders by thermal plasma decomposition of the carbonates of these metals. It was shown the dependence of process parameters and grain size of initial powder on the composition of final product which was ether metal powder, collected in the container as well as the nanopowder with crystallite size of 70 - 90 nm, collected on the inner wall of the reaction chamber. The occurrence of metal oxides in the final products was confirmed and discussed.

Open access

S. Księzarek, M. Woch, D. Kołacz, M. Kamińska, P. Borkowski and E. Walczuk

Abstract

The paper outlines technologies currently used for the production of the Ag-Re10 and Ag-SnO2Bi2O3 contact materials in a form of wires and solid and bimetallic rivets. Their characteristic parameters, including physical and mechanical properties and microstructure, are given. It has been found that the level of these parameters, particularly electrical properties (resistance to electric arc erosion), is unsatisfactory considering the present requirements, which applies mainly to the new Ag-Re10 [wt%] alloy, so far not fully technologically mastered. Therefore, under this work a new method for the production of this type of materials has been designed and the related research works were undertaken. The new-generation contact materials in a form of nanostructured composites will be characterised by similar chemical compositions as those specified above but with increased functional properties, including enhanced resistance to arc erosion. In this paper preliminary results of the examination of structure and properties of semi-products obtained by new technology based on powder metallurgy techniques are presented. Conditions for pressure consolidation and plastic consolidation applied for material processing into wires and rivets (solid and bimetallic) have been determined.

Open access

D. Kołacz, S. Księżarek, M. Woch, J. Karwan-Baczewska, M. Staszewski, K. Rudnicki, P. Borkowski and A. Sienicki

Abstract

A new silver-based composite material with an addition of 1 and 10 mass % of rhenium, for prospective application in the production of electric contacts, has been presented. The paper shows results of the research and experimental works aimed at developing technology for fabrication of semiproducts (wires and bimetallic contacts) by classical powder metallurgy methods and by a method enabling production of nanocrystalline composite. At each stage of the processes involved, physical, mechanical and technological properties of the materials were investigated. Particular attention was given to final products and semiproducts prepared in a form of bimetallic contacts. It was found that the composite with nanocrystalline structure may be a good material for ecological electric contacts.