Evaluation of basic feed in dairy cow nutrition]

The basic feeds hay, grass silage and corn silage out of 70 dairy farms were investigated for the correct evaluation of their concentration of raw protein (RP) and gross energy (NEL) lactation. Three different kinds of rations were grouped: type A (estimated feed mass, table data contents), type B (weighed feed mass, table data contents), type C (weighed feed mass, analysed contents). Concerning gross energy lactation significant differences between C and A and C and B could be detected. Calculations of the expected milk yield (Milk Yield Potential, MYP) out of gross energy lactation and of raw protein were carried through and compared, using each, analysis data and table standards. MYP out of raw protein in basic feeds significantly exceeds the possible milk yield out of gross energy concentration, referring to table standards and analysis data as well. Raw protein-MYP of analysed data was significantly higher than of table standards, whereas gross energy MYP calculated with analysed data did not agree with table standards.     

The influence of Borna disease viral infection on dairy cow reproduction

We investigated the influence of Borna disease virus (BDV) infection on the clinical state of dairy cows. Sera from 149 cows were examined using enzyme-linked immunosorbent assay and western blotting detect antibodies to the BDV-nucleoprotein antigen. Among 149 investigated cows, 25 (16.8%) showed a positive reaction to BDV antigen. No significant difference existed in milk production or medical history between seropositive and seronegative cows. Although the estrus cycle appeared normal even in the seropositive cows, the frequency of artificial insemination and calving-to-conception intervals significantly increased in seropositive cows. Therefore, fertilization failure was recognized in the BDV-antibody positive cows.     

Chronic copper toxicity in a dairy cow

A three year old Holstein dairy cow fed a ration containing a copper supplement died of chronic copper poisoning. The concentration of copper in the liver was 331 ppm (wet weight). The typical lesions of chronic copper toxicity including icterus, hepatic fibrosis and hemoglobinemic nephrosis were found at necropsy. The chronic copper toxicity was not considered to be a herd problem since the liver copper concentration in a slaughtered cull animal and blood samples taken from five animals in the same herd were within normal limits.     

Mechanisms linking metabolic status and disease with reproductive outcome in the dairy cow

Culling for infertility remains the main reason for disposal of dairy cows, limiting productive lifespan. In extreme cases, ovulation is inhibited, preventing the possibility of conception. More often cows do conceive, but fail to remain pregnant owing to intrinsic problems in the embryo and/or to a poor-quality reproductive tract environment. Both aspects have a genetic component and are also influenced by management practices affecting nutrition and health. The relative importance of these factors varies among heifers, first-lactation and older cows. A common theme, however, is that an internal signalling system exists which reduces fertility when the cow is in an unsuitable metabolic state to sustain a pregnancy. This may be directly related to nutrient shortage caused by inadequate feed intake, or because available nutrients are being prioritized towards growth or milk production, away from reproduction. Evidence is presented for the involvement of the somatotrophic axis (GH, IGF1, insulin, IGFBP2) and leptin as key metabolic signalling molecules. Another emerging theme is the interaction between metabolism and disease that affects the fertility. Common examples include (i) calf diseases causing inadequate heifer growth and increased age at first calving; (ii) poor peripartum energy status reducing the capacity of the uterus to involute and mount an effective immune response, thereby increasing the likelihood of endometritis; and (iii) development of mastitis after conception, a contributory factor to both early and late embryo mortality. Finally, recent evidence suggests that times of metabolic stress cause mitochondrial damage that also contributes to a reduction in longevity.     

The occurrence of Fusarium toxins in feed

Fusariotoxins can be found in imported feed as well as in crops from the Middle-Europe-Region. Concerning frequency of contamination, zearalenone is most important in the Federal Republic of Germany. From the grains, maize and oats are mainly affected. Frequency and intensity of contamination however, variates, depending on several factors as climate or genetical resistance. Typical districts with high frequency of contamination cannot be found in the FRG at the present status of knowledge. Feed-intoxications by zearalenone predominantly can be seen in pigs, cases with ruminants, horses or fowl rarely can be found. As imported feeds--especially those of the by-products of the wet-milling technique of maize--can be contaminated with zearalenone, a consequent control is demanded. Additionally culture techniques, genetical selection, seed treatment and harvesting should be optimized. A scientific-based tolerable limit till now cannot be stated. There are however some hints, that female pigs show cystic degenerations of the ovary receiving 50 microgram per kg diet. Naturally contaminated feed with 100 microgram fed for several weeks to growing female pigs induced signs of hyperestrogenism. Trichothecene contamination was found with lower frequency in the Federal Republic especially with DON, which dominates in Austria and some districts of the USA. From the contaminated feeds, maize and oats should be mentioned with priority. Ensiled products of the maize plant show some degradation during the ensiling process. Husks contain higher levels than the endosperm. No differences between conventionally and alternatively (biologic dynamic) grown crops could be found. A value for a tolerable daily intake cannot be stated at the present status of knowledge.(ABSTRACT TRUNCATED AT 250 WORDS)     

奶牛乳房炎发病原因的综述

奶牛乳房炎发病率高，每年给奶业生产造成严重的经济损失，其主要病因是致病菌对机体的感染。本文试图从奶牛自身性状、营养、环境、管理4个方面分析可能导致致病菌对机体感染的原因，以期为乳房炎的防治提供参考。