Biomedical subjects

M Nielen

Publications and source records attributed to M Nielen.

44 records · Page 3Linked to original sources

PubMed1994

Development of an on-line mastitis detection system within an integrated knowledge-based system for dairy farm management support.

Some aspects of automated clinical mastitis detection and diagnosis are discussed. Knowledge representation techniques for the different steps in the diagnostic process are presented. The main focus of this paper is on automated early detection, based on data that are automatically collected in the milking parlour. Principal component analysis, logistic regression and back-propagation neural networks were used in the analysis of the automatically collected data. The 3 techniques did not differ greatly in performance. All the techniques performed better when data from milking with observed clinical signs were used, compared with data from milking before clinical symptoms were noticed. Healthy quarters were mostly correctly classified by all techniques. It seems unlikely that all clinical mastitis cases can be detected at milking before visible clinical signs occur.

Animals↗

PubMed1994

Evaluation of two cowside tests for the detection of subclinical ketosis in dairy cows.

The goal of this study was to evaluate the sensitivity and specificity of two cowside tests for subclinical ketosis in dairy cows. The tests utilize milk and urine samples, respectively. One hundred and eighty-five cows, one to sixty days postpartum, were sampled for milk, urine, and blood. Subclinical ketosis was defined with serum beta-hydroxybutyrate measurements. The sensitivity and the specificity of both tests at different beta-hydroxybutyrate levels were estimated. When subclinical ketosis was defined at beta-hydroxybutyrate levels of 1.4 mmol/L and higher, the milk test had sensitivity of 90% and specificity of 96%. The urine test lacked specificity (values < 67%), but sensitivity was 100% at beta-hydroxybutyrate levels of 1.4 mmol/L upward. Both the milk and urine test can be used to monitor subclinical ketosis in a herd. Milk testing is preferred, because of the easy obtainability of milk combined with the overall better test characteristics.

3-Hydroxybutyric Acid↗

PubMed1993

The use of negative practice for the control of pica behavior.

The treatment of a 33-year-old female disabled by mental retardation and Prader-Willi syndrome who exhibited pica is described. Negative practice was administered following each occurrence of the target behavior, that is, biting off and chewing on inedible objects. Data were collected within a reversal design. The results indicated that pica was reduced to a near zero level. Follow-up data collected after 7 months while the procedure was continued revealed a sustained suppression of pica.

Adult↗

PubMed1993

Relations between on-line electrical conductivity and daily milk production on a low somatic cell count farm.

To study the relation between on-line electrical conductivity and daily milk production, data of 1389 cow days were analyzed. After correction for cow effects and DIM, a rise of 1 mS of the mean electrical conductivity caused a decline of .88 kg/d in milk production. A rise of 1 ln(SCC) unit was associated with an additional decline of .54 kg/d in milk production. In cows without clinical mastitis during the test period, the losses associated with mean electrical conductivity and ln(SCC) were 1.06 and .45 kg/d of milk production, respectively. Electrical conductivity and SCC were associated with daily production loss; the effects were additive. Therefore, electrical conductivity and SCC can be utilized as indirect tests of subclinical mastitis.

Animals↗

PubMed1992

[Endometrial growth in continuous, estrogen substitution monotherapy with Estraderm TTS (0.05 mg/die) in 31 postmenopausal females].

To prevent hyperplasia and carcinoma of the endometrium during Estrogen Replacement Therapy (ERT), addition of progestogens once a month is considered mandatory. There is, however, no good scientific basis for this assumption. Since the addition of progestogens has several disadvantages, it is important to minimise the frequency of progestogen addition. Vaginosonography is a rather new technique, which has not yet been used for monitoring ERT. This study uses the growth of the endometrium, as it was measured by vaginosonography, as a parameter for stimulation of the endometrium by estrogens. ERT with Estraderm 50 twice a week was started in postmenopausal women. The endometrial thickness at the beginning was less than 3 millimeters. During estrogen treatment the endometrial thickness was determined every 6 to 10 weeks. As long as there was little or no increase during the estrogen treatment, no progestogen was added. Where there was a considerable growth, progestogen was added. With the use of vaginosonography, it is possible, to distinguish "fast growers" (women whose endometrium responded fast) from "slow growers".

Administration, Cutaneous↗

PubMed1992

Electrical conductivity of milk: measurement, modifiers, and meta analysis of mastitis detection performance.

The physics, physiology, and pathology of electrical conductivity of milk are described. Based on a meta analysis, the use of electrical conductivity as a mastitis detection tool is discussed. Most reports were based on subclinical mastitis data. The gold standards of the different reports are discussed. With an overall sensitivity of 66% and an overall specificity of 94%, the predictive value of a positive electrical conductivity test remains low in a low prevalence population. The use of on-line systems for clinical mastitis detection is discussed. On-line systems that combine multiple data and perform multifactorial analyses will be of interest to the dairy industry.

Animals↗

PubMed1992

The economics of naturally occurring twinning in dairy cattle.

To determine the additional costs and returns of twin calvings in dairy cattle, an economic model was developed on the personal computer. Data used in the model were recorded on 33 farms over 6.5 yr and included 381 twin calvings. For missing information, assumptions were made from the literature. Additional calf returns turned out to be $2.96. Total additional cost were $71.47, consisting of $100.92 for milk reduction, $39.51 for increased premature culling, $19.25 for increased occurrence of abortion, $5.69 for increased therapy, and $6.09 for increased calving interval. Total losses were on average $171.47 - $62.69 = $108.51 per twin birth. Realistic changes in input variables could not change this negative outcome to a positive result. Therefore, it was concluded that it is not profitable to select to increase the number of twins in dairy cattle.

Animals↗

PubMed1989

Twinning in dairy cattle: A study of risk factors and effects.

Twin calvings on Dutch dairy farms were studied using data collected through a routine herd health and production management program. Over a period of 6.5 yr, 381 twin calvings (762 calves) of a total of 11,951 calvings were recorded on 33 farms. The 381 twin calvings were compared with a referent group of 1,536 calvings that was randomly selected from the orginal 11,951 calvings. Risk factors for twin calvings were parity, season, herd and previous twinning. High cumulative milk production was associated with cows conceiving twins. Treatment for infertility in the preceding lactation was an equivocal risk factor. Twin calvings increased the risk of abortion, retained placenta, fertility-related treatment, as well as the number of days open and the number of inseminations per conception. Although twin calvings resulted in more calves born per dam, the number of available replacement heifers did not increase. After twin calving, cows produced slightly less milk and were culled more often than single calving cows. To adapt appropriate management practices for cows carrying twins, an early and reliable method for detecting twin pregnancies is needed.

Journal Article↗