Søren Højsgaard

Intestinal degradation in pigs of rye dietary fibre with different structural characteristics

In order to investigate the effects of dietary fibre (DF) characteristics on carbohydrate degradation and the metabolism in the large intestine, pigs were fed on four rye-bread diets (based on whole rye, pericarp/testa, aleurone or endosperm) with differences in characteristics and amount of DF. The degradability of DF in the large intestine varied greatly between diets. The pericarp/testa DF was hardly degraded in the large intestine, whereas endosperm DF was extensively and rapidly degraded in the caecum. Caecal degradation of aleurone DF was also limited, leaving more material to be degraded in the colon. The undegradable pericarp/testa DF was characterized by high contents of lignin, cellulose, ferulic acids and highly substituted arabinoxylans (the major DF component in rye). Ingestion of this diet resulted in increased faecal bulk and reduced transit time, but with low colonic pH and the lowest concentrations of shortchain fatty acids (SCFA). The aleurone diet, on the other hand, led to a fermentation pattern which may be considered more optimal, with lower colonic pH and higher concentrations of SCFA, in particular butyric acid. Despite the large differences in carbohydrate fermentation only minor significant effects on the presence of protein degradation products and on histological measurements (height and diameter of colonic crypts and thickness of the muscularis external) were observed.

Degradation of rye arabinoxylans in the large intestine of pigs

Four types of rye bread (based on whole rye, pericarp/testa, aleurone or endosperm) differing in arabinoxylan (AX) structure were fed to pigs. Collected intestinal material was extracted with cold water and 4 M potassium hydroxide, and the AX were characterised by methylation analyses. The endosperm AX were extensively and readily degraded in the caecum (0.78), whereas pericarp/testa AX were undegraded in the intestinal tract of pigs. Aleurone AX were also degraded to a large extent (faecal digestibility 0.73) but at a slower rate, and, in agreement, structural modification of aleurone AX also took place beyond the proximal colon. The differences in AX degradability correlated well with differences in water and alkali extractability and differences in structural characteristics of the AX. Endosperm AX were thus characterised by a large content of water-extractable AX and pericarp/testa AX by a very high degree of (mono- and double-) xylose substitution. In contrast, aleurone AX were characterised by the presence of an alkali-extractable AX with a very low degree of substitution, which precipitated upon dialysis of the alkali extract. The faecal xylose substitution patterns were similar irrespective of diet. The study thus showed that the structural characteristics of a dietary fibre component influenced dietary fibre degradation in pigs, which may hold important implications for the colonic health in monogastrics.

Improved Detection of Reproductive Status in Dairy Cows Using Milk Progesterone Measurements

This study tested a model for predicting reproductive status from in-line milk progesterone ;measurements. The model is that of Friggens and Chagunda [Theriogenology 64 (2005) 155]. Milk progesterone measurements (n = 55 036) representing 578 lactations from 380 cows were used to test the model. Two types of known oestrus were identified: (1) confirmed oestrus (at which insemination resulted in a confirmed pregnancy, n = 121) and (2) ratified oestrus (where the shape of the progesterone profile matched that of the average progesterone profile of a confirmed oestrus, n = 679). The model detected 99.2% of the confirmed oestruses. This included a number of cases (n = 16) where the smoothed progesterone did not decrease below 4 ng/ml. These cows had significantly greater concentrations of progesterone, both minimum and average, suggesting that between cow variation exists in the absolute level of the progesterone profile. Using ratified oestruses, model sensitivity was 93.3% and specificity was 93.7% for detection of oestrus. Examination of false positives showed that they were largely associated with low concentrations of progesterone, fluctuating around the 4 ng/ml threshold. The distribution of time from insemination until the model detected pregnancy failure had a median of 22 days post-insemination. In this test, the model was run using limited inputs, the potential benefits of including additional non-progesterone information were not evaluated. Despite this, the model performed at least as well as other oestrus detection systems.

BIFROST—block recursive models induced from relevant knowledge, observations, and statistical techniques

Abstract The theoretical background for a program for establishing expert systems on the basis of observations and expert knowledge is presented. Block recursive models form the basis of the statistical modelling performed by the program. These models, together with various model selection methods for automatic model selection, are presented. Additionally, the connection between a block recursive model and expert systems based on causal probabilistic networks is treated. A medical example concerning diagnosis of coronary artery disease forms the basis for an evaluation of the expert systems established.

Quantifying degree of mastitis from common trends in a panel of indicators for mastitis in dairy cows

This paper has 2 objectives. First, it argues that it is beneficial to regard degree of infection with respect to mastitis as a latent quantity varying continuously from 0 (truly healthy) to 1 (full-blown clinical mastitis). This quantity is denoted as degree of infection (DOI). The DOI is based on extracting common characteristics from a panel of indicators measured repeatedly over time. The indicators used in this paper are electrical conductivity (EC), somatic cell count (SCC), and the immune response related enzyme lactate dehydrogenase (LDH). Second, this paper presents a statistical model for such data and a corresponding method for estimating the DOI from a panel of indicators. An empirical proof of concept is provided. Using DOI, there was a significant difference between the DOI of mastitic and healthy control cows beginning 5 d before the mastitic cows were treated for mastitis.

Split models for contingency tables

A framework for log-linear models with context specific independence structures, i.e. conditional independencies holding only for specific values of the conditioning variables is introduced. This framework is constituted by the class of split models. Also a software package named YGGDRASIL which is designed for statistical inference in split models is presented. Split models are an extension of graphical models for contingency tables. The treatment of split models includes estimation, representation and a Markov property for reading off independencies holding in a specific context. Two examples, including an illustration of the use of YGGDRASIL are presented.

Energy balance of individual cows can be estimated in real-time on farm using frequent liveweight measures even in the absence of body condition score.

Existing methods for estimating individual dairy cow energy balance typically either need information on feed intake, that is, the traditional input-output method, or frequent measurements of BW and body condition score (BCS), that is, the body reserve changes method (EB(body)). The EB(body) method holds the advantage of not requiring measurements of feed intake, which are difficult to obtain in practice. The present study aimed first to investigate whether the EB(body) method can be simplified by basing EB(body) on BW measurements alone, that is, removing the need for BCS measurements, and second to adapt the EB(body) method for real-time use, thus turning it into a true on-farm tool. Data came from 77 cows (primiparous or multiparous, Danish Holstein, Red or Jersey) that took part in an experiment subjecting them to a planned change in concentrate intake during milking. BW was measured automatically during each milking and real-time smoothed using asymmetric double-exponential weighting and corrected for the weight of milk produced, gutfill and the growing conceptus. BCS assessed visually with 2-week intervals was also smoothed. EB(body) was calculated from BW changes only, and in conjunction with BCS changes. A comparison of the increase in empty body weight (EBW) estimated from EB(body) with EBW measured over the first 240 days in milk (DIM) for the mature cows showed that EB(body) was robust to changes in the BCS coefficients, allowing functions for standard body protein change relative to DIM to be developed for breeds and parities. These standard body protein change functions allow EB(body) to be estimated from frequent BW measurements alone, that is, in the absence of BCS measurements. Differences in EB(body) levels before and after changes in concentrate intake were calculated to test the real-time functionality of the EB(body) method. Results showed that significant EB(body) increases could be detected 10 days after a 0.2 kg/day increase in concentrate intake. In conclusion, a real-time method for deriving EB(body) from frequent BW measures either alone or in conjunction with BCS measures has been developed. This extends the applicability of the EB(body) method, because real-time measures can be used for decision support and early intervention.

The effect of change of the diet and feeding regimen at weaning on duodenal myoelectrical activity in piglets

This study investigated the effect of the change of diet and feeding regimen at weaning on myoelectrical activity of the intestine of piglets. For this purpose the electromyographic recordings of duodenal myoelectrical activity were carried out in relation to the different weaning status of piglets. Six piglets, in two experimental trials were surgically modified with two serosal, bipolar electrodes on the duodenum. The myoelectrical activity was recorded in the same piglets before weaning when they were sucking their sow and after weaning when the diet was changed to solid dry food (standard commercial concentrate for weaned pigs). In sucking piglets the intestinal myoelectrical activity pattern exhibited triple-phased migrating myoelectric complex (MMC), undisturbed by sow nursing. After weaning, feeding with solid food induced a long-term post-prandial pattern with higher frequency of electrical response activity (ERA) when compared with phase II of the MMC. The duration of the MMC cycles increased with time over the experiment by proportionately 0•11 and 0•14 in the periods before and after weaning. However, weaning significantly shortened MMC cycle duration by proportionately 0•21. The duration of phase II was significantly prolonged with time over the experiment by 0•07 to 0•10 and it was not affected by weaning. Phase III of MMC were of constant duration over the whole experimental period. In summary, changes in the diet and feeding regimen have an influence on the characteristics of intestinal myoelectrical activity in piglets around weaning.

Oestrus Detection in Dairy Cows Using Likelihood Ratio Tests

Abstract This paper addresses detection of oestrus in dairy cows using methods from statistical change detection. The activity of the cows was measured by a necklace attached sensor. Statistical properties of the activity measure were investigated. Using data sets from 17 cows, diurnal activity variations were identified for the ensemble and for the individual cows. A diurnal filter was adapted to remove the daily variation of the individual. Change detection algorithms were designed for the actual probability densities, which were Rayleigh distributed with individual parameters for each cow. A generalized likelihood ratio algorithm was derived for the compensated activity signal and detection algorithm was tested on 2323 days of activity, which contained 42 oestruses on 12 cows in total. The application of statistical change detection methods is a new approach for detecting oestrus in dairy cows and the results are shown to outperform earlier approaches in respect to combined statistics of false alarms and missed detections.

Myoelectrical activity of gastric antrum in conscious piglets around weaning

We investigated gastric myoelectrical activity in piglets around weaning. The study was carried out on the same piglets before and after weaning. Before weaning, the piglets were kept with their littermates and nursed by the sow, then they were weaned on solid dry food (standard concentrate for weaning pigs) and fed three times a day. Gastric myoelectrical activity was recorded in conscious animals using bipolar electrodes implanted on the wall of the terminal antrum. A cyclic activity pattern of the antral region in the stomach was present in both suckling and weaned piglets and consisted of quiescence and an activity phase. Sows milk under nursing conditions significantly decreased the frequency of response potentials in ERA (electrical response activity). However, milk did not influence the basic electrical rhythm (BER) i.e., frequency of ECA (electrical control activity) and did not affect the periodicity of the cyclical activity. After weaning, ingestion of solid feed increased the BER, the frequenc...