776 research outputs found
Surveillance of emerging diseases in cattle: Application to the Schmallenberg virus epidemic in the Netherlands
No full textAnimal health surveillance is an essential component to protect animal health, facilitate trade, and protect public health. Reliable surveillance systems are able to rapidly identify outbreaks of emerging animal diseases in previously free areas to enable the implementation of control measures. In the late summer of 2011, Schmallenberg virus (SBV) emerged in ruminants in north-western Europe causing fever, drop in milk production and diarrhoea in adult cattle, as well as congenital malformations in new-born calves and lambs. SBV is a vector-borne virus, transmitted by the vector Culicoides biting midges. Due to the novelty of the virus, there was an immediate need for information regarding the epidemiological characteristics of SBV to inform surveillance and control strategies. This thesis showed that SBV infected a large fraction of the ruminant population in the Netherlands during the 2011/2012 epidemic. Grazing of cattle was identified as a herd-level risk factor for high within-herd prevalence and malformations in calves. However, the impact of the epidemic on cattle reproductive performance, milk production and mortality appeared to be limited. This provided confidence that control measures such as vaccination were unneeded. Also, syndromic surveillance for early detection of emerging diseases in cattle was assessed. It was concluded that a syndromic surveillance system based on milk production or reproductive performance data could have an added value, yet complementary to passive surveillance systems. Finally, this thesis underlined the need for a tailored surveillance strategy, adapted to the changing objectives during the different epidemiological phases of an emerging disease outbreak
Changes in ruminal volatile fatty acid production and absorption rate during the dry period and early lactation as affected by rate of increase of concentrate allowance
Get PDFThe aim of the present experiment was to study changes in volatile fatty acid (VFA) production using an isotope dilution technique, and changes in VFA fractional absorption rate (k aVFA) using a buffer incubation technique (BIT) during the dry period and early lactation, as affected by the postpartum (pp) rate of increase of concentrate allowance. The current results are complementary to previously reported changes on rumen papillae morphology from the same experiment. From 50 d antepartum to 80 d pp, VFA production rate was measured 5 times and k aVFA was measured 10 times in 12 rumen-cannulated Holstein Friesian cows. Cows had free access to a mixed ration, consisting of grass and corn silage, soybean meal, and (dry period only) chopped straw. Treatment consisted of either a rapid (RAP; 1.0 kg of DM/d; n = 6) or gradual (GRAD; 0.25 kg of DM/d; n = 6) increase of concentrate allowance (up to 10.9 kg of DM/d), starting at 4 d pp, aimed at creating a contrast in rumen-fermentable organic matter intake. For the BIT, rumen contents were evacuated, the rumen washed, and a standardized buffer fluid introduced [120 mM VFA, 60% acetic (Ac), 25% propionic (Pr), and 15% butyric (Bu) acid; pH 5.9 and Co-EDTA as fluid passage marker]. For the isotope dilution technique, a pulse-dose of 13C-labeled Ac, Pr, and Bu and Co-EDTA as fluid passage marker was infused. The rate of total VFA production was similar between treatments and was 2 times higher during the lactation (114 mol/d) than the dry period (53 mol/d). Although papillae surface area at 16, 30, and 44 d pp was greater in RAP than GRAD, Bu and Ac production at these days did not differ between RAP and GRAD, whereas at 16 d pp RAP produced more Pr than GRAD. These results provide little support for the particular proliferative effects of Bu on papillae surface area. Similar to developments in papillae surface area in the dry period and early lactation, the k aVFA (per hour), measured using the BIT, decreased from 0.45 (Ac), 0.53 (Pr) and 0.56 (Bu) at 50 d antepartum to 0.28 (Ac), 0.34 (Pr) and 0.38 (Bu) at 3 d pp. Thereafter, k aVFA (/h) rapidly increased up to 0.67 (Ac), 0.79 (Pr), and 0.79 (Bu) at 80 d pp. Although papillae surface area was greater at 16, 30, and 44 d pp in RAP than GRAD, no differences in k aVFA between RAP and GRAD were observed during these days showing papillae surface area is not the limiting factor for k aVFA during early pp adaptation
Preference of goats (Capra hircus L.) for tanniniferous browse species available in semi-arid areas in Ethiopia
Get PDFThe objectives were to determine browse species preference of goats using dry matter intake (DMI) as a proxy, to compare preference when offered in combination with polyethylene glycol (PEG) and to establish relationships between browse species intake and chemical compositional data. Air-dried leaves of Acacia etbaica, Cadaba farinosa, Capparis tomentosa, Dichrostachys cinerea, Dodonaea angustifolia, Euclea racemosa, Maerua angolensis, Maytenus senegalensis, Rhus natalensis and Senna singueana were used. Two cafeteria trials, each lasting 10 days, were conducted using four local mature male goats of 2–2.5 years receiving a daily ration of grass hay (4% of body weight) and 200 g wheat bran. In trial 1, goats were offered 25 g of each browse species for a total of 30 min with intake, time spent on consumption and the number of visits to specific browse species recorded at 10-min intervals. In trial 2, the same procedure was followed except that 25 g of PEG 4000 was added to the daily wheat bran ration. Crude protein and neutral detergent fibre in browse species ranged from 69.0–245.5 to 159.8–560.6 g/kg dry matter (DM) respectively. Total phenols and total tannins contents ranged between 3.7–70.6 and 2.5–68.1 mg tannic acid equivalent/g DM, respectively, and condensed tannins 1.7–18.4 Abs550 nm/g DM. Preference indicators measured in the first 10 min of browse species intake differed significantly among browse species and with PEG (p < 0.0001). Principal components explained 69.9% of the total variation in browse species DMI. Despite the high tannin levels, D. cinerea, R. natalensis and A. etbaica were the most preferred species regardless of PEG presence. Tannin levels at the observed browse species DMI did not determine preference, instead, preference appeared to be based on hemicellulose. Determining browse species preference is essential to exploit them to improve nutrient utilization and control parasites in goats
Modeling the effects of infection status and hygiene practices on Mycobacterium avium subspecies paratuberculosis contamination in bulk tank milk
No full textInfectious diseases in dairy cattle are of significant concern to dairy industries because of their huge impact on animal health, milk production, and economics. Mycobacterium avium subsp. paratuberculosis (MAP)is a pathogenic bacterium that causes Johne's disease, one of the important endemic infectious diseases in dairy cattle. Contamination of bulk tank milk with MAP can occur through direct shedding into milk by infected cows (internal route), fecal contamination (fecal route), or introduction of soil and water containing MAP (environmental route). Humans can be exposed to MAP via raw milk consumption; additionally, there are reports of MAP survival in milk after pasteurization. The risk of human consumption is particularly important due to an association between MAP and human Crohn's disease. In the current study, we used a probabilistic modeling framework to predict the level of MAP contamination per liter in the bulk tank milk and weigh the relative importance of each contamination route. Our model focused on several different infection statuses and the contribution of each group to environmental and fecal contamination, in addition to internal route shedding. We assessed the influence of common hygiene practices, such as washing of udders before milking and the use of milk filters, on the concentration of MAP in bulk tank milk. We extracted parameters and their distributions from national surveys and thorough literature search. Our baseline model comprising all hygiene practices provided an average estimate of 0.76 log CFU/L for the final concentration of MAP in bulk tank milk, with a maximum of 6.70 log CFU/L and a minimum of 0.04 log CFU/L depending on herd size and the ratio of infection statuses. Results from sensitivity analyses indicated that the average fecal contamination showed the greatest impact on the final MAP concentration per liter in bulk tank milk, followed by herd size and washing efficiency. This study emphasized that good hygiene practices are crucial for maintaining the quality of raw milk in an endemically-infected dairy herd
A review of methods used to adjust for cluster effects in explanatory epidemiological studies of animal populations
No full textThis paper reviews explanatory studies in the veterinary epidemiology literature, in which clusters (herds) were sampled and individual responses were measured. The studies were taken from the first ten volumes of Preventive Veterinary Medicine. The objectives of the review were: (1) to describe the statistical methods used to adjust for cluster effects; (2) to provide estimates of intracluster correlations for various health and production outcomes; and (3) for studies ignoring cluster effects, to estimate the proportion of significant inferences that would be rejected if cluster effects were included. Of the 67 papers reviewed, 36 (54%) used some form of adjustment for clustering. Using a fixed effect for herd was employed most frequently (27 papers). Four of the 67 papers used a matched design, two used a weighted analysis, and three papers included a random herd effect. An estimate of the intracluster correlation (^ρ{variant}) was calculated when sufficient data were present. This estimate ranged from 0.0017 (lamb mortality data), to 0.46 (prevalence of brucelence serotiter). Most intracluster correlations ranged form 0.01 to 0.15. In the papers where ρ{variant} was estimated from the data, the variance inflation factor ranged from 1.1 to 13. In 36 of the 67 (54%) papers reviewed, all inferences were accepted. In 30 of these 36, the authors correctly accounted for clustering, and in the other six the inference would not have changed after adjustment for clustering. In the remaining 31 (46%) papers, changes in inference were predicted. The proportion of incorrect inferences could be estimated in 20 of these 31 papers
The intention of North-Western Ethiopian dairy farmers to control mastitis
No full textUnderstanding the intentions of dairy farmers towards mastitis control is important to design effective udder health control programs. We used the Theory of Planned Behavior (TPB) to explore the intentions of North-Western Ethiopian dairy farmers towards implementing non-specified mastitis control measures (nsMCMs) and towards implementing 4 specific MCMs. Face to face interviews were held with 134 dairy farmers to study associations between their intentions and any of three factors (attitude, subjective norm and perceived behavioral control) that, according to the TPB, determine intentions. The majority of the farmers (93%) had a positive intention to implement nsMCMs, whereas a smaller majority of farmers had the intention to implement the specific MCMs to improve udder cleaning (87%), to improve stall hygiene (78%), to improve feeding of cows (76%), and to perform foremilk stripping (74%). Farmers had a more positive attitude, but lower subjective norm and lower perceived behavioural control towards implementing nsMCMs compared with implementing most specific MCMs, although the subjective norms for stall hygiene and perceived behavioural control for improving feeding of cows were also low. Attitude was positively associated with intentions to implement nsMCMs, to improve cleaning of the udders, to improve stall hygiene and to implement foremilk stripping. Both the intention to improve udder cleaning and to implement foremilk stripping, were positively associated to subjective norms towards these MCMs. Our data can help tailor intervention programs aiming to increase the intention of Ethiopian dairy farmers to implement MCMs and thus to improve udder health in this country. We show that such programs should primarily focus on changing attitude and secondarily on improving the farmers’ subjective norms
Effects of fibrolytic enzymes and lactic acid bacteria on fermentation quality and in vitro digestibility of Napier grass silage
No full textAn experiment was conducted to evaluate the effect of xylanase and cellulase derived from dried tomato pomace treated with Aspergillus niger and fermented juice of epiphytic of lactic acid bacteria (FJLB) on fermentative quality and in vitro digestibility of Napier grass silages. Thus, we treated Napier grass silage with or without fibrolytic enzymes (ENZ) in combination with or without FJLB. The pH values of silages treated with FJLB, but not ENZ, were found to be lower than the other silages during the ensiling process. The content of water soluble carbohydrates (WSC) of all silages was likely to decrease during fermentation in all silages. However, after 30 days of ensiling, the addition of ENZ resulted in higher WSC content when compared to the other treatments. At 30 day of ensiling, the crude protein of silage was higher in silage treated with FJLB. The gas production related to the soluble fraction was higher in silage treated with ENZ but total gas production was similar between treatments. The latter is in line the observation that the degradability of organic matter also was not different between treatments. It is concluded that neither the fermentation quality nor the in vitro digestibility of organic matter is improved when Napier grass is ensiled with both FJLB and fibrolytic enzymes compared with FJLB alone
Identifying poor metabolic adaptation during early lactation in dairy cows using cluster analysis
Get PDFCurrently, cows with poor metabolic adaptation during early lactation, or poor metabolic adaptation syndrome (PMAS), are often identified based on detection of hyperketonemia. Unfortunately, elevated blood ketones do not manifest consistently with indications of PMAS. Expected indicators of PMAS include elevated liver enzymes and bilirubin, decreased rumen fill, reduced rumen contractions, and a decrease in milk production. Cows with PMAS typically are higher producing, older cows that are earlier in lactation and have greater body condition score at the start of lactation. It was our aim to evaluate commonly used measures of metabolic health (input variables) that were available [i.e., blood β-hydroxybutyrate acid, milk fat:protein ratio, blood nonesterified fatty acids (NEFA)] to characterize PMAS. Bavarian farms (n = 26) with robotic milking systems were enrolled for weekly visits for an average of 6.7 wk. Physical examinations of the cows (5-50 d in milk) were performed by veterinarians during each visit, and blood and milk samples were collected. Resulting data included 790 observations from 312 cows (309 Simmental, 1 Red Holstein, 2 Holstein). Principal component analysis was conducted on the 3 input variables, followed by K-means cluster analysis of the first 2 orthogonal components. The 5 resulting clusters were then ascribed to low, intermediate, or high PMAS classes based on their degree of agreement with expected PMAS indicators and characteristics in comparison with other clusters. Results revealed that PMAS classes were most significantly associated with blood NEFA levels. Next, we evaluated NEFA values that classify observations into appropriate PMAS classes in this data set, which we called separation values. Our resulting NEFA separation values [<0.39 mmol/L (95% confidence limits = 0.360-0.410) to identify low PMAS observations and ≥0.7 mmol/L (95% confidence limits = 0.650-0.775) to identify high PMAS observations] were similar to values determined for Holsteins in conventional milking settings diagnosed with hyperketonemia and clinical symptoms such as anorexia and a reduction in milk yield, as reported in the literature. Future studies evaluating additional clinical and laboratory data, breeds, and milking systems are needed to validate these finding. The aim of future studies would be to build a PMAS prediction model to alert producers of cows needing attention and help evaluate on-farm metabolic health management at the herd level
In vitro digestibility and fermentability of selected insects for dog foods
Get PDF<p>Insects are considered as a sustainable protein source for future pet foods. Here we aimed to evaluate the protein quality of larvae of the black soldier fly (Hermetia illucens, BSF), housefly (Musca domestica, HF) and yellow mealworm (Tenebrio molitor, YMW) and to evaluate the fermentation characteristics of their indigestible fractions. Clean freeze-dried larvae were subjected to in vitro simulated canine gastric and small intestinal digestion. Undigested insect residues, shrimp chitin and fructooligosaccharides (positive control, FOS) were incubated for 48 h with inoculum with fresh feces from three dogs simulating large intestinal fermentation. The AA profiles differed among the larvae with proteins from BSF and YMW larvae containing more Val and less Met and Lys than HF larvae. The in vitro N digestibility of the HF (93.3%) and YMW (92.5%) was higher than BSF larvae (87.7%). The BSF larvae also had lower in vitro digestibility values for essential AA (92.4%) and non-essential AA (90.5%) compared to the larvae of the HF (96.6 and 96.5%) and YMW (96.9 and 95.3%). Gas production for FOS increased rapidly during the first 6 h. Low and similar amounts of gas were found for HF larvae and chitin whereas gas production slowly increased over 30 h and was slightly higher at 48 h for BSF than for chitin. Gas production for YMW increased considerably between 6 and 20 h. At 48 h, gas produced for undigested residues was comparable to shrimp chitin and lower than FOS (P </p
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