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Abstract

Objective—To describe myoelectric patterns in the intestines of cows after electrode implantation.

Animals—7 lactating Simmental-Red Holstein cows.

Procedure—Cows were implanted with 7 pairs of bipolar silver electrodes (1 each in the ileum, cecum, and proximal loop of the ascending colon (PLAC) and 4 in the spiral colon). Myoelectric activity was monitored during 10 periods within the first 3 weeks after surgery. Recordings from the first 2 weeks were compared with recordings from the third week, which was considered a steady-state condition.

Results—Significant changes over time were detected for 18 of 57 variables, including 3 variables describing myoelectric activity of the ileum, 6 variables of the cecum, 6 variables of the PLAC, and 3 variables of the spiral colon. Compared with values for the steadystate condition, 16 variables differed significantly for the 14-day period after surgery (7 variables until day 11, 2 variables until day 8, 4 variables until day 5, 1 variable until day 3, and 2 variables until day 2 after electrode implantation). None of the variables had significant changes that lasted only 1 day after surgery.

Conclusions and Clinical Relevance—Significant changes were observed for several variables of myoelectric activity in all intestinal segments until as late as 11 days after electrode implantation, whereas a steady-state condition was reached 14 days after surgery. Effects of drugs, manipulations, or nutrition regimens on myoelectric activity of the bovine digestive tract should be evaluated no sooner than 2 weeks after electrode implantation. (Am J Vet Res 2004;65:797–805)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To compare concentrations of acetic, propionic, butyric, and i- and n-valerianic acids in digesta samples obtained from the rumen, cecum, proximal loop of the ascending colon (PLAC), and rectum of healthy cows and cows with cecal dilatation or dislocation (CDD).

Animals

20 cows with CDD and 20 healthy cows.

Procedure

Samples were collected from all sites during surgical correction of CDD and also from the rectum 1, 2, and 3 days after surgery (group CDD). Samples from healthy (control) cows, matched on the basis of diet and milk yield, were obtained at a slaughterhouse. Concentrations of volatile fatty acids (VFA) were analyzed by use of gas chromatography. Absolute concentration of each VFA was additionally corrected for pH to allow calculation of the concentration of undissociated VFA.

Results

Absolute concentration and concentration of the undissociated form of all analyzed VFA were significantly increased in samples collected from the cecum and PLAC of cows in group CDD, compared with concentrations for control cows. Within 3 days after surgery, significant decreases of the absolute concentration of butyric, i- and n-valerianic acids, and undissociated i- and n-valerianic acids were evident in samples obtained from the rectum of group-CDD cows. Concentrations of VFA in samples obtained from the rectum during surgery correlated with corresponding VFA concentrations in samples obtained from the PLAC.

Conclusions

Concentrations of VFA are increased in the cecum and PLAC of cows with CDD. However, the role of increased concentrations of VFA in the etiopathogenesis of CDD is unknown. (Am J Vet Res 1999;60:1540–1545)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine the effect of feeding frequency and cow-specific factors on diurnal variations of blood metabolites concentrations.

Animals

40 dairy cows from 2 herds.

Procedure

Each herd was fed concentrate at a specific feeding frequency (automatic vs twice daily). Blood samples were collected 4 times daily. Plasma concentrations of glucose, nonesterified fatty acids (NEFA), and β-hydroxybutyrate (BHBA) were analyzed, and concentrations of urea, cholesterol, and total protein (TP) were determined in serum samples. A multivariate repeated-measures ANOVA was used to test the effect of time, feeding frequency, production group, parity, days after parturition, and daily milk yield on diurnal variations of metabolites.

Results

Concentrations of glucose, BHBA, and urea remained relatively constant in the herd that was fed by use of automatic distribution of concentrate; however, significant diurnal patterns were detected in the herd fed only twice daily. Only slight differences in glucose and urea concentrations were detected between high- and low-producing cows, but concentration of BHBA was significantly influenced by number of days in lactation. In contrast, diurnal variations in NEFA and cholesterol concentrations were similar between the 2 herds but differed with regard to production group. Concentrations of TP did not have relevant diurnal patterns and did not differ between production groups.

Conclusions and Clinical Relevance

Diurnal variations and feeding frequency affect glucose, BHBA, and urea concentrations in cows. In contrast, concentrations of NEFA, cholesterol, and TP appear to be less sensitive to time of sample collection. Feeding frequency, composition of feed, or both, have a major impact on blood metabolites concentrations. (Am J Vet Res 1999;60:1493–1499)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To evaluate applicability of a human osteocalcin (OC) immunoradiometric assay (IRMA) for use with equine serum and compare it with a bovine radioimmunoassay (RIA) previously proven valid for such samples, and to describe the effect of type and breed of horses on serum OC concentration.

Animals

100 healthy horses of either sex, classified as type I or II (draught or warmblood, respectively). Each type was represented by 2 breed groups, each comprising 25 horses.

Procedure

Blood samples were collected in the morning, and the serum was separated. Osteocalcin was measured, using commercially available RIA and IRMA kits, according to the manufacturer's instructions. All samples were evaluated in duplicate.

Results

The human IRMA did not recognize equine OC. Significant variations in the bovine RIA results were observed between types of horses. Draught horses had lower OC concentration, compared with warmblood horses. Significant difference was not observed between breeds for type of horse. Sex had no influence on serum OC values, but age was a significant covariable for both types of horses.

Conclusions

No crossreactivity exists between the equine and human amino- and/or carboxy-terminus of OC, using this particular human IRMA kit. Difference in blood OC concentration exists between draught and warmblood types of horses.

Clinical Relevance

Use of this human IRMA kit is not valid for equine serum. Horse type must be taken into account when evaluating OC concentration in research or clinical situations, especially if small variations in OC concentration are expected. (Am J Vet Res 1997;58:574–578)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To characterize and compare in vitro contractility patterns of sections of abomasal wall harvested from cattle of 3 dairy breeds.

Sample Population—Longitudinal and circular smooth muscle preparations harvested from the antrum and body of the abomasum of 30 recently slaughtered Holstein-Friesian, Brown Swiss, and Simmental X Red Holstein cows.

Procedure—Spontaneous isometric contractions of specimens in tissue baths of modified Krebs solution were recorded during a 4-hour period. Maximal amplitude, frequency of contractions, and change of basal tension were used to characterize contractility. Statistical analyses were used to test for differences among time periods, among breeds, between specimen locations, and between fiber orientations.

Results—Myoactivity patterns of abomasal smooth muscle preparations are highly variable and differ on the basis of location and fiber orientation. Frequency of contractions differed significantly among time periods for longitudinally oriented specimens with decreasing frequencies of contractions over time. Maximal amplitude of the longitudinally oriented specimens from the antrum increased significantly, whereas maximal amplitude of the circularly oriented specimens from the antrum decreased significantly. Values did not differ significantly among breeds.

Conclusions and Clinical Relevance—Patterns of spontaneous contractility of abomasal wall specimens are not homogeneous. During a 4-hour recording period, maximal amplitude and frequency of contractions of specimens varied significantly with respect to orientation and location; however, spontaneous contractile myoactivity did not differ significantly among breeds. Therefore, breed predisposition for displaced abomasum is not correlated with spontaneous activity of smooth muscle specimens. (Am J Vet Res 2002;63:1687–1694)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To evaluate use of a reinforced polytetrafluoroethylene vascular graft for treatment of an artificial defect of mucosa of the teat cistern in lactating cows.

Design

Prospective study.

Animals

9 clinically normal lactating dairy cows.

Procedure

A 20-mm wide circumferential area of mucosa was sharply excised from the cistern of 1 teat on each cow 10 days after spontaneous calving, and the lesion was covered by a graft. After 14 days of passive milk drainage, routine milking was resumed. Follow-up examinations were performed during the next 2 lactation periods and included evaluation of wound healing, location and sonographic appearance of the implant, milk flow and yield, and somatic cell counts. Cows were slaughtered, and teats and mammary glands were examined microscopically.

Results

Implants had partially to totally collapsed within 30 to 90 days. Milk flow was significantly increased by day 15 of the first lactation, but decreased significantly by day 300 of lactation 1. At the end of lactation 1, milk flow had ceased in 3 out of 7 quarters. Only 3 of 9 quarters drained through grafted teats were milkable at the end of the study. Somatic cell counts of these quarters were significantly increased in the first lactation period. At necropsy, 2 grafts were in the teat cistern, but only 1 was incorporated into the mucosa by connective tissue. The mucosa was thickened in all teats with grafts, and there was epithelial metaplasia and granulation tissue proliferation.

Clinical Relevance

Use of a polytetrafluoroethylene graft can preserve patency in the first lactation period. However, the graft may not be sufficiently incorporated into the mucosa if routine machine milking is resumed 2 weeks after implantation. (Am J Vet Res 1999;60:56–62)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To describe the effects of an abrupt increase of concentrates in the diet of dairy cows on myoelectric activity of the spiral colon and on fermentation patterns in the rumen and large intestine.

Animals—6 healthy lactating Simmental X Red- Holstein cows.

Procedure—The diet of 6 cows implanted with bipolar electrodes in the spiral colon was changed from hay only to a ration of 50% hay:50% starch-rich concentrates during a period of 60 hours. Myoelectric activity of the spiral colon, concentrations of absolute and undissociated volatile fatty acids (VFA), and pH of ruminal and large intestinal contents were monitored before, during, and after the dietary change.

Results—Significant changes in patterns of myoelectric activity of the spiral colon were restricted to phases III and IV of the bovine migrating myoelectric complex and to propagation velocity. Significant alterations were not observed in pH or VFA concentrations in ruminal fluid, but pH decreased and VFA concentrations increased significantly in fecal specimens after the change of diet.

Conclusion and Clinical Relevance—Although rumen fluid is of limited value for measurement of certain indicators of fermentation, fecal samples can be used for measurement of pH and VFA concentrations, which serve as indicators of fermentation patterns in the large intestine. Increased concentrations of VFA and low pH in large intestinal digesta have a minimal influence on myoelectric activity of the spiral colon. Increased luminal VFA concentrations are unlikely to play an important role in the etiopathogenesis of motility disorders of the large intestine in cattle. (Am J Vet Res 2002;63:857–867)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare the effect of various concentrations of sodium butyric acid and sodium valerianic acid, as well as various osmolarities, on contractility of ex-vivo intestinal wall specimens obtained from the cecum and spiral colon of each of several healthy cows.

Sample Population—Full-thickness preparations of intestinal wall, dissected parallel to the longitudinal smooth muscle layers, harvested from freshly slaughtered healthy cows.

Procedure—Specimens of intestinal wall were incubated for 5 minutes with various concentrations of sodium butyric acid and sodium valerianic acid as well as various osmolar concentrations of NaCl, using a crossover design. Isometric contractions were induced 7 times with carbachol (CH; 5 X 10–6 mol/L). Contractility was defined as the maximum amplitude of contraction and the amplitude of contraction 2 minutes after addition of CH.

Results—Repeated addition of CH did not result in a significant effect on contractility of specimens from the cecum and spiral colon. Contractility after addition of CH was not significantly affected by prior incubation with various concentrations of sodium butyric acid or sodium valerianic acid or after an increase of osmolarity. Maximum amplitude of contraction was significantly higher in specimens from the spiral colon, compared with specimens from the cecum.

Conclusions—Increases in concentrations of sodium butyric acid or sodium valerianic acid and increases in osmolarity did not inhibit contractility of intestinal wall specimens from the cecum and spiral colon of a group of healthy cows. (Am J Vet Res 2000;61: 678–683)

Full access
in American Journal of Veterinary Research