Single Kernel Sampling Method for Maize Starch Analysis While Maintaining Kernel Vitality

A nondestructive protocol for maize kernel starch sampling was developed, enabling starch preparation from a single kernel for analysis of starch structure while also maintaining the vitality of the seed. To develop the single kernel sampling (SKS) method, maize genotypes varying in starch structure including ae, wx, su2, du and normal in the W64A inbred line were used. Crude endosperm material was removed from the kernel crown, soaked, ground, washed, and dissolved in 90% DMSO. The sample represented ≈10% of the total kernel. Endosperm starch was also isolated from the same genotypes by a standard multikernel isolation (MKI) method. Starches isolated by the two methods were debranched and analyzed by high‐performance size‐exclusion chromatography (HPSEC) and fluorophore‐assisted carbohydrate electrophoresis (FACE). HPSEC and FACE showed similar results for the two sampling methods for degree of polymerization (DP) ≤ 50. We concluded that the material obtained by SKS could be used for identifying amylopectin structural differences among genotypes. Kernel sampling for SKS had no effect on germination, thus plants could be grown for subsequent genetic crosses and analysis. The SKS method may be useful for the screening of populations of maize kernels from genotypes producing novel amylopectin structure, and allow the growth of novel genotypes for further analysis.     

Genetic-diet interactions in the Hyperkalemic Periodic Paralysis syndrome in quarter horses fed varying amounts of potassium: IV. Pre-cecal and post-ileal absorption of potassium and sodium

During an experiment to determine the genetic-diet interactions in genetically predisposed Quarter Horses, biphasic symptoms of Hyperkalemic Periodic Paralysis (HYPP) were observed when the HYPP H/N broodmares were fed the higher potassium rations. ¹ The cause of those symptoms was assumed to be: 1) the difference in absorption times of the highly absorbable potassium citrate in the concentrates and the potassium contained in the cells of the grains and hays in the rest of the rations, 2) partial absorption of potassium in the small intestine followed by no absorption from the cecum and further absorption in the large colon or 3) a combination of both of the above explanations. Since previously cannulated ponies were available in this laboratory, an experiment was designed to determine which of those possibilities was the most likely.

Three ponies, weighing an average of 132 kg, with posterior-ileal cannulas were used in a 3×3 Latin square experiment to determine the amounts of potassium and sodium that would be absorbed pre-cecally and post-ilealy. The ponies were fed the same rations as the mares in the previously described experiment (see part I), which provided approximately 1.1, 1.9 and 2.9% potassium by weight as fed. Samples of water, feces, ileal contents and blood were collected. Water, feed, ileal and fecal samples were analyzed for sodium and potassium concentration.

Apparent absorption of potassium prior to the cecum was 97% when the ponies were fed the low potassium diet and 98% when they were fed the higher potassium diets. Three percent and 2% of the potassium was absorbed from the hindgut when the ponies were fed the low potassium diet and the higher potassium diets, respectively. Nine percent and 16% of sodium was absorbed pre-cecally when the ponies were fed the low potassium diet and the higher potassium diets, respectively. Ninety-one and 84% of the sodium was absorbed from the hindgut, when the ponies were fed the low potassium diet and the higher potassium diets, respectively for 99–100% total absorption of both sodium and potassium from all diets.

These results indicate that the potassium from the three diets was absorbed pre-cecally, and that the process took up to nine hours, resulting in bi-phasic HYPP symptoms in the HYPP H/N mares in the companion experiment. This information can be used to better understand the relationship between dietary potassium, plasma K⁺ concentration and HYPP symptoms.     

Composting characteristics of three bedding materials

Horse manure management is becoming a major concern in suburban areas of the United States. An average horse can produce eight to ten tons of manure per year, accumulating at a rate of two cubic feet per day, including bedding. If properly composted, the manure and bedding can be transformed into a very useful, odorless, pathogenfree product. The objective of this trial was to compare the characteristics of recycled chopped phone book paper, sawdust and wheat straw bedding during composting. Six horses were stalled on three bedding types: recycled phone book paper, sawdust and straw. Each day manure and soiled bedding types were separately collected and transported to compost sites over an eight-day period. Three compositing bins were each hand constructed from wooden pallets with 10 cm slats. The front of the bin was left open for manipulation of materials during the composting process. Initial volumes of the soiled bedding materials were 1m³, 1m³, and 1.5m³ for paper, sawdust and straw, respectively. Temperatures were taken for each bedding materials using a 51 cm REOTEMP compost thermometer. Temperatures were taken on Day 0 and every four days over the 65-day trial (n=52). Temperature was used to determine the need for moisture addition and aerating by turning to keep the piles microbially active. On Day 37 the C:N ratio was adjusted by the addition of ammonium sulfate, 0.1 kg, 0.1 kg and 0.14 kg for sawdust, phone book paper and straw piles, respectively. Mean standard error and range for compost temperatures (C) were: phone book paper, 33.17±10.33 (13–52); sawdust, 45.6±9.35 (27–58); straw, 30.42±6.57 (16–39). The sawdust composted more readily as compared to the phone book paper or straw. The paper and straw had poorer structure, which caused compaction of the material when moistened; thus, porosity, oxygen supply and microbial activity were reduced.     

Evaluation of the analgesic properties of acepromazine maleate, oxymorphone, medetomidine and a combination of acepromazine-oxymorphone

Objective To determine the presence and duration of analgesia after oxymorphone, acepromazine maleate, acepromazine‐oxymorphone combination and medetomidine administration in dogs. Study design Blinded, controlled study. Animals Six adult beagle dogs. Methods Each dog participated in five trials receiving acepromazine maleate (0.2 mg kg^?1 IM), oxymorphone (0.2 mg kg^?1 IM), acepromazine‐oxymorphone drug combination (0.2 mg kg^?1 each IM), medetomidine (20 µg kg^?1 IM) and sterile saline (control). Two specially designed instruments were used for analgesia determination: a heat device (HD) utilized a linear ramped intensity incandescent bulb and a pressure device (PD) consisted of a pneumatic cylinder that protruded a 2.5‐cm bolt. The minimum pressure and heat necessary to produce an avoidance response were determined. Analgesia testing was performed prior to and at 30‐minute intervals for six hours after drug administration. Results Oxymorphone, acepromazine‐oxymorphone and medetomidine significantly elevated both pressure and heat response thresholds compared to controls and acepromazine. Both medetomidine and acepromazine‐oxymorphone provided a significantly longer duration of analgesia than oxymorphone. No adverse effects were observed at any of the thermal or pressure application sites. Conclusions Oxymorphone, medetomidine and acepromazine‐oxymorphone produced significant analgesia with medetomidine and acepromazine‐oxymorphone providing the longest duration of analgesia.     

Hormonal response to dobutamine cardiac stress testing in a conscious canine model of early left ventricular dysfunction induced by chronic rate overload

The aims of this study were to investigate (1) hormonal activation before and during dobutamine cardiac stress testing (DST) in a canine model of early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP) and (2) the relationship between this hormonal profile and carnitine concentrations.Before the pacing period, the 6 dogs were assigned to 2 groups according their baseline total plasma carnitine concentration. A DST was performed on each dog before activation of the pacemaker and every 3 to 4 days during development of 3 progressive stages of ELVD (stages 1, 2 and 3). Plasma atrial natriuretic factor (ANF), angiotensin II (ANG II) and endothelin-1 (ET-1) levels were measured at the start and at the end of each DST. Effects of ELVD, DST and plasma carnitine concentration on these measurements were tested.The RRVP induced a significant increase of ANF and ANG II and a non significant trend toward increase of ET-1 in all dogs.Before the pacing period, ANF remained constant during the DST in dogs with normal total plasma carnitine concentration, while it significantly decreased in dogs with low total plasma carnitine concentration. Dobutamine stress testing induced a significant decrease in ANF in all dogs in ELVD. Dobutamine infusion induced a significant increase in ANG II in all dogs before as well as during the pacing period while ET-1 was unchanged.These results suggest that investigation of the hormonal profile before and after a dobutamine challenge might provide important diagnostic information in dogs with asymptomatic or mildly symptomatic cardiac dysfunction of different origins.