Physical characterization of fatty acid supplements with varying enrichments of palmitic and stearic acid by differential scanning calorimetry.

Saturated fatty acid supplements commonly fed to dairy cows differ in their fatty acid (FA) profile. Some supplements with very high enrichments of palmitic acid (PA) or stearic acid (SA) have been reported to have low total-tract digestibility. Saturated FA have the potential to form crystalline structures at high purity that may affect digestibility. Differential scanning calorimetry (DSC) is a thermal technique commonly used in materials science to measure the change in heat flow as energy is absorbed or released from a sample during heating, and it was used to characterize a series of experimental and commercial fat supplements. Our hypothesis was that products with very high enrichment of either PA or SA would differ in thermal characteristics compared with those that include moderate levels of a second FA because of the formation of secondary crystalline structures, which may contribute to decreased digestibility. First, replicated runs demonstrated low variation in melting temperature (MT) and enthalpy (coefficient of variation <4%). The effect of physical form was evaluated by comparing an initial thermal cycle to a second, successive thermal cycle after samples had resolidified in the test pan. Melting temperature was slightly increased by 1.3°C by the second cycle compared with the first, but there was no change in enthalpy. Next, supplements with 98% SA, 98% PA, and an SA/PA (44%/55%) blend with undetectable levels of unsaturated FA were compared. Melting temperature of the SA/PA mixture was 61.2°C and similar to the expected MT of PA (62.9°C). However, the MT of the high-purity SA and PA were increased to 73.7°C and 67.8°C, respectively, and enthalpy increased by 12.5% compared with the SA/PA blend. An FA stock highly enriched in SA (>98%) had the highest MT, and one moderately enriched in PA (∼85%) that contained 10.1% unsaturated FA had the lowest enthalpy value of all FA supplements and experimental stocks that were characterized. Differential scanning calorimetry may be useful to screen and design supplements with improved physical properties that may be associated with digestibility.

Preparation, characterization, and pharmacokinetics in swine of a florfenicol enteric formulation prepared using hot-melt extrusion technology.

The objective of this work was to manufacture an enteric formulation of florfenicol (FF) using hot-melt extrusion (HME) technology and to evaluate its in vitro dissolution and in vivo pharmacokinetics. For the HME process, hypromellose acetate succinate LG (HPMCAS-LG) was the enteric polymer mixed with FF, and the two components were extruded with a standard screw configuration at a speed of 50 rpm. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FT-IR) were performed to characterize the HME extrudate. The release percentage of the enteric formulation in the acidic stage was <10% of the loaded FF, whereas that in the phosphate buffer stage was >80%. Pharmacokinetic evaluations in swine revealed that the enteric formulation had a longer t1/2λ and MRT than commercially available FF powder (FULAIKA® ), indicating that the novel formulation exhibited enteric and sustained release properties. Compared with the commercial product, the relative bioavailability of the enteric formulation reached up to 117.2%. This study suggests that this formulation may have potential for future commercialization.

Effects of replacing soybean meal with chickpea seeds in the diet on mechanical and thermal properties of tendon tissue in broiler chicken.

The efficiency of the musculoskeletal system of broiler chickens, in particular during locomotion and in ensuring its supportive function, depends directly on the adequate function and mechanical endurance of soft tissues, including tendons. However, little is known whether the properties of musculoskeletal soft tissues can be influenced by changes of dietary protein. We substituted soybean meal with raw chickpea seeds as the primary protein source in the diet and studied the effects it had on the mechanical and thermal properties of drumstick tendons in broiler Ross 308 chickens. In the experiment, 160 chicks were divided into 2 groups, receiving in their diet either soybean meal (n = 80) or chickpea seeds (n = 80). The experiment lasted 42 days. The physical condition of the drumstick tendons was analyzed on the basis of a tensile test and the results of thermal denaturation as measured by a differential scanning calorimetry. The mechanical evaluation of tendon tensile strength of the broilers fed with chickpea seeds demonstrated an increase in the ultimate strain (for over 22%, P < 0.04) and total energy absorbed by the tendon until rupture (for over 57%, P < 0.05) as when compared to the group fed with soybean meal. Thermal analysis demonstrated alterations in tendon collagen cross-linking as transition onset temperature decreased (from 63.8 to 61.8°C, P < 0.001), whereas the calorimetric enthalpy increased (from 16.2 to 22.1 J⋅g-1, P < 0.05) in the group fed with chickpea seeds. In summary, this study demonstrated that dietary protein source can impact the physical properties of tendons and showed that thermal analysis can be a useful tool for studying the effect of nutrition on the development and structural changes in tendons of broiler chickens.

Improved cryopreservation of in vitro-produced bovine embryos using a chemically defined freezing medium.

This study evaluates a new synthetic substitute (CRYO3, Ref. 5617, Stem Alpha, France) for animal-based products in bovine embryo cryopreservation solutions. During the experiment, fetal calf serum (FCS) and bovine serum albumin (BSA) were used as references. A combination of a thermodynamic approach using differential scanning calorimetry and a biological approach using in vitro-produced bovine embryo slow-freezing was used to characterize cryopreservation solutions containing CRYO3, FCS and BSA. The CRYO3 and fetal calf serum (FCS) slow-freezing solutions were made from Dulbecco's phosphate-buffered saline containing 1.5 m ethylene glycol, 0.1 m sucrose and 20% (v.v(-1)) of CRYO3 or FCS. The bovine serum albumin (BSA) solution was made by adding 0.1 m sucrose to a commercial solution containing 1.5 m ethylene glycol and 4 g L(-1) BSA. These solutions were evaluated using three characteristics: the end of melting temperature, the enthalpy of crystallization (thermodynamic approach) and the embryo survival and hatching rates after in vitro culture (biological approach). The CRYO3 and FCS solutions had similar thermodynamic properties. In contrast, the thermodynamic characteristics of the BSA solution were different from those of the FCS and CRYO3 solutions. Nevertheless, the embryo survival and hatching rates obtained with the BSA and FCS solutions were not different. Similar biological properties can thus be obtained with slow freezing solutions that have different physical properties within a defined range. The embryo survival rate after 48 h of in vitro culture obtained with the CRYO3 solution (81.5%) was higher than that obtained with the BSA (42.2%, P = 0.000 12) and FCS solutions (58%, P = 0.016). Similarly, the embryo hatching rate after 72 h of in vitro culture was higher with the CRYO3 solution (61.1%) than with the BSA (31.1%, P = 0.0055) and FCS solutions (36%, P = 0.018). We conclude that CRYO3 can be used as a chemically defined substitute for animal-based products in in vitro-produced bovine embryo cryopreservation solutions.

Differential scanning calorimetric studies of superficial digital flexor tendon degeneration in the horse.

Differential scanning calorimetry (DSC) of equine superficial digital flexor tendons revealed the presence of a small exothermic peak at 23 degrees C of unknown origin, and a large endothermic peak at 70 degrees C due to denaturation of cross-linked collagen fibres. In the central degenerated core of damaged tendons the denaturation temperature remained at 70 degrees C but the enthalpy decreased in relation to the extent of degeneration of the tendon. We suggest that this reduction in enthalpy is due to depolymerisation and denaturation of the collagen fibres. This contention is supported by the observed increased activity of the degradative enzyme cathepsin B secreted by the fibroblasts. DSC analysis of cultured porcine tendon fibroblasts revealed a multicomponent endotherm, denaturation beginning at 46 degrees C, a temperature capable of being achieved within the tendon during intensive exercise. DSC clearly has considerable potential in complementing morphological and biochemical studies to determine the aetiology and progress of equine tendon degeneration.