Galyon Hailey, Vibostok Samuel, Duncan Jane, Ferreira Gonzalo, Whittington Abby, Havens Kirk, McDevitt Jason, Cockrum Rebecca
Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Department of Macromolecular Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Polymers (Basel). 2022 May 21;14(10):2103. doi: 10.3390/polym14102103.
Using polyhydroxyalkanoate (PHA) materials for ruminal boluses could allow for longer sustained release of drugs and hormones that would reduce administration time and unneeded animal discomfort caused by continuous administration. The objective of this study was to determine ruminal degradability and kinetics of biodegradable polymers and blends. A proprietary PHA-based polymer, poly(butylene succinate--adipate) (PBSA), PBSA:PHA melt blends, and forage controls were incubated in rumen fluid for up to 240 h. Mass loss was measured after each incubation time, and digestion kinetic parameters were estimated. Thermogravimetric, differential scanning calorimetry, and intrinsic viscosity analyses were conducted on incubated samples. Generally, across treatments, mass loss was significant by 96 h with a minimum increase of 0.25% compared to 0 h but did not change thereafter. Degradation kinetics demonstrated that polymer treatments were still in the exponential degradation phase at 240 h with a maximum disappearance rate of 0.0031 %/h. Melting temperature increased, onset thermal degradation temperature decreased, and intrinsic viscosity decreased with incubation time, indicating structural changes to the polymers. Based on these preliminary findings, the first stage of degradation occurs within 24 h and PHA degrades slowly. However, further ruminal degradation studies of biodegradable polymers are warranted to elucidate maximum degradation and its characteristics.
将聚羟基脂肪酸酯（PHA）材料用于瘤胃丸剂可以使药物和激素实现更长时间的持续释放，从而减少给药时间以及连续给药引起的不必要的动物不适。本研究的目的是确定可生物降解聚合物及其混合物的瘤胃降解性和动力学。将一种基于PHA的专利聚合物、聚（丁二酸丁二醇酯-己二酸酯）（PBSA）、PBSA与PHA的熔融共混物以及草料对照物在瘤胃液中孵育长达240小时。在每个孵育时间后测量质量损失，并估算消化动力学参数。对孵育后的样品进行热重分析、差示扫描量热分析和特性粘度分析。总体而言，在所有处理中，到96小时时质量损失显著，与0小时相比至少增加了0.25%，但此后没有变化。降解动力学表明，聚合物处理在240小时时仍处于指数降解阶段，最大消失速率为0.0031%/小时。随着孵育时间的增加，熔点升高，起始热降解温度降低，特性粘度降低，表明聚合物的结构发生了变化。基于这些初步发现，降解的第一阶段发生在24小时内，PHA降解缓慢。然而，有必要对可生物降解聚合物进行进一步的瘤胃降解研究，以阐明最大降解及其特性。
