Digestibility Kinetics of Polyhydroxyalkanoate and Poly(butylene succinate-co-adipate) after In Vitro Fermentation in Rumen Fluid

Abstract

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-co-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.

Rumen Microflora: A Symbiotic Powerhouse for Digestion and Biodegradation – Unveiling Microbial Warriors in the Fight against Plastic Pollution

“…The discovery of plastic-degrading capabilities within rumen microflora offers a promising new avenue for plastic waste management. Ruminant diets naturally include cutin, a plant polyester with structural similarities to some synthetic plastics (Galyon et al, 2022). This suggests that rumen microbes may have evolved enzymes capable of degrading certain types of plastics.…”

Clearance of Biodegradable Polymer and Polyethylene Films from the Rumens of Holstein Bull Calves

“…Many thanks to Randy Chambers of William & Mary College (Williamsburg, VA, USA) for their assistance in the conceptualization of this work. The Animals 2023, 13, 928 13 of 14 authors acknowledge that the data contained within this article was previously published in a MSc thesis, "Ruminal Degradation of Polyhydroxyalkanoate and Poly(butylene succinate-co-adipate" [32].…”

“…We previously evaluated the in vitro ruminal degradation of PHA, PBSA, PBSA:PHA melt-blend, and low-density polyethylene (LDPE) polymers in rumen fluid for 10 days. This study demonstrated the potential for biodegradable polymers to begin the degradation process within 24 h in rumen fluid [10]. We further evaluated the in situ ruminal degradation of PHA, PBSA, PBSA:PHA, and LDPE films in dairy cattle for 150 d [11].…”

Long-term in situ ruminal degradation of biodegradable polymers in Holstein dairy cattle

“…We previously evaluated in vitro digestion kinetics of PHA, PBSA, and a PBSA:PHA blend after fermentation in rumen fluid over 240 h ( Galyon et al, 2022 ). The results of that experiment indicated that the beginning stages of degradation may occur within 24 h of fermentation in rumen fluid.…”

“…Compared with the results of our in vitro fermentation study of these products, in situ degradation was increased. In vitro degradation of PHA resulted in 0.53% mass loss by 10 d, with a fractional disappearance rate of 0.002%/h ( Galyon et al, 2022 ), whereas in situ degradation of PHA resulted in a remarkable 55% mass loss by 14 d and a fractional degradation rate of 7.84%/d.…”