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

Hailey Galyon; Samuel Vibostok; Jane Duncan; Gonzalo Ferreira; Abby Whittington; Rebecca Cockrum

doi:10.3168/jdsc.2022-0319

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

JDS Commun. 2022 Dec 22;4(2):70-74. doi: 10.3168/jdsc.2022-0319. eCollection 2023 Mar.

Authors

Hailey Galyon¹, Samuel Vibostok², Jane Duncan¹, Gonzalo Ferreira¹, Abby Whittington^{2

3}, Rebecca Cockrum¹

Affiliations

¹ School of Animal Sciences, Virginia Tech, Blacksburg 24061.
² Department of Macromolecular Science and Engineering, Virginia Tech, Blacksburg 24061.
³ Departments of Chemical Engineering and Materials Science and Engineering, Virginia Tech, Blacksburg 24061.

Abstract

Using biodegradable materials such as polyhydroxyalkanoates (PHA) and poly(butylene succinate-co-adipate) (PBSA) to develop single-use agricultural plastics like bale netting may reduce the negative effects of plastic accumulation in the rumens of cattle. The objective of this research was to assess the long-term degradation of PHA, PBSA, and a PBSA:PHA blend (Blend) compared with a low-density polyethylene (LDPE) control. Polyhydroxyalkanoate, PBSA, Blend, and LDPE films were incubated in the rumens of 3 cannulated, nonlactating Holsteins for up to 150 d. In situ disappearance (ISD) and residue length were assessed after every incubation time. Data were analyzed with PROC MIXED in SAS and adjusted by Tukey's method to determine least squares differences between polymer treatments, incubation time, and their interaction. By 30 d, PHA achieved 100% degradation, with initiation occurring at 14 d indicated by ISD and a reduction in residue length. Poly(butylene succinate-co-adipate) and Blend did not achieve any significant ISD, but fragmentation of PBSA occurred at 60 d and fragmentation of Blend at just 1 d, likely due to abiotic hydrolysis. Low-density polyethylene achieved no ISD, and residue length did not change over incubation time. We propose that a PBSA:PHA blend is a valid alternative to polyethylene single-use agricultural plastic products based on its fragmentation within 1 d of incubation.