Intake and digestibility by gestating sheep offered alfalfa silage wrapped with plastic with or without an oxygen-limiting barrier after extended time delays up to three days

Authors: NIYIGENA, V. - University Of Arkansas; COFFEY, K. - University Of Arkansas; Coblentz, Wayne; PHILIPP, D. - University Of Arkansas; RHEIN, R. - University Of Arkansas; YOUNG, A. - University Of Arkansas; CALDWELL, J. - Delacon Usa, Inc; SHANKS, B. - Lincoln University Of Missouri

Submitted to: Animal Feed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2019
Publication Date: 6/20/2019
Citation: Niyigena, V., Coffey, K.P., Coblentz, W.K., Philipp, D., Rhein, R.T., Young, A.N., Caldwell, J.D., Shanks, B.C. 2019. Intake and digestibility by gestating sheep offered alfalfa silage wrapped with plastic with or without an oxygen-limiting barrier after extended time delays up to three days. Animal Feed Science and Technology. 254:114193. https://doi.org/10.1016/j.anifeedsci.2019.05.016.
DOI: https://doi.org/10.1016/j.anifeedsci.2019.05.016

Interpretive Summary: Voluntary forage intake is the major dietary factor determining level and efficiency of ruminant production. Intake of ensiled forages is affected by a number of factors including fermentation quality, which in turn is affected by the presence of oxygen during fermentation. The objective of this study was to evaluate the impacts of delayed wrapping of large round bales of alfalfa, and wrapping with a plastic that contained an oxygen-limiting barrier, on the subsequent voluntary intake and digestibility of baled alfalfa silages by gestating sheep. This has resulted in current recommendations for almost immediate wrapping of moist forage following baling to avoid further oxygen exposure. Simple observations of the silage fermentation measurements across the time delay between wrapping and baling evaluated in this study (0, 1, 2, or 3 days) support recommendations for wrapping as soon as possible following baling. However, based on the intake and digestibility data observed in this study for baled alfalfa silages, it is apparent that animal performance should not be impacted until the wrapping of silage bales is delayed beyond 24 h. It should be further noted that silage wrap containing an oxygen-limiting barrier is not necessary if seven layers of plastic are used.

Technical Abstract: Poor silage fermentation can affect its acceptance by livestock. Alfalfa from 3 field blocks were baled in large round bales (moisture concentration'='591'±'43.0'g/kg) and then wrapped with 7 layers of plastic either with (EOB) or without (CW) an enhanced oxygen barrier on the day of baling, or 1, 2 or 3 d after baling in order to examine those effects on subsequent intake and digestibility by gestating sheep. Alfalfa was chopped after approximately 5 mo. of fermentation, and then offered for individual ad libitum consumption by 16 gestating ewes [63.5'±'1.71'kg avg. body weight (BW)] in a 3-period (63-day) digestion study. Silage moisture and nitrogen (N) decreased linearly (P < 0.05), acid-detergent fiber (ADF) increased linearly (P < 0.05), and neutral-detergent fiber (aNDF) increased at a decreasing rate (linear; quadratic P < 0.05) with wrapping delay within EOB but not CW (P = 0.23). Lactic acid expressed as g/kg of total silage acids decreased linearly (P < 0.05) within CW and decreased at an increasing rate (linear; quadratic P < 0.05) within EOB with increasing wrapping delay, likely because of aerobic deterioration. Digestible organic matter intake (DOMI) decreased linearly (P'=' 0.03) within EOB and quadratically (P'=' 0.02) within CW (wrap type × wrapping time after baling interaction; P'=' 0.04), but other intake and digestibility measurements were not affected (P'=' 0.15) by wrap type or its interaction with wrapping time after baling. Intake of DM and OM (DMI and OMI, g/kg BW) as well as digestible DMI (g/kg BW) responded linearly and quadratically (P = 0.03) with wrapping delay after baling by initially increasing to 1 d after baling, then declining sharply thereafter. Digestibility of aNDF increased linearly (P = 0.04) with wrapping delay which was likely related to reduced DMI. These values align somewhat closely with those for forage quality and fermentation profiles. Therefore, managing alfalfa silage to ensure more desirable fermentation should also result in higher digestible OMI, which will improve the overall energy status of ruminants.