ARS | Publication request: Chemical composition, intake by sheep, and in situ disappearance in cannulated cows of bermudagrass hayed at two moisture concentrations and treated with a non-viable lactobacillus-lactic acid preservative

Submitted to: Animal Feed Science And Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 28, 2011
Publication Date: December 20, 2011
Citation: Bass, A.E., Philipp, D., Coffey, K.P., Caldwell, J.D., Rhein, R.T., Young, A.N., Coblentz, W.K. 2011. Chemical composition, intake by sheep, and in situ disappearance in cannulated cows of bermudagrass hayed at two moisture concentrations and treated with a non-viable lactobacillus-lactic acid preservative. Animal Feed Science And Technology. 171:43-51.

Interpretive Summary: Bermudagrass is a major summer hay crop in the southeastern U.S., making it one of the most important forage crops throughout that region. In spite of its popularity with hay producers, frequent precipitation events early in the growing season make curing of bermudagrass hay challenging, and put this valuable cash crop at risk. In some circumstances, hay preservatives can help with this challenge. But, to date, only a few studies have investigated the efficacy of Lactobacillus-lactic acid based hay preservatives generally, and even fewer have been targeted toward responses within bermudagrass. This study was designed to evaluate the influence of the preservative on bermudagrass baled at two different moisture levels (17.4 or 26.7%). Evaluation was based on the chemical composition of hays as well as intake by sheep and digestibility in cattle. In this study, treating bermudagrass at time of mowing with a Lactobacillus-lactic acid preservative did not offset the negative effects of spontaneous heating during storage on post-storage forage quality and digestibility. Baling treated bermudagrass at moisture concentrations that exceed normal recommendations for safe storage (>18%) may negatively affect post-storage hay quality and induce spontaneous heating similar to untreated hays. Additionally, utilizing this type of product may not result in desirable improvements relative to untreated control hays with respect to intake and digestibility by either sheep or cows.

Technical Abstract: Bermudagrass [Cynodon dactylon (L.) Pers.] is commonly used for grazing and haying in the southern USA, but hay curing can be challenging due to frequent rainfall events during spring and early summer. An existing stand of ‘Greenfield’ bermudagrass was divided into 12 plots using a randomized complete block design with a 2×2 factorial treatment arrangement to evaluate the influence of a non-viable Lactobacillus-lactic acid preservative and moisture concentration at baling on chemical composition, intake by sheep, and in situ disappearance in cattle. At time of mowing, half of the plots in each block were either spray-treated (T) or not treated (U) with 81 mL/t forage dry matter (DM) of the preservative solution. Hay was then baled at target moisture concentrations of either 174 g/kg DM (L) or 267 g/kg DM (H). Maximum temperature and heating degree days were greater (P<0.05) from H compared with L during the 42-d storage period. An interaction between spray and moisture treatments tended (P<0.10) to affect recovery of DM; recoveries for LT (0.992) differed (P<0.10) from HT (0.913), but LU and HU were intermediate between the spray-treated hays, and did not differ from either (P>0.10). Post-storage nutritive value was largely influenced by moisture treatments only. Intake and digestibility, and in situ DM disappearance of these same hays were determined using 16 wether lambs (43 ± 3.7 kg initial BW), or six ruminally cannulated cows (617 ± 3.5 kg initial BW), respectively. Dry matter intake by sheep was not affected by either treatment factor (P>0.05), but DM digestibility and digestible DM intake were greater (P<0.05) from U compared with T. The in situ immediately soluble DM portion was greater from (P<0.05) L compared with H, but the reverse was true for the potentially degradable DM fraction. The lag time tended (P<0.10) to be greater from H compared with L. Treating bermudagrass with a non-viable Lactobacillus acidophilus-lactic acid spray product at time of baling may not offset the negative effects on forage quality and digestibility of baling bermudagrass hay at excessive moisture concentrations.