Effect of granule size on dissociation of calcium salts of palm fatty acid distillate. W.-L. Ong1, R. Kirkland2, J. Newbold3, and K.-H. Ng*

WL Ong, Richard Kirkland, JR Newbold, KH Ng

Research output: Contribution to conferencePaperpeer-review


Calcium salts of palm fatty acid distillate (CaS) are among the most
common rumen-protected fat supplements used on dairy farms. Rumen active oil sources have negative effects on rumen microbes, fiber digestion and milk fat production, and it is important to ensure supplements used are stable under rumen conditions but subsequently dissociate in the acidic conditions of the abomasum. In this study we investigated the effect of granule size of CaS (<0.5 mm, 1–2 mm, 2–3 mm, 3–4 mm) on dissociation pattern in different pH conditions across a range of time points from 0 to 24 h. Samples of CaS were sieved to different granule sizes. To understand the relative stability of the CaS of different sizes, we carried out in vitro dissociation study using a series of buffers with different pH values coupled with ICP-AES analysis to detect the released calcium (Ca). The CaS samples were pre-washed with water and dried
at 60°C overnight. One gram of the prewashed and dried samples were
either digested with 20 mL of 3M HCl (70°C, 2 h) for complete recovery
of Ca or incubated with 40 mL each of buffers of different pH values at
different time points at 39°C with shaking (200 rpm). The released Ca
was separated from undigested solids by filtering and centrifugation.
The Ca content in the digested solids and buffers was measured by ICPAES. Release of Ca (%) per gram of CaS was determined as: % of Ca
released = (amount of Ca released in the buffer/total amount of Ca in
the CaS) × 100%. We found that at 16-h incubation, CaS of < 0.5 mm
granule size would have 24.5% and 41.6% of Ca dissociated at pH 6.5
and pH 5.6. In contrary, for the large granule size of 3–4 mm, the Ca
dissociation was 8.6% and 24.4%, respectively. Our results suggest that
small granules break down more extensively in acidic conditions than
larger granules and Ca release (dissociation) increases with incubation
time at a specific pH.
Original languageEnglish
Publication statusPrint publication - 12 Jul 2021
EventAmerican Dairy Science Association annual meeting -
Duration: 11 Jul 202114 Jul 2021


ConferenceAmerican Dairy Science Association annual meeting
Abbreviated titleADSA 2021


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