1. Mean daily ruminal pH values of 5.6 to 6.4 have been reported for dairy cows fed high-quality pasture (Van Vuuren et al., 1992; Stockdale, 1994; Carruthers et al., 1997; O’Mara et al., 1997; Kolver et al., 1998a).
  2. A lower ruminal pH is associated with higher concentrations of VFA, ruminally degradable OM, and OM intake, and with a lower milk fat percentage, forage NDF content and particle length index (Allen 1997; Mertens, 1997).
  3. Supplementing pasture-based Jersey cows with 60g Acid Buf/cow/day significantly increases 4% fat corrected milk by when compared to un-supplemented Jersey cows (Van Dyk et al., 2015).
  4. Supplementing 70g of Acid Buf + 10g Marine MgO to pasture based Holstein cows, significantly increased 4% fat corrected milk by 1.1 litre when compared to un-supplemented control cows. (Rafferty et al., 2019).
  5. Over a 24-hour period, rumen pH of cows on pasture tends to be the lowest around 22:00. (Van Wyngaard et al., 2018).
  6. Rate of feed consumption peaks at noon and reaches its lowest point around midnight (Shabi et al., 2002).
  7. NDF disappearance decreased linearly with increasing concentrate feeding levels (Van Wyngaard et al., 2018).
  8. Pasture DMI decreased with increasing concentrate feeding level, whereas total DMI, GE intake and ME intake increased (Bargo et al., 2003).
  9. Concentrate supplementation in pasture-based systems reduced ruminal pH, increased total VFA concentration and reduced NH3-N concentration. When fed at high levels in maize-based form (>8 kg of DM/cow/day), it reduced the rate of pasture degradability (Bargo et al., 2002, 2003).
  10. A survey of 100 predominantly pasture based dairy farms in Australia, indicated 10% of cows experienced rumen acidosis (ave. pH=5.73); 30% of cows experienced suboptimal rumen function (ave. pH=6.18) and the rumens of 60% of cows can be classified as normal functioning rumens (ave. pH=6.33) (Bramley et al., 2008).
  11. Fibre digestibility is reduced when pH drops below 6.2 (Grant and Mertens, 1992; Grant, 1994; Calsamiglia et al., 1999).
  12. Pastures contain significant amounts of oligofructans, which can play a role to induce acidosis and laminitis (Theofner et al., 2004).

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