0748 Effects of supplementing lactating dairy cow ration with sodium sesquicarbonate on reticulorumen pH, rumination, and dry matter intake

The objective of this study was to assess the effects of sodium sesquicarbonate (SQ-810), a reticulorumen buffer, on rumen pH, rumination time, and DMI. Sixteen early lactation multiparous, Holstein cows were housed in a tie-stall barn and milked twice daily at the University of Kentucky Coldstream Dairy from October 31, 2015, to January 1, 2016. Cows were balanced by parity and milk production and then split into 2 treatment groups for a crossover study with a low-buffer (LB; n = 8) group and a high-buffer (HB; n = 8) group. The base total mixed ration (TMR) contained 0.16 kg/d sodium bicarbonate. The LB group did not receive SQ-810 whereas the HB group received 0.30 kg of SQ-810 as fed. Eight cows proceeded through sequence 1: three 21-d periods receiving the LB diet in period 1, the HB diet in period 2, and the LB diet in period 3. The remaining 8 cows proceeded through sequence 2: three 21-d periods receiving the HB diet in period 1, the LB diet in period 2, and the HB diet in period 3. Each group was fed ad libitum and DMI was collected. All cows were administered an iNovotec Animal Care (iNovotec Animal Care, Austria) reticulorumen pH and temperature bolus. Daily rumination time was recorded using HR tags (SCR Engineers Ltd., Netanya, Israel) and CowManager SensOor (SENRUM) tags (Agis Automatisering, Harmenlen, Netherlands). Low pH was calculated as the total time pH was <5.60. The MIXED procedure of SAS was used to evaluate the effects of cow, sequence, treatment and period on each parameter measured. Rumen pH and low pH time (pH < 5.60) were influenced by treatment (P < 0.01). Rumen pH was 5.82 ± 0.07 for LB cows and 5.85 ± 0.07 for HB cows. Low pH time (pH < 5.60) was greater (P < 0.01) for LB days (64.17 ± 11.71 min/d) than for HB days (56.31 ± 11.71 min/d). Dry matter intake was 25.68 ± 0.61 kg/d for LB cows and 26.53 ± 0.61 kg/d for HB cows. Treatment affected SCR rumination times (P < 0.01) for LB cows (457.84 ± 19.15 min/d) and HB cows (435.02 ± 19.15 min/d). Rumination time measured using SENRUM was not significantly different between treatments. The addition of SQ-810 to the TMR significantly increased reticulorumen pH and DMI (P < 0.01). This research demonstrates the positive effects of SQ-810 rumen buffer in a lactating cow diet.