The effect of buffering dairy cow diets with limestone, Acid Buf or sodium bicarbonate on production response and rumen metabolism

Mubiayi Beya, Michel (2007-12)

Thesis (MScAgric)--University of Stellenbosch, 2007.

Thesis

ENGLISH ABSTRACT: The objective of this study was to evaluate the effect of different buffers in dairy cow diets on milk production and composition and on sefocted rumen metabolism parameters. A high concentrate TMR, formulated to be potentially acidotic, was used to construct three dietary treatments in which Acid Buf (the skeleton remains of the sea weed Lithothamnium calcareum) was compared against limestone (control) and sodium bicarbonate plus limestone. One basal diet was formulated and treatment diets contained either 4 g/kg DM of Acid Buf, 3.7g/kg DM of limestone+ 8 g /kg of sodium bicarbonate or 3.5 g/kg DM limestone (control), respectively. The response to treatment- was measured using 6 ruminally cannulated lactating Holstein cows allocated to treatments according' to a 3 x 3 (n=2) balanced Latin square design, with three treatments and three periods. The total experiment period was 66 days in which· every cow received each diet for a period of 15 days prior to the data collection period of 7 days. Rumen fluid was collected for volatile fatty acid (VF A), lactic acid and ammonia concentration. Rumen pH was monitored continuously every 10 minutes for two days using a portable data logging system and in-dwelling electrodes. During each data collection period, milk was collected and analyzed for its solid and mineral contents. Feed consumption was recorded individually. The impact of acidity was clearly visible, especially from the period from mid:..day to mid-night when rumen pH dropped below 5.5 for a longer period (13 h) in the control (limestone) treatment than in the sodium bicarbonate (7.7 h) and· Acid Buf (4 h) treatments. The minimum rumen pH was lower for the control (5.14) than for the Acid Buf treatment (5.42), while the pH in the sodium bicarbonate treatment (5.37) did not differ from other treatments. The dietary buffers did not have a significant irppact on rumen VF A, lacticacid and ammonia concentrations. Daily milk yield was higher for the Acid Buf (31.8kg) treatment than for the sodium bicarbonate (29.l kg) and control (27.6 kg), treatments. Milk fat content was higher for the Acid Buf ( 42.1 g/kg) and sodium bicarbonate ( 41.8 g/kg) treatments and control (38.6 g/kg) treatments. Treatment had no effect on milk crude protein content (34.7 g/kg, 33.8 g/kg and 34.3 g/kg for the Acid Buf, sodium bicarbonate and control treatments, respectively). The trial indicated that supplementing high concentrate diets for lactating dairy cows with Acid Buf at a level of 90 g/cow per day has a greater impact on rumen pH, milk production and milk composition than 180 g/cow per day of sodium bicarbonate and that sub-clinical acidosis could reduce daily milk input by 4 kg/cow. Key words: Acid Buf, Buffer, Rumen metabolism, Milk production

AFRIKAANSE OPSOMMING: Die doel van die studie was om die invloed van verskillende buffers in melkbeesdiete op melkproduksie en melksamestelling, asook op bepaalde rumenparameters, na te gaan. 'n Volledige dieet met 'n hoe kragvoerinhoud, wat geformuleer is om potensieel asidoties te wees, is gebruik om drie dieetbeehandelings saam te stel waarin Acid Buf (die skeletoorblyfsels van die seegras Lithothamfzium calcareum) vergelyk is met voerkalk (kontrole) en natriumbikarbonaat plus voerkalk. Een basale dieet is dus geformuleer en die behandelingsdiete het onderskeidelik 4 g/kg DM Acid Buf, of 3.7g/kg DM voerkalk + 8 g/kg natriumbikarbonaat, of 3.5 g/kg DM voerkalk (kontrole) bevat. Ses rumengekannuleerde lakterende Holsteinkoeie is ewekansig aan die behandelings toegeken in 'n gebalanseerde) x 3 (n=2) Latynse vierkantontwerp met drie behandelings en drie periodes. Die totale eksperimentele periode was 66 dae, waartydens elke koei elke bebandeling vir 15 dae ontvang heet voor die datakolleksieperiode van 7 dae. Rumennloeistof is versamel vir die bepaling van vlugtige vetsure (VVS), melksuur en ammoniakbepalings. Rumen pH is voortdurend, elke 10 minute, oor 'n twee-dae periode gemeet met behulp van draagbare dataloggers en pH elektrodes wat binne-in die rumen geset~l was. Melkmonsters is gedurende elke datakolleksieperiode versamel en ontleed vir totale vastestof- en mineraalinhoud. Voerinname is individueel bepaal. Die invloed van rumen-suurheid is duidelik waargeneem, veral gedurende die middag- tot middernagperiode toe die rumen pH in die kontrolebehandeling vir !anger periodes (13 ure) tot onder 5.5 gedaal het as in die geval van die natriumbikarbonaatbehandeling (7. 7 ure) en Acid Buf-behandeling ( 4 ure ). Die minimum rumen pH was laer vir die kontrolebehandeling (5.14) as vir die Acid Buf-behandeling (5.42), terwyl die van die natriumbikarbonaatbehandeling (5.37) nie van die antler behandelings verskil het nie. Die dieetbuffers het nie 'n betekenisvolle invloed op die rumen VVS-, melksuur- of ammoniak-konsentrasies gehad nie. Daaglikse melkproduksie was hoer vir die Acid Buf-behandeling (31.8 kg) as vir die natriumbikarbonaat- (29. l kg) en kontrolebehandelings (27.6 kg). Die melkvetinhoud was hoer vir die Acid Buf- ( 42.1 g/kg) en natriumbikarbonaatbehandelings (41.8 g/kg) as vir die kontrolebehandeling (38.6 g/kg). Behandeling het egter nie 'n betekenisvolle invloed op die melkprotereninhoud gehad nie (34.7 g/kg, 33.8 g/kg and 34.3 g/kg vir die Acid Buf-, natriumbikarbonaat- en kontrolebehandelings, onderskeidelik). Die studie het aangedui dat die aanvulling van hoe-kragvoerdiete vir melkkoeie met Acid Bufteen 90 glkoei per dag 'n groter impak op rumen pH, melkproduksie en melksamestelling het as natriumbikarbonaat teen 180 g/koei per dag en dat sub-kliniese asidose die melkproduksie met soveel as 4 kg per dag kan verlaag. Sleutelwoorde: Acid Buf, Buffer, Rumen metabolisme, Melkproduksie

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/50754
This item appears in the following collections: