Two experiments were carried out to evaluate different dietary buffers and their influence on (1) rumen pH in dairy cows and (2) milk production in dairy cows. The supplements included were calcareous marine algae (CMA; Lithothamnion calcareum), with or without marine magnesium oxide (MM; precipitated magnesia derived from seawater), and sodium bicarbonate (SB). Dietary treatments in experiment 1 consisted of the control [32.9% starch and sugar, and 19.9% neutral detergent fiber from forage per kg of dry matter (DM)] including no dietary buffer (CON); the control plus 0.45% DM CMA (CMA); the control plus 0.45% DM CMA and 0.11% DM MM (CMA+MM); the control plus 0.9% DM SB (SB). Diets were formulated to a dry matter intake (DMI) of 18 kg per cow/d. Dietary treatments in experiment 2 also consisted of CON (28.3% starch and sugar, and 23% neutral detergent fiber from forage per kg of DM), CMA, CMA+MM, and SB and were formulated to achieve identical intakes of experimental ingredients (80 g of CMA, 80 g of CMA plus 20 g MM, and 160 g of SB per cow/d) with a DMI of 22.6 kg per cow/d. Experiment 1 used 4 rumen-cannulated dairy cows in a 4 × 4 Latin square design. Rumen pH was measured over five 2-h periods, following feeding, using rumen pH probes. In experiment 2, 52 multiparous and 4 primiparous cows (62.7 ± 3.4 d in milk) were assigned to 4 experimental treatments for 80 d. Both CMA treatments maintained a greater mean rumen pH than the CON during 4 of the 5 periods following feeding and the CON had a greater number of hours below rumen pH 5.5 compared with all other treatments. Dry matter intakes tended to be higher on the SB compared with CON. The CMA treatment increased the production of milk fat and protein yield (kg/d) compared with all other treatments. Both CMA and CMA+MM increased milk fat yield compared with CON but were similar to each other and SB. Protein yield was highest in the CMA treatment compared with CON, CMA+MM, and SB. All 3 buffer treatments increased milk fat concentration compared with CON but did not differ from each other. The SB treatment reduced milk protein concentration and milk production efficiency, energy-corrected milk per kilogram of DMI. Results indicate that the addition of CMA can benefit milk fat and protein production when included in diets based on typical feedstuffs of the northern European region. The use of CMA when compared with SB, in such diets, can increase milk protein production and milk production efficiency.

Subacute ruminal acidosis (SARA) is assumed to be a common disease in high-yielding dairy cows. Despite this, the epidemiological evidence is limited by the lack of survey data. The prevalence of SARA has mainly SARA is the most representative of on-farm conditions.

The objective of this study was to quantify the effect of a combined calcium, magnesium and anti-oxidant bolus on early lactation energy status and milk production performance of multiparous dairy cows compared to control, and calcium only bolus intervention. Multiparous (n=91) cows from a large Irish dairy herd, with a below-average incidence of hypocalcaemia, were enrolled in this study and randomly assigned to either a control (CON, n=30), a calcium only bolus (ABC, n=30) or a combined calcium, magnesium and anti-oxidant (Cow Start calcium) bolus (CSC, n=31). CON cows received no bolus and ABC and CSC cows received two boluses at 0-and 12-hours post-partum. Early lactation energy status was studied by recording milk ketone (beta hydroxybutyrate (BHBA)) levels at day 14 and day 28 post-partum, body condition scoring (BCS) of cows at week 0, 2, 4, 6, 8 and 12 post-partum and by weighing cows at week 0, 2, 4, 6 and 8 post-partum. Cows in the CSC group recorded significantly (P < 0.05) lower milk BHBA levels (0.43 mg/dL) when compared to CON (0.98 mg/dL) and a trend (P < 0.10) towards lower milk BHBA when compared to ABC (0.74 mg/dL). The CSC group also showed a trend (P < 0.07) towards reduced body condition loss between calving and nadir (-0.39 BCS units) when compared to ABC (-0.53 BCS units). Milk production volumes were significantly increased (P < 0.05) by 1.3kg per day from day 5 of lactation until day 90 for the CSC group (30.7kg/day) when compared to CON (29.4kg/day), with a trend (P < 0.10) of 0.8 kg per day toward higher milk production when compared to the ABC group (29.9 kg/day). Body weight change (kg), Milk Fat % and kg, Milk Protein % and kg, fat:protein ratio, combined milk components (milk fat and milk protein kg), and energy corrected milk were recorded and analysed, with no significant differences observed. Results of this study indicate that cows supplemented with the CSC bolus responded favourably to treatment with regard to improved metabolic status in the critical early lactation post-partum period when compared to control and a calcium only bolus intervention. Results of this study suggest that supplementing dairy cows with a combined calcium, magnesium and antioxidant oral boluses will have beneficial effects for early lactation dairy cows.

The objective of this experiment was to compare the effects of calcareous marine algae (CMA; Acid Buf, Celtic Sea Minerals) with a limestone-based control on feed intake, milk production, energy balance, serum mineral metabolites, and inflammatory markers in transition dairy cows. Twenty-two multiparous and 10 primiparous cows were assigned to 2 treatments from 25 d before expected parturition until 42 d postpartum. Cows were assigned to treatment according to a randomized complete block design based on parity, preexperimental body condition score, previous 305-d milk yield, and either fat + protein yield (for multiparous cows) or predicted transmitting ability for milk yield and fat + protein yield (for primiparous cows). Cows were fed a negative dietary cation-anion difference [−50 mEq/kg] total mixed ration (TMR) based on corn silage, grass silage, and straw during the prepartum period and a 50:50 forage: concentrate TMR based on grass silage, corn silage, and concentrate during the postpartum period. The 2 dietary treatments consisted of a control (CON), which contained limestone as the primary calcium source, and CMA, in which limestone was replaced by CMA at 0.42% and 0.47% of dry matter for the pre-and postpartum periods, respectively. The dietary treatments were fed as 2 different concentrate pellets added to the TMR. Cows fed the CMA diet had higher dry matter intake in both the prepartum (+1.08 kg) and postpartum (+0.94 kg) periods compared with cows fed the CON diet. Fat yield (+0.11 kg), fat concentration (+0.43%), and 4% fat-corrected milk (+1.56 kg) were higher in cows fed CMA than in cows fed CON. The concentration of plasma serum amyloid A was reduced and that of serum P was increased on the CMA treatment compared with the CON treatment. These findings demonstrate the benefits of supplementing CMA to dairy cows during the transition period compared with a CON treatment containing limestone as the primary Ca source.

The objective of this study was to evaluate both the safety, and efficacy of supplementation at calving with a combined oral calcium and anti-oxidant bolus on post-partum metabolic status, fresh cow energy status, vaginal mucous score and early lactation milk production performance. Multiparous (n=103) cows from 3 dairy herds in Ireland were enrolled in this study and randomly assigned to either a control (CON, n=51) group or an oral bolus supplemented (BOL, n=52) group. CON cows received no oral boluses. BOL cows received 2 oral boluses, at 0 and 18 hours (hrs) after calving. Cows were fed a standard dry cow diet of second cut grass silage with supplemental pre-calving minerals, and fewer than 2.3% of all fresh cows (n=899) in these herds were treated for clinical milk fever (below target incidence level). Trial-eligible cows treated with IV calcium at calving were excluded from the trial. No adverse events associated with bolus safety were observed. The bolus was adminstered with ease and was well-tolerated by all animals. Calving and early lactation disease events were recorded. Metabolic status was evaluated by using milk ketone (beta hydroxybutyrate (BHBA)) testing at day 14 and day 21 postpartum. Cows in the BOL group recorded significantly lower milk BHBA levels (0.46mg/dl) compared to CON cows (0.67mg/dl), (p<0.0001). Milk yield, Milk Fat % and kg, Milk Protein % and kg, combined milk components (milk fat and milk protein kg) and somatic cell counts (SCC) were recorded but no significant differences were observed. Results of this study indicate that the bolus is safe to use in post-partum dairy cows. Furthermore, cows responded favourably to treatment with the bolus with regard to improved metabolic status in the critical post-partum period. Results of this study suggest that supplementing dairy cows with oral boluses can have beneficial effects, even in dairy herds with a below-average incidence of hypocalcaemia.