Effects of feeding calcareous marine algae to Holstein cows beginning prepartum on postpartum performance and serum metabolites
Bernard, John K.
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Thirty-six multiparous Holstein cows and 12 springing heifers were used in a 9 wk randomized design trial to determine the effect of feeding calcareous marine algae (Acid Buf, Celtic Sea, Ireland) from 3 wk prepartum through 6 wk postpartum on dry matter intake (DMI) , milk yield and composition, and blood and urine metabolites. Within parity, animals were assigned randomly to one of four treatments with a 2 × 2 factorial arrangement. Prepartum diets were supplemented with 0 (CON) or 50 g/d calcareous marine algae (CMA) resulting in a DCAD of -3 and -5 meq/100g, respectively. Postpartum diets were supplemented with either 317 g/d sodium bicarbonate (NBC) or 100 g/d CMA to achieve a DCAD of 35 and 17 meq/100g, respectively. No differences (P = 0.6142) were observed in prepartum DMI which averaged 11.9 and 12.2 kg/d for CON and CMA, respectively. Postpartum DMI, milk yield, percentage of milk fat, protein, lactose, and SNF were not different (P > 0.10) among treatments and averaged 18.0, 38.1, 4.02, 2.71, 4.75, and 8.37; 19.8, 39.0, 3.96, 2.85, 4.74, and 8.38; 19.4, 37.3, 4.01, 2.71, 4.75, and 8.41; and 20.0 kg/d, 38.1 kg/d, 4.24%, 2.81%, 4.72%, and 8.37% for CON-NBC, CMA-NBC, CON-CMA, and CMA-CMA, respectively. Milk protein yield was higher (P = 0.0453) for cows fed CMA prepartum compared with CON; 1.09 and 1.02 kg/d, respectively. Interactions of prepartum treatment and wk were observed for yield of milk fat (P = 0.0222), energy-corrected milk (ECM, P = 0.0395) and 3.5% fat-corrected milk (FCM, P = 0.0290) because of higher yields for cows fed CMA during wk 2 and 6 compared with CON. An interaction of prepartum treatment and wk (P < 0.05) was also observed for milk efficiency (ECM/DMI, FCM/DMI) because of lower efficiencies for cows fed CMA during wk 1 and 4 compared with CON; however, efficiencies tended to reverse and were numerically higher for CMA compared with CON during wk 6. Serum Na concentrations were greater (P < 0.05) for cows fed CON prepartum or NBC postpartum compared with CMA. Postpartum urinary concentrations of Na exhibited an interaction among treatments (P = 0.0353) and were higher for CON-NBC and CMA-NBC compared with CON-CMA and CMA-CMA; 121.21, 105.43, 41.24 and 59.55 mmol/L, respectively. Similar interactions of treatments (P < 0.05) were also observed for serum urea N and creatinine postpartum. Postpartum urinary K concentrations were higher (P = 0.003) for cows fed CMA postpartum compared with NBC; 155.60 and 118.40 mmol/L, respectively. Results of this trial indicate that cows feeding CMA prepartum does not affect DMI or serum metabolites prepartum, but supported higher milk protein yields and increases in ECM and FCM postpartum. Efficiency of milk production was higher for CON during wk 1 and 4, but was not different afterwards. Performance and serum metabolite concentrations of cows fed CMA postpartum were comparable with that of cows fed NBC except for changes in serum and urinary concentration of Na related to dietary intake of Na. Key words: DCAD, milk yield, milk composition