Effect of anionic salts in concentrate mixture and calcium intake on some blood and urine minerals, acid-base balance and feed intake of dry pregnant cows on grass silage based feeding

Abstract

Twelve Ayrshire and eight Friesian cows were randomly assigned to one of four prepartum diets in a 2 x 2 factorially designed experiment to determine the effect of anionic diet and calcium (Ca) intake on Ca metabolism, acid-base status and feed intake of grass silage based diets during the dry period. Four diets provided either 34 g or 74 g total dietary Ca/day, and were either anionic or cationic. Dietary cation-anion balance (DCAB), calculated as milliequivalents [(Na+ + K+) - (Cl- + S2-)], was -247 mEq/kg dry matter (DM) in the low DCAB group and +34 mEq/kg DM in the high DCAB group. DCAB was formulated using NH4Cl, (NH4)2SO4 and MgCl2 as anionic salts. Cows received grass silage (5.2 kg DM), hay (0.9 kg DM) and concentrate mixture (1.6 kg DM) until calving. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, the day after calving and 1 week following calving. The results indicate that the reduction of cation-anion balance induced mild metabolic acidosis and increased the ability of the cow to maintain blood Ca concentration. However, DCAB should be higher since urinary pH decreased markedly (< 6) and so remarkable changes in some blood electrolyte concentrations were noticed.;

Milk Fever Control Principles: A Review

“…The study done by [67] is not included in the calculations, as they did not include a group receiving feed with a negative DCAD. In 2 of the studies [73] and [107] the milk fever incidence was zero among cows in the positive as well as negative DCAD group (RR = 1). Excluding these results from the calculations, the RR changes from 0.35 to 0.19.…”

“…vary considerably between the different studies. For instance some studies included cows of second or first parity [73,107,70], whereas others [10,79,67,41,8,36,37,39] only included "high risk" cows (≥ third parity). The interpretation of Fig.…”

“…On the other hand [96] and [93] argue that low calcium and a low DCAD supplement each other and they therefore believe such a combination to be superior to the combination high Ca – low DCAD. [36] and [107] question whether the dietary calcium level has any influence at all on the blood calcium concentration at parturition in cows on an acidifying ration. It is noted, however, that when limestone is used to achieve a high level of dietary calcium, the alkalinising effect of the added calcium carbonate may be a factor of consideration [37].…”

“…Several studies have shown a negative effect on the dry matter intake (DMI) when adding anionic salts to the ration [32,78,36,107,70], whereas others found no effect on DMI [10,79]. [112] have shown that decreased feed intake and a negative energy balance before calving increase plasma NEFA and concentration of liver triglyceride at calving.…”

Effect of anionic salts and potassium intake on some blood and urine minerals and acid-base balance of dry pregnant cows on grass silage based feeding

“…However, Tucker et al (1991) found that udder oedema regressed postpartum more rapidly in cows previously fed a low DCAB (-30 mEq/kg DM) relative to cows fed a high DCAB (+90 mEq/kg DM). In an earlier study (Tauriainen et al, 1998a) severe udder oedema was unexpectedly observed in a high proportion of cows when the DCAB was -247 mEq/kg DM, but the incidence was not routinely evaluated and as such these findings were not documented.…”