Changing Dietary Electrolyte Balance for Dairy Cows in Cool and Hot Environments

Abstract

Two Latin square studies, each containing eight primiparous cows (four Holstein, four Jersey), were conducted to determine the effect of changing dietary electrolyte balance during cool and hot environmental conditions on performance of lactating dairy cows. Electrolyte balance, expressed as Na + K - Cl in milliequivalents per kilogram of diet, was altered by changing K and Cl content in the diet using potassium bicarbonate or calcium chloride. Maximum and minimum temperatures averaged 26.7 and 15.0 degrees C during the cool phase and 32.3 and 22.5 degrees C during the hot phase of the study. Milk yield improved linearly with increasing electrolyte balance with nonsignificant treatment by phase interaction, whereas DMI of cows improved quadratically with increasing dietary electrolyte balance. A treatment by phase interaction for DMI was detected, although intake of DM reached a plateau at a similar dietary electrolyte balance during the cool and hot phases. Body (milk) temperature of cows appeared to be related to the level of feed consumed and varied by treatment within phase. Body (milk) temperature was higher during the hot phase of the experiment. Blood bicarbonate and pH were lowest in cows offered the low electrolyte balance (high Cl) diet, and blood and urinary Na + K-Cl increased linearly with increasing dietary electrolyte balance. The response to dietary electrolyte balance appeared to be mediated through blood buffering and the impact on physiologic systems of the cow.

Effect of dietary cation–anion difference on ruminal metabolism, total apparent digestibility, blood and renal acid–base regulation in lactating dairy cows

“…Similar results were also reported by West et al (1991 and, which observed that urinary cation-anion difference was increased with DCAD increase. Hu and Murphy (2004) described that urinary concentrations of K and Cl linearly increased as its respective dietary concentrations were increased, whereas urinary Na concentration rose in a quadratic form according to the level of this mineral in the diet.…”

“…In contrast, Fredeen et al (1988) described that blood concentration of Na was reduced with DCAD reduction. Other studies, Tucker et al (1988);West et al (1991) and Marques et al (2011), did not observe effect of DCAD on blood concentrations of Na and K. Therefore, there are different results about the effect of DCAD on blood concentrations of Na and K; which may be due to the different methodologies that were used to study DCAD, as following: type of anionic or cationic salt used; DCAD levels studied; type of diets (TMR or concentrate supplementation of dairy cows grazing pasture, as well as forage : concentrate ratio) and mineral concentration of diets evaluated.…”

“…The pCO 2 reduction suggested an increase in respiratory rate that may occur in order to compensate metabolic acidosis, as CO 2 is a gas that when dissolved in water forms carbonic acid, which dissociates into H + and HCO 3 − contributing to biological fluids acidification. Thus, when blood pH is reduced, dairy cows can raise their respiratory rate to increase CO 2 elimination (West et al, 1991 andBlock, 1994).…”

Resposta em parâmetros sanguíneos e urinários de vacas leiteiras ao aumento no balanço cátion-aniônico da dieta

“…West et al (1991); Joyce et al (1997) A concentração de Na no sangue é mantida relativamente constante por meio da regulação do consumo e excreção do elemento (Swenson, 1984). Uma possível explicação para os resultados obtidos seria a resposta compensatória dos rins, ou seja, conforme o BCAD aumentou, com consequente aumento da ingestão de Na, pode ter ocorrido maior excreção urinária desse mineral, mantendo sua concentração no sangue.…”

Influence of dietary cation–anion difference in finishing diets fed to Holstein steers during periods of high ambient temperature on feedlot performance and digestive function

“…In principle, corrections in blood acid-base balance and associated electrolyte losses may be achieved through modification of the DCAD. Diets formulated with DCAD of 250 mEq/kg DM have been recommended for optimal growth in chickens (Mongin 1981) and pigs (Austic and Calved 1981;Patience et al 1987), and 200-370 mEq/kg DM for optimal milk yield in lactating dairy cattle West et al 1991). The DCAD is usually manipulated by the addition of weak buffers such as NaHCO 3 , KHCO 3 and K 2 CO 3 .…”