<b>Effect of dietary cation-anion balance, on milk production and physiological responses of lactating dairy Holstein cows in hot weather</b> - DOI: 10.4025/actascianimsci.v26i1.1959

Abstract

The objective was to evaluate the response of lactating dairy cows to dietary Na, K, and Cl while holding cation-anion balance constant. Nine lactating Holstein cows, blocked according to age and previous milk yiel, and assigned randomly to replicated 3x3 Latin esquares with experimental period of 3 week, Diets contained corn silage and concentrate ration in a 50:50 rate (DM basis) and were formulated to provide + 32 mEq of (Na + K) – Cl/100 g diet DM via one of three variations: 1) control treatment plus 1.57% of KCl in DM basis, 2) control treatment plus 1.22% of NaCl in DM basis, 3) control treatment. Samples of milk were collected a week one day for fat analysis, protein, lactose and non fatty solids. The treatments did not influence the production of milk, although the addition of NaCl has contributed to a better total production of 20.58kg against 19.78kg for the addition of KCl and in the production of milk for the morning of 13.77kg against 13.1kg. The fat, protein, lactose and total solids content, didn't present significant alterations in function of the use of KCl and NaCl in the diet. The best consumption of DM was observed for the animals receiving the treatment NaCl (17.48kg) against the treatment control (16.98kg), although it has not had significant effect. Larger values of somatic cells were found for the animals receiving the treatment NaCl (813.48 x 1000 células/mL of milk), and the smallest value for the treatment KCl (496.81 x 1000 células/mL of milk). The air temperature of the morning went to climatic variable that presented significant effect in the milk production and in the food consumption. Larger effect was verified for the treatments KCl and control (b = -0.18) proceeded by the treatment NaCl (b = 0.07). Rectal temperature and respiratory rate did not suffer effect of the cation-anion balance, but larger values were found for the period of the afternoon. The balance dietary cation-anion of +32 mEq/100 g of DM of the diet, did not demonstrate positive effect in the production and in the quality of the milk, even so it allowed to maintain the consumption and the physiologic answers of the animals inside of the desirable parameters.