EFFECTS OF A REDUCED P SUPPLY IN COMBINATION WITH ADEQUATE OR HIGH CA INTAKE ON PERFORMANCE AND MINERAL BALANCES IN DAIRY GOATS DURING PREGNANCY AND LACTATION

In a two-factorial trial (2 x 2) lasting from week 7 of lactation to week 6 of the following lactation, four goats per treatment received P intakes either according to NRC (1981) recommendations (aP) or reduced to assumed net requirements (rP) and Ca intakes either (aCa) according to NRC (1981) or twice this rate (hCa). Feed intake, changes in live weight, milk yield, reproductive performance and digestibility of organic matter were not significantly affected by dietary contents of P or Ca. Plasma concentrations of inorganic P decreased and of Ca increased as a result of reducing P intake, whereas both values were unaffected by doubling Ca intake. P balances were determined at seven stages of the trial. At the beginning, goats fed rP lost 0.2-0.6 g P daily, in later stages, their P balances did not differ significantly from those goats fed aP. Ca intake had no consistent effect on P balance. Ca balance was not significantly affected by intake of either Ca or P.