Intake and nutrient digestibility of growing Nellore heifers and steers fed two levels of calcium and phosphorus

Abstract Text: An experiment was conducted to evaluate intake and nutrient digestibility of Nellore heifers and steers fed two levels of calcium and phosphorus. Thirty two Nellore heifers and eighteen Nellore steers were used. Four animals from each gender were used as baseline reference animals and slaughtered at the beginning of the experiment. Four animals from each gender were fed at maintenance (MAIN) and 10 steers and 24 heifers were assigned to the ad libitum (ADLIB) group. The ADLIB heifers were further divided into four groups. Treatments were: 1) Ca and P fed at requirements (CaPR) with a 50:50 of roughage:concentrate (R:C) diet; 2) CaPR with at  70:30 R:C diet; 3) 43% of the Ca and 80% of the P requirement (CaPL) with a 50:50 R:C diet; and 4)  CaPL with a  70:30 R:C diet. The ADLIB steers in this experiment were fed CaPR. Half of the steers and the heifers were slaughtered at d 50 and the other animals were slaughtered a d 100 of the feeding period while all MAIN animals were slaughtered at d 100. Total feces and urine were collected from all animals 72 hours prior to slaughter. Dry matter digestibility and apparent absorption and retention of Ca and P were similar across Ca and P treatments. Final body weight and, consequently, average daily gain was higher (P<0.05) in heifers receiving the high concentrate diet compared to the low concentrate diet while the levels of Ca and P did not affected (P>0.05) the performance. Under the conditions of this experiment, the level of dietary Ca and P can be reduced in the diet and not impact intake, digestibility or performance of growing Nellore heifers and steers.

Keywords: minerals, sugarcane, performance