Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 6/24/2010
Publication Date: 7/11/2010
Citation: Bjelland, D.W., Esser, N.M., Weigel, K.A., Hoffman, P.C., Coblentz, W.K. 2010. The Effect of Feeding Dairy Heifers Diets With and Without Supplemental Phosphorus for 18 Months on Growth, Reproductive Efficiency, and Lactation Performance. Joint Meeting of the ADSA, AMSA, ASAS and PSA. 93:419. Interpretive Summary:
Technical Abstract: The phosphorous (P) requirements for dairy heifers (0.20–0.35%) and endogenous levels (0.20–35%) of P in feeds fed to dairy heifers are similar, suggesting that the need for supplemental P in dairy heifer diets may be minimal. Because long-term studies are unavailable, 183 Holstein heifers and 182 backcross Holstein × Jersey heifers were fed diets with (SP = 0.38% of dry matter (DM)) and without (NP = 0.28% of DM) supplemental phosphorus from 4 to 22 mo of age in a replicated pen design. Heifers were evaluated for body weight (BW), external bone/frame growth, dystocia, calf BW, reproductive efficiency, and first lactation performance. Data were analyzed using a mixed model with effects of season of birth, age of dam, pen number as a heifer, sire, sire birth year, and days in milk. No breed × diet interactions were observed. Heifers fed NP had similar average daily gain from 170 to 410 (0.86 vs. 0.83 kg/d) and 410–650 (0.85 vs. 0.86 kg/d) d of age as compared with heifers fed SP. At 22 mo of age, heifers fed NP were wider at the hip but did not differ in BW, hip height, body length, heart girth, cannon bone circumference or pelvic area as compared with heifers fed SP. As heifers, services per conception (1.45 vs. 1.39), age at pregnancy (451 vs. 452 d), and age at first calving (726 vs. 727 d) were not different between heifers fed NP or SP. At parturition, heifers fed NP or SP had similar dystocia scores and calves were similar in BW. Complete first lactation data (305 d) were available for 333 primiparous cows, and cows fed NP as heifers produced similar milk (8702 vs. 8714 kg), fat (330 vs. 328 kg) and protein (274 vs. 277 kg) as cows fed SP as heifers. Days open (152 vs. 160 d), days in milk at first breeding (76 vs. 76 d), and services per conception (1.82 vs. 1.85) were also similar for primiparous cows fed NP or SP as heifers. Data suggest there was no growth, reproductive or lactation benefit to feeding dairy heifers diets containing 0.38% P as compared with 0.28% P.