Differing planes of pre- and postweaning phase nutrition in Holstein heifers: I. Effects on feed intake, growth efficiency, and metabolic and development indicators

摘要

The objectives of this study were to determine the effectsof pre- and postweaning planes of nutrition on feedand metabolizable energy (ME) intake, growth, concentrationsof glucose, insulin, insulin-like growth factor 1(IGF-1), and β-hydroxybutyrate (BHB) in blood andrumen volatile fatty acids (VFA) from birth to 25 wkof age in Holstein heifers. Heifer calves (n = 36) wererandomly assigned to receive either a low (5 L/d ofwhole milk) or high (10 L/d of whole milk) preweaningplane of nutrition from 1 to 7 wk of age, and either alow (70% concentrate dry total mixed ration) or high(85% concentrate dry total mixed ration) postweaningplane of nutrition from 11 to 25 wk of age. Frombirth to 25 wk of age, feed intake was recorded daily,and body measures were obtained weekly. Circulatinghormone and metabolite concentrations were measuredbiweekly and total ruminal VFA, fecal starch, and bodycondition were assessed monthly. Overall, average dailygain and body weight were greater for heifers offeredincreased planes of nutrition during both the pre- andpostweaning phases. Heifers offered the high preweaningplane had greater milk intake (7.7 ± 0.1 vs. 4.5 ±0.1 L/d) but lower starter intake (0.3 ± 0.04 vs. 0.7± 0.04 kg/d) during the preweaning phase than thoseoffered the low plane. High preweaning plane heifersalso had greater ME intake from wk 1 to 7, but lessME intake at wk 9 (5.3 ± 0.3 vs. 6.6 ± 0.2 Mcal/kg)than those offered the low plane. Furthermore, overallglucose (118.8 ± 2.9 vs. 110.1 ± 2.9 mg/dL) and IGF-1(101.6 ± 3.6 vs. 75.9 ± 3.6 ng/mL) concentrations weregreater for high versus low preweaning plane heifers,although circulating insulin and BHB did not differbetween preweaning plane groups. However, heifersoffered the high preweaning plane had reduced totalrumen VFA concentrations compared with heifers offeredthe low plane in the preweaning phase (47.3 ±2.0 vs. 55.6 ± 2.1 mM). During the postweaning phase,dry matter intake and ME were consistently greaterin heifers offered the high postweaning plane. Overallinsulin (2.0 ± 0.1 vs. 1.8 ± 0.1 ng/mL), glucose (97.1 ±0.6 vs. 92.1 ± 0.6 ng/mL), IGF-1 (178.0 ± 4.8 vs. 155.8± 4.8 ng/mL), and BHB concentrations (8.8 ± 0.2 vs.8.1 ± 0.2 ng/mL) were greater in heifers offered thehigh than the low postweaning plane. In addition, heifersoffered the high postweaning plane had increasedVFA concentrations in the postweaning phase (73.4 ±1.3 vs. 63.9 ± 1.3 mM) compared with heifers offeredthe low postweaning plane. The results indicated thatincreasing the pre- and postweaning planes of nutritionalong with energy levels positively influenced severalindicators associated with heifer development before 25wk of age. Nevertheless, there was limited interactionin growth and development indicators between the 2phases.