Can Differing Pre- and Post-Weaning Phase Nutrition Change Intake, Growth and Hasten Puberty in Holstein Heifer Calves?

摘要

The objective was to determine the effects pre- and post-weaning diets with differing energy levels have on the energy intake, growth, and insulin-like growth factor 1 (IGF-1) concentrations in Holstein heifer calves. Animals were randomly assigned toeither a low (n = 14) or high (n = 14) pre-weaning diet (5 L/d or 10 L/d of pasteurized whole milk, wk 1 to 8.5), and to either a low (n = 14) or high (n = 14) ad-libitum post-weaning dry TMR diet [30% straw and 70% concentrate or 15% straw and 85% concentrate, from wk 9 to 25 of age], in a 2x2 factorial experiment. Free choice concentrate was available to all calves in the pre-weaning phase, and feed intake was recorded daily from birth to 26 wk of age. Once weekly, all calves were weighed and blood sampled. Metabolizable energy (ME) intake was increased in calves offered the pre-weaning high-plane diet from wk 1 (high= 3.38Mcal/d, low = 2.54Mcal/d, pO.001) to 8 (high = 5.73Mcal/d, low = 4.90Mcal/d, p = 0.02). Regardless of pre-weaning treatment, offering a high plane of nutrition post-weaning increased ME intake from wk 11 (high = 9.52Mcal/d, low = 8.53Mcal/d, p = 0.003) to 25 (high = 22.05Mcal/d, low = 17.38Mcal/d, p < 0.001). Average daily gain (ADG) was calculated on a monthly basis, and rate ofgain differed between treatments only in month 1 (high= 0.80 kg ADG, low = 0.49 ADG, p = 0.009). Serum IGF-1 concentrations, measured every other week, were greater in high-plane calves in wk 3, 5, and 7 during the pre-weaning phase. In the post-weaningphase, the same trend continued, as IGF-1 tended to be greater in high-plane calves in wk 15,17, 19, and 21. Early life elevated planes of nutrition offer possible advantages as energy intake and IGF-1 concentrations were increased, although differencesin growth were not detected.