Effects of weaning age on growth, nutrient digestibility and metabolism, and serum parameters in Hu lambs

This study was conducted to investigate the effect of weaning age on growth performance, nutrient digestion and metabolism, and serological indicators, and to obtain an optimal weaning age in Hu lambs. Forty-eight newborn Hu lambs (birth weight, 2.53 ± 0.14 kg) were randomly divided into 4 groups. The lambs in control group (ER) suckled their dams. The lambs in other three experimental groups were weaned on milk replacer at 10, 20, and 30 days of age (EW10, EW20, and EW30 groups), respectively. The results were as follows: 1) lambs in EW10 and EW30 groups had a lower (P < 0.05) ADG than those in ER group within 10 days post-weaning; the weaned lambs began to show a higher (P < 0.05) ADG than those in ER group after 20 days post-weaning. 2) EW10 and EW20 groups had a higher (P < 0.05) creep feed intake than EW30 and ER groups from 15 to 60 days of age. 3) The apparent digestibility of dry matter, organic matter, gross energy, nitrogen, ether extract and phosphorus, and the deposition of nitrogen and phosphorus did not differ (P > 0.05) among groups; however, the apparent digestibility and deposition of calcium in early weaned lambs were lower (P < 0.05) than those in ewe-reared lambs. 4) The albumin content in EW30 group was lower (P < 0.05) than that in ER group; the globulin content in EW30 group was higher (P < 0.05) than that in other groups; the content of serum insulin-like growth factor-Ⅰ in weaned lambs tended to increase compared with lambs in ER group. Finally, the growth rate of lambs decreased within 10 days post-weaning, but early weaning boosted creep feed intake, leading to better growth and health later in life. The Hu lambs can be weaned on milk replacer and creep feed at 10 days of age.