Abstract:
Spanish wether and doeling kids (4.5 months of age; 13.4 kg initial BW) were used to determine influences of different quality diets consumed continuously or after a lower quality diet on characteristics of growth. The experiment consisted of two 9-week periods. Diets were low quality forage (L, prairie hay supplemented with soybean meal), high quality forage (H, dehydrated alfalfa pellets) and 70% concentrate (C). Kids on two treatments consumed L in Period 1, with half switched to C and half to H in Period 2 (LC and LH, respectively). The CC treatment entailed C consumption in both periods, and HH kids were fed H in both periods. For HC, H was fed in Period 1 followed by C in Period 2. DM intake ranked (P<0.05) LC and LH<CC<HC and HH in Period 1 (502, 352, 386, 610 and 636 g per day) and CC and LC<LH, HC and HH in Period 2 (652, 621, 833, 808 and 836 g per day for CC, LC, LH, HC and HH, respectively). ADG was lowest among treatments (P<0.05) for LC and LH in Period 1 (78, 1, −1, 84 and 80 g per day) and was 53, 82, 112, 92 and 73 g per day in Period 2 for CC, LC, LH, HC and HH, respectively (S.E. = 11). Empty body fat concentration at the end of Period 1 was greatest for the C diet and lowest for L (P<0.05; 12.2, 6.4 and 9.0% for C, L and H, respectively), and protein concentration was greatest among treatments (P<0.05) for L (16.8, 20.1 and 18.1% for C, L and H, respectively). At the end of Period 2, empty body fat concentration was 22.0, 15.9, 14.4, 20.1 and 15.2% (S.E.=1.94), and protein concentration was 16.8, 16.9, 17.9, 16.5 and 17.6% (S.E.=0.35) for CC, LC, LH, HC and HH, respectively). In summary, kids on the L diet in Period 1 mobilized fat to accrete a small amount of protein. Continuous consumption of C resulted in high fat accretion relative to H in both periods. Consumption of H in Period 1 followed by C in Period 2 resulted in growth characteristics slightly different from those with continual intake of C, with a lower concentration of protein in accreted tissue for HC. The diet in Period 2 for kids previously consuming L did not markedly affect tissue accretion. In conclusion, the nature of the diet consumed by young Spanish goats can impact current and subsequent rate and composition of BW gain.