Dairy goat performance with different dietary concentrate levels in late lactation.

Alpine yearling doelings (22; 44+/-1.0kg) and mature does (25; 59+/-1.7kg) were used in an experiment with 16 weeks in late lactation, 8-13 weeks dry and 12 weeks in the subsequent lactation. Diets of 20, 35, 50 or 65% concentrate and 2.18, 2.34, 2.49 and 2.62Mcal/kg ME, respectively (20C, 35C, 50C and 65C treatments, respectively), were consumed ad libitum in late lactation, with a 35% concentrate diet (2.18Mcal/kg ME) in the first 4 weeks of the dry phase and 50% concentrate (2.65Mcal/kg ME) until kidding. Other goats consuming 20 or 35% concentrate in late lactation received 65 (2.65Mcal/kg ME) or 50% concentrate, respectively, in the dry phase (20A and 35A treatments, respectively). All goats consumed a 50% concentrate diet (2.42Mcal/kg ME) in the subsequent early lactation. DM intake in late lactation was similar among treatments (1.95, 2.21, 2.17, 2.10, 1.99 and 2.00kg per day for 20C, 35C, 50C, 65C, 20A and 35A, respectively; S.E.=0.098) and greater (P<0.05) for does versus doelings (2.16 versus 1.98kg per day; S.E.=0.058); DM intake in the dry phase was similar among treatments. Relative to BW, DM intake was greater (P<0.05) for doelings than for does in late lactation (4.16 versus 3.43% BW) and early lactation (4.56 versus 3.80% BW). The effect of dietary treatment on milk production in late lactation varied with parity (P<0.05); milk production by doelings was 1.39, 1.49, 1.43, 1.57, 1.29 and 1.52kg per day and by does was 1.01, 1.89, 2.38, 1.63, 1.17 and 1.34kg per day for 20C, 35C, 50C, 65C, 20A and 35A, respectively; S.E.=0.200). BW change during the entire 16 weeks late lactation phase was greater (P<0.05) for 65C than for other treatments except 50C (6.9, 5.6, 9.1, 10.4, 5.8 and 4.0kg for 20C, 35C, 50C, 65C, 20A and 35A, respectively; S.E.=1.28), although BW at kidding and litter weight were similar among treatments. BW, DM intake and milk production in the first 12 weeks of the subsequent lactation were not affected by dietary treatment or parity. In conclusion, with moderate to high quality forage in late lactation and a moderate level of concentrate in the dry period, the level of concentrate fed in late lactation and in the dry period may not affect subsequent lactation performance regardless of parity. Milk production by doelings in late lactation appears relatively less responsive to dietary concentrate level than that by does.