409
Comparison of delayed weaning on lamb growth and parasitism while grazing red clover
The objective of this study was to compare weaning at 60 versus100 days of age on lamb growth and parasitism while grazing red clover, followed by a feedlot phase where lambs were taken to a similar final weight. Each weaning treatment consisted of 3 replicate fields of 6 lambs per field, blocked by initial starting weight. Single lambs were used. Treatments were weaned (WEAN) lambs and lambs left with its mother for the pasture phase (NURSE). Paddock size matched stocking density between ewes with lambs and weaned lambs. At 100 days of age lambs were moved into a feedlot and finished on an 85% grain 15% forage diet to approximately 59 kg. Statistics were run using SAS Proc Mixed with PDIFF for mean separation. At the end of the pasture phase, lamb live weight was greater (P < 0.05) for the NURSE lambs (LSM ± SEM) (38.92 ± 2.09 kg) compared with the WEAN lambs (31.82 ± 2.09 kg). When grazing pasture, ADG was greater (P < 0.05) for the NURSE (360 ± 27 g/d) compared with the WEAN (196 ± 27 g/d) lambs. Packed Cell Volumes were lesser (P < 0.05) for the WEAN lambs (30.9 ± 0.5) at 35 d than the NURSE lambs (34.2 ± 0.5). Fecal egg counts were not different for the WEAN lambs (66.4 ± 12.3) at 35 d compared to the NURSE lambs (31.9 ± 12.3) (P > 0.05). Weaning at 100 d produced greater gains and lower measures of parasitism on red clover compared to weaning at 60 d.
Keywords: Lamb, Growth, Weaning