Effects of medicated urea-molasses block supplementation on productivity and gastrointestinal nematode infestation of sheep in central Kenya

Abstract

A 14 months study was undertaken to determine the effects of feeding medicated urea-molasses blocks on production parameters and gastrointestinal (GI) nematode parasitism of sheep under field conditions in central Kenya. Forty five Corriedale crossbred female lambs with an average age of 6 months were initially treated subcutaneously with ivermectin (0.2 mg/kg body weight) and randomly assigned into 3 groups: group I were fed fenbendazole incorporated urea-molasses blocks (MUMB), group II urea-molasses blocks (UMB) and group III (control) received no block supplementation (NBS). Parameters measured included fecal egg counts (FEC), worm burdens (WB), live-weight (LW) and greasy wool production.

Significant differences (p < 0.05) were found in LW changes of the MUMB group compared with the NBS (from September) and the UMB (from October) groups, respectively. The mean LW responses of the UMB group were significantly (p < 0.05) greater than those of the NBS group. On study termination, the MUMB group had gained an average of (+ s.d.) 21.9 + 2.4 kg, the UMB group 17.3 + 2.7 while, NBS group gained 10.9 + 2.6 kg. Greasy wool production was significantly higher (p < 0.05) in the supplemented groups and the rank order of production/animal was 3.6 kg (MUMB), 3.3 kg (UMB) and 2.1 kg (NBS). The estimated monetary gain/animal based on meat and wool production were equivalent to US$ 47.51, US$ 37.26 and US$ 27.59 for the MUMB, UMB and NBS groups, respectively. The FEC for the MUMB group differed significantly (p < 0.05) compared to those of the UMB and NBS groups. However, no significant differences (p > 0.05) in FEC were found between the UMB and NBS groups. On necropsy, the mean (+ s.d.) group WB for MUMB was 425 + 76, for UMB 1279 + 240 while that of NBS was 1619 + 402. Haemonchus contortus was the predominant nematode recovered from slaughtered sheep on study termination. These results indicate that the MUMB was effective in reducing and maintaining a low level of GI nematode infestation with subsequent improved performance of grazing young sheep.