Abstract:
The aim of this study was to assess the effect of different levels of diatomaceous earth (DE) on the growth performance, carcass characteristics and faecal egg counts of lambs receiving feedlot diets. A total number of fifty (50) Ronderib X Merino lambs (male and female) with an average body weight of ± 37 kg were used in this study. The animals were divided on a stratified body weight and faecal egg count (FEC) basis into five (5) groups of ten (10) lambs each, namely; T0, T1, T2, T3 and T4. Animals in all the groups were provided with the same standard feedlot diet that only differs in DE inclusion levels. Diets were formulated to contain DE at four different inclusion levels, namely 0.5% (T1), 1.0% (T2), 1.5% (T3) and 2% (T4) of the diet. T0 (0% DE) served as the control group. The animals were fed two times a day at 07:00 and 16:00 respectively. Faecal samples were taken at two-hour intervals between 8:00 and 16:00 before the start of the project and faecal egg counts were done to determine the average FEC. The sheep were also weighed prior to treatments being applied to allocate the animals to the different groups on a stratified FEC and body weight basis. Body weights of all the animals were recorded weekly, while faecal samples were collected on a two-weekly basis to determine FEC. Eye muscle area (longissimus dorsi) and fat depth were measured at the start and again at the end of the project before slaughtering. After a 46-day feeding period (20 July – 04 September 2017) the lambs were fasted overnight and slaughtered. All carcass traits were recorded for each animal. No significant differences were observed between the different groups in terms of weekly body weights, body weight change (BWC) and average daily gain (ADG). The inclusion of different DE levels did not have a significant effect on most of the eye muscle area, fat depth, carcass and fat measurements. Regarding FEC, there was a general decrease in the roundworm counts from the start to the end of the project, while the coccidia counts showed a general increase. However, the results did not show a positive response in FEC with the inclusion of different levels of DE. From the results of this study, it can be concluded that DE at different inclusion levels did not have a positive effect on most of the measured parameters.
