The effect of feeding clinoptilolite on food intake and performance of growing lambs infected or not with gastrointestinal nematodes

The objective was to assess the effect of feeding clinoptilolite (a natural zeolite) on food intake and performance of growing lambs infected or not with gastrointestinal (GI) nematodes. The experiment was carried out over a period of 3 months, starting in February 2003. Twenty-four entire lambs of the indigenous Greek dairy breed Karagouniko were used. They were weaned at 6 weeks of age. Lambs were given free and continuous access to a nutritionally non-limiting pelleted concentrate that was either a basal diet (B) or a 'zeolite diet' (Z). The latter (Z) was formulated by supplementing B with clinoptilolite at a level of 3%. Both diets had similar crude protein (CP) and metabolisable energy (ME) contents. A 2×2 factorial design consisting of two feeding treatments (B and Z) and two levels of parasitic status, infected (I) and uninfected (U) was used. Hence, taking into account their live weight (LW), lambs were randomly assigned to one of four (n=6), treatment groups: BU (basal-uninfected), BI (basal-infected), ZU (zeolite-uninfected) and ZI (zeolite-infected). At that point (day 1), lambs of groups BI and ZI were infected with a single dose of 15 000 L3 larvae of GI nematodes. Feed intake and LW were measured weekly. At the same time faecal samples were obtained directly from the rectum of each individual animal. Sixty-two days later, all lambs were slaughtered and their abomasums with intestines were removed in order to recover the adult worms. There was a significant interaction (P<0.01) between group and week on average food intake. Lambs in groups BU and BI did not increase their feed intake to the same extent as those in groups ZU and ZI. There was also a significant difference (P<0.05) in the LW of lambs at slaughter, with lambs of groups ZU and ZI being the heaviest. Average growth rates were significantly (P<0.05) different between lambs of different groups; lambs of groups ZU and ZI were growing to a faster rate compared with those of groups BU and BI, respectively. However, there were no significant differences in carcass characteristics between lambs of the four groups. The faecal egg counts (FEC) were significantly (P<0.001) reduced in lambs of ZI group; the latter was also the case for worm burdens assessed on the day of slaughter. This study suggests that there is a potential for using clinoptilolite in sheep rations as a natural alternative that could prevent the build up of GI nematodes.