The effect of ammoniated maize stover inclusion in diets on growth performance, physiological characteristics and meat quality in lambs

Abstract

Context The exploration of alternative feed sources for lambs to offset the expensive conventional ingredients is imperative. Aims To determine whether the inclusion of graded levels of ammoniated maize stover in lamb diets will positively influence growth performance, health and meat quality. Methods Thirty-two female meatmaster lambs aged 5–6 months (eight lambs per treatment) were fed isonitrogenous and isoenergetic diets containing 0%, 10%, 20% and 40% ammoniated maize stover (AMS) over a period of 7 weeks. Key results The lambs fed the AMS10 diet had a greater feed intake than did those fed AMS0, with lambs fed AMS20 and AMS40 not different from each other. Lambs fed on AMS10 and AMS20 grew faster than those fed on AMS40, but AMS0-fed lambs did not differ from any of the other groups. Similarly, feed conversion ratio (FCR, 5.25) was greater for lambs fed on AMS40 than for those on either AMS10 or AMS20, but those on AMS0 did not differ from the other groups. There were no significant differences in any of the mean values for haematological parameters; however, haematocrit was below the normal range for healthy lambs in all dietary treatments. Inclusion of AMS had no effect on the slaughter weight of lambs or any carcass characteristics apart from the dressing percentage. The lambs fed the AMS20 diets had a significantly higher dressing percentage than did all other groups. Ultimate pH (pHu) values were significantly higher on lambs fed on AMS40 than for all other groups. pHu values among AMS0, AMS10 and AMS20 were similar. Shear force for lambs on AMS40 diet was less than that for AMS0, but neither differed significantly from the other two groups. Conclusions Observations from the study showed that ammoniated maize stover may be included into lamb diets at least at 20% without adverse effects on growth performance, the health, and meat-quality characteristics of the lambs. Implications Ammoniated maize stover can therefore be a cheaper feed source for lambs in feedlot systems as it primarily replaces lucerne and maize grain.