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1364
The potential of a buffer (calcified marine algae) or plant extract (Capsicum) in combination with or to replace an ionophore (monensin) in lamb feedlot diets
Ionophore antibiotic supplementation is standard practice in almost all feedlots in South Africa and many other countries due to its positive effects on feed efficiency and feed intake. Public concern over the emergence of antibiotic resistant bacteria and the consumers’ demand for safe, high quality nutritious food has stimulated the search for natural alternatives to ionophores in ruminant diets. The objective of this study was to evaluate the effect of a buffer (calcified marine algae (AB)) and/or plant extract (Capsicum (Caps)) in combination with or replacing an ionophore (monensin (Mon)) on the performance of lambs in a commercial feedlot. Two thousand three hundred and twenty-seven lambs were randomly allocated to six different treatments with six pens per treatment with pen being the experimental unit. Treatments were: 1) Mon; 2) AB; 3) Caps; 4) AB + Mon; 5) Caps + Mon and 6) AB + Caps. Mean starting live weight of lambs was 30.9 kg. The lambs were individually weighed on day 0, 10, 21, 35, 50 and at slaughter. All lambs were slaughtered at a pre-determined end live weight of ± 48kg. Average daily gain, dry matter intake, feed conversion ratio, cold carcass mass, rumen fluid pH and rumen score were amongst the parameters determined. The corn (23% – 37%), alfalfa hay (20% – 10%) based diets (starter, grower and finisher) were the same for all treatments with adjustments to the specific treatments. Days on feed were different between some treatments (P<0.05). Difference in rumen pH (day 30 minus day 13) as well as rumen pH on day one and three were different between some treatments (P<0.05). Other performance parameters such as average daily gain and feed conversion ratio did not differ between treatments (P>0.05). Results suggest that monensin can be successfully replaced in lamb feedlot rations with natural alternatives (AB and/or Caps) with little impact on production performance. Further research, however, is needed on determining the dietary dependant responses and adaptation of rumen microbial populations. Furthermore, the cost: benefit ratio should be determined under the prevailing conditions in different countries.
Keywords:
Ionophore, Calcified Marine Algae, Capsicum.