Evaluation of Monongo Nut meals as a source of protein in broiler rations
Mwangala, Sicecani, Justin
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The potential of Mongongo (Ricinodendron rautanenii schinzj as a source of protein in broiler rations was investigated. In the first trial, Soybean-based and Mongongobased diets were formulated and fed ad libitum to broilers for six weeks. The treatments were: SOY (Soybean alone); SOY + A (Soybean + methionine + lysine); MG (Mongongo alone); MG + A (Mongongo + methionine + lysine); MG + A + T (Mongongo + methionine + lysine + tryptophan). In the second trial the first three treatments in the first trial (SOY, SOY + A and MG) were reformulated, while three other treatments; HMG (Heat treated Mungongo alone), HMG + A (Heat -treated Mongongo + methionine + lysine), and HMG + A + T (Heat-treated Mongongo + methionine + lysine +tryptophan) were also formulated and fed for another six-week period. Mongongo meal was heated to 125°C for 15 minutes in an attempt to deactivate the supposedly present antinutritional factor, ricin. A Completely Randomized Design (CRD) with 5 treatments in the first trial, and 6 treatments in the second trial replicated 3 times was used. There were no significant differences in feed intake between birds on SOY and those on SOY + A in both trials. However, feed intake, live, dressed and carcass weights for birds on Soybean-based diets were higher than those for birds on Mongongo-based diets. Addition of amino acids, lysine and methionine, increased intake and improved the performance of birds on Mongongo diet in terms of live, dressed and carcass weights more when Mongongo was untreated by 502%, 507% and 571% respectively, while when heat-treated the performance was improved by 149%, 203% and 239% respectively.Addition of the amino acid, tryptophan, increased the performance of birds on Mongongo diet in IV terms of live, dressed and carcass weights by 15%, 15% and 16% respectively, only when Mongongo was heat-treated, but reduced the performance of birds on Mongongo diet when it was untreated by 6%, 7% and 5%, respectively. Heat treating Mongongo increased the performance of birds in terms of live, dressed and carcass weights by 95%, 92% and 105% respectively. Feed Conversion Ratios (FCRs) for the treatments were in the order: MG > SOY > SOY +A > HMG > HMG +A + T > HMG + A during the second trial, while during the first trial the order was MG > SOY > MG + A + T > SOY + A > MG + A. Liver and gizzard weights expressed as percentages of carcass weights were higher in birds on Mongongo-based diets than those on soybean-based diets. Carcass crude protein percentages differed in the order: SOY + A > SOY > HMG + A + T > HMG + A >MG >HMG, whereas carcass fat percentages were in the order: MG > HMG > HMG + A > HMG + A + T > SOY > SOY +A. Mongongo-based carcasses had higher (P<0.05) fat percentages. Carcass calcium and phosphorus percentages were in the same order: SOY + A > SOY > HMG + A + T > HMG + A >MG > HMG. Carcasses of birds fed Mongongo-based diets had lower (P<0.05) ash percentages than those for birds fed Soybean-based diets. The order of carcass ash percentages was: SOY + A > SOY > HMG + A + T > HMG -f A > HMG > MG. Mongongo nut meal can be used as a source of protein in broiler rations when it is untreated and supplemented with amino acids lysine and methionine (MG + A). However the performance of birds fed this diet in terms of live, dressed and carcass weights is not as good as that for birds fed Soybean based diet supplemented with the same amino acids lysine and methionine. Heat treating Mongongo and supplementing with amino acid tryptophan increased the performance of birds fed Mongongo diet in terms of live, dressed and carcass weights, although this increase was not as good as the overall performance of birds fed untreated Mongongo supplemented with amino acids lysine and methionine and those fed Soybean based diets.
- Agricultural Sciences