The Nutritive Value of Treated Maize Cobs

Abstract

Two experiments were conducted at Kitale National Agricultural Research Station to study the effect of grinding and chemical treatment on the nutritive value of maize cobs. In Experiment I the digestibility of treated maize cobs was studied using Romney Marsh weather sheep in a 2x3 factorial design. Maize cobs were ground through 10 and 6 mm screen sizes. Three chemical treatments were applied to each grinding and these were: 1. sodium hydroxide (4.5 g per 100 g cob dry matter) 2. m&gadi soda (9.C g per 100 g cob dry matter) 3. distilled water (Contiel). Cobs were treated for 24 hours using one litre of solution to one kilogram of m\ize cobs, In vivo digestion coefficients of crude protein and ether extract were lowered (P< 0.01) by finer grinding of the maize cobs. Finer grinding did not affect (P >0.05) in vivo digestibility of dry matter, crude fibre, CVJC, ADF and cellulose. Chemical treatment of maize cobs improved (P< 0.01 or P <0,05) in vivo digestibility of dry matter, crude fibre, ether extract, CWC, ADF and cellulose _In vivo dry matter digestion coefficients were 44.68, 54,15 i and 61.57 percent for rations containing maiiie cobs treated with water, NaOH and magadi soda respectively and were different (P< 0.05) from each other. The increase in in vivo digestibility of crude fibre, CWC and cellulose due to treatment of maize cobs with magadi soda was higher (P< 0.01) than on the control and NaOH treated cobs. In vivo ADF digestion coefficients for control, NaOH and magadi soda treated cobs were different (P< 0.05) from each other. Chemical treatment lowered (P< 0.01) the in vivo digestibility of crude protein. In vivo digestibility of crude protein was 28.02, 16.98 and 18.17 percent for rations based on control, NaOH and magadi soda treated cobs respectively. In vivo crude protein digestibility was higher (P< 0.01) on control cobs than on cobs treated with NaOH and magadi soda. The interaction between grinding and chemical trec*c- ment of maize cobs affected (P< 0,01) in vivo digestibility of crude protein and ether extract. In vivo digestibility of dry matter was marginally affected (P - 0.05) uy the same interaction. In vivo digestibility of crude fibre, CVJC, ADF and cellulose were not affected (P> 0.05) by the interaction between grinding and chemical treatment of maize cobs. In Experiment II rations based on maize cobs treated with water, NaOH and magadi soda v/ere fed ad libitum to young dairy cattle grazing on Nandi Setaria/Silver Leaf Desmodium pasture. Pasture quality and animal performance were monitored. Xlll Total weight gains as percent of the initial weight were 29.72, 40.87 and 42.02 for cattle fed rations containing maize cobs treated with water, NaOH and magadi soda respectively. Total weight gain as a percent of initial weight was higher (P< 0.05) on rations containing NaOH and magadi soda treated cobs than on the ration containing control cobs. Average daily gains were 0.38, 0.48 and 0.50 kg for animals fed rations with control, NaOH and magadi soda treated cobs respectively and were not significantly (P> 0.05) different from each other. Maize cob intake per animal per day was 3.35, 5.11 and 2.56 kg dry matter when animals were fed rations containing maize cobs treated with water, NaOH and magadi soda respectively. During the first month of the experimental period there were no differences in weight gain patterns between the three experimental groups of animals indicating a requirement for a long adaptation period to chemically treated maize cobs