Intake and Digestibility by Lambs of Low-Quality Sudan-Grass Hay Supplemented with Mineral Mixtures Having Different Acid-Alkali Ash Values

Abstract

Eighteen wether lambs were randomly assigned to treatments consisting of three mineral supplements (A, B, C) having different alkali-acid residues and compositions and two levels (0 and 1 g) of a vitamin A and D supplement. Sudan-grass hay and water were provided ad libitum and the supplements were fed twice each day. Nutrient digestibilities and nutritive values were determined and voluntary consumption of dry matter (DM), energy and water measured. No parameter studied was significantly affected by feeding the vitamin mixture. Total digestible nutrients (TDN) and all digestibility values were highest when supplement A with low alkalinity was fed. Ration digestible and metabolizable energy (ME) (kcal/g DM) were significantly increased (P < .05) when lambs received either supplement A or B, compared to values from lambs given the control supplement C. Dry matter (g), digestible energy (DE) (kcal/kg.75), digestible protein (g/kg.75) and water (ml) intakes were significantly greater (P < .05) for lambs given supplement A or B than those given supplement C. Significantly higher plasma urea nitrogen (PUN) in lambs supplemented with the more alkaline (B) mineral mixture indicated greater ammonia production and/or absorption. It is concluded that the addition of a simple mineral mixture to low-quality Sudan-grass hay may significantly increase ration intake, digestebility and nutritive value and further, to obtain maximum utilization of forage nutrients by mineral supplementation, the supplement should be formulated to provide a slightly alkaline ash.