Influence of limestone levels on apparent digestibility of roughage-based diet, by sheep

Abstract

Eighteen crossbred male sheep (mean weight 34.42±0.74 kg) were used to study the effect of limestone addition (0.22; 0.93 and 2.32%), on apparent digestibility of the roughage-based diet. Ration was composed of Cynodon dactilon hay (650 g), cassava root meal (150 g), urea (15 g), NaH₂PO₄ (8.9 g) and trace-mineralized salt (10 g). Sheep were kept in metabolism cages for two periods of 21 days, with total fecal collection on the last 7 days. Additionally, in the second period, ruminal liquid was collected. Statistical analyses were performed using SAS procedures considering two blocks (except for ruminal liquid), three treatments and three replicates. The digestibilities of dry matter, organic matter, neutral detergent fiber, acid detergent fiber and crude energy decreased linearly (P<0.05) with the addition of limestone in the ration. Crude protein digestibility was not affected by the treatment (P>0.05). Ca concentration, as well as fecal pH also increased linearly with limestone in the diet (P<0.01). Ca content and pH of the ruminal liquid were not affected by the treatments. It was concluded that limestone addition to this type of diet reduces the digestibility of the ration.