A data-analysis of lime addition on the nutritive value of sugarcane in Brazil

Abstract

A statistical analysis of data from published studies was conducted to evaluate the effect of the addition of lime to fresh sugarcane in terms of its chemical composition, digestibility, and animal performance. A data set that included 55 treatment means from 20 refereed journal articles was collected and analyzed using a mixed model regression analysis with a random study effect. Lime addition directly increased dry matter (DM), ash, and Ca contents, as well as Ca:P ratio, and lowered organic matter (OM) concentration. The alkaline nature of lime linearly raised the sugarcane pH. Conversely, the concentration of nonfiber carbohydrates (NFC) was quadratically reduced by lime addition, whereas there was a quadratic increase in the neutral detergent fiber (NDFall), indigestible neutral detergent fiber (iNDF), and lignin (sa) and a linear increase in potentially digestible neutral detergent fiber (g/kg OM). The proportion of hemicellulose in the NDFall was unchanged by lime addition; thus, net fiber hydrolysis was not observed. The only beneficial effect of lime on the chemical composition of sugarcane was a linear decrease in the iNDF:NDFall ratio. The addition of lime to sugarcane did not affect DM intake or chewing behavior, although it increased the intake of NDFall. However, the mean NDFall intake was 0.87kg/100kg body weight, which is markedly lower than the reported value for traditional forages (1.00–1.20kg/100kg body weight). Indeed, NDFall digestibility was quadratically improved, but it was not enough to offset the loss of NFC across air exposure which, in turn, led to a linear decrease in the diet DM digestibility. Thus, lime treatment linearly decreased the average daily gain. It was concluded that lime increased fiber digestibility, but this effect did not offset the loss of water soluble carbohydrates, leading to a lower nutritive value of fresh sugarcane and a decrease in animal performance.