Effects of feeding different levels of dietary fiber through the addition of corn stover on nutrient utilization of dairy heifers precision-fed high and low concentrate diets

Abstract

The objective of this experiment was to assess the effects of manipulating dietary fiber by replacing corn silage (CS) with lower quality forage as corn stover (CST) when used in high concentrate (HC) and low concentrate (LC) diets for precision-fed dairy heifers. Eight Holstein heifers (335.6 ± 7.41 kg of body weight) were randomly assigned to 2 levels of concentrate: HC (20% forage) and LC (80% forage), and to a forage type sequence [0% of forage as corn stover (CST), 100% corn silage (CS); 20% CST, 80% CS; 40% CST, 60% CS; and 60% CST, 40% CS] within concentrate level administered according to a split-plot, 4 × 4 Latin square design (21-d periods). Heifers fed HC had higher apparent total-tract dry matter digestibility (DMD). Increasing the fiber level by increasing the amount of CST in the diet resulted in a linear decrease of DMD and organic matter digestibility. Heifers fed LC diets had higher neutral detergent fiber (NDF) digestibility and tended to have lower acid detergent fiber (ADF) digestibility than those fed HC diets. Substituting CS with 20% CST resulted in the highest NDF and ADF digestibilities. Digestibility of N was not different, but N retention increased for HC and decreased quadratically for LC diets. Heifers fed HC diets decreased fecal output, and CST linearly increased these parameters. Urine volume tended to be higher for HC-fed heifers, and increasing dietary fiber through CST inclusion tended to decrease urine output. This shift in water excretion resulted in similar total manure output. Total purine derivative excretion did not differ between treatments, but interacted with CST addition, resulting in a linear increase in microbial protein flow to the duodenum in HC-fed heifers and in a linear decrease in LC diets as CST increased. In conclusion, increasing dietary fiber through CST decreased DMD and organic matter digestibility linearly, whereas NDF and ADF digestibility were maximized when 20% CST was added to HC and LC diets. Microbial protein synthesis increased and decreased linearly with CST addition in HC and LC diets, respectively. Retention of N increased and decreased quadratically with CST addition in HC and LC diets, respectively. Total manure excretion was not different between HC or LC diets.

Precision-feeding dairy heifers a high rumen-degradable protein diet with different proportions of dietary fiber and forage-to-concentrate ratios

“…This allowed cellulose to be retained longer and be further digested in the LF diets. Starch digestibility seems to be increased by higher retention time of LF diets (Lascano and Heinrichs, 2011), as well as by a more numerous amylolytic bacteria population associated with this type of diet (Brown et al, 2006). These results are in agreement with observations in the present study and with the ones reported in limit-fed sheep and cattle (Colucci et al, 1989;Murphy et al, 1994).…”

“…Total-tract digestibility of DM, OM, NDF, ADF, and cellulose were lower for HF diets. Apparent DM and OM dC were similar to results observed by Lascano and Heinrichs (2011) when heifers were fed LF or HF diets composed of a combination of 40 or 80% CS and corn stover. Digestibility of NDF and ADF followed a similar pattern as DM and OM apparent digestibility (Zanton and Heinrichs, 2009;Lascano and Heinrichs, 2011).…”

“…Apparent DM and OM dC were similar to results observed by Lascano and Heinrichs (2011) when heifers were fed LF or HF diets composed of a combination of 40 or 80% CS and corn stover. Digestibility of NDF and ADF followed a similar pattern as DM and OM apparent digestibility (Zanton and Heinrichs, 2009;Lascano and Heinrichs, 2011). In a limited intake scenario, the kp of the whole digesta was reduced (Colucci et al, 1990), allowing more time for hemicellulose to be digested evenly within different forage proportions Table 2.…”

“…In a recent study in which dairy heifers were precision-fed different dietary fiber proportions within 2 different F:C treatments, N retention was increased quadratically in the LF diet whereas the opposite effect was observed for HF diets (Lascano and Heinrichs, 2011). Similar patterns in microbial protein flow to the duodenum and N retention suggest that, in a limited intake scenario, synchrony between fiber, kp, F:C, and protein degradability can be manipulated to increase N utilization in dairy heifers.…”

Parameters of Protein Metabolism in Goats Fed Diets With Different Portion of Sugarcane Bagasse

“…Marsetyo et al (2006) reported that supplementations of barley and barley plus protein increased microbial protein synthesis and efficiency of microbial protein synthesis in steers. High concentrate supplementation for low quality forage based diet elevated microbial protein synthesis in dairy heifers (Lascano and Heinrichs, 2011). Moorby et al (2006) suggested that increasing microbial protein synthesis supported enhancing milk yield in dairy cows when they fed on diets with lower forage to concentrate ratio.…”