<b>Estimates of <i>in situ</i> digestibility and fibrous compounds in feeds for ruminants

Abstract

ABSTRACT. Current paper assesses the relationship between in situ incubation time, particle size and types of materials on estimates of indigestible fractions of dry matter (iDM) and neutral detergent fiber (iNDF) in cattle feed and feces. Samples of soybean meal, alfalfa and feces of cattle fed on high concentrated diets were analyzed. The samples were processed in a Wiley mill, with 0.5 and 1.5 mm porosity for food and 1.5 mm for feces, which were packed in 4 × 5 cm F57 bags (Ankon ® ) and nonwoven fabric (100 g m -2) of two brands. The material was divided into two groups, with and without treatment with acetone, and five replications. Samples of each group were incubated in the rumen of a multiparous cow adapted to a 70:30 diet, forage:concentrate diet, for 240 hours. The iDM and iNDF levels were evaluated sequentially to interpret the percentages of undigested material. Data underwent analysis of variance (ANOVA, p < 0.05) and means were compared by Tukey's test (p < 0.05). Material, size of particles and incubated material affected iDM and iNDF estimates.

<b>Evaluation <i>in situ</i> digestibility of alfalfa in different grinds and textiles

“…They also reported that iDM fraction is made up of essentially insoluble components, similar to the iDF and iADF fractions. Although data in current experiment corroborate the theory by Casali et al (2008), Kuwahara et al (2015) reported that more intense grindings may overestimate iDM and iNDF rates at an average of 6.57% for alfafa when grinding shifted from 1.5 mm to 0.5 mm for a fixed period of 240 hours. When the concept by Mertens (1993), previously discussed, is taken into consideration, coupled to the description by Detmann et al (2008) as a slightly precise concept, results of current analysis (Figure 2 and Tables 2 and 3) reveal that the nylon textile in the three grindings had lower iDM and iNDF rates when compared to other treatments (p < 0.05) in the initial period of incubation.…”

“…When the concept by Mertens (1993), previously discussed, is taken into consideration, coupled to the description by Detmann et al (2008) as a slightly precise concept, results of current analysis (Figure 2 and Tables 2 and 3) reveal that the nylon textile in the three grindings had lower iDM and iNDF rates when compared to other treatments (p < 0.05) in the initial period of incubation. After 96 hours of incubation, all materials and grindings are likely to have similar rates where the differences between material, times and grinding may be due to the contamination of F57 and TNT textiles, as reported by Casali et al (2009) and Kuwahara et al (2015).…”

“…In fact, results reveal that rates of fibrous components of feed may be directly related to incubation time. Although Casali et al (2008) reported difference in incubation time for sugarcane only, with different grindings, Kuwahara et al (2015) registered that alfafa ground at 0.5 mm (37.84% NDF) overestimated iDM and iMDF rates. According to Casali et al (2008), 3.0 mm grindings may cause lack of precision in results, attributing the smallest specific surface for microbial activities (Nocek, 1997).…”

“…Feed quality, however, is related to management, soil fertility and mainly the type of forage grass. Since alfafa is a high quality forage grass, albeit characterized by high digestibility and fast ruminal degradation (Rodrigues, Comeron, & Vilela, 2008), it should be focused upon in assessments for the recuperation of indigestible fractions such as internal indicators, inconsistencies of results for incubation time and material used in in situ assays, as already analyzed by Detmann et al (2007) and Kuwahara Souza, Soares, Costa, and Meirelles (2015).…”

“…However, there is a decrease in the integrity of the material in long incubation periods, even though no difference exists when compared to the Ankom ® system (Valente et al, 2011). Since preciseness of results is required, Kuwahara et al (2015) enhance the existence of variability in the quality of the material on the Brazilian market.…”