In situ and in vitro estimation of mineral release from common feedstuffs fed to cattle

Abstract

SUMMARYThe objective of the current study was to quantify the dry matter (DM) digestibility, and total ash (TA) and mineral release from 12 concentrate and 12 forage feedstuffs commonly fed to cattle using in situ and in vitro methods. Concentrate and forage feedstuffs were incubated in the rumen of ruminally cannulated beef bulls at eight different time points. Two different trials were conducted for concentrates and forages, with maximum incubation time of 72 and 120 h, respectively. The residue from samples incubated for 24 h were treated with pepsin and hydrochloric acid to simulate abomasum digestion in vitro. The initial and residual samples after in situ and in vitro incubations were measured. An asymptotic model was adopted for estimating solubility of minerals, disappearance rate of DM, and TA. Correlations between feedstuff contents and mineral release were evaluated. Residual samples from rumen fermentation after 24 h were incubated in simulated abomasal conditions and mineral release was measured. Cluster analysis was performed to group feedstuffs in relation to TA release. Large variability was observed between concentrate and forage feedstuffs for all constituents analysed. Large variability was observed for the effective ruminal degradation of TA and individual mineral release. When feedstuffs were clustered according to the immediately soluble fraction (‘a’), the insoluble by potentially releasable fraction (‘b’) and the release rate of ‘b’ (‘kd’,/h) estimates of TA ruminal release, four groups were identified. From group ‘1’ to group ‘4’, an increase in the soluble fraction and a reduction in both moderate releasable fraction and release rate was observed. Neutral detergent fibre content had a negative correlation with mineral release in the rumen, while mineral content had a positive correlation. These results demonstrate that mineral solubilization in the digestive tract is not the limiting factor for mineral absorption from the feedstuffs tested.

In situ and in vitro techniques for estimating degradation parameters and digestibility of diets based on maize or sorghum

“…After the incubation period, the bags were washed in running water followed by washing with cold tap water by hand by the same person. The endpoint for washing was the high clarity of rinse water (Zanetti et al ., 2017). The 0 h bags were not incubated in the rumen, but as with the incubated bags, they were rinsed in running water.…”

“…The Journal of Agricultural Science (Zanetti et al, 2017). The 0 h bags were not incubated in the rumen, but as with the incubated bags, they were rinsed in running water.…”

“…However, only a few studies have correlated the digestibility results from in situ or in vitro procedures with the values obtained by in vivo procedures (National Research Council, 2001; Ghoorchi et al ., 2013; Lopes et al ., 2015). Furthermore, most in vitro and in situ studies have evaluated individual ingredients rather than complete diets (Holt et al ., 2016; Zanetti et al ., 2017; Fernandes et al ., 2018).…”

Copper, iron, zinc and tannin concentrations throughout the digestive tract of tropical goats and sheep fed a high‐fibre tannin‐rich diet

“…Although micromineral requirements for these local breeds are undocumented and breed/type differences in mineral metabolism have been identified for cattle (Dermauw et al, 2014;Ward et al, ), the degree of mineral bioavailability is influenced by the types and quantity of inhibitory compounds that are available in the feedstuffs (Zanetti et al, 2017). For example, depending on the concentrations of S and Mo in the diet, antagonistic interactions might cause variation in the ability of feeds to provide absorbable copper and hence influence requirements in ruminants (Underwood & Suttle, 1999).…”

Effects of additives on fermentation profile and in situ rumen degradability of elephant grass silage cv. BRS Capiaçu

“…After the end of incubation, the bags were washed in running cold water. The end point to finish the washing bags was the high clarity of the rinse water (Zanetti et al, 2017).…”