Characterization of the variation in the daily excretion of faecal constituents and digestibility predictions in beef cattle fed feedlot diets using near-infrared spectroscopy

Abstract

Six heifers were individually housed and assigned to once (FF1) or twice (FF2) daily feeding regimes over backgrounding and finishing periods. Following adaptation, total faecal collections were conducted at 4-h intervals and at 24-h intervals over 4 d, and near-infrared spectroscopy (NIRS) was used to predict faecal organic matter (OM), starch, nitrogen (N), neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL). At each interval, NIRS calibrations were used to estimate faecal constituents and ADL to calculate apparent (aTTD) and estimated (eTTD) total tract digestibility. Faecal dry matter (DM) (%), NDF, and ADF varied among 4-h interval samples in the backgrounding period and faecal DM, starch, NDF, ADF, and ADL in the finishing period. Faecal starch was able to predict aTTD during both feeding periods (backgrounding: R2 = 0.96, P < 0.01; finishing: R2 = 0.98, P < 0.01). The NIRS calibrations for predicting aTTD using the 4-h interval samples or the 4-d–24-h composite were least accurate for NDF and ADF. Most 4-h interval samples could be used to predict eTTD of nutrients, and aside from starch in the finishing period, there were no differences in eTTD using faecal samples collected over 4-h intervals versus those collected over 4 d. Spot faecal samples collected at any time point from multiple cattle have the potential to predict digestibility. Timing of sampling after feeding must be standardized to predict starch digestibility during the finishing period, with samples between 0–4 h and 8–16 h generating estimates of both starch concentration and digestibility that were closest to that derived from 4-d–24-h composite samples.

The use of visible/near-infrared spectroscopy to predict fibre fractions, fibre-bound nitrogen and total-tract apparent nutrients digestibility in beef cattle diets and faeces

“…The ADL content in this study was similar to that found by Jancewicz et al (2016), in a study performed on beef heifers fed a forage-based diet consisting of 50:50 grass hay:barley silage diet (on a DM basis). The faecal N content was comparable to that reported by Jancewicz et al (2016) and , although the CP content of the diet was lower in the present trial (12.81 versus 13.5 and 13.4-14.6%DM). This could be due to a lower digestibility of the dietary protein fed in our trial.…”

“…The aNDF and ADF content of faeces was slightly higher in comparison to those reported by other authors on beef heifers (Jancewicz et al 2016) and beef steers which is explained by the greater amount of fibre sources in our diets. The ADL content in this study was similar to that found by Jancewicz et al (2016), in a study performed on beef heifers fed a forage-based diet consisting of 50:50 grass hay:barley silage diet (on a DM basis). The faecal N content was comparable to that reported by Jancewicz et al (2016) and , although the CP content of the diet was lower in the present trial (12.81 versus 13.5 and 13.4-14.6%DM).…”

“…It was also applied on faecal samples with promising prediction of feed intake, diet quality and digestibility in different livestock species (Dixon and Coates 2009;Tran et al 2010;Decruyenaere et al 2012;Tolleson and Schafer 2014;Lyons et al 2016;N uñez-S anchez et al 2016;Johnson et al 2017;Brogna et al 2018). The NIRS digestibility prediction of DM, OM, CP, NDF, ADF, ADL and starch in faeces obtained using the total collection procedure as a reference method showed encouraging results on beef heifers and steers (Boval et al 2004;Jancewicz et al 2016;. However, the literature on beef cattle lacks information regarding dietary and faecal N fractions as well as data concerning the NIRS prediction of nutrients ttaD calculated using the faecal uNDF.…”

Predictability of growth performance in feedlot cattle using fecal near infrared spectroscopy

“…Although none of the average fecal concentrations reported in the commercial feedlot samples appeared unusual, the largest discrepancy identified occurred with fecal NDF, which was on average 3% lower than previous estimates from research feedlot studies. This is not likely due to an error with NIRS as the average fecal NDF in a subset of these samples that were analyzed using wet chemistry was also lower than reported in previous studies (46.0% ± 8.02%; Jancewicz et al 2016). As we did not analyze the diets that were fed to the commercial feedlot cattle, it was impossible to determine if the lower fecal NDF was a result of lower NDF intake.…”

“…Research by Owens and Zinn has shown that the accuracy of starch digestibility predictions can be improved by including additional variables such as fecal N (Zinn et al 2011), dry matter (DM) or organic matter (OM) digestibility, and starch intake (Owens et al 2016). Methods to predict other nutrient digestibilities, particularly neutral detergent fiber (NDF), from their fecal concentrations have been examined (Fredin et al 2014;Jancewicz et al 2016;Owens et al 2016), as well as indirect relationships between OM digestibility and fecal crude protein (CP) (Lukas et al 2005). Because fecal samples contain information relevant to feed digestion, monitoring how efficiently cattle are utilizing nutrients could directly benefit the efficiency and profitability of feedlot cattle production.…”