Use of n-alkanes to estimate feed intake in ruminants: a meta-analysis

Abstract

Precise techniques to estimate feed intake by ruminants is critical to enhance feed efficiency and to reduce greenhouse gas emissions and nutrient losses to the environment. Using a meta-analysis, we evaluated the accuracy of the n-alkane technique to predict feed intake in cattle and sheep, and assessed the relationships between feed intake and fecal recovery of n-alkanes. The database was composed of 28 studies, including 129 treatments (87 and 42 for cattle and sheep, respectively) and 402 animals (232 cattle and 170 sheep) fed at troughs, from published studies. Relationships between observed (in vivo measurement) and predicted feed intake by C31:C32 and C32:C33 n-alkane pairs were evaluated by regression. Meta-regression addressed the relationships between the difference in fecal recovery of n-alkane pairs and the error in intake estimation, as well as the amount and duration of C32 n-alkane dosing. Regression of observed intake on n-alkane-based estimates revealed good relationships in cattle (adjusted R² = 0.99 for C31:C32, and adjusted R² = 0.98 for C32:C33; P < 0.0001) and in sheep (adjusted R² = 0.94 for C31:C32, and adjusted R² = 0.96 for C32:C33; P < 0.0001). Fecal recovery of natural n-alkanes showed coefficient of variation about 15 and 16% for C31 and C33, respectively in cattle. In sheep, the coefficient variation was 8 and 14% for C31 and C33, respectively. The relationships between the difference of fecal recovery of n-alkane pairs and the error in feed intake estimation in cattle were characterized by an adjusted R² = 0.83 for C31:C32 (P < 0.0001) and adjusted R² = 0.93 for C32:C33 (P < 0.0001). In sheep, they were characterized by an adjusted R² = 0.69 for C31:C32 (P < 0.001) and adjusted R² = 0.76 for C32:C33 (P < 0.001). The n-alkane technique provided reliability for estimating feed intake in cattle and sheep in barn experiments. The present meta-analysis demonstrated that without correction for differences in fecal recovery of n-alkane pairs, deviation in feed intake prediction would occur. However, further research is necessary to determine the relationship between the n-alkane dosing procedure (daily amount and duration of dosing) and fecal recovery of n-alkane.

Influence of Cuticular Waxes from Triticale on Rumen Fermentation: A Metabolomic and Microbiome Profiling Study

“…56 This is consistent with the applications of n-alkane as molecular markers to estimate feed intake in cattle and sheep. 57 On the other hand, compounds like aldehydes, primary alcohols, and fatty acids of cuticular waxes are ones easy to be degraded through biological and chemical means due to their structure and functional groups. 58 Therefore, the rumen metabolites detected in the current study might have already contained the metabolites originated from the degradation of plant cuticular wax.…”

Evaluation of N-alkanes as Faecal Markers to Estimate Diet Composition, Feed Intake, and Digestibility in European Bison (Bison bonasus)

“…Many authors that studied the faecal recovery of n-alkanes in cattle [11], goats [24], sheep [10,[25][26][27][28], and other wild ruminant species as the moose [29] and fallow deer [30] suggested that n-alkanes are incompletely recovered in their faeces. For that reason, it is recommended that the application of correction factors is to adjust for incomplete faecal recovery prior to diet composition calculations [9,26,29,31]. Hence, a correction of faecal n-alkane concentrations for their incomplete recovery was applied to avoid potential bias when estimating diet composition.…”

Reducing performance variation of piglets in a multi-suckling system

“…Similarly, a strong relationship was found between the prediction error of feed intake and the difference in faecal recovery of the alkane pair in cattle (R 2 =0.75, P <0.001 for both C31:C32 and C32:C33) (Bezabih et al, 2012). In addition, a meta-analysis in ruminants showed a strong relationship between the difference in faecal recovery of n-alkane pairs (=1-natural/dosed) and feed intake prediction error (1predicted/measured), with the adjusted R 2 of 0.83 (P <0.001) for C31:C32 and adjusted R 2 of 0.93 (P <0.001) for C32:C33 (Andriarimalala et al, 2020). In our study C32:C36 seems to have better estimation accuracy of feed intake than Yb:Cr.…”

“…In recent years, the dual marker method, which is widely used in ruminant studies (Ferreira et al, 2007;Chavez et al, 2011;Andriarimalala et al, 2020), has received increased attention for its application in pigs as well (Sehested et al, 1999;Ferre et al, 2000;Mendes et al, 2007;Staals et al, 2007;Kanga et al, 2012). Alkanes have been often applied as markers, as they naturally occur in cuticular waxes of herbages, are non-toxic to animals, and have a low digestibility by animals (Wright, 2017).…”

“…In herbivores, various dual marker techniques have been used for the determination of individual intake of forages, grass, clover and browses (Andriarimalala et al, 2020). These methods are based on the measurement of the ratio between two indigestible markers in faeces.…”