Phenotypic and genetic relationships among feeding behavior traits, feed intake, and residual feed intake in steers fed grower and finisher diets1

Abstract

Data from a 3-yr feeding trial of crossbred steers (n = 331) were used to examine the relationship between feeding behavior traits and feed efficiency in steers fed grower and finisher diets, successively. There were 2 feeding periods each year whereby the steers were fed a grower diet in the first feeding period (P1) and a finisher diet in the second feeding period (P2). Each feeding period lasted for a minimum of 10 wk, ad libitum. In addition to feed intake, records on 3 measures of feeding behavior [feeding duration (FD), head-down time (HDT), and feeding frequency (FF)] were collected using the GrowSafe feeding system. Residual feed intake (RFI) was calculated by regression, after which the steers were classified as low (<0.5 SD), medium (±0.5 SD), or high (>0.5 SD) from the mean. The steers had greater (P < 0.001) FD, HDT, and FF when the grower diet was fed but greater feeding rate (FR) when the finisher diet was fed. Including the measures of feeding behavior as covariates to the feed intake prediction model containing ADG, metabolic midweight, and ultrasound backfat accounted for more variation in DMI than models that did not contain these additional parameters. The FD and HDT were significantly different (P < 0.05) among the RFI classes regardless of the feeding period, whereas no differences (P > 0.90) were found for FR among the RFI classes. For the growing period and finishing period, respectively, FD had phenotypic correlations with HDT (0.79, 0.83), FF (0.14, 0.55), DMI (0.38, 0.34), and FR (-0.34, -0.21). Heritability estimates in P1 and P2 for FD, HDT, and FF were 0.25 ± 0.16, 0.14 ± 0.11; 0.14 ± 0.15, 0.09 ± 0.10; and 0.56 ± 0.19, 0.59 ± 0.18, respectively. Genetic correlations between P1 and P2 were 0.91 ± 0.26, 0.93 ± 0.37, and 0.94 ± 0.11 for FD, HDT, and FF, respectively. The results suggest that it may be appropriate to include feeding behavior traits as covariates to indicate measure(s) of animal activity in the calculation of RFI. Feeding behavior phenotypes were greater during the grower-fed period than the finisher-fed period. During these feeding periods, efficient steers exhibited fewer FF, shorter FD, and shorter HDT than inefficient steers.

Evidence of residual feed intake reranking in crossbred replacement heifers

“…Heifers had fewer feeding events {P = 0.003) in P2 than in PI, which may reflect changes in the heifers reaching puberty as the majority of the heifers (143) reached puberty in P2 (Basarab et al, 2011). This study did not agree with Durunna et al (2011b) where steers had greater feeding duration and headdown time in PI, but the feeding event frequency was greater in P2. Both studies reported that the eating rate was greater in the second feeding period, indicating that the heifers in this study consumed more feed over a similar or slightly shorter duration.…”

Residual feed intake studies in Angus-sired cattle reveal a potential role for hypothalamic gene expression in regulating feed efficiency1,2

“…Feed intake is positively correlated with RFI and differences in DMI between low and high RFI cattle are associated with differences in feeding behavior exhibited by the 2 groups (Golden et al, 2008;Lancaster et al, 2009;Kelly et al, 2010;Montanholi et al, 2010;Durunna et al, 2011;Hafla et al, 2013). The addition of feeding behavior traits such as frequency or duration of feeding bouts to RFI models has been reported to explain up to 35% of the variation in DMI not explained by ADG and MidWt 0.75 in base RFI models (Lancaster et al, 2009;Kelly et al, 2010;Kayser and Hill, 2013).…”

Genetic parameters and genotype × environment interaction for feed efficiency traits in steers fed grower and finisher diets1

“…Feeding duration (a measure of activity) was included as an additional covariate in the analysis of RFI to account for differences in feeding behavior (Basarab et al,, 2011;Durunna et al,, 2011b),…”