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

Abstract

The objective of this study was to examine the genetic parameters and genetic correlations of feed efficiency traits in steers (n = 490) fed grower or finisher diets in 2 feeding periods. A bivariate model was used to estimate phenotypic and genetic parameters using steers that received the grower and finisher diets in successive feeding periods, whereas a repeated animal model was used to estimate the permanent environmental effects. Genetic correlations between the grower-fed and finisher-fed regimens were 0.50 ± 0.48 and 0.78 ± 0.43 for residual feed intake (RFI) and G:F, respectively. The moderate genetic correlation between the 2 feeding regimens may indicate the presence of a genotype × environment interaction for RFI. Permanent environmental effects (expressed in percentage of phenotypic variance) were detected in the grower-fed steers for ADG (38%), DMI (30%), RFI (18%), and G:F (40%) and also in the finisher-fed steers for ADG (28%), DMI (35%), metabolic mid-weight (23%), and RFI (10%). Heritability estimates were 0.08 ± 0.10 and 0.14 ± 0.15 for the grower-fed steers and 0.42 ± 0.16 and 0.40 ± 17 for the finisher-fed steers for RFI and G:F, respectively. The dependency of the RFI on the feeding regimen may have serious implications when selecting animals in the beef industry. Because of the higher cost of grains, feed efficiency in the feedlot might be overemphasized, whereas efficiency in the cow herd and the backgrounding segments may have less emphasis. These results may also favor the retention (for subsequent breeding) of cows whose steers were efficient in the feedlot sector. Therefore, comprehensive feeding trials may be necessary to provide more insight into the mechanisms surrounding genotype × environment interaction in steers.

Genetic and environmental variation in methane emissions of sheep at pasture1

“…Even small limitations, for example, automatic feeder pens where animals may have to wait to use the feeder, can result in moderate improvements in efficiency (e.g., 7.6%; Robinson et al, 2013). The review of Basarab et al (2013) noted that estimated genetic correlations (r g ) of RFI on different diets ranged from 0.55 to 0.67, with a slightly lower estimate (r g = 0.50) for the same group of steers measured in growing vs. finishing periods (Durunna et al, 2011). Similar correlations are likely for grazing vs. lot-fed animals.…”

CELL BIOLOGY SYMPOSIUM: Genetics of feed efficiency in dairy and beef cattle1

“…This is particularly true if the already observed G×E interactions for feed effi ciency (Durunna et al, 2011b) result in management protocols for animals differing in feed effi ciency. The "saved" energy in more effi cient animals is likely to have implications for the animal, and this can be best identifi ed by aggressive selection for the phenotype under investigation and evaluating the impact in contrasting production systems.…”

Growth performance, feed digestibility, body composition, and feeding behavior of high– and low–residual feed intake fat-tailed lambs under moderate feed restriction1

“…However, it is important to know whether the animals that were efficient or inefficient on a feeding regime are also efficient or inefficient on other feeding conditions such as programmed or restricted feeding regimes. A few reports indicated that phenotypic expression of RFI in cattle (Herd et al, 2006;Durunna et al, 2011) and sheep (Redden et al, 2011) may vary under different feeding strategies. Restriction feeding, in which animals are fed at some level that is less than ad libitum, has been suggested to improve feed efficiency (Sainz, 1995).…”