Genetics of feed efficiency and feeding behavior in crossbred beef steers with emphasis on genotype-by-environment interactions

• Author / Creator

  Durunna, Obioha Nnamdi

• This study examined whether crossbred steers had different production, feed efficiency and feeding behavior performances when they were fed a grower or finisher diet or both, in successive feeding periods. Major feed efficiency traits were residual feed intake (RFI) and gain to feed ratio (G:F) while feeding behavior traits were feeding duration (FD), head-down time (HDT) and feeding frequency (FF). Some steers received a grower diet in the first feeding period and a finisher diet in the second period (feed-swap); the control groups received only the grower or finisher diet in both periods. Compared to the control groups, about 7% more steers in the feed-swap group changed their RFI performance by 0.5 SD by the second period. Using steers in the feed-swap group (n = 331), the study observed greater (P < 0.05) FD, HDT and FF when the steers received the grower diet. Genetic correlations between the two feeding periods for this group were 0.78, 0.80, 0.78, 0.50, 0.91, 0.93 and 0.94 for DMI, ADG, G:F, RFI, FD, HDT, and FF, respectively. The genetic correlations may indicate the existence of genotype-by-environment interaction for DMI, ADG, RFI and G:F. The heritability estimates for the feed-swap group were greater in the grower-fed period for FD (0.25 vs 0.14) and HDT (0.14 vs 0.09) but were greater in the finisher-fed period for ADG (0.23 vs 0.08), DMI (0.34 vs 0.15), RFI (0.42 vs 0.08), G:F (0.40 vs 0.14) and feeding frequency (0.59 vs 0.56). The results indicate that the RFI, G:F, ADG and DMI measured on a grower or finisher diet may be considered as different traits for beef cattle genetic evaluations.

• Subjects / Keywords

  • Feed efficiency
  • Beef steers
  • Feeding behaviour
  • Genotype-by-environment interaction

• Graduation date

  Fall 2011

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3N90V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.