Abstract
The aim of this study was to determine the association of residual feed intake (RFI) with growth performance, blood metabolic parameters, and body composition factors in growing lambs. Individual body weight (BW) and dry matter intake (DMI) were determined in 137 male Hu lambs that were given a pellet feed four times a day for 50 d. RFI did not show a correlation with metabolic BW (MBW) or average daily gain (ADG), but it showed a positive correlation with DMI and feed conversation ratio (FCR). Organ weight and intestine length had a large influence on RFI in lambs. The low-RFI lambs have smaller rumen and longer duodenum indicating the less feed intake and more sufficient absorption rate of low-RFI lambs. The smaller organs like liver, lung and kidney in low-RFI lambs may be related to lower energy consumption and slower metabolic rate. The observed bigger testis was in low-RFI lambs was another cause of the improved feed efficiency. Finally, the plasma concentrations of thyroxine (T4) and adrenocorticotropic hormone (ACTH) were lower in the ELow-RFI group than in the EHigh-RFI group. This study provides new insight into the biological processes underlying variations in feed efficiency in growing lambs.
Highlights
Feed accounts for 65–70% of the cost in the sheep industry, and improving feed efficiency (FE) is important for the economy and the environment
The least-square means for residual feed intake (RFI) and feed conversation ratio (FCR) in the high-RFI lambs were higher than those in the the medium-RFI lambs (P < 0.001), while the least-square means for the medium-RFI lambs were greater than those for the low-RFI lambs (P < 0.001)
There was no significant difference in average daily gain (ADG), initial body weight (BW), metabolic BW (MBW), and final BW (P > 0.05) between the high, medium, and low-RFI groups
Summary
Feed accounts for 65–70% of the cost in the sheep industry, and improving feed efficiency (FE) is important for the economy and the environment. It was Koch et al who proposed the use of RFI6, which is regarded as a sensitive and accurate method to estimate FE7–9. RFI is defined as the difference between the actual feed intake and the predicted intake based on the body size and performance of each animal. A low RFI indicates less feed consumption and less waste generation with no effect on the weight, production and body size of the animals. Studying the regulation mechanism of RFI can reduce the cost of feed and protect the environment by reducing the emission of carbon and methane[10]. The aim of this study was to determine the associations between RFI, slaughtering performance, blood metabolic parameters and body composition in growing sheep
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
