and Implications Ten generations (G) of divergent selection for residual feed intake (RFI) was practiced in Yorkshire pigs. This study shows that feed efficiency based on RFI was moderately heritable and responded to selection. Pigs selected for increased feed efficiency from the low RFI line ate less, grew slightly slower, and were leaner than pigs from the high RFI line. Thus, the results of this study show that selection for decreased RFI can improve feed efficiency and can be included in an economic selection index in addition to growth for reducing feed cost.
and Implications For ten generations, purebred Yorkshire pigs were divergently selected for increased and decreased feed efficiency based on residual feed intake when fed a standard corn and soybean-meal based diet. In this study, gilts and barrows born in generations 8, 9, and 10 were fed either a standard diet or an alternative diet that incorporated byproducts while reducing corn and soybean-meal, resulting in a lower energy, higher fiber diet. Genotype by diet interactions were investigated by estimating heritabilities, genetic correlations, response to selection, and genome wide associations for six traits based on these two diets. Results indicate that feed efficiency is a genetically complex trait that appears to be genetically different depending on the diet fed. Thus, genetic gains made by selection on standard diets may not be fully expressed in swine production systems that use alternative diets, particularly those incorporating byproducts.
and ImplicationsThe objective of this study was to determine if Yorkshire gilts become habituated to the process of weighing. A total of 192 pure bred Yorkshire gilts were used. The gilts were housed in 12 pens, 16 gilts/pen providing a space allowance of 0.82 m 2 /gilt. Gilts were weighed every 2-wks for a maximum of eight scores/ gilt. Gilts were scored while on the weigh scale for activity using a whole number scale of one to five (1 = calm, minimal movement; 5 = continuous rapid movement and an escape attempt) at two different time points, T = 0 (as soon as the back gate was closed and T = 15, 15 sec after the back gate was closed. Analyses were done using Proc Mixed of SAS. The differences during round one between T = 0 and T = 15 was 1 point on the 5 point scale. By round eight this had dropped down to a difference of 0.2. During the first round over both time points the gilts scored on average 2.5, by round 5 this had dropped down to around 1.5 at which point it stabilized. In conclusion, Yorkshire gilts appear to become habituated to the process of weighing over the course of a trial, and as such do not seem to find the process highly aversive.
and Implications Animals divergently selected for low and high residual feed intake (RFI) were fed either a high energy, low fiber (HELF) or low energy, high fiber (LEHF) diet. Regardless of line, pigs fed the LEHF diet had carcasses with reduced fat depth, loin depth, and greater percent lean. Line had no significant effect on carcass composition traits possibly due to line by sex interactions. Within the low RFI line, barrows had heavier carcasses with greater fat depth, while gilts had carcasses with a greater percent lean. Diet was the largest factor in final carcass composition of pigs in this study.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.