|ARTEGOITIA, VIRGINIA - University Of Nebraska|
|Tait Jr, Richard|
|LEWIS, RONALD - University Of Nebraska|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2017
Publication Date: 10/13/2017
Publication URL: http://handle.nal.usda.gov/10113/5852194
Citation: Artegoitia, V.M., Foote, A.P., Tait Jr, R.G., Kuehn, L.A., Lewis, R.M., Wheeler, T.L., Freetly, H.C. 2017. Endocannabinoid concentrations in plasma during the finishing period are associated with feed efficiency and carcass composition of beef cattle. Journal of Animal Science. 95(10):4568-4574. https://doi.org/10.2527/jas2017.1629.
Interpretive Summary: Anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are the most studied and first identified endocananbinoids (EC), related to the control of feed intake and energy metabolism. We have previously shown that blood concentration of EC was positively associated with feed efficiency and leaner carcasses in finishing steers. However, it is not clear whether animal growth during the finishing period might influence the concentration of endocannabinoids. Therefore, we sought to quantify EC in early (d 0), mid (d 42) and late (d 83) periods of growth trial of finishing beef cattle. Changes in EC concentration during growth might be able to better identify differences in cattle feed efficiency and carcass composition than single independent measures of EC concentrations. The objective of this study was to quantify the ECs in plasma during the finishing period and determine their association with production traits and carcass composition in finishing beef calves. Individual intake and gain were measured on 236 calves (n = 127 steers and n = 109 heifers) for 84 d on a finishing ration. Blood samples were collected on d 0 (early), d 42 (mid) and d 83 (late) of days on feed. The concentration of 2-AG was the predominant EC in blood at early finishing stages and rapidly decreased. Concurrently, concentration of AEA in blood increased during finishing in the calves. Differences in EC concentrations during finishing period may be related with animal growth. The more efficient animals had higher AEA concentration at mid-late stages of the finishing period consistent with our previous findings. However, AEA concentration at early stage of the finishing period, particularly in steers, was negatively associated with cattle feed efficiency. The ability of plasma AEA to predict carcass composition diverged between heifers and steers, being positively associated with fat thickness, hot carcass weight and USDA-calculated yield gain in heifers. These results provide evidence that different stages on animal growth are related to circulating EC concentration and, primarily AEA concentration, was associated with cattle feed efficiency, although its associations with carcass composition differed by sex.
Technical Abstract: We previously have shown that plasma concentrations of endocannabinoids (EC) are positively correlated with feed efficiency and leaner carcasses in finishing steers. However, whether the animal growth during the finishing period affects the concentration of EC is unknown. The objective of this study was to quantify anandamide (AEA) and 2-arachidonyl glycerol (2-AG) in plasma during different stages of the finishing period and identify possible associations with production traits and carcass composition in beef calves. Individual DMI and BW gain were measured on 236 calves (n = 127 steers and n = 109 heifers) for 84 d on a finishing ration. Blood samples were collected on d 0 (early), 42 (mid), and 83 (late) of days on study (DOS). Cattle were slaughtered 44 d after the feeding study. Plasma concentration of AEA at 0 DOS was indirectly associated with the G:F (P < 0.01) and directly associated with residual feed intake (RFI; P < 0.05) in steers. In contrast, plasma concentration of AEA at 83 DOS was directly associated with the G:F and indirectly associated RFI in heifers and steers (P < 0.01). In addition, AEA concentration at 42 and 83 DOS was positively associated with ADG and DMI (P < 0.01) in heifers and steers. Furthermore, 2-AG concentration at 42 DOS was positively associated with ADG in steers (P < 0.01) and heifers (P < 0.10). Plasma concentration of AEA was positively associated (P < 0.05) with HCW, USDA-calculated yield grade, and 12th-rib fat thickness in heifers, whereas no associations were found in steers. In contrast, 2-AG concentration was not associated with any carcass traits. These results provide evidence that circulating EC change during animal growth and that AEA concentration may be a useful predictor of growth and feed efficiency and, in females, of carcass attributes.