The effects of in ovo feeding (IOF) of creatine pyruvate (CrPyr) on the hatchability, growth performance and energy status of embryos and broilers (Arbor Acres) were investigated. Five treatments were arranged as non-injected treatment (Control), 0.6 ml physiological saline (0.75%) injected treatment (Saline), and IOF treatments injected with 0.6 ml physiological saline (0.75%) containing 3, 6 or 12 mg CrPyr (CrPyr3, CrPyr6 or CrPyr12) into the amnion per fertile egg on day 17.5 of incubation. After hatching, 80 male chicks from each treatment with similar weight close to the average BW of their pooled group were selected and randomly assigned into eight replicates of 10 chicks each. The results showed that the hatchability was not affected among groups, whereas the hatching weight of broilers in CrPyr12 was significantly higher than the control and saline groups (P<0.05). At 21 day post-hatch, the BWs of broilers in CrPyr6 and CrPyr12 were increased relative to the control and saline groups (P<0.05). Chickens in CrPyr6 and CrPyr12 exhibited higher BW gain and feed intake than the control and saline groups during 8 to 21 days post-hatch and the entire experiment period (P<0.05). Compared with the control and saline groups, the total and relative weight of pectoral muscle of embryos or chickens were greater in CrPyr6 and CrPyr12 at 19th day of incubation (19 E), hatch, 3 and 21 days post-hatch (P<0.05). The concentrations of glucose and glycogen in liver were increased in CrPyr6 and CrPyr12 at 19 E and hatch (P<0.05). Neither glycogen nor glucose concentration in pectoral muscle was altered among treatments (P>0.05). Irrespective of dosage, the concentrations of creatine and phosphocreatine, and activities of creatine kinase in embryos were enhanced in CrPyr treatments at 19 E when compared with the control and saline groups (P<0.05). The activities of glucose-6-phosphatase in liver in CrPyr6 and CrPyr12 treatments were higher than the control and saline groups at 19 E (P<0.05). In conclusion, these results indicated that IOF of CrPyr, especially at the level of 12 mg/egg, could improve energy status of embryos and hatchlings, which was useful for enhancing hatching weight, BW and pectoral muscle weight until the end of the experiments at 21 days post-hatch in broilers.

The effects of pyruvate (Pyr), creatine pyruvate (Cr-Pyr) and creatine (Cr) on lipid and protein metabolism were compared in broiler chickens. A total of 400 1-day-old male birds (Aconred) were allocated to four groups, each of which included four replicates (25 birds per replicate). Treatments consisted of unsupplemented basal diet (Control), basal diet containing 2% Pyr, basal diet containing 3% Cr and basal diet containing 5% Cr-Pyr. Cr-Pyr and Pyr significantly decreased the hepatic triglyceride and serum total cholesterol concentration (P < 0.01). Cr-Pyr markedly increased the serum non-esterified fatty acid and high-density lipoprotein cholesterol concentrations (P < 0.05), whereas the expression of carnitine palmitoyl transferase I (P < 0.05) and peroxisome proliferators-activated receptor-α (P < 0.01) mRNA in the liver were both decidedly enhanced in the Cr-Pyr group. The relative leg muscle weight was higher in the Cr-Pyr group than in the control group, whereas the serum uric acid content and hepatic glutamic-oxaloacetic transaminase activity were lower in the Cr-Pyr and Cr groups (P < 0.05), respectively. Muscle insulin-like growth factor I (P < 0.05) expression was enhanced, and the myostatin (P < 0.01) mRNA level was reduced in both the Cr-Pyr and Cr groups. In addition, Cr-Pyr did not alter body weight or the feed conversion ratio. These results indicate that, compared with Pyr and Cr alone, Cr-Pyr has a bifunctional role in broiler chickens, in that it influences both lipid and protein metabolism.