Alpha-Ketoglutarate: An Effective Feed Supplement in Improving Bone Metabolism and Muscle Quality of Laying Hens: A Preliminary Study

Abstract

The aim of the experiment was to assess the effect of dietary alpha-ketoglutarate (AKG) supplementation on performance, serum hormonal indices, duodenum and jejunum histomorphometry, meat quality characteristics, bone quality traits and cartilage degradation in laying hens with a mature skeletal system. Forty-eight 30 week-old Bovans Brown laying hens were randomly assigned to a control group or the group fed the basal diet plus 1.0% AKG. The experimental trial lasted 30 weeks. The supplementation of AKG increases blood serum content of leptin, ghrelin, bone alkaline phosphatate and receptor activator of nuclear factor kappa-Β ligand, while osteoprotegerin and osteocalcin decrease. While dietary AKG was given to laying hens negatively influenced villus length, crypt depth, villus/crypt ratio and absorptive surface area in duodenum and jejunum, these changes have no effect on feed intake, weight gain, nor laying performance. In breast muscles, no significant changes in skeletal muscle fatty acid composition were observed, however, a higher shear force and decreased cholesterol content following AKG supplementation were noted, showing the improvement of muscle quality. While dietary AKG supplementation did not affect the general geometric and mechanical properties of the tibia, it increased collagen synthesis and enhanced immature collagen content. In medullary bone, an increase of bone volume fraction, trabecular thickness, fractal dimension and decrease of trabecular space were observed in AKG supplemented group. The trabeculae in bone metaphysis were also significantly thicker after AKG supplementation. AKG promoted fibrillogenesis in articular cartilage, as indicated by increased cartilage oligomeric matrix protein immunoexpression. By improving the structure and maintaining the proper bone turnover rate of highly reactive and metabolically active medullar and trabecular bones AKG showed its anti-osteoporotic action in laying hens.

Cholesterol Content, Fatty Acid Profile and Health Lipid Indices in the Egg Yolk of Eggs from Hens at the End of the Laying Cycle, Following Alpha-Ketoglutarate Supplementation

“…The diet had no effect on overall laying rate (95.8 ± 0.4% and 96.6 ± 0.4% in the Control and AKG group, respectively; p = 0.108) and daily feed intake (118 ± 1 g per hen and 117 ± 1 g per hen in the Control and AKG group, respectively; p = 0.226), as reported previously [35]. There were also no differences in egg mass (60.79 ± 0.98 g and 62.60 ± 0.59 g in the Control and AKG group, respectively; p = 0.120) and egg yolk mass (16.65 ± 0.32 g and 17.40 ± 0.37 g in the Control and AKG group, respectively; p = 0.134) between groups.…”

“…The presence of C17:1c9 (heptadecenoic acid) in the egg yolk, irrespective of AKG supplementation in our study, may be a result of the microbial activity in the intestinal tract of the hens, which was additionally modified by AKG [35]. Existing data regarding the FA profile of egg yolk indicate that further studies involving the intestinal microbiome are needed with regards to the role of the intestinal microbiome on yolk lipid composition.…”

“…Synthetized FA are transported to the ovary by the bloodstream like other lipids and are deposited in egg yolk [34]. Furthermore, we have recently shown that AKG administered to laying hens decreased cholesterol content in blood and breast muscles of laying hens [35].…”

Changes in the Intestinal Histomorphometry, the Expression of Intestinal Tight Junction Proteins, and the Bone Structure and Liver of Pre-Laying Hens Following Oral Administration of Fumonisins for 21 Days

“…An increase in trabecular thickness, albeit not statistically significant, was sufficient to maintain the same BV/TV, even when trabecular space increased. Fractal dimension measurements reflect the roughness of the bone image texture, which is related to the bone microarchitecture and is an indicator of intensity of bone loss [38][39][40]. Lower fractal trabeculae dimensions of FB-intoxicated pre-laying hens related to the complex bone structure indicated a greater loss of bone.…”

“…Slides were counterstained with Mayer's hematoxylin (MHS32-1L Sigma-Aldrich, St. Louis, MO, USA). Slides were examined using an Olympus CX43 microscope (Olympus, Tokyo, Japan) [40].…”