Ghrelin Immunoreactive Cell Amounts in the Abomasum in 4-Month-Old Calves by Feeding Different Amounts of Prebiotics and New Synbiotics

Immunohistochemical distributions of leptin, ghrelin and obestatin hormones in bull and ram abomasum

In most mammals, leptin plays central and peripheral roles in a wide range of metabolic activities including feed consumption and digestion, energy expenditure and the regulation of carbohydrate-fat accumulation. Ghrelin is a strong appetite-stimulating hormone, while obestatin has the opposite effect of ghrelin. The latter is released during feeding, causing a sense of satiety. This study aimed to reveal if the metabolic hormones, as well as OB-R and GHS-R, were present in bull and ram abomasums. Streptavidin-biotin peroxidase method was implemented to determine the expressions and localizations of metabolic hormones and their receptors, and obestatin. Immunoreactivity for leptin and obestatin was present in the cytoplasms of luminal and glandular cells, while smooth muscle cells were immunoreactant for ghrelin, in both bull and ram abomasums. Immunoreactivity for OB-R was present in luminal and glandular cell, parietal cell cytoplasms, and blood vessels. Immunoreactivity for GHS-R, on the other hand, was found in glandular epithelial cell cytoplasms and parietal cell cytoplasms, in both bull and ram abomasums. Leptin immunoreactivity was detected in the glandular epithelial cells and stroma, and particularly in the parietal cells. Ghrelin immunoreactivity was not observed in glandular epithelial cells. Obestatin immunoreactivity was found intensely in the bull abomasum, while moderate immunoreactivity was observed in the ram abomasums. As such, leptin, ghrelin and obestatin hormones were expressed in bull and ram abomasums, similar to the abomasums of other species. It is believed that these hormones play important roles in the digestive system activities and the regulation of energy in bulls and rams.

The amount of ghrelin-immunoreactive cells in the abomasum and intestines of 13-14-week-old calves supplemented with Jerusalem artichoke flour alone or in combination with Saccharomyces cerevisiae yeast

Background and Aim: The use of antibiotics in animals for disease prevention and productivity has been banned in the European Union since 2006. Possible alternatives can be used prebiotics, probiotics, and synbiotics. These compounds can improve feed digestion and absorption in the gastrointestinal tract with identical nutrient uptake, while imparting the feeling of satiety, which reduces the activity of ghrelin-immunoreactive (IR) cells. The number of studies performed on the activity of ghrelin-IR cells in ruminants is insufficient. In particular, there are few such studies in calves during the transition period from being a relatively monogastric animal to a ruminant. The present study aimed to evaluate the effect of Jerusalem artichoke flour (containing ∼50% prebiotic inulin) and a new, commercially unavailable synbiotic (combination of Jerusalem artichoke flour and Saccharomyces cerevisiae strain 1026) on the amount of ghrelin-IR cells in the abomasum and intestines of 13-14-week-old calves. Materials and Methods: Fifteen crossbreed, Holstein Friesian and Red Holstein calves (Bos taurus) (32±4 days, 72.1±11.34 kg) were used. Calves were allocated into three groups: Control group (CoG, n=5) received the standard diet, prebiotic group (PreG, n=5) received 12 g of flour of Jerusalem artichoke (Helianthus tuberosus) per head containing 6 g of prebiotic inulin in addition to the standard diet, and synbiotic group (SynG, n=5) received a synbiotic in addition to the standard diet which consisted of two different products: 12 g of flour of Jerusalem artichoke per head containing 6 g of prebiotic inulin and probiotic 5 g of a yeast S. cerevisiae strain 1026. Feed additives were added to the concentrate once a day for 56 days. On days 1, 28, and 56, the live weight of the calves was determined. On day 56 of the experiment, three calves from each group were slaughtered. Histological samples were collected from the two parts of each calf abomasum: Pars pylorica and pars fundalis and the middle part of the duodenum and jejunum. Immunohistochemical tissue staining methods were used to detect ghrelin-IR cells. Results: The live weight of the slaughtered calves on day 56 was 115.3±21.73 kg in CoG, 130.0±17.32 kg in PreG, and 119.0±7.94 kg in SynG. Ghrelin-IR cells were more abundantly localized in the cytoplasm of the abomasum muscle gland cells in pars fundalis and pars pylorica, and to a lesser extent in the duodenum and jejunum. The number of ghrelin-IR cells in the abomasal fundic gland area was significantly higher in the CoG, than in the PreG and SynG (p=0.0001), while the difference between the PreG and SynG was not significant (p=0.700). Conclusion: The addition of Jerusalem artichoke flour and its combination with the yeast S.cerevisiae stain 1026 in calves resulted in a lower number of ghrelin-IR cells in the abomasum, duodenum, and jejunum and, although insignificantly, increased live weight (p=0.491), suggesting that calves in these groups with the same feed intake as the CoG had a better breakdown of nutrients, thus having a longer feeling of satiety.