142 Preliminary Study: Effect of concentrate feed amount on histochemical characteristics of pituitary, blood metabolites and organ development in young Japanese black heifers.

Abstract Improving feed efficiency and productivity are critical in the beef industry. The growing phase is a key stage for establishing the physiological foundation for fattening. The growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis plays a crucial role in the growth of cattle. We previously reported that differences in early nutrition affect GH secretion pattern, skeletal muscle and bone development (Gotoh et al., 2000). This study aimed to examine the effects of early nutrition on the histochemical characteristics of pituitary, blood metabolites and organ development in Japanese black heifers. Six Japanese black heifers (n=6) were used. These heifers were divided into two groups from 5 to 10 months of age: a concentrate-fed group (CF, n=3), which received concentrate feed at 3.0% of body weight (BW), and a roughage-fed group (RF, n=3), which received concentrate feed at 1.5% of BW. Both groups had ad libitum access to roughage. Blood samples were collected for endocrine analysis, and anatomical traits were evaluated post-harvest at 10 months of age. Pituitary glands were processed for histological analysis. GH-releasing cell density in the pituitary gland didn’t differ (P > 0.46) between CF and RF groups. Serum γ-Glutamyl Transpeptidase (γ-GT) concentration was significantly higher (P < 0.05) in CF group, while IGF-1, Insulin, Total Protein, Albumin, Total cholesterol, Non-esterified fatty acids, Blood urea nitrogen, and Aspartate aminotransferase didn’t differ (P > 0.44) between CF and RF group. In organ traits, the liver and subcutaneous fat were significantly heavier (P < 0.05), and the pancreas tended to be heavier (P < 0.1) in CF group compared to RF group. When considering BW ratios, the liver, and subcutaneous fat were heavier (P < 0.05) in CF group, while the rumen, omasum, reticulum small intestine, and large intestine were significantly lighter (P < 0.05) compared to RF group. In conclusion, it was suggested that early nutrition during the growing phase affected organ development and blood composition, but not the histochemical characteristics of the pituitary gland.