The potential of antibodies raised against insulin-like growth factor-1 (IGF-1) as a treatment to enhance the anabolic actions of IGF-1 has been demonstrated in both rodent and ruminant models. We investigated whether treatment of genetically normal rats with anti-IGF-1 immunoglobulin (Ig, raised in cattle) would enhance growth and if anti-IGF-1 Ig treatment would ameliorate live-weight loss in genetically normal rats offered a severely protein-restricted diet. Scatchard analysis was used to characterise ammonium sulphate precipitated bovine anti-IGF-1 Ig. Anti-IGF-1 Ig binding to 125I-IGF-1 yielded an almost linear Scatchard plot, with a Hill co-efficient of 0.951 ± 0.012, indicating a single class of IGF-1 binding sites. The affinity of anti-IGF-1 Ig for IGF-1 was 2.14 ± 0.66 × 109 l/mol. The non-immune Ig preparation did not bind IGF-1. Rats were offered either a diet with a normal protein level (20%) or protein restricted (4% protein), and each dietary group was further treated with twice-daily i.p. injections of either diluent phosphate buffered saline, non-immune Ig or anti-IGF-1 Ig. Dietary protein level had a significant effect on live-weight gain, but there was no effect of non-immune Ig or anti-IGF-1 Ig on live-weight gain. Treatment with anti-IGF-1 Ig prevented the significant depression of cumulative dietary intake observed in diluent, and non-immune Ig treated groups offered the 4% protein diet. The cumulative dietary intake of the anti-IGF-1 Ig treated, 4% dietary protein group did not differ significantly from those of the groups offered the 20% protein diet. In addition, within the 4% dietary protein group, rats treated with non-immune Ig exhibited a cumulative feed intake that was intermediate between that of the diluent treated and anti-IGF-1 Ig treated groups (P < 0.05). Size exclusion chromatography was used to characterise in vitro125I-IGF-1 binding in end-point plasma from each treatment group. In comparison to control groups, anti-IGF-1 Ig treatment resulted in substantially increased 125I-IGF-1 binding in the 30 to 40 kDa region and a concomitant reduction in elution of free 125I-IGF-1. Protein restriction markedly depressed IGF-1 binding at ∼150 kDa in the plasma of diluent and non-immune Ig treated groups. Anti-IGF-1 Ig treatment was effective in preventing this decrease in ∼150 kDa binding. Thus, anti-IGF-1 Ig appears to have a beneficial effect on dietary intake in protein-restricted rats, which is associated with induced changes in IGF-1 binding profiles in plasma.

The immunoglobulins of bovine colostrum provide the major antimicrobial protection against microbial infections and confer a passive immunity to the newborn calf until its own immune system matures. The concentration in colostrum of specific antibodies against pathogens can be raised by immunising cows with these pathogens or their antigens. Immune milk products are preparations made of such hyperimmune colostrum or antibodies enriched from it. These preparations can be used to give effective specific protection against different enteric diseases in calves and suckling pigs. Colostral immunoglobulin supplements designed for farm animals are commercially available in many countries. Also, some immune milk products containing specific antibodies against certain pathogens have been launched on the market. A number of clinical studies are currently in progress to evaluate the efficacy of immune milks in the prevention and treatment of various human infections, including those caused by antibiotic resistant bacteria. Bovine colostrum-based immune milk products have proven effective in prophylaxis against various infectious diseases in humans. Good results have been obtained with products targeted against rotavirus, Shigella flexneri, Escherichia coli, Clostridium difficile, Streptococcus mutans, Cryptosporidium parvum and Helicobacter pylori. Some successful attempts have been made to use immune milk in balancing gastrointestinal microbial flora. Immune milk products are promising examples of health-promoting functional foods, or nutraceuticals. This review summarises the recent progress in the development of these products and evaluates their potential as dietary supplements and in clinical nutrition.