Arginine Supplementation For Improved Reproductive Performance in Beef Cattle

The reproductive efficiency of beef cows has long been a major determinant of success for cattle producers nationwide, and any method of improvement to this efficiency will aid the industry in being more profitable. Arginine has been proven as an effective nutrient for enhancing embryonic survival in non-ruminant species. Arginine improves the intrauterine environment by increasing levels of nitric oxide (NO) and polyamines, which promote angiogenesis, increase the amounts of nutrients for the fetus, and enhance placental and fetal development. Therefore, its use in ruminant species should provide an effective means of improving pregnancy rates among cow-calf producers. This study also establishes for the first time that two extracellular amino acids (AAs), glutamate and citrulline, may be able to bypass the rumen and its microbes without undergoing significant degradation. This was substantiated in two in-vivo studies with multiple ruminant species and in one in-vitro study. The experimental results go against the long-held notion that all AAs undergo extensive degradation when exposed to the rumen’s microbial population. The fact that no degradation of extracellular citrulline occurs in the rumen allows for the provision of this AA to ruminants as an economically viable and easily implemented means for cow-calf producers to increase arginine concentrations in cows. Collectively, the results of this thesis research indicate that dietary supplementation with citrulline is a useful, cost-effective method for improving reproductive efficiency across the beef cattle industry