Fine-tuning and balancing diets for essential amino acids has become a common practice during recent years. In general, lysine and methionine are the main limiting amino acids in dairy cow diets. Histidine has been identified as the first limiting amino acid mainly in cows fed grass silage-based diets. However, new research shows histidine may be a limiting amino acid in corn silage-based diets as well.
In a series of studies conducted at The Pennsylvania State University’s Dairy Teaching and Research Center, researchers evaluated the effects of histidine supplementation of low-protein diets on lactation performance of high-producing dairy cows. In the first work (2015), the authors supplemented a metabolisable protein (MP) deficient diet, already supplemented with rumen-protected methionine,with 50 g of a rumen-protected histidine product (bioavailability =54%).
The diet, based on corn silage (43.3% of DM), was formulated to contain 15.5% of protein in dry matter (DM) basis and provide 96% of the MP requirements (according to the Dairy National Research Council; NRC, 2001). The results, published in the Journal of Dairy Science, showed that supplementing histidine:
- Increased DM intake (28.3 vs 26.6 of kg DM/day).
- Increased milk protein content (3.26 vs. 3.16%).
- Increased milk protein yield (1.46 vs. 1.37kg/day).
- Tended to increase glucose in blood (80.4 vs. 74.6mg/dL).
Continue reading this article published in International Dairy Topics.
