Effect of rumen protected methionine on blood parameters, milk production and milk composition of Alpine dairy goats

The growing trend of production and consumption of goat milk and its products in the modern dairy industry requires improving milk production and composition by nutritional methods. Optimal imbalance of biodegradable and non-biodegradable protein in ruminants can limit microbial protein production, nitrogen utilization efficiency, fiber digestion, and access to optimal amino acid levels in the small intestine. Supplementation of protein sources with low degradability improves nitrogen utilization efficiency and optimal amino acid pattern at the surface of the small intestine. Microbial amino acids meet the animal's need if the animal is in a state of maintenance or minimal growth, while to achieve maximum growth or production the need must be met by non-biodegradable protein in the rumen. Maximum production requires sufficient amounts of essential amino acids, so to support the physiological and production needs of livestock, the use of protected amino acid supplements in the rumen is recommended. Protected amino acids lysine and methionine are more commonly known as milk-limiting amino acids, and methionine also plays a unique role as a starting amino acid in protein synthesis. This study was performed to evaluate the protected methionine and its effects on milk production and composition in Alpine dairy goats.

The experiment was performed in a completely randomized design with at least 15 replications per treatment, so that 45 Alpine lactating goats with 200 lactation days for 4 weeks, randomly were allocated for three experimental diets included: 1- Basal diet plus 2 g of commercially protected methionine 2- Control (basal diet without protected methionine) 3- Basal diet plus 2 g of protected methionine synthesized in vitro.

The results showed that methionine coating significantly reduced the degradability of methionine in the rumen (p <0.001). Also, the effect of experimental treatments on milk production and composition as well as blood parameters such as albumin, cholesterol, total protein, glucose and triglyceride was not significant in lactating goats (p> 0.05).

using protected methionine can significantly reduce the degradability of methionine in the rumen but may has no effect on milk production and composition as well as blood parameters in dairy goats at farm situation, Of course more studies and data are needed.