Effect of Different Amounts of Protein and Varying Proportions of Corn Silage and Alfalfa hay on Performance and Nitrogen Excretion of Dairy Holstein Cows

Four treatments were conducted to determine the effects of Varying Proportions of Corn Silage and Alfalfa hay (as forage source) and crude protein (CP) levels in mid lactating Holstein cows on milk production and content and nitrogen efficiency. Diets with low crude protein but with rumen degradable protein (RUP) suitable can be effective both for economic and environmental factors. In addition to the protein intake type of feed ingested may be important. Two forage corn silage and alfalfa hay in the diet of dairy cows are very common. Corn silage is a source of fermentable carbohydrate and alfalfa is also rich in RDP. The proportion of these sources of forage in the diet can have an impact on the use of nitrogen.
Sixteen primiparous (n=8) and multiparous (2-5) (n=8) cows were allocated to one of four diets in balanced randomized complete design in two periods (28 day). The diets were as follows: 1) 19% CP, 2) 17% CP and, 3) 15% CP and 4) 17% CP and Diets consisted of 50% forage and 50% concentrate (dry matter basis) and alfalfa hay- to-corn-silage ratios for the forage part of the diet: 80:20, 80:20, 20:80, and 20:80.
DMI in cows feed experimental diet have significant different (P Overall, based on N utilization as well as milk production, 17% protein in diets utilizing various proportions of alfalfa hay and corn silage as the forage source appeared sufficient for cows producing 27.56 kg/d of milk in this study. Reducing protein to this amount (17%) can reduce N excretion, especially environmentally labile urinary N, without affecting milk production. Use of four treatments with different levels of protein and varying proportions of corn silage and alfalfa hay can’t affect on milk yield, but with increasing concentration of protein, nitrogen excretion increased.