Protein contents in the diet of holstein milking cows in a tie stall

The effect of diets with crude protein ‒ CP (10, 12, 14 and 16% in dry matter ‒ DM) levels in crossbred Holstein cows with milk production (MP) of 13 kg/day were evaluated. The feed consisted of 75% corn silage and 25% concentrate. There was a linear increase in the intake of all components of the diet, except for total carbohydrates and non-fibrous carbohydrates (NFC), which decreased linearly. The intake of total digestible nutrients (TDN) presented a quadratic effect, with maximum estimated value of 10.13kg/day at a level of 15.62% of CP in the diet. The digestibility of CP, EE, neutral detergent fiber and neutral detergent fiber corrected for ash and protein increased linearly. However, the digestibility values for DM, OM, NFC and TDN presented a quadratic effect, with maximum estimated values of 65.09, 67.23, 78.35 and 67.92 at levels of 15.39, 15.22, 12.62 and 15.68% CP, respectively. The MP, without and with a correction to 3.5% fat, body weight variation and composition of the milk increased linearly, except for lactose which had no effect. The level of 14% CP in the diet is more suitable for feeding cows with average milk production of 13kg/day.

bovines; intake; nutrition; digestibility; milk

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