Alfalfa protein concentrate as a less ruminally degradable protein source for high-producing dairy cows

الملخص EN

Ten multiparous Holstein gh-pro،^cing dairy cows.

Dairy cows؛(SBM) and alfalfa protein concentrate (APC) as supplemental protein sources for h with an average milk production of 35.2 kg/day were paired and randomly assigned to one of the treatments.

A double 21 reversal design was employed with 35 days per period.

The comparison between treatments was made during the last days of each period.

Experimental diets, containing 60% corn silage and 10 % alfalfa hay, were formulated to be soenergetic (crude protein, 15.6%; net energy for lactation, 1.60 Mcal/kg DM).

Fifty percent of؛ nd،؛ isonitrogenous dietary nitrogen was provided by test proteins.

Animals were fed four times daily.

Chromic oxide boluses, 50 g/day were used to estimate digestion coefficients.

Ruminai protein degradability in vivo (%) and in situ (%) were 56.8, 68.3 and 47.3, 35.3 for SBM and A?c, respectively.

Dry matter intake (kg/day) was 19.1 and 18.6 for cows fed SBM and APC, 6.2 respectively.

Rumina) parameters of cows fed SBM vs APC were: pH, 6.6 vs 6.7; ammonia nitrogen (mg/di), 10.8 vs P < 0.01); total volatile fatty acids (mM), 86.3 vs 84.6 (P < 0.05); acetate (%), 50.8 vs 64.9 (P < 0.01); propionate) (%), 24.8 vs 19.6 (P < 0.01); butyrate (%), 10.7 vs 11.5.

Digestion coefficients (%) in cows fed SBM vs APC were: dry matter, 65.3 vs 61.8; crude protein, 67.6 vs 61.1 (P < 0.05); neutral detergent fiber, 51.1 V.V 52.5; acid detergent ± 28.2 fiber, 47.7 vs 49.0.

A slightly higher (P> 0.05) amount of milk was produced by cows fed APC (28.6 ± 3.5 vs 3.8 kg/day).

Each additional gram of undegradable intake protein provided by APC contributed to a 5-gram increase in .4 % fat-corrected milk production