Effect of particle size and partial replacement of alfalfa hay by soya bean hulls on nutrient intake, total tract digestibility and rumen degradability of diets by Holstein steers

This study examined the effect of alfalfa hay (AH) particle size and the replacement of soya bean hull (SH) for AH within the diet of restricted fed Holstein steers on dry matter intake (DMI), total tract digestion, ruminal digestion, ruminal pH and ammonia nitrogen content, and faecal pH. Four rumen-cannulated Holstein steers averaging 353 +/- 9.6kg of BW were assigned to a 4x4 Latin square experiment with four periods and a 2x2 factorial arrangement of treatments. Factor A was AH particle size (fine vs. coarse) and factor B was diet SH content (0% vs. 10%; substituted for AH). Steers were fed at 1% of body weight of TMR containing 400g/kg forage and 600g/kg concentrate. Chopping of AH to fine particles decreased (p=0.01) amount of dietary materials retained on the medium sieve (8mm). The inclusion of SH significantly increased (p=0.01) materials retained on the 1.18-mm sieve and tended to decrease (p=0.07) materials on 19-mm sieves. The inclusion of SH increased (p=0.01) ether extract (EE) intake and increased (p=0.07) DMI. Inclusion of SH increased (p=0.01) EE digestion and decreased (p<0.01) faecal pH. Neither AH particle size nor SH inclusion in diets affected (p>0.10) the insitu ruminal degradability coefficients of DM (a', 'b', 'c' or 'a+b'). No interaction of AHxSH was seen on nutrient intake, digestibility and insitu ruminal degradability of Holstein steers.