Effects of length of cut and mechanical processing on utilization of corn silage harvested at the black line stage of maturity by lactating dairy cows

Abstract

The effects of length of cut and mechanical processing on corn silage utilization by dairy cows were evaluated. Corn silage treatments were harvested at the black line stage of maturity and chopped at a theoretical length (TLC) of 9.5 mm without processing (Control) or at a TLC of 19 mm with processing at roller clearances of 1, 3, or 5 mm. Eight multiparous Holstein cows were assigned in a replicated 4 x 4 Latin square design with 21-day periods. Corn silage treatments were fed in diets containing 78.3% corn silage and 21.7% soybean meal (DM basis). Treatments had no significant effects on DMI, milk and 4% FCM production. The efficiency of converting DMI to FCM tended to be greater with processing at a roller clearance of 1 and 3 mm than at other clearances. Apparent total tract digestibility of starch tended to be lowest for cows fed control silage, and increased as roller clearance decreased. Ruminal ammonia concentrations in cows fed control silage were numerically higher than in cows fed proccesed silages. These results suggest that when corn silage is harvested at the black line of maturity, roller clearance should be 3 mm or less with a TLC of 19 mm.

Effect of roll clearance of mechanical processing of corn silage harvested at the black‐line stage of maturity on carbohydrate and protein utilization in dairy cows

“…In our study, the effect of MP on ruminal starch digestibility was small. In addition, average length of cut of processed CS at a TLC of 19 mm was similar to that of CS harvested at 9.5 mm TLC without MP (Hara & Tanigawa 2010). Therefore, ruminal and total tract NDF digestibility might have been unaffected by MP.…”

“…1). Hara and Tanigawa (2010) also observed that MP had no effect on the ruminal fluid parameters of lactating dairy cows fed CS harvested at the black‐line stage. Processing tended to increase the ruminal VFA concentration and reduce ruminal pH (Dhiman et al .…”

“…(2001) suggested that higher DM intake for processed CS could be related to the decreased CS particle length, increased ruminal passage rate, and improvement in silage fermentation. Hara and Tanigawa (2010) observed that the fermentation characteristics of CS harvested at the black‐line stage were desirable for good silage fermentation, and the DM intake of lactating dairy cows was similar, irrespective of MP. In our study, MP had no significant effect on DM and nutrient intake.…”

“…(2007) indicated that MP of corn kernels resulted in quicker bacterial attachment after feeding, possibly due to increased damage on the surface area of the plant material. Intact corn kernels present in the CS tended to be lower as the roll clearance decreased from 5 mm to 1 mm (Hara & Tanigawa 2010). Improvements in ruminal and total tract starch digestibility supported the fact that MP with 1–3 mm roll clearance increased the availability of starch in the corn kernel to microbial attachment and digestible enzymes.…”

“…The roll clearance of MP affects nutrient digestibility and production responses, but few published data are available on the effects of roll clearance. Hara and Tanigawa (2010) suggested that when CS was harvested at the black‐line stage of maturity, the efficiency of converting DM intake to 4% fat‐corrected milk tended to be greater with processing at a roll clearance of 1 and 3 mm than at 5 mm clearance with TLC of 19 mm. However, few studies examined the effects of the roll clearance of MP on ruminal nutrient utilization by cows fed CS harvested at the black‐line stage of maturity.…”