Crude protein degradability, protein digestible in the intestine and net energy for lactation of whole crop barley in various vegetative stages

Abstract

Crude protein degradability (CP deg), protein digestible in the intestine (PDI) and net energy of lactation (NEL) content of whole crop spring barley were estimated by means of the in situ method using three steers fitted with rumen cannulas and fed near the maintenance level of nutrition. Barley was cut in five consecutive vegetative stages (end of the earing, S1, end of the flowering, S2, middle of the milky stage of the grain, S3, beginning of the dough stage, S4, middle of the dough stage, S5, including S5 silage).

CP deg, PDI and NEL were significantly (P < 0.01) affected by the growth stage.

The relationships of the CP deg (%), PDI (g/kg DM) and NEL (MJ/kg DM) to the vegetative stage of barley quantified on a decimal scale (X) were as follows: CP deg = 40.1 + 0.46X (I²yx =82%), PDI = ‐330.8 + 12.86X‐0.1007X²(I²yx = 83%), and NEL = ‐0.48 + 0.0802X (I²yx = 86%), resp.

Compared with drying at 60 °C ensiling increased CP deg (P < 0.01) and NEL (P < 0.05), whereas PDI was not affected (P > 0.05).

Key words:

• Whole crop barley
• Vegetative stage
• Protein degradability
• Rumen
• Intestine
• Net energy of lactation