THE EFFECT OF FEEDING LEVEL ON INTAKE AND DIGESTIBILITY OF RHODES GRASS (CHLORIS-GAYANA, CV KUNTH) BY DAIRY-COWS

The effects of feeding level (FL) on intake and digestibility was stud ied using eight lactating dairy cows fed on primary and secondary grow ths of 6, 8, 10 and 12 week old Rhodes grass. For each growth, eight f eeding levels were used and the cows were randomly assigned to two blo cks of treatments, each containing four levels of feeding and four pla nt ages in a double 4 x 4 Latin square arrangement. All forages were f ed green and unchopped and levels of organic matter (OM) fed per day v aried from 1.7 to 4.8 and from 2.8 to 5.4 kg per 100 kg BW for 1st and 2nd growth forages, respectively. The cows consumed more leaves than stems. Refusals had lower crude protein (CP) and true in vitro organic matter digestibility and were higher in neutral detergent fibre (NDF) than the feed on offer. Selection against stems increased with age of the forage. The level of feeding had no significant effect on OM, CP and NDF digestibility in vivo. Intake of OM, digestible OM, leaves and stems increased significantly with increasing FL and decreased with a ge of the Ist cut forages (P < 0.001). In the 2nd cut age was signific ant for all parameters except intake of NDF and FL for all parameters except stems (P < 0.05). Cows fed 1st cut forages did not reach maximu m intake within the range of FL used. At the maximum refusal level of about 25%, intake was still increasing. The curves for 2nd cut approac hed maximum intake at about 40% refusals, Calculations of optimal FL f or the best compromise between excess feed and intake above maintenanc e (VAP-max: maximum value for animal production) showed increasing. FL and decreasing VAP-max with age in the Ist cut but no trend for the 2 nd cut. (C) 1997 Elsevier Science B.V.