Effects of housing and feeding system on digestibility of nutrients of a concentrate mixture in feed rations with varying concentrate / hay ratios in growing sheep

The purpose of this study was to investigate in growing male lambs (genotype Merino) the influence of housing and feeding system on the digestibility of nutrients of a concentrate mixture in rations with various concentrate/hay ratios. A total of six digestion experiments was carried out. First, a conventional digestion experiment in a digestion cage (C) was carried out for the used hay. In five further experiments the digestibility of nutrients of feeding rations (concentrate and hay) were investigated both in C and in group penning (P). The animals in P (two animals per box) had access to computerized feeding stations which allowed recording of the individual daily feed intake. For collecting the faeces a special harness was used for each animal. The rations consisted of various ratios of a concentrate mixture (pelleted) and hay (first cut). The share of concentrate mixture in the daily feeding ration increased from 50 % in intensity level 1, to 70 % in level 2, and 83 % in level 3. The digestion experiment of the feeding intensity level 3 was only carried out with method P. There was a significant effect of feeding level and feeding system on the digestibility of the concentrate mixture. In C the digestibility of organic mass, crude fat, crude fibre and NfE decreased significantly from feeding level 1 to feeding level 2, whereas P demonstrated a less significant effect for the digestibility of crude fibre and NfE from level 1 to level 2. The digestibility of organic mass was basically maintained with increasing feeding levels. Within the same feeding level differences between the feeding systems were observed. The digestibility of organic mass, crude fat and crude fibre was lower in C compared to P. The differences of these nutrient digestibilities increased from feeding level 1 to level 2. The calculated content of metabolizable energy of the concentrate mixture decreased with increasing feeding level in both C and P, with differences being more pronounced in C.

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