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Effect of forage to concentrate ratio in complete diets offered to sheep on voluntary food intake and some digestive parameters

  • C. Valdés (a1), M. D. Carro (a1), M. J. Ranilla (a1) and J. S. González (a1)


Twelve mature ewes were used to study the effect of forage: concentrate ratio in complete diets on voluntary intake and some digestive characteristics. Diets consisted of four combinations of chopped lucerne hay and a concentrate (390 g cracked barley grains, 440 g cracked maize grains and 170 g soya-bean meal per kg of concentrate) in the following proportions (fresh matter basis): 0·8:0·2 (C20), 0·6:0·4 (C40), 0·4:0·6 (C60) and 0·2:0·8 (C80). Diets were offered over two 42-day periods and, in each of them, three sheep received one of the four diets, with the restriction that no animal received the same diet in both periods. Chromium Ill-mordanted fibre was used as a marker to estimate passage rate of digest a and microbial nitrogen supply (MNS) was estimated from the urinary excretion of purine derivatives. The increase in the proportion of concentrate affected linearly (P < 0·05) the voluntary intake of food, the mean values being 36·8, 37·9, 36·3 and 30·0 g dry matter (DM) per kg live weight per day for C20, C40, C60 and C80 diets, respectively. Apparent digestibility of DM, organic matter (OM) and crude protein increased linearly (P < 0·01) with the proportion of concentrate in the diet, whereas that of cellulose evolved auadratically (P < 0·05), reaching a minimum value in the C80 diet. Digestible OM intake was unaffected (P > 0·05) by the proportion of concentrate in the diet. Both particulate passage rate from the rumen and through the caecum and proximal colon decreased linearly (P < 0·05) as concentrate proportion in the diet increased. MNS (g/day) was not affected (P > 0·05) by the diet, whereas its efficiency (g/kg digestible OM intake) tended (P < 0·10) to increase with the proportion of concentrate in the diet.



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Effect of forage to concentrate ratio in complete diets offered to sheep on voluntary food intake and some digestive parameters

  • C. Valdés (a1), M. D. Carro (a1), M. J. Ranilla (a1) and J. S. González (a1)


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