Fernando Vicente - Academia.edu (original) (raw)
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Papers by Fernando Vicente
Proceedings of the British Society of Animal Science, 1999
It is widely accepted that purine bases (PB) could overestimate microbial production when used as... more It is widely accepted that purine bases (PB) could overestimate microbial production when used as microbial markers as result of rumen by-pass of dietary PB. Free nucleic acids are rapidly degraded when incubated in rumen content either in vitro or in vivo (McAllan and Smith, 1973) and nylon bag disappearance of food PB seems to confirm their low contribution to duodenal flow (Pérez et al. 1996). However isotopic labelling of microbial PB (Pérez et al. 1997) have resulted in much higher estimates of non microbial PB arriving to duodenum, which were attributed to differential uptake of dietary PB by bacterial and protozoal populations leading to lack of representativeness of the reference bacterial sample. The present experiment aimed to know if estimation of microbial contribution to duodenal PB could be biased by differences between rumen bacterial and protozoal populations in 15N enrichment of PB.
Journal of Dairy Science, 2003
Journal of the Science of Food and Agriculture, 2004
Knowledge of duodenal flow of digesta is needed in many nutritional studies involving ruminants. ... more Knowledge of duodenal flow of digesta is needed in many nutritional studies involving ruminants. For this purpose, the double-marker technique1 is the most used and it requires the joint utilization of a solid and a liquid phase marker. Ytterbium chloride and CrEDTA are ...
Journal of Animal Physiology and Animal Nutrition, 2005
Objectives: Near-infrared reflectance spectroscopy (NIRS) was used to predict the chemical compos... more Objectives: Near-infrared reflectance spectroscopy (NIRS) was used to predict the chemical composition, the apparent digestibility and the content of digestible nutrients and energy of commercial extruded compound foods for dogs.
Animal Feed Science and Technology, 2000
Four crossbred Holstein±Friesian heifers (initial live weight 306 AE 6X1 kg) ®tted with rumen and... more Four crossbred Holstein±Friesian heifers (initial live weight 306 AE 6X1 kg) ®tted with rumen and duodenal cannulae were randomly allocated to one of two dietary treatments in a double 2 Â 2 crossover design. Both diets were composed of (g/kg as fed) 250 barley straw and 750 concentrate. The concentrate consisted of (g/kg as fed) 655 corn and 225 barley (Diet C) and 225 corn and 655 barley (Diet B), respectively. During Period 1, two heifers were given Diet C and the other two heifers were given Diet B and all four heifers were infused intraruminally, during four sequential 16-day intervals, with four levels of effective rumen degradable protein (ERDP). ERDP was given as an iso-nitrogenous mixture of urea and casein at 0, 25, 50 or 75 g/kg of concentrate intake. Animals offered Diet B ate more DM, OM and NDF than those offered Diet C (97.6, 89.9 and 37.6 g/kg versus 94.4, 87.3 and 31.9 g/kg metabolic live weight (W 0.75), respectively (P`0X05). Starch digestion did not differ signi®cantly between diets, but ®bre was better digested in Diet C than in Diet B, i.e. 56.5% versus 47.5%, 51.3% versus 36.4% and 50.5% versus 40.2% for arabinose, xylose and cellulose±glucose digestibilities, respectively (P`0X05). Mean rumen ammonia concentrations increased linearly from 29.1 mg/l when no ERDP was infused to 184.5 mg/l when ERDP was infused at the highest level. Ruminal pH was lower (P`0X05) in animals offered Diet B than those offered Diet C (6.29 versus 6.46) and in ERDP-supplemented rather than unsupplemented diets (6.73 versus 6.28). However, pH never fell below 5.5. There were no differences in effective rumen degradability between Diets B and C, and increasing the ERDP supply promoted an increase in straw (P`0X05) and corn (P`0X1) DM disappearance from polyester bags. The diets without ERDP infusion were apparently de®cient in degradable N because rumen microbial yield increased from 76.0 to 102.5 g N/d (P`0X05) when ERDP infusion rate was increased from 0 to 25 g/kg of concentrate, irrespective of which type of grain concentrate was used. With further increases in ERDP, microbial yield maintained constant and there was no further Animal Feed Science and Technology 88 (2000) 59±77
Proceedings of the British Society of Animal Science, 1999
It is widely accepted that purine bases (PB) could overestimate microbial production when used as... more It is widely accepted that purine bases (PB) could overestimate microbial production when used as microbial markers as result of rumen by-pass of dietary PB. Free nucleic acids are rapidly degraded when incubated in rumen content either in vitro or in vivo (McAllan and Smith, 1973) and nylon bag disappearance of food PB seems to confirm their low contribution to duodenal flow (Pérez et al. 1996). However isotopic labelling of microbial PB (Pérez et al. 1997) have resulted in much higher estimates of non microbial PB arriving to duodenum, which were attributed to differential uptake of dietary PB by bacterial and protozoal populations leading to lack of representativeness of the reference bacterial sample. The present experiment aimed to know if estimation of microbial contribution to duodenal PB could be biased by differences between rumen bacterial and protozoal populations in 15N enrichment of PB.
Journal of Dairy Science, 2003
Journal of the Science of Food and Agriculture, 2004
Knowledge of duodenal flow of digesta is needed in many nutritional studies involving ruminants. ... more Knowledge of duodenal flow of digesta is needed in many nutritional studies involving ruminants. For this purpose, the double-marker technique1 is the most used and it requires the joint utilization of a solid and a liquid phase marker. Ytterbium chloride and CrEDTA are ...
Journal of Animal Physiology and Animal Nutrition, 2005
Objectives: Near-infrared reflectance spectroscopy (NIRS) was used to predict the chemical compos... more Objectives: Near-infrared reflectance spectroscopy (NIRS) was used to predict the chemical composition, the apparent digestibility and the content of digestible nutrients and energy of commercial extruded compound foods for dogs.
Animal Feed Science and Technology, 2000
Four crossbred Holstein±Friesian heifers (initial live weight 306 AE 6X1 kg) ®tted with rumen and... more Four crossbred Holstein±Friesian heifers (initial live weight 306 AE 6X1 kg) ®tted with rumen and duodenal cannulae were randomly allocated to one of two dietary treatments in a double 2 Â 2 crossover design. Both diets were composed of (g/kg as fed) 250 barley straw and 750 concentrate. The concentrate consisted of (g/kg as fed) 655 corn and 225 barley (Diet C) and 225 corn and 655 barley (Diet B), respectively. During Period 1, two heifers were given Diet C and the other two heifers were given Diet B and all four heifers were infused intraruminally, during four sequential 16-day intervals, with four levels of effective rumen degradable protein (ERDP). ERDP was given as an iso-nitrogenous mixture of urea and casein at 0, 25, 50 or 75 g/kg of concentrate intake. Animals offered Diet B ate more DM, OM and NDF than those offered Diet C (97.6, 89.9 and 37.6 g/kg versus 94.4, 87.3 and 31.9 g/kg metabolic live weight (W 0.75), respectively (P`0X05). Starch digestion did not differ signi®cantly between diets, but ®bre was better digested in Diet C than in Diet B, i.e. 56.5% versus 47.5%, 51.3% versus 36.4% and 50.5% versus 40.2% for arabinose, xylose and cellulose±glucose digestibilities, respectively (P`0X05). Mean rumen ammonia concentrations increased linearly from 29.1 mg/l when no ERDP was infused to 184.5 mg/l when ERDP was infused at the highest level. Ruminal pH was lower (P`0X05) in animals offered Diet B than those offered Diet C (6.29 versus 6.46) and in ERDP-supplemented rather than unsupplemented diets (6.73 versus 6.28). However, pH never fell below 5.5. There were no differences in effective rumen degradability between Diets B and C, and increasing the ERDP supply promoted an increase in straw (P`0X05) and corn (P`0X1) DM disappearance from polyester bags. The diets without ERDP infusion were apparently de®cient in degradable N because rumen microbial yield increased from 76.0 to 102.5 g N/d (P`0X05) when ERDP infusion rate was increased from 0 to 25 g/kg of concentrate, irrespective of which type of grain concentrate was used. With further increases in ERDP, microbial yield maintained constant and there was no further Animal Feed Science and Technology 88 (2000) 59±77