Abstract
Nine crossbred castrated lambs fitted with rumen and duodenum cannula and fed a diet of hay and concentrate formulated with ground corn and soybean meal as main ingredients were used to assess the duodenal ideal amino acid pattern. Three synthetic amino acid mixtures with different profile of essential amino acids were duodenally infused in order to get three different amino acid patterns flowing into the duodenum. The mixtures were designed to have similar amino acid profile as rumen microbial protein (Pm), casein (Pc) and modified muscle amino acid (Pmm). Results showed a lower urine nitrogen excretion (p=0.05), a higher nitrogen retention (p=0.04) and bodyweight gain with treatment Pmm. The modified muscle amino acid pattern also promoted a lower ratio of Gly to other amino acids in plasma (Gly/OAA) and a higher RNA and RNA/DNA concentration in the liver of the sheep. Meanwhile, the urea concentration in plasma was reduced and the insulin concentration was increased with Pmm treatment. No differences in glucose and growth hormone concentration in plasma were found among three treatments. All results obtained indicate that the modified muscle amino acid pattern (Lys 100%, Met+Cys 39%, Thr 76%, His 41%, Arg 72%, Leu 158%, Ile 81%, Val 105%, Phe 81% and Trp 13%) was the best for growing sheep.
Highlights
Caucasian Merino, weighing between 25 and 30 kg), fitted with permanent rumen cannula and a T-shaped cannula at the proximal duodenum, were used in a completely randomized design with three treatment groups of three sheep each
Three synthetic amino acids mixtures with different profile of essential amino acids were intraduodenally infused at rate of 6.443 g/d in order to get three different patterns of amino acids in the digesta flowing into the duodenum
Intake and digesta nutrient flows at the duodenum of sheep fed soybean meal (SBM) diet before amino acids infusion are presented in table 2
Summary
Caucasian Merino, weighing between 25 and 30 kg), fitted with permanent rumen cannula and a T-shaped cannula at the proximal duodenum, were used in a completely randomized design with three treatment groups of three sheep each. Three synthetic amino acids mixtures with different profile of essential amino acids (table 1) were intraduodenally infused at rate of 6.443 g/d in order to get three different patterns of amino acids in the digesta flowing into the duodenum. A: Rumen microbial protein amino acid pattern (Pm), as the ruminal microbial protein amino acid profile reported by McCance and Widdowson (1978). C: Modified muscle protein amino acid pattern (Pmm), increased 50% of methionine and 50% of threonie) based on the muscle protein amino acid pattern in lamb (McCance and Widdowson, 1978). Infused amino acids were calculated from an incremental model as follows: The amino acid profile of the digesta flowing to the duodenum is closely related to animal production. In the case of the growing animals, a logical alternative would be to consider the amino acid pattern in carcass protein as the ideal protein (Meister, 1965), as was found to be the case with chicken and rats (Williams et al, 1954)
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