Tycholis Tanya J, Cant John P, Osborne Vern R, Shoveller Anna K
Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
Procter and Gamble Co., Pet Care, Lewisburg, OH, 45338, USA.
BMC Vet Res. 2014 Aug 12;10:177. doi: 10.1186/s12917-014-0177-8.
Decreasing the rate of protein emptying from the stomach may improve efficiency of utilization of dietary amino acids for protein deposition. Some studies in rats and humans have shown casein to be more slowly released from the stomach than whey protein. To test if casein induces a slower rate of gastric emptying in cats than whey protein, L-[1-(13)C]phenylalanine (Phe) was dosed orally into 9 adult cats to estimate gastric emptying and whole-body Phe flux.
Concentrations of indispensable amino acids in plasma were not significantly affected by dietary protein source. First-pass splanchnic extraction of Phe was not different between diets and averaged 50% (SEM = 3.8%). The half-time for gastric emptying averaged 9.9 min with casein and 10.3 min with whey protein, and was not significantly different between diets (SEM = 1.7 min). Phenylalanine fluxes were 45.3 and 46.5 μmol/(min · kg) for casein- and whey-based diets, respectively (SEM = 4.7 μmol/(min · kg)).
In adult cats fed frequent small meals, the replacement of casein with whey protein in the diet does not affect supply or utilization of amino acids. These two milk proteins appear to be equally capable of meeting the dietary amino acid needs of cats.
降低蛋白质从胃排空的速率可能会提高膳食氨基酸用于蛋白质沉积的利用效率。一些在大鼠和人类中的研究表明，酪蛋白从胃中释放的速度比乳清蛋白慢。为了测试酪蛋白是否比乳清蛋白在猫中诱导更慢的胃排空速率，将L-[1-(13)C]苯丙氨酸（Phe）口服给予9只成年猫，以估计胃排空和全身Phe通量。
血浆中必需氨基酸的浓度不受膳食蛋白质来源的显著影响。两种饮食之间Phe的首过内脏提取率没有差异，平均为50%（标准误=3.8%）。酪蛋白组胃排空的半衰期平均为9.9分钟，乳清蛋白组为10.3分钟，两种饮食之间没有显著差异（标准误=1.7分钟）。酪蛋白和乳清蛋白饮食的苯丙氨酸通量分别为45.3和46.5μmol/（分钟·千克）（标准误=4.7μmol/（分钟·千克））。
在频繁少食的成年猫中，用乳清蛋白替代饮食中的酪蛋白不会影响氨基酸的供应或利用。这两种乳蛋白似乎同样能够满足猫的膳食氨基酸需求。
