This study explored the effects of protein oxidation during milk processing on spatial learning and memory in rats. Increasing the heating time, fat content, and inlet air temperature during processing by boiling, microwave heating, spray-drying, or freeze-drying increases milk protein oxidation. Oxidative damage done to milk proteins by microwave heating is greater than that caused by boiling. Dityrosine (DT), as a kind of tyrosine oxidation product, is the most important marker of this process, especially during spray-drying. Rats received diets containing either SWM (spray-dried milk powder diet), FWM (freezedried milk powder diet), FWM + LDT (freeze-dried milk powder + low dityrosine diet, DT: 1.4 mg kg À1 ), or FWM + HDT (freeze-dried milk powder + high dityrosine diet, DT: 2.8 mg kg À1 ) for 6 weeks. We found that the SWM group, the FWM + LDT group, and the FWM + HDT group appeared to have various degrees of redox state imbalance and oxidative damage in plasma, liver, and brain tissues. Further, hippocampal inflammatory and apoptosis genes were significantly up-regulated in such groups, while learning and memory genes were significantly down-regulated. Eventually, varying degrees of spatial learning and memory impairment were demonstrated in those groups in the Morris water maze. This means that humans should control milk protein oxidation and improve the processing methods applied to food.
ObjectiveThis study was conducted to determine the apparent and standardized total tract digestibility (ATTD and STTD) of phosphorus (P) in corn, soybean meal (SBM), and canola meal (CM), and additivity of values for ATTD and STTD of P in corn, SBM, and CM in diets fed to growing pigs.MethodsThirty-six growing barrows (initial body weight of 21.6±1.7 kg) were placed in metabolism crates and allotted to a completely randomized design with 6 diets and 6 pigs per diet. Six diets were formulated using corn, SBM or CM as the sole source of P, or corn and SBM, or corn and CM, or corn, SBM, and CM as the P source in each diet, respectively. Fecal samples were collected for 5 d following a 7 d adaptation period to the diets.ResultsValues for ATTD and STTD of P in corn, SBM, and CM in growing pigs were 33.12% and 37.76%, 50.19% and 56.62%, 34.93% and 39.45%, respectively. The ATTD and STTD of P in SBM were greater (p<0.05) than those in corn and CM. However, there were no differences in the ATTD or STTD of P between corn and CM. The determined STTD of P in the mixture of corn and SBM, corn and CM, and corn, SBM, and CM is not different from the calculated STTD values.ConclusionValues for STTD of P in corn, SBM, and CM are additive in their mixture fed to growing pigs.
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