1 The effect of tea polyphenols on growth performance
Tea polyphenols can increase the activity of CAT and other antioxidant enzymes, and at the same time can synergize with vitamin C to increase the antioxidant level of the body. In addition, tea polyphenols kill pathogenic bacteria by binding to viral proteins and other substances, or metabolizing to produce hydrogen peroxide, and also promote the growth of beneficial bacteria to improve the intestinal environment and the health level of the organism, thus promoting growth. Li Yongyi et al. autonomously divided into three groups, the diets were supplemented with 0, 0.05%, 0.1% of tea polyphenols, and each diet treatment was divided into stress and non-stress groups, and the stress group was injected with 10 mg/kg body weight of herbicidal fast to cause oxidative damage in piglets so as to construct a stress model, and the results showed that the tea polyphenols treatment group had no significant effect on the growth performance of the non-stress group, while the average daily weight gain of the emergency group was increased by 138.2%, 294.4% (P < 0.05), average daily feed intake increased by 58.5%, 125.2% (P < 0.05), and meat ratio decreased by 37.1%, 45.7% (P < 0.05), which significantly improved the growth performance. Xu Kun et al. used fattening pigs as experimental subjects, and the average daily weight gain of fattening pigs increased by 7.8%, 11.9%, and 14.0% after adding 0.1%, 0.3%, and 0.5% of tea polyphenol preparation to the ration, respectively (P < 0.05). One study reported that the addition of 0.04% tea polyphenols to the feed significantly increased the net weight gain and average daily weight gain of fattening pigs after 6 weeks, similar to the results of Chao Yame et al. on fattening pigs. In contrast, Wang Jianhua and Wang Yulong found that tea polyphenols (added at 0.5% and 1.0%) and tea extract (added at 250g/t and 500g/t) had no significant effect on the growth performance of fattening pigs. The inconsistency in the results of different trials may be caused by the inconsistent nutritional levels of the base feeds used in the trials, the treatment cycles, and the different purity and addition of tea polyphenols.
2 Effect on antioxidant capacity
Oxidative stress can reduce animal immunity and production performance, tea polyphenols as feed additives have a strong antioxidant capacity, can effectively scavenge free radicals and prevent oxidative damage to the body. The ways in which tea polyphenols improve the antioxidant level of the body include.
(1) phenolic hydroxyl groups provide hydrogen ions, which react with oxygen radicals and abort oxidative chain reactions.
(2) Inhibiting the activity of free radical light-emitting enzymes such as lipoxygenase and peroxidase.
(3) increasing antioxidant activities such as GSH and SOD.
(4) regulating Nrf2, MAPK and other signaling pathways.
Zhang Xiangyan et al. studied with reserve sows and found that the addition of 100 mg/kg of tea polyphenols to the basal ration increased the total serum antioxidant capacity of sows by 22.73% and 11.14% at 90 d gestation and 10 d postpartum, respectively (P < 0.05), and reduced the malondialdehyde content by 28.68% and 12.38%, respectively (P < 0.05), with improved antioxidant capacity. The SOD and GSH contents in the eye muscle of growing pigs increased significantly when tea polyphenols were added at 300 mg and 400 mg per kg of diet, in which the SOD content increased by 32.6% and 30.3% (P < 0.05), GSH content increased by 18.8% and 32.2% (P < 0.05), and malondialdehyde content decreased by 48.0% and 53.3% (P < 0.05) in the eye muscle of the two groups, respectively. 53.3% (P < 0.05). Similarly, the addition of 400 mg/kg of tea polyphenols to the diets of fattening pigs significantly increased the hepatic antioxidant capacity and significantly affected the expression of related genes. In a study on piglets, it was found that the addition of 0.8% superfine tea powder (containing 25% tea polyphenols) to the diet increased the serum CAT, GSH and SOD levels by 73.9%, 477.8% and 84.6%, respectively (P < 0.05), and decreased malondialdehyde levels by 17.9% (P < 0.05) in the treated group ...
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