Two tea polyphenols in the pig application effect

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 of weaned piglets after 35 d; the small intestinal mucosa CAT, GSH and SOD The contents of CAT, GSH and SOD in the small intestine mucosa increased by 55.8%, 50.0% and 55.5% (P < 0.05), respectively, and the content of malondialdehyde decreased by 18.1% (P < 0.05), which enhanced the antioxidant capacity of piglets.

This shows that tea polyphenols can regulate the antioxidant capacity of pigs and improve the health level of the organism.

3 Effect on the immunity of the body

The level of body immunity is closely related to the antioxidant function, and it was found that tea polyphenols can regulate the non-specific and specific functions of the animal body, and then regulate the immune function. Tea polyphenols can act as immunomodulators to increase the activity of natural killer cells, macrophages and complement, and regulate the synthesis of cytokines, thus regulating the non-specific immunity of the body. On the other hand, tea polyphenols promote the secretion of antibodies by lymphocytes and increase the specific immunity of the body. Yan Li et al. found that IgA concentration in the jejunum of piglets treated with 0.4% and 0.8% superfine tea powder increased by 18.2% and 26.8% (P < 0.05), respectively, and IL-2 concentration increased by 20.6% (P < 0.05) compared with the control group after 35 d of addition to the diet, and there was no significant effect when the addition amount was 0.2%. Li Yongyi et al. found that tea polyphenols promoted the differentiation of T cells to CD4+ and inhibited the differentiation to CD8+, increased secretion of interleukin 2 and 4 by lymphocytes, increased IgA, IgG and IgM content in blood, and increased immune function of piglets.

4 Effect on meat quality

Meat quality is an important index of pig production. Long-distance transportation or slaughtering causes stress to pigs, and the body cannot effectively remove free radicals, which will cause oxidative damage to muscles and increase the lactic acid content in pork, leading to a decrease in pH and lowering the quality of pork. Tea polyphenols can effectively relieve the oxidation state of the body, reduce the lactic acid content in muscle, reduce muscle drip loss and enhance water retention; meanwhile, they can prevent fatty acid oxidation in pork, reduce cholesterol content and improve meat quality. Xu Kun et al. reported that after 90 d of fattening pigs treated with tea polyphenols in the diet, the pH of pork in the test groups with 0.1% and 0.3% of addition significantly increased and the water loss rate decreased, while the effect on meat quality was less at 0.5% of addition. The experimental results of Wang et al. showed that the pork meat color a value increased by 70.8% (P < 0.09) after the addition of 1.0% of tea polyphenols in the ration compared with the control group, and there was a trend of improvement on pork tethering power and tenderness. Similar results were obtained in the studies of Yulong Wang et al. and Yao Bo et al. And one study found that the addition of 0.04% tea polyphenols in the ration treated fattening pigs for 6 weeks, and there was a trend of increase in pork pH after 24h of slaughter (P=0.09), but in general tea polyphenols treatment had no significant effect on meat quality, and similar results were obtained by Jun Chen on growing pigs with eye muscles. The results suggest that appropriate levels of tea polyphenol addition can improve pork quality, while the differences in results between studies may be due to different amounts of addition and different treatment cycles.

5 Effect on reproductive performance of sows

It was found that tea polyphenols improve animal reproductive performance, and the main mechanisms of action include: (1) increasing the antioxidant level of sows to protect oocytes from oxidative stress damage; (2) increasing the immune function of sows, increasing the immunoglobulin content in colostrum, and thus improving piglet survival; (3) increasing the concentration of progesterone in sow serum, which is beneficial to embryo development and improving embryo survival. Xiao Yong found that when 200 mg/kg and 300 mg/kg of catechins were added to the diets of post-breeding sows (3-5 litters), the number of live litters increased by 33.3% and 31.0% (P < 0.05), respectively, and the number of stillbirths decreased by 88.0% (P < 0.05) compared with the control group; when 400 mg/kg was added, the reproductive performance of sows tended to increase, but it was not In addition, the addition of tea polyphenols significantly increased the content of immunoglobulin IgG and IGM in colostrum, and increased CAT, GSH and SOD in sow serum. The results of Xing-Yan Zhang et al. showed that the addition of 100 mg/kg tea polyphenols to the diet of primiparous sows, fed from 3 d of breeding to weaning, showed that the litter size of sows in the tea polyphenols-treated group increased by 1.46 piglets (P < 0.05), the litter size of live piglets increased by 1.76 piglets (P < 0.05), and the average weaning litter size increased by 1.1 piglets (P < 0.05) compared with the control group. The sows' estrus interval was 1.45 d earlier than that of the control group (P < 0.05), the reproductive performance was improved, and the antioxidant indexes in the sows' serum were significantly improved.

6 Semen preservation

In order to improve the utilization rate of breeding boars and reduce reproductive diseases in livestock, preserving semen for artificial insemination has become a widely used technique, which can effectively improve reproductive efficiency. It is worth noting that reactive oxygen species generated during semen preservation can damage spermatozoa and reduce their activity, while the antioxidant function of tea polyphenols helps semen preservation. Dongqi Xie et al. reported that the addition of tea polyphenols to semen basal dilutions revealed that sperm survival, sperm quality and total antioxidant capacity of sperm were significantly improved when adding 0.02%, 0.04% and 0.08% mass fractions of tea polyphenols, and the malondialdehyde and bacterial content of semen were significantly lower than that of the control group; the effect was not significant when the addition amounts were 0.01% and 0.16%. Huang Mingguang et al. added tea polyphenols at a concentration of 0.04% to the sperm dilution solution for semen cryopreservation, and the sperm viability of the tea polyphenols-treated group was 54.5% higher than that of the control group after semen thawing (P < 0.05), while the quality of sperm after freezing was not significantly affected when the added concentration was higher or lower than 0.04%.