阅读说明：本技术 改善环江香猪生长性能和肉品质的饲料及饲喂方法 (Feed for improving growth performance and meat quality of Huanjiang fragrant pigs and feeding method ) 是由 赵曦晨 孔祥峰 刘雅婷 丁浩 王凯 于 2021-02-01 设计创作，主要内容包括：本发明公开了一种改善环江香猪生长性能和肉品质的饲料,所述饲料中蛋白质的质量百分比含量为18.42%或16.70%或14%。本发明所述的饲料可有效改善环江香猪的生长性能和肉品质,进而提高环江香猪的养殖效率。本发明所述饲料配方科学合理,与各阶段环江香猪的生长发育特点相适应,饲料产品的生产工艺简便,为常见的配合饲料生产方式,符合环江香猪的养殖实际情况。(The invention discloses a feed for improving the growth performance and meat quality of a Huanjiang fragrant pig, wherein the mass percentage of protein in the feed is 18.42 percent, 16.70 percent or 14 percent. The feed provided by the invention can effectively improve the growth performance and meat quality of the Huanjiang fragrant pig, and further improve the breeding efficiency of the Huanjiang fragrant pig. The feed formula of the invention is scientific and reasonable, is suitable for the growth and development characteristics of the Huanjiang fragrant pig at each stage, has simple and convenient production process of feed products, is a common compound feed production mode, and accords with the actual culture condition of the Huanjiang fragrant pig.)

1. The feed for improving the growth performance and the meat quality of the Xiangjiang pig is characterized in that the mass percentage of protein in the feed is 18.42 percent, 16.70 percent or 14 percent.

2. The feed according to claim 1, wherein the mass percentage of the protein in the feed is 18.42% at the 5-10 kg body weight stage; when the weight is 10-20 kg, the mass percentage content of protein in the feed is 16.70%; when the weight of the feed is 20-30 kg, the mass percentage content of the protein in the feed is 14%.

3. A feeding method for improving the growth performance and meat quality of Huanjiang pigs is characterized in that when the Huanjiang pigs are in a 5-10 kg weight stage, the addition amount of protein in feed is 18.42%; when the weight of the Huanjiang pig is in a 10-20 kg stage, the addition amount of protein in the feed is 16.70%; when the weight of the Huanjiang fragrant pig is 20-30 kg, the addition amount of protein in the feed is 14%.

Technical Field

The invention belongs to the technical field of feeds, and particularly relates to a feed for improving the growth performance and meat quality of a Huanjiang pig and a feeding method.

Technical Field

Pork is the main meat consumer product of residents in China and accounts for more than 60% of the whole meat consumption. Therefore, the safe supply of pork is critical to the national civilian life. With the progress of genetic breeding technology, the breeding efficiency of live pigs is greatly improved, the pork yield is continuously increased, and the demand of consumers on the pork quantity is basically met. The improvement of the breeding efficiency of domestic pigs is mainly benefited by the excellent quality breeding pigs introduced from abroad and the adoption of a modern breeding management mode, and the excellent quality breeding pigs introduced from abroad and having fast growth and high lean meat percentage quickly occupy the domestic pig market under the large environment of market economy. Although local pig breeds in China are rich in resources, the local pig breeds in China are slow in growth speed, low in lean meat percentage and high in fat percentage, so that the local pig market in China is impacted comprehensively, and some breeds even have been extinct. Meanwhile, local pig breeding in China lacks matched large-scale breeding standards, and large-scale development and utilization of the local pig breeding are severely restricted. Under the background of epidemic situation epidemic such as African swine fever in China, as local pigs are mainly bred by farmers, the biological safety level of the breeding farms is poor, and more local pig species face an extinct crisis. Therefore, the enhancement of the protection and the utilization of the pig resources of the excellent local variety in China is more urgent and important.

With the improvement of the living standard of residents in China, the demand of consumers on high-quality pork is increasing. Although the breeding technology improves the meat yield of the pigs, the breeding technology also brings about a plurality of problems of meat quality reduction and the like. The Guangxi Huanjiang pig is one of the excellent local pig breeds in China, can be eaten when the weight of the Guangxi Huanjiang pig reaches 6-8 kg, has the advantages of thin skin and thin bone, no fishy smell and no greasiness, freshness, tenderness, aroma and the like, can be used for making roasted suckling pigs and white-cut pigs, and is deeply popular with consumers. Therefore, the method can meet the demand of people on high-quality pork by enlarging the breeding scale of the Huanjiang fragrant pig. However, the feeding management of the Huanjiang fragrant pigs is relatively extensive at present, so that the problems of diarrhea, high mortality rate, slow growth and the like exist in pig raising production. In addition, the feed formula of the Huanjiang pig is not scientific and reasonable enough, and digestion and absorption are affected by insufficient or excessive protein supply of the feed and too high addition of green and coarse feed. Because the standard of the nutrition requirement of the Huanjiang fragrant pig is not established at present, the Chinese pig nutrition requirement standard (2004) is used as a reference to establish a feed formula in production. Local pigs in China are various in types, and have different physique, size and the like, and the standard is not necessarily suitable for the Huanjiang fragrant pigs. Therefore, the nutritional requirements and feeding standards of the Huanjiang fragrant pigs are established, and the method has important significance for the industrialized production of the Huanjiang fragrant pigs.

The post-weaning conservation phase is the key phase of the growth and development of the Xiangjiang pigs. The existing research mainly focuses on the influence of feed additives such as probiotics, prebiotics and amino acids on the growth performance, intestinal health and meat quality of the Xiangjiang pigs at the conservation stage, and no report is found on the research on the protein requirement of the Xiangjiang pigs suitable for the feed.

The insufficient or excessive supply of the protein serving as a material basis of the life activities of organisms can influence the growth and development of animals, such as reduction of reproductive performance of sows, feed intake of weaned piglets, daily gain and the like, and can also influence the carcass properties and meat quality of livestock and poultry, thereby reducing the breeding efficiency of the livestock and poultry. Diet protein is an important factor affecting pork quality. For example, protein feed restriction (5.4% CP reduction) can improve the meat quality of castrated boars, and reducing the diet protein level (3% CP reduction) can increase the intramuscular fat content of growing-finishing pigs. However, it has also been considered that reducing the feed protein levels (3.4% CP and 2.5% CP) in growing-finishing pigs does not affect their meat quality. In addition, increasing the protein level (14% CP-18% CP) of the diet of the long white pigs or the big white pigs reduces the water retention capacity and tenderness of the pork and reduces marbling. Similar reports have been made for local pig studies. For example, decreasing the diet protein level (by 1% CP) decreases the meat color score of 15-30 kg of Luchuan pigs, and increases marble score and intramuscular fat content. However, the protein level (17.91 percent CP and 15.52 percent CP in the stage of 10-20 kg, and 16.38 percent CP and 15.04 percent CP in the stage of 20-50 kg) of the feed does not influence the intramuscular fat content of the Chang pigs in the growing and fattening stages. Whether the protein level of the feed can affect the meat quality of the Huanjiang fragrant pig is not clear at present. Therefore, the determination of the appropriate feed protein addition amount of the Huanjiang pigs in the conservation stage has important practical significance for improving the breeding efficiency and reasonably utilizing protein feed resources, and simultaneously lays a foundation for the protection, development and utilization of excellent local pig resources.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the feed and the feeding method for improving the growth performance and the meat quality of the Huanjiang pigs.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the feed for improving the growth performance and the meat quality of the Xiangjiang pig contains 18.42% or 16.70% or 14% of protein by mass percent. Specifically, the mass percentage content of protein in the feed is 18.42% at the weight stage of 5-10 kg; when the weight is 10-20 kg, the mass percentage content of protein in the feed is 16.70%; when the weight of the feed is 20-30 kg, the mass percentage content of the protein in the feed is 14%.

The feeding method for improving the growth performance and the meat quality of the Huanjiang pigs is characterized in that when the Huanjiang pigs are in a 5-10 kg weight stage, the addition amount of protein in the feed is 18.42%; when the weight of the Huanjiang pig is in a 10-20 kg stage, the addition amount of protein in the feed is 16.70%; when the weight of the Huanjiang fragrant pig is 20-30 kg, the addition amount of protein in the feed is 14%.

The Huanjiang fragrant pigs involved in the invention include but are not limited to Huanjiang fragrant pigs in autonomous counties of south clan of Huanjiang, in particular Huanjiang fragrant pigs in four villages and towns of Ming Lun, Dongxing, Longyan and Shunle in the prefecture. The invention researches the protein requirement of the feed of the Huanjiang pig for the first time. The feed provided by the invention can effectively improve the growth performance and meat quality of the Huanjiang fragrant pig, thereby improving the breeding efficiency. The feed formula of the invention is scientific and reasonable, is suitable for the growth and development characteristics of the Huanjiang pigs in various weight stages, has simple and convenient production process of feed products, is a common compound feed production mode, and accords with the actual culture condition of the Huanjiang pigs.

Drawings

FIG. 1 is a secondary fitting curve of the ratio of the protein level of a feed to the feed weight of 5-10 kg of fragrant pigs around river;

FIG. 2 is a quadratic fitting curve of the protein level of the feed and the weight of 10-20 kg of Yunjiang fragrant pig powder;

FIG. 3 is a quadratic fitting curve of the protein level of the feed and the average daily gain of 10-20 kg of Xiangjiang pigs;

FIG. 4 is a secondary fitting curve of the protein level of a feed and the average daily feed intake of 20-30 kg of Xiangjiang pigs;

FIG. 5 is a secondary fitting curve of the protein level of a feed and the average daily gain of 20-30 kg of Xiangjiang pigs;

FIG. 6 is a secondary fitting curve of the protein level of the diet and the diarrhea rate of 20-30 kg of Xiangjiang pigs.

Detailed Description

1. Design of experiments

5-10 kg weight stage: by adopting a single-factor test design, 220 pigs with the fragrance of the girdling river and the weight of about 5kg are selected, the halves of the piglets and the castrated boars are randomly divided into 5 groups, each group has 8-10 repetitions, and each repetition has 5 pigs. The piglets and the castrated boars are raised in different stalls. 5 groups were fed with diets having crude protein levels of 14%, 16%, 18%, 20% and 22%, respectively, the feed raw material composition and nutritional ingredients being shown in Table 1. The test period was 28 days.

10-20 kg weight stage: by adopting a single-factor test design, selecting 84 pigs with a fragrant girdling pig and half pigs with a weight of about 10kg in a good health state, randomly dividing the pigs into 5 groups, and feeding the pigs in a single fence, wherein each group has 15-19 repetitions, and each repetition has 1 pig. The feed with crude protein levels of 12%, 14%, 16%, 18% and 20% was fed to each group, and the feed raw material composition and nutritional ingredients are shown in table 2. The test period was 28 days.

20-30 kg weight stage: by adopting a single-factor test design, 60 Huanjiang xiang pigs which are in good health state and have the weight of about 20kg and half of piglets and castrated boars are selected and randomly divided into 5 groups, each group is 12 in number of repetitions, and 1 pig is repeated every time, and are fed in a single fence. The feed is fed by 10%, 12%, 14%, 16% and 18% of the feed, and the raw material composition and the nutrient content of the feed are shown in table 3. The test period was 26 days.

The design of the feed formula of the Xiangjiang pig refers to Chinese pig nutrition requirement standard (2004), NRC (2012) and an ideal amino acid model, and uses a standard ileum digestible amino acid and digestion energy system. The formulation follows an equipotent principle, with the Lys, Met, Thr and Trp levels in each group remaining consistent and meeting the recommended amounts for the corresponding phase of NRC (2012), with other nutrient levels meeting or slightly exceeding the recommended amounts of NRC (2012). The experiment adopts powder feeding, free food intake and drinking water, less feeding and more meals, and the rest feeding management is carried out according to a local pig farm management manual.

Table 15 ~10 kg of feed formula (each raw material in parts by weight) for Huanjiang fragrant pig

Note: the corn, the bean pulp and the wheat bran are calculated according to the actually measured energy value and the crude protein value when the feed formula is designed; lysine is L-lysine (purity 98.5%), methionine is DL-methionine (purity 99%), threonine is L-threonine (purity 99%), and tryptophan is L-tryptophan (purity 99%); the premix is a mixture of mineral elements and vitamins, wherein the types of the mineral elements and the corresponding contents of the mineral elements in each kg of feed are respectively 128mg of copper, 97.6mg of manganese, 109mg of zinc and iron197.6mg, selenium 1mg, iodine 1mg, cobalt 1mg, vitamin A32500 IU, vitamin D and corresponding content in each kg of feed₃10000IU, vitamin E80 IU and vitamin K₃10mg of vitamin B₁10mg/kg, vitamin B₂25mg of vitamin B₆8mg of vitamin B₁₂0.075mg, D-biotin 0.075mg, folic acid 5mg, nicotinamide 100mg, D-pantothenic acid 50mg, choline 1600 mg. The same applies below.

Table 210-20 kg feed formula (each raw material in parts by weight) for Huanjiang fragrant pig

Table 320-30 kg feed formula (each raw material in parts by weight) for Huanjiang fragrant pig

2. Index measurement

(1) Growth performance

During the test period, the daily feed intake of the test pigs was recorded in columns. Fasting is carried out 12h before the test at each stage is finished, the fasting body weight of the test pig is weighed head by head, and the average daily gain, the average daily feed intake and the feed-weight ratio are calculated. The specific calculation formula is as follows:

daily gain (end weight-initial weight)/test day

Average daily food intake-daily food intake/test days per column

Average daily feed intake/daily gain per column

(2) Index of meat quality

After slaughtering, taking the longissimus dorsi sample, and detecting the conventional meat quality indexes including pH value, drip loss, meat color and the like according to the national agricultural industry standard (NY/T821-. In addition, the content of free amino acid in the muscle is detected by a full-automatic amino acid analyzer according to GB 5009.124-2016, and the content of long-chain fatty acid in the muscle is detected by a gas chromatograph according to GB 5009.6-2016.

(3) Fecal nitrogen content

Feces samples were collected 5 days before the end of the test, daily before feeding in the afternoon, 10% H by weight/volume (10:1)₂SO₄Fixing nitrogen in the solution. And finally, uniformly mixing and drying the excrement samples in the same column, and detecting the nitrogen content in the excrement samples by using a flow injection instrument.

3. Data statistics

Experimental data were analyzed using the GLM program of SAS (8.1) statistical software and multiple comparisons were performed by Duncan. All data are in columns as basic analytical units. P <0.05 indicates significant difference, and 0.05< P <0.10 indicates trend of difference.

The effect is as follows:

1. feeding effect of different crude protein level feeds on 5-10 kg of Huanjiang pigs

As can be seen from Table 4, the end weight, average daily feed intake, average daily gain and diarrhea rate of the various groups of Xiangjiang pigs did not change significantly (P > 0.05). The 16% CP group and 18% CP group significantly reduced the feed-to-weight ratio (P <0.05) compared to the 14% CP group. Although the diarrhea rate of the 5-10 kg Huanjiang pigs is not significantly influenced by the diet with different protein levels (P is greater than 0.05), the nitrogen content in the excrement is significantly influenced, and the nitrogen content in the excrement of the 16% CP group, the 18% CP group, the 20% CP group and the 22% CP group is significantly higher than that of the 14% CP group (P is less than 0.05), which is basically consistent with the change of the diarrhea rate of each group. In addition, analysis after quadratic curve fitting of the feed weight ratio found that the diet protein level to reach the optimum feed weight ratio (1.806) was 18.42% (fig. 1), which is close to the diet protein level of the 18% CP group. The results show that the feed weight ratio of the Huanjiang fragrant pig with 18% of CP can be obviously reduced by 5-10 kg, and the feed cost is further saved.

TABLE 4 influence of different protein level diets on growth performance, diarrhea rate and fecal nitrogen content of 5-10 kg of Xiangjiang pigs

As shown in table 5, compared with the 22% CP group, the muscle brightness values of the 18% CP group and the 20% CP group tended to decrease (P ═ 0.10), and the protein levels of different diets did not significantly affect other meat quality indexes of the 5-10 kg cijiang xiang pigs (P > 0.05). The above results demonstrate that the 18% CP or 20% CP diet can improve the meat quality of the cijiang xiang pigs by reducing the brightness values.

TABLE 5 influence of different protein level diets on the quality of longissimus dorsi of 5-10 kg Huanjiang pigs

As can be seen from Table 6, the contents of FAA, EAA, NEAA and TAA in the longissimus dorsi of the Xiangjiang pigs of 5-10 kg are not significantly affected by different protein-level diets (P is greater than 0.05), but the contents of free Met, Leu and Phe in the 14% CP group muscles are significantly higher than those in the other 4 groups (P is less than 0.05), and the content of free Gly in the 16% CP group muscles is significantly higher than those in the other 4 groups (P is less than 0.05). The above results indicate that a 16% CP diet can improve meat flavor by increasing muscle free Gly content, but too high a diet protein level can reduce the content of essential amino acids in the muscle portion.

TABLE 6 influence of different protein level diets on the content of free amino acids in the longissimus dorsi of 5-10 kg Huanjiang pigs (μ g/g)

Note: ala, alanine; arg, arginine; asp, aspartic acid; cys, cysteine; glu, glutamic acid; gly, glycine; his, histidine; ile, isoleucine; leu, leucine; lys, lysine; met, methionine; phe, phenylalanine; pro, proline; ser, serine; thr, threonine; tyr, tyrosine; val, valine; FAA, flavor amino acids; EAA, essential amino acids; NEAA, non-essential amino acids; TAA, total amount of amino acids.

As can be seen from Table 7, although the diets at different protein levels had no significant effect on the SFA, MUFA and PUFA content in the longissimus dorsi of 5-10 kg of Cyclojiang xiang pigs (P >0.05), the contents of longissimus dorsi C15:0, C17:0, C18:0, C20:1 and C22:3n3 (P <0.05) were significantly affected. Wherein the content of 18% CP group C15:0 is significantly higher than that of 14% CP group, 16% CP group and 20% CP group (P <0.01), and has no significant difference with 22% CP group; the 18% CP and 22% CP groups C17:0 content was significantly higher than the 14% CP and 20% CP groups (P <0.01), with no significant difference from the 16% CP group; the 14% CP group C18:0 content was significantly higher than the 16% CP group and the 22% CP group (P ═ 0.01); the 18% CP group C22:0 content was significantly higher than the 16% CP group (P ═ 0.10); the 20% CP group and 22% CP group C20:1 content was significantly higher than the 14% CP group (P ═ 0.01); the 18% CP and 20% CP groups C20:3n6 content was significantly higher than the 14% CP group (P ═ 0.04); the 20% CP group C22:3n3 content was significantly higher than the other groups (P ═ 0.01). The results show that although the total amount of MUFA and PUFA in the longissimus dorsi of the Huajiang xiang pigs of 5-10 kg is not influenced by different protein-level feeds, the contents of C15:0, C17:0, C22:0 and C20:3n6 can be obviously improved by 18% of CP feeds, and the contents of C20:1, C20:3n6 and C22:3n3 in the muscle can be obviously improved by 20% of CP feeds, so that the nutritional value of the Huajiang xiang pigs can be improved.

TABLE 7 influence of different protein level diets on the longissimus dorsi long chain fatty acid content (%)

Note: c14:0, myristic acid; c15:0, pentadecanoic acid; c16:0, palmitic acid; c16:1, palmitoleic acid; c17:0, heptadecanoic acid; c18:0, stearic acid; c18:1n9C, oleic acid (cis); c18:1n9t, oleic acid (trans); c18:2n6C, linoleic acid (cis); c18:3n6, gamma-linolenic acid; c20:0, arachidic acid; c20:1, arachidonic acid; c20:2, eicosadienoic acid; c20:3n6, arachidonic acid; c20:4n6, arachidonic acid; c22:0, behenic acid; c22:3n3, docosatrienoic acid; c22:6n3, docosahexaenoic acid; c24:0, tetracosanoic acid; SFA, saturated fatty acids; MUFA, monounsaturated fatty acid; PUFA, polyunsaturated fatty acids.

In conclusion, the feed protein level of 5-10 kg of Huanjiang fragrant pigs reaching the optimal feed weight ratio is 18.42%; the meat quality of the fragrant pig with the 18% CP or the 20% CP can be improved by reducing the brightness value and increasing the content of saturated fatty acid and unsaturated fatty acid in muscle; the 16% CP diet can improve meat flavor by increasing the content of flavor amino acid Gly in muscle.

1.2 feeding effect of different crude protein level feeds on 10-20 kg of Huanjiang pigs.

As shown in Table 8, the diets with different protein levels have no significant effect on the weight of 10-20 kg of Yunjiang xiang pigs, the average daily feed intake and the feed-weight ratio (P >0.05), but have significant effects on the diarrhea rate and the fecal nitrogen content (P < 0.05). Wherein, the diarrhea rate of the 18% CP group and the 20% CP group is obviously higher than that of the other 3 groups (P <0.05), the fecal nitrogen content of the 18% CP group and the 20% CP group is also higher than that of the other 3 groups, although the fecal nitrogen content of the 18% CP group is numerically higher than that of the 14% CP group, no statistical difference exists, and the change of the fecal nitrogen content of each group is basically consistent with the result of the diarrhea rate. In addition, the average daily gain of the 14%, 16% and 18% CP groups tended to be higher than that of the 12% CP group (P ═ 0.07), and the average daily gain of the 22% CP group was 12.6% higher than that of the 12% CP group, but was not statistically significant. The feed protein levels to achieve the best end and average daily weight gains were found to be very close by a quadratic curve fit of the end and average daily weight gains (fig. 2, fig. 3), with inflection points at (16.70, 26.28) and (16.75, 527.28), respectively, which closely approximate the experimental effect of the 16% CP group. The results show that the average daily gain of the 16% CP feed can be improved under the condition that the diarrhea rate of the 10-20 kg Huanjiang pigs is not influenced.

TABLE 8 influence of different protein level diets on the growth performance, diarrhea rate and fecal nitrogen content of 10-20 kg of Xiangjiang pigs

As shown in Table 9, the meat color and the meat color of the Huanjiang pigs of 10-20 kg are graded and sorted by different protein levelsGraininess score, drip loss, cooked meat rate and pH_48hWithout significant influence (P)>0.05), but the pH value 45min after slaughter of the xiangjiang xiang pigs in the 18% CP group and the 20% CP group was significantly higher than that in the other 3 groups (P)<0.05). The normal pH value at 45min after slaughter is about 6.3, and the pH value is too low (pH)_45min<5.80) may lead to the development of PSE meat (white muscle), while too high a pH (pH)_45min>6.70) may be associated with insufficient storage of muscle glycogen and may lead to DFD meat (dark dry meat). Therefore, either too high or too low of post-mortem pH can affect consumer sensory evaluation and pork shelf life. The pH value of pork reaches the minimum level (5.6-5.8) after slaughtering for 48 hours, then the pork is kept for a period of time, and then the pH value slowly rises along with autolysis and growth of microorganisms. The above results indicate that pork appearance of the Xiangjiang pigs in the 16% CP group, the 18% CP group and the 20% CP group is normal, but pork appearance of the Xiangjiang pigs in the 20% CP group is more beneficial to prolonging shelf life.

TABLE 9 influence of different protein level diets on the quality of longissimus dorsi of 10-20 kg Huanjiang pigs

As shown in table 10, although the diets at different protein levels had no significant effect on the NEAA content in the longissimus dorsi free amino acids of 10-20 kg cijiang xiang pigs (P >0.05), the EAA and TAA contents of the 12% CP group tended to be lower than those of the other 4 groups (P ═ 0.08). Furthermore, FAA content was significantly higher in the 18% and 20% CP groups than in the other 3 groups (P ═ 0.003). Free Asp, Glu, Arg, Ala and Gly in muscle are important flavor amino acids and can influence the flavor taste of pork, and the content of free Asp in 18% CP group tends to be higher than that in 12% CP group and 20% CP group (P is 0.07); the free Glu content was significantly higher in the 18% CP group and the 20% CP group than in the other 3 groups (P ═ 0.009); the content of free Arg in the 12% CP group was significantly higher than in the 16%, 18% and 20% CP groups (P ═ 0.004); free Ala content in the 12% CP group was significantly lower than in the 16%, 18% and 20% CP groups (P ═ 0.04); the free Gly content of the 12% CP group was significantly lower than that of the other 4 groups (P ═ 0.02). In addition, the free His, Thr, Ser and Tyr content in the 12% CP group is significantly higher than that in the 20% CP group (P < 0.05); the free His, Thr, Ser and Tyr content of the 12% CP group is obviously higher than that of the 20% CP group (P < 0.05); the free Ser and Tyr content of the 16% CP group is obviously higher than that of the 20% CP group (P < 0.05); free Met, Ala and Pro content of 12% CP group was significantly lower than 18% CP group and 20% CP group (P < 0.05); the 12% CP group branched chain amino acids (Val, Ile and Leu) content was significantly lower than the other 4 groups (P < 0.05). The results show that the 18% CP or 20% CP diet can obviously improve the contents of FAA and EAA in the longissimus dorsi of the Huajiang fragrant pigs by 10-20 kg, and improve the nutritional value of the Huajiang fragrant pigs.

TABLE 10 influence of different protein levels of diet on the content of free amino acids in the longissimus dorsi of 10-20 kg Huanjiang pigs (μ g/g)

Note: ala, alanine; arg, arginine; asp, aspartic acid; cys, cysteine; glu, glutamic acid; gly, glycine; his, histidine; ile, isoleucine; leu, leucine; lys, lysine; met, methionine; phe, phenylalanine; pro, proline; ser, serine; thr, threonine; tyr, tyrosine; val, valine; FAA, flavor amino acids; EAA, essential amino acids; NEAA, non-essential amino acids; TAA, total amount of amino acids.

As can be seen from Table 11, the MUFA content of the longissimus dorsi of the loop-river fragrant pigs in the 14% CP group, 10-20 kg, was significantly lower than that in the 12% CP group and the 18% CP group (P ═ 0.02). In addition, the 20% CP group C15:0, C17:0, C22:0 and C22:6n3 content was significantly higher than the 12% CP group (P < 0.05); the 12% CP group C20:1 and C18:2n6C content was significantly lower than the other groups (P < 0.05); the 12% CP group C20:0 content was significantly higher than the 20% group (P ═ 0.02); the content of 12% CP group C18:1n9t (P ═ 0.08), C18:1n9C (P <0.05) was significantly higher than 14% CP group and 16% CP group; the 14% CP group C18:3n6 content was significantly higher than the other 4 groups (P ═ 0.04). The results show that the 20% CP diet can improve the contents of the muscle C15:0, C17:0, C22:0, C22:6n3, C20:1 and C18:2n6C of the Huanjiang pigs by 10-20 kg, and is beneficial to improving the nutritional value of the Huanjiang pigs.

TABLE 11 influence of different protein levels of diet on the longissimus dorsi long chain fatty acid content (%)

Note: c14:0, myristic acid; c15:0, pentadecanoic acid; c16:0, palmitic acid; c16:1, palmitoleic acid; c17:0, heptadecanoic acid; c18:0, stearic acid; c18:1n9C, oleic acid (cis); c18:1n9t, oleic acid (trans); c18:2n6C, linoleic acid (cis); c18:3n6, gamma-linolenic acid; c20:0, arachidic acid; c20:1, arachidonic acid; c20:2, eicosadienoic acid; c20:3n6, arachidonic acid; c20:4n6, arachidonic acid; c22:0, behenic acid; c22:3n3, docosatrienoic acid; c22:6n3, docosahexaenoic acid; c24:0, tetracosanoic acid; SFA, saturated fatty acids; MUFA, monounsaturated fatty acid; PUFA, polyunsaturated fatty acids.

In conclusion, the feed protein level of 10-20 kg of Huanjiang fragrant pigs reaching the optimal production performance is 16.70%; although none of the 16%, 18% and 20% CP diets affected the appearance color of pork, the 20% CP diet was more conducive to extending shelf life; both the 18% CP and 20% CP diets improved the meat quality of the cijiang xiang pigs by increasing muscle FAA and EAA content. In addition, the 20% CP diet can improve the nutritional value of the Huanjiang fragrant pig by increasing the content of saturated fatty acid and unsaturated fatty acid in muscle.

1.3 feeding effect of different crude protein level feeds on 20-30 kg of Huanjiang pigs

As shown in table 12, different protein level diets had significant effects on the end weight, average daily feed intake, average daily gain, diarrhea rate, and fecal nitrogen content of 20-30 kg cijiang xiang pigs (P < 0.05). The average daily food intake was significantly higher in the 14% CP group and the 16% CP group than in the 18% CP group (P ═ 0.03), with no significant difference from the 10% CP group and the 12% CP group (P > 0.05). The average daily gain between the 10%, 14% and 16% CP groups was not significantly different, but was significantly higher than that of the 18% CP group (P ═ 0.001), and the 18% CP group and the 12% CP group were not significantly different, and accordingly, the end weight and the average daily gain showed the same trend (P ═ 0.08). The material weight ratio of the 10% CP group and the 16% CP group is significantly lower than that of the 18% CP group (P is 0.045), and the 12% CP group and the 14% CP group have no significant difference from the 18% CP group. In addition, the diarrhea rate and fecal nitrogen content were significantly higher in the 18% CP group than in the other 4 groups (P <0.05), and the change in fecal nitrogen content for each group was consistent with the results for diarrhea rate. In addition, the inflection points to achieve the optimal average daily food intake (fig. 4), average daily weight gain (fig. 5) and minimum diarrhea rate (fig. 6) were found to be (14.07, 1576.85), (13.64, 534.08) and (12.44, 10.87), respectively, by performing quadratic curve fitting on the average daily food intake, average daily weight gain and diarrhea rate. The results show that the average daily feed intake and the average daily gain of 20-30 kg Huanjiang pigs in the 14% CP group are optimal.

TABLE 12 influence of different protein level diets on the growth performance, diarrhea rate and fecal nitrogen content of 20-30 kg of Xiangjiang pigs

As shown in Table 13, the feed with different protein levels had a maximum myocyte yellowness value b, marbling score and pH value of 20-30 kg of Huajiang fragrant pigs_45minHas significant influence (P)<0.05). Wherein the 14% CP group yellowness value b is significantly higher than the other 4 groups (P ═ 0.02); the 12% CP group marbling score was significantly higher than the 16% CP group and the 18% CP group (P ═ 0.02), but the 16% CP group, the 18% CP group, and the 10% CP group and the 14% CP group were not significantly different; pH of 10% CP group_45minSignificantly lower than the other 4 groups (P)<0.01), 18% CP group pH_45minThe content of the protein in the protein is significantly higher than that in the 12% CP group, but has no significant difference with the 14% CP group and the 16% CP group. The 10% CP group cooked meat rate tended to be higher than the 16% and 18% CP groups (P ═ 0.08), but did not differ significantly from the 12% and 14% CP groups. The results show that the meat quality of 12% CP group Huanjiang pigs is better.

TABLE 13 influence of different protein-level diets on the quality of longissimus dorsi of 20-30 kg Huanjiang pigs

As shown in table 14, the FAA content of 20-30 kg of the longissimus dorsi of the cijiangxiang pigs in the 10% CP group was significantly higher than that in the 16% CP group and the 18% CP group (P ═ 0.02), and the EAA and TAA content in the 10% CP group and the 12% CP group was significantly higher than that in the 18% CP group (P ═ 0.099, P ═ 0.02). Muscle free Asp, Glu, Arg, Ala and Gly are important flavor amino acids, but the contents of single flavor amino acids in the longissimus dorsi of 20-30 kg of the Xiangjiang fragrant pigs are not obviously influenced by the diet at different protein levels (P is more than 0.05); muscle free His and Thr content in the 10% CP group was higher than in the 18% CP group (P ═ 0.09, P ═ 0.004); muscle free Ser (P <0.04), Ile (P <0.05) and Leu (P ═ 0.08) were all lower in the 18% CP group than in the other groups. The results show that the feed protein level (18% CP) can reduce the contents of longissimus dorsi flavor amino acid and branched chain amino acid of 20-30 kg of the Huanjiang pigs, and further reduce the nutritional value of the Huanjiang pigs.

TABLE 14 Effect of different protein level diets on the content of free amino acids in the longissimus dorsi of 20-30 kg Huanjiang pigs (. mu.g/g)

Note: ala, alanine; arg, arginine; asp, aspartic acid; cys, cysteine; glu, glutamic acid; gly, glycine; his, histidine; ile, isoleucine; leu, leucine; lys, lysine; met, methionine; phe, phenylalanine; pro, proline; ser, serine; thr, threonine; tyr, tyrosine; val, valine; FAA, flavor amino acids; EAA, essential amino acids; NEAA, non-essential amino acids; TAA, total amount of amino acids.

As shown in Table 15, the MUFA content in the longissimus dorsi of the 18% CP group of 20-30 kg Huanjiang pigs was lower than that in the 14% CP group (P ═ 0.09). In addition, the 18% CP group C15:0(P <0.05) and C20:1(P ═ 0.08) contents were higher than the other groups, but the C18:1n9C content was significantly lower than the 12% CP group and the 14% CP group (P < 0.05). The above results indicate that too high a diet protein level (18% CP) will reduce the MUFA content by reducing the muscle C18:1n9C content, thereby affecting the nutritional value of cijiang fragrant pig pork.

TABLE 15 influence of different protein level diets on the longissimus dorsi long chain fatty acid content (%) -of 20-30 kg Huanjiang pigs

Note: c14:0, myristic acid; c15:0, pentadecanoic acid; c16:0, palmitic acid; c16:1, palmitoleic acid; c17:0, heptadecanoic acid; c18:0, stearic acid; c18:1n9C, oleic acid (cis); c18:1n9t, oleic acid (trans); c18:2n6C, linoleic acid (cis); c18:3n6, gamma-linolenic acid; c20:0, arachidic acid; c20:1, arachidonic acid; c20:2, eicosadienoic acid; c20:3n6, arachidonic acid; c20:4n6, arachidonic acid; c22:0, behenic acid; c22:3n3, docosatrienoic acid; c22:6n3, docosahexaenoic acid; c24:0, tetracosanoic acid; SFA, saturated fatty acids; MUFA, monounsaturated fatty acid; PUFA, polyunsaturated fatty acids.

In conclusion, the average daily feed intake and average daily gain of 20-30 kg of Huanjiang pigs reach the best value when the protein level of the feed is 14%; the 12% CP diet can improve the meat quality of the Huanjiang pig, but the diet with high protein level (18% CP) can reduce the meat quality of the Huanjiang pig by 20-30 kg by reducing the contents of longissimus dorsi flavor amino acid, branched chain amino acid and MUFA.