In June 2000, the US Food and Drug Administration (FDA) approved selenium-enriched yeast Sel-PlexTM (SP) as an organic selenium source for broilers. Typically, the selenium added to the animal feed is an inorganic form of sodium selenate (NaSe). SP is a mixture containing various organic selenium compounds (Kelly et al., 1995), the main form being selenomethionine in the yeast cell protein component. Organic selenium in SP is readily available and can be actively absorbed from the intestine via the Na+-dependent neutral amino acid pathway, while selenite is passively absorbed (Schrauzer, 2000). In addition, it has been reported that SP-induced growth is more effective than sodium selenate, which can accelerate the feather growth rate of slow-feeding male broiler chickens and normal female broiler chickens (Edens et al., 2000). At the same time, in terms of accumulation and retention in broiler tissues (Norheim et al., 1985) and in reducing thoracic muscle drip loss (Edens, 1996; Downs et al, 2000; Naylor et al, 2000), SP is superior to sodium selenate. The beneficial effects of adding SP have spurred interest in the poultry industry. Therefore, it is crucial to clarify the effects of organic selenium on the physiological and biochemical stability of broilers.
The purpose of this study is as follows: (1) to determine the effect of selenium source on the performance of broilers; (2) to determine the effect of selenium source on the yield of broiler carcass; (3) to determine the effect of selenium source on broiler breast muscle drip loss; 4) Determine the effect of selenium source on serum thyroxine levels in broilers.
1 Materials and methods 1.1 Animal welfare
The project was accredited by the Animal Management and Use Committee of the State University of North Carolina and under the supervision of the committee. Animal management and use instruction manuals were used in the trial to manage all animals used in the test methods.
1.2 Test treatment
A series of experiments were conducted to determine the effect of SP on the performance of high-yield Arbor Acres x Arbor Acres cocks. Place 40 chickens in each of the 32 flat chickens. The area of ​​each chicken bar is 1.09 × 3.72 m2. There are 2 feeders, 1 pula pine drinker and fresh pine shavings in each chicken bar. Bedding.
1.3 Test diet
The trial used chicks, growth and finishing diets from the North Carolina Agricultural Research Service (Table 1). The young chicks were fed broilers aged 1-16 days, containing 3 177 kcal/kg metabolizable energy and 22.5% crude protein; the growing diet was fed broilers aged 16-35 days, containing 3 168 kcal/kg of metabolic energy and 19.5% crude protein; the finishing diet was fed broilers aged 35-42 days, containing 3 160 kcal/kg metabolizable energy and 17.5% crude protein. SP or sodium selenate was added at a level of 0.2 mg of selenium per kg of feed. The young, growing, and finishing diets contained 0.28, 0.28, and 0.24 mg/kg selenium, respectively. The average feed consumption per chicken was adjusted to 2 lb. for young chicks, 5 lb for growing diet, and 2 lb for finishing diet. A completely random statistical design was arranged using a 2 x 2 factor.
Add selenium to the diet as follows: diet 1: no selenium added; diet 2: sodium selenate at 0.2 mg/kg selenium; diet 3: SP at 0.2 mg/kg selenium; day Grain 4: Sodium selenate (0.1 mg/kg selenium) + SP (0.1 mg/kg selenium) was added.
1.3 Measurement indicators
Body weight (BW) was measured at 2, 4, and 6 weeks of age, and feed conversion ratio (FCR) and mortality were calculated over 6 weeks. A total of 40 chickens were randomly drawn from each treatment to calculate the percentage of each divided part of the body weight. At 6 weeks of age, 20 chickens were drawn from each treatment to determine the loss of pectoral muscle drip. During the carcass processing, the pale, soft, juicy (PSE) state of the chest muscles and the incidence of PSE between treatments were determined. At 2, 4, and 6 weeks of age, 20 chickens were sampled from each treatment and blood samples were taken to determine the levels of serum thyroid hormone, thyroxine (T4), and triiodothyronine (T3).
1.4 Statistical analysis
Statistical analysis of the test data was performed using a general linear model statistical analysis (SAS, 1996). The difference between the means was determined by the least significant difference method (SAS, 1996), and the difference significance was expressed as p < 0.0.5.
Table 1 % of basic diet composition
| ingredient | Young chick diet | Growing diet | Finishing diet |
Grain soybean limestone dicalcium phosphate poultry fat poultry coarse grinding powder | 59.08 | 68.61 | 76.62 |
2 test results
2.1 Production performance
Tests have shown that the performance of broilers supplemented with SP is significantly improved compared to broilers without selenium or sodium selenate (Table 2). At 42 days of age, the weight of SP broilers fed was higher than that of broilers fed no selenium or sodium selenate. The broiler weight of the selenate and SP combination treatment groups did not increase compared with the SP group. All selenium sources can improve FCR, and adding SP or SP+ sodium selenate treatment is better than adding only sodium selenate. Compared with the sodium selenite group and the non-added selenium group, although the broiler chickens in the SP group increased their body weight at 2 weeks of age, they showed significant effects at 4 to 6 weeks of age. The FCR of both selenium sources was increased compared to the non-selenium-treated group. In terms of raw feathers, feeding 0.2mg/kg SP increased compared with sodium selenate and no selenium group, although the effect of 0.1mg/kg SP and 0.1mg/kg sodium selenate combination group was between SP and sodium selenate. However, it is still significantly better than no selenium group (Table 2). Table 2 Effect of selenium source on average body weight, feed conversion ratio, mortality and feather weight
deal with | Weight/kg | Feed/weight | mortality rate/% | Feather weight / (live weight /%) |
| Diet 1 Diet 2 Diet 3 Diet 4 SEM | 2.38 b 2.43 a,b 2.45 a 2.45 a 0.99 | 1.93 a 1.87 b 1.84 b,c 1.82 c 0.005 | 2.3a 2.5 a 2.3 a 2.3 a 0.01 | 6.24 c 6.55 b 6.95 a 6.62 a,b 0.005 |
Note: a, b, c indicates that the average value of different superscripts in one column is significantly different (P<0.05), the same below.
2.2 Production of carcass segmentation
According to the percentage of carcass weight, the visceral, claw and neck yields of SP treated chickens were relatively high (Table 3). SP treatment of chicken calves and thighs accounted for an increase in carcass weight percentage compared to chickens without selenium treatment, and the weight percentage of large pectoral muscles was slightly reduced (Table 4).
Table 3 Effect of selenium source on the percentage of carcass segmentation in carcass
| Source of selenium | Internal organs | claw | head | neck | fat | rib cage |
| Diet 1 Diet 2 Diet 3 Diet 4 SEM | 13.84ab 13.91ab 14.78a 13.29ab 0.35 | 5.13ab 5.33ab 5.42a 5.38ab 0.10 | 2.96a 2.96a 3.01a 3.07a 0.06 | 5.04ab 4.84ab 5.26a 4.96ab 0.11 | 1.47a 1.47a 1.50a 1.46a 0.02 | 6.35a 6.58a 6.57a 6.69a 0.17 |
Table 4 Effect of selenium source on the percentage of carcass segmentation in carcass
| Source of selenium | Calf | thigh | wing | Large pectoral muscle | Pectoralis minor muscle | skin | Back |
| Diet 1 Diet 2 Diet 3 Diet 4 SEM | 12.18ab 12.58ab 12.86a 12.58ab 0.18 | 15.06a 15.29a 15.49a 15.44a 0.24 | 9.56a 9.73a 9.87a 9.70a 0.19 | 16.69a 16.37ab 15.90b 16.12ab 0.22 | 4.28a 4.15a 4.14a 4.21a 0.07 | 2.43a 2.39a 2.48a 2.37a 0.10 | 18.25a 17.57a 18.02a 17.76a 0.27 |
2.3 Pectoral muscle drip loss
Compared with feeding SP and not adding selenium, the loss of water in the chest muscle of the sodium selenate chicken was increased.
2.4 serum thyroid hormone
Serum T4 levels in chickens not treated with selenium were higher than those treated with SP or sodium selenate. No difference in serum T4 due to selenium source was observed at 2 to 6 weeks of age. The serum T3 level of the seldom-free broiler chicken was lower than that of the broiler with sodium selenate or SP. The serum T3 level of the selenate-treated chicken was slightly lower than that of the broiler fed SP.
2.5 PSE pectoral muscle
The data showed that SP treatment reduced the incidence of PSE in the chest muscles of broilers fed in spring and summer compared to sodium selenate. In reducing the incidence of PSE meat, lower levels of SP (0.1 mk/kg selenium) are equivalent to or better than higher levels of sodium selenate (0.3 mk/kg selenium).
3 Discussion
According to the National Research Council (1994), the amount of selenium that can support the growth and development of normal broilers is 0.1 mg/kg. In this study, the average amount of selenium in the basal diet was 0.26 mg/kg, which should meet the needs of broilers for selenium, but the data from this trial showed that broilers with faster growth and higher yield had more selenium. High demand, and the addition of organic selenium is better than inorganic selenium. The data from this trial showed that broilers fed selenate were lagging behind broilers fed SP at 6 weeks of age, and these broilers were slow to grow in the first 5 weeks (Edens, 1996, 2001; Edens et al., 2000), meaning Broilers fed selenate lost metabolic energy, while the metabolic energy of SP broilers was preserved and stored. These observations are consistent with the report of Choct et al. (2004). Choct et al. found a similar increase in FCR in broilers fed organic selenium.
Selenium in sodium selenate may be related to the oxidation process. The oxidation process can promote the damage of cell membrane after broiler death and accelerate the water loss of the processed chest muscle. The drip loss of the pectoral muscle is neither due to the addition of SP nor because no selenium is added, but the addition of sodium selenate causes the highest rate of drip loss in the broiler's chest muscles. These data are consistent with data observed by Mahan Ìs (1999) pigs (13.7% reduction in drip loss) and Downs et al (2000) and Hess et al (2003) in broiler chicks (47% reduction at 24 h after slaughter). The data from this study showed that the loss of pectoral muscle drip loss on broilers fed organic selenium was 17% lower than that of broilers fed sodium selenate after 5 days of slaughter.
The problem of high incidence of PSE meat in high-yield meat animals has become increasingly prominent. Ferket et al. have conducted extensive research on pigs and turkeys, and they report that adding high levels of VE to the diet can solve the PSE problem in turkeys, suggesting that oxidation problems may be related to PSE in poultry meat after slaughter (Ferket et al.) , 1994). Van Laack et al. (2000) observed that when the chicken after slaughter was not cooled, the rate of glycolysis of the muscles increased and the pH decreased rapidly, at which point PSE gradually occurred. The chicken meat produced in this way is pale, with reduced hydraulic power and poor texture (Ferket et al., 1994). The data in this study indicate that oxidative stress can cause PSE poultry after slaughter. Broilers fed selenate are more likely to develop PSE than broilers fed SP, indicating that organic selenium in SP can be compared in tissues. Good retention (2000, Downs et al. reported that organic selenium retention in SP increased more than 2 times), stable release of organic selenium combined with glutathione/glutathione peroxidase antioxidant system for reducing chicken The PSE is important.
In this study, it was found that the yield of the corpus callosum was affected by the source of selenium. According to the percentage of carcass weight, the yield of viscera, claws and neck of SP animals was significantly increased (P<0.05). A large visceral weight may indicate that the feed is slower through the intestines and longer in the intestinal contents, which allows the feed to be used more efficiently. Increased paw and neck yields and larger heads reflect increased growth in broilers fed SP. Feeding SP significantly increased the yield of chicken calves and thighs (P < 0.05). In this test, the production of pectoralis major muscle of male broilers fed SP was slightly lower than that of chickens without selenium. It can be assumed that this is because earlier growth plumes cause cysteine ​​or selenocysteine ​​from the pectoral muscle. Freeing causes a slight delay in the growth of the pectoralis major (Edens, 1996). This may indicate that the addition of higher levels of SP (0.3 mg/kg or higher) may be better than the 0.2 mg/kg used in this study. Naylor et al. (2000) and Choct et al. (2004) reported that in the study with the addition of 0.25 mg/kg SP, SP-related yields were increased in broiler calves, thighs, and feathers, while chest muscle yield was not reduced.
Data from thyroid hormones indicate that the conversion of T4 to T3 is more effective when SP is added as a source of selenium. Because thyroid hormones are involved in raw feathers, higher T levels in chickens fed SP may be associated with the feeding of SP to broilers in the study and earlier in the study of feeding SP to broilers (Edens, 1996; Edens et al., 2000; Naylor et al., 2000; Choct et al., 2004) are associated with an increase in the growth rate of chickens.
In addition, T3 is also involved in the growth rate of animals (Jianhua et al., 2000). The increase in T4 to T3 conversion rate means an increase in growth rate and an increase in potential production efficiency, as demonstrated by the broiler trials fed SP in this study. .
4 Conclusion
This study showed that the addition of SP can improve the performance of broilers and improve the physiological response of broilers. Supporting selenomethionine in SP may be an essential way to add selenium in the modern poultry industry. Improve broiler performance, such as weight gain, PCR and increase the yield and quality of chicken during broiler processing, indicating that SP is better than sodium selenate. The increase in growth performance may be due to the fact that the addition of organic selenium in the SP improves the antioxidant status of the broiler.
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