Increase the number of litters in sows through nutritional regulation

The litter size trait is one of the most important traits for pig production. The world famous animal genetics breeder Chris HaLey estimates that if the sow’s litter size per litter can be increased by one, then the British pig industry will be Net profit of £700 million is netted, while the entire European Community receives a net profit of approximately £2 billion per year (C. Haley et al., 1990). Many genetic breeders have attempted to increase pig litter size through genetic selection, but have achieved limited genetic progress and are costly. This article reviews the use of nutritional regulation to increase the number of litters in sows.

1 energy

Energy is contained in three major nutrients such as protein, carbohydrates and fat, and is the thermal basis for all life activities. If the energy supply is insufficient, it will affect the growth and development of the ovarian follicles and the maturation of the oocytes. The deposition of a large amount of fat in the ovarian tissue also affects the growth and development of the follicles and the oocyte maturation. The inheritance of litter size is very low, Hartog (1980) Toplist et al (1983) study that the impact of sow energy intake on litter size is not very obvious. According to Libal et al., when the sow ME intake increased from 6.0 Mcal to 7.0 Mcal, the litter size decreased by an average of 1.96. Song Yu et al. (1995) showed that low-energy diets can increase the absolute number of litters. Yu Guiyang et al (2002) [1] found that the energy level of gestational diet protein had a greater effect on litter size (P<0.05), and the highest litter size in the test group II with high energy and high protein was (11.8±2.26). ). Qian Lichun et al. (2001) [2] studied the effect of energy on the litter performance of sows. 24 sows were randomly divided into three groups (control group, trial I and trial II) fed 12.6, 13.4 and 14.2 MJ, respectively. For the diet with /kg energy, the test results were as follows: Compared with the control group, the litter size of the test group II increased by 15.61%, while the difference between the test group I and the control group was not significant.

2 protein

The protein is made up of more than 20 amino acids. The current research hotspot is the ideal protein. The so-called ideal protein means that the amino acid composition ratio of the protein in the diet is consistent with the amino acid requirement ratio of the animal. NRC (1998) concluded that dietary crude protein levels have an effect on sows over 3, and sows in low crude protein diets have a decreasing trend. Camphell et al (1995) showed that the Lys level of primiparous sows during lactation increased from 0.62% to 1.51%, and litter size increased. Mahan (1998) showed that dietary protein had no effect on litter performance. Pond (1973) reported that feeding low-protein diets during pregnancy had no effect on litter size, but reduced the growth rate of suckling piglets. Yu Guiyang et al (2002) [1] study showed that: crude protein and energy levels in pregnancy diet were: CP, 14.3% to 15.7% and DE, 12.62 ~ 13.08 MJ / kg; crude protein and energy levels in lactation diets They are: CP, 16.89%~18.28% and DE, 13.00~13.78MJ/kg; sows have better reproductive performance, which can reach 10.4~11.8 litters, and the number of live litters is 9.5~10.5. Zhou Xiangyan et al (2002) [3] found that the energy level of gestational diet protein had a greater effect on litter size (P<0.05), and the highest number of litters in the trial group II with high energy and high protein (11.8±2.0). ), 25.53% and 13.46% more than the test group I and the control group, respectively, 35.48% and 10.25% of the live birth.

3 mineral elements

3.1 chromium

Chromium can improve the reproductive performance of animals. Organic chromium is an important active ingredient of GTF (glucose tolerance factor), which promotes the transfer of insulin to its cellular receptors, thereby improving the efficiency of energy utilization in glucose and feed, and using transferred nutrients for tissue protein synthesis. To reduce the nutrients required for the synthesis of fat tissue fat, so as to meet the nutritional requirements of fetal development in pregnant sows. Lindeman et al (1995) and Trout et al (1995) showed that Cr3+ assists insulin in the hypothalamus, and hypothalamic gonadotropin stimulates the release of luteinizing hormone (LH) from the pituitary gland. LH acts on the ovaries, promotes follicular maturation and ovulation, thereby improving The number of litters. Lindemann et al. (1997) showed that the total number of litters in the sows with 200ug/kg pyridine carboxylate was increased by 1.1 compared with the 0ug/kg group, and the number of live litters increased by 2.3 (p<0.01). . Similar results were obtained by Compbell et al. (1996). Mo Jingchuan et al. (1999) [4] showed that the sows used 200 g/kg of organic chromium throughout the gestation and lactation period, and the average number of live litters increased by 2, and the average number of litters increased by 0.13. The number of litter deaths decreased by an average of one, and the conception rate and delivery rate reached 100%, which was significantly different from the control group (P<0.05). Qian Lichun et al. (2000) [5] fed sows with 0 mg/t, 200 mg/t and 400 mg/t carboxylic acid pyridinium (calcium), which were the control group and the experimental group. 1 and test group 2, the results showed that the chromium pyridinium chloride had little effect on the litter size of pregnant sows, the test group 1 and the control group had the same number of litters, while the test group 2 had a decreasing trend, less than the control group. 1.2 heads / tires. Liang Xianwei [6] et al. (2002) found that compared with the control group (without adding chromium), the test group (250 ug/kg of chromium added) improved the reproductive performance of the sow, and the number of live litters increased by 4.07%. >0.05).

3.2 zinc

Zinc is an indispensable element in pig nutrition. It is a component or activating factor of various enzymes and various hormones, and plays an important biological role in pig growth and reproduction. Zou Xiaoting et al. (2002) [7] studied the reproductive performance of different dietary zinc levels on sows. The results showed that the addition of 50 mg/kg zinc in the diet was sufficient to prevent zinc deficiency in sows. The number of litters in the 75, 100, and 125 mg/kg zinc groups increased by 0.5, 1.0 (P < 0.05) and 0.87 (P < 0.05) heads/fetal.

3.3 Selenium

Studies by American and New Zealand scholars have found that feeding sows with selenium-deficient diets can cause sows to have a reproductive cycle that is characterized by irregular estrus or estrus, a small number of litters and a stillbirth. Yan Gang et al (1999) [8] found that 0.15mg/kg and 0.30mg/kg of inorganic selenium were added to the sow diet, respectively, and the results were 10.50±1.50 and 10.67±1.67, respectively. Significantly; the difference in the results of adding 0.15, 0.30mg / kg organic selenium in the diet was not significant. Mapan supplemented the diet of the sows with 0.1mg/kg selenium. After two trials, the first breeding cycle showed that the number of litters in the two groups was similar to that in the control group without selenium. During the breeding cycle, the number of litters was higher than that of the control group. Wang Hao et al (1982) showed that the sows prenatal injection of 0.2% sodium selenite physiological saline and vitamin E 5 mg, the litter size can be increased by 62.5%-83.3%.

3.4 iron

Sows lose a lot of iron during pregnancy and breastfeeding, especially high-yield sows often exhibit iron deficiency anemia, so iron is very important for sow reproductive performance. Frobis and Lillle (1976) given a single dose of 500 mg of glucose iron to sows 2 weeks before delivery failed to increase hemoglobin concentrations in sows and piglets, but increased litter size. Parisini et al. (1999) showed that chelated iron can increase the fertility of sows, and that each sow can produce 15 more pigs per year. Guise and Penny (1990) [9] found that 1600 mg of iron was intramuscularly injected within 3 weeks before birth, which had a certain effect on the number of live births and shortened the interval of returning sows. It is estimated that each sow can produce up to 0.45 per year. Gu Huaxiao (1995) [10] showed that the number of piglets raised in the sows fed with amino acid iron was (22.6 piglets/head sows), which was 8 higher than the average level (20.9 piglets/head sows). %. Vajar (1976) studies showed that diets containing 100-155 mg/kg iron were given to sows 30 days before and after delivery. Compared with ferrous sulfate, amino acid chelated iron increases sow hemoglobin levels, and there is no difference in litter size.

4. Vitamins

4.1 Vitamin A

Vitamin A has the beneficial effects of maintaining the vision and epithelial cell integrity, promoting growth and development, and enhancing the body's disease resistance. VA is necessary to maintain sow reproductive function and embryonic development (Thompson et al., 1984). Beta-carotene is also called provitamin A. In recent years, studies have shown that β-carotene can regulate reproduction and other physiological functions. MTCoffey et al. (1993) showed that injecting beta-carotene or vitamin A into sows during weaning increased litter size in sows. Cottey and Britt's test results showed that when the sow was weaned, on the day of breeding, and 7 days after mating, 200 mL of β-carotene or 5000 IU of vitamin A palmitate was injected, and the number of live litters increased significantly, which was increased by 18%. Young sows were given weekly injections of 228 mg of β-carotene from the day of breeding until 3 weeks after delivery. Compared with untreated sows, the experimental pigs had lower embryonic mortality and litter size per litter. More (Brief and Chew, 1985). Kirkwood et al. (1988) reported that feeding VA (3.0-7.5 mg, kg diet) to sows from breeding began to increase litter size.

4.2 Vitamin E

Vitamin E supplementation improves sow reproductive performance. The NRC (1998) need for pregnant sows and lactating sows is estimated to be 441 U/Kg of diet. Roche believes that the level of vitamin E in the sow diet should be checked when the stillbirth accounts for 5% of the litter size. Malm (1976) reported that during the lactation lactation, a semi-homoured diet group supplemented with vitamin E 100 mg/kg and 8% lard or corn pouches was given a diet containing vitamin E 0.3 mg/kg, resulting in sow litter size. Increased (10.0 VS 8.7 or 11.3 VS 8.0), the difference is not significant. Whitehair et al (1985) found that the addition or intramuscular injection of vitamin E to dams during pregnancy increased the number of piglets and reduced the mortality of piglets before weaning. This is consistent with the reports of Aelamseon (1949) and Chine (1974). Adams (1982) and Patton (1986) reported that vitamin E supplementation in the sows through the parenteral route significantly increased the number of live piglets at birth, an increase of 3.1. Mahan (1991) showed that feeding a sow with a vitamin E fortified diet during pregnancy can increase litter size. In 1994, Mahan reported that supplementation of 44 IU/Kg or 66 IU/Kg of vitamin E to sow diets could increase live births. Due to the presence of the placental barrier, Mahan, 1991, believes that the amount of vitamin E transported through the placenta to the fetus is small, so the antioxidant capacity of newborn piglets is low (Loudouslager, 1986), so it is necessary to add high levels of vitamin E to the diet. . (Guo Pin Chain, 1997) The test results showed that the average number of litters in the test sows was increased by 1.6 (P<0.05) and the survival rate of weaning was increased by 9.2%.

4.3 folic acid

Studies have shown that supplementation of folic acid to sows can improve reproductive performance in sows. Zeng Zhonghua [11] (2002) added 5 mg of folic acid per kilogram to the test group sows in the diet, and the control group did not add. The results showed that the control group had 178 litters of 18 litters, with an average of 9.89 heads; the experimental group had 18 litters of litter size. 215 heads, an average of 11.94 heads per litter, an increase of 20.7%. Eleven trials at five US universities showed that folic acid was added to sows compared with the control group, increasing litter size. Lindemann (1989), Thaleer (1989) and Matte (1992) showed that folic acid supplementation in gestational sow diets and lactating sow diets showed that folic acid supplementation did increase litter size and supplemented folic acid during pregnancy. It is a critical period to improve the reproductive performance of sows. The main effect of supplementing folic acid in sows is to increase litter size and increase embryo survival rate.

4.4 Biotin

Cunha (1968) first proposed adding biotin to the diet to improve the reproductive performance of the sow. 1998 NRC believes that biotin can improve the reproductive performance of sows, including litter size, number of weaned pigs, weaned pig litter weight, and time interval from weaning to hair. Kornegay (1986) summarized the relevant research from 1977 to 1986: "Under certain conditions, the addition of biotin to the sow diet will increase the litter size and conception rate, and shorten the interval between weaning and estrus. Zhang Xiaoqiang et al. Studies have shown that the addition of 300ug/kg, 400ug/kg, and 500ug/kg biotin to sow feed is 10%, 14%, and 14.3% higher than that of unadded live pigs. Peng Guoliang [12] (1994) The sows in groups 1, 2, and 3 were added with 0.15, 0.20, and 0.25 ppm biotin in their basal diets from the day of breeding, and the control group was not added; the results showed that litters and litters in litters 1, 2, and 3 were tested. The number of live litters is larger than that of the control group. Volker (1994) added 100-200 ug/kg biotin to a basal diet with an effective biotin content of 155 ug, which increased the litter size of the sow. %-14%, the number of weaned piglets increased by 3%-17%. Lewis [13] et al. (1991) and Bryant et al. (1985) also obtained similar results. Brooks (1977) showed that 227ug/kg was added to the diet. Biotin, litter size increased by 95%, and weaned piglets increased by 10%. But Watkin (1991) findings It is clear that the addition of biotin has no effect on the reproductive performance of the sow, so it is considered unnecessary to supplement the sow diet with biotin. This may be due to the different feeding conditions and the different types and ages of the pigs. of.

4.5 Choline

Studies have shown that adding choline to sows can improve their reproductive performance. Zhang Hua [14] et al (1994) l-2 days after breeding, each sow muscle intramuscular injection of 15-25 ml of progesterone, 7 days after pregnancy, daily feeding with choline chloride 0.1% solution 50 ml Until the sows were stopped 3 days before delivery; the control sows neither intramuscularly injected progesterone nor choline chloride. The comparison between the two groups increased the total number of litters by 4.1 and the number of live litters was 3.6. . Chen Xiaoqing [15] (1994) found that the test group sows added 2 g and 1.5 g of choline chloride per kilogram in the feed during pregnancy and lactation, and the test group produced an average of 15.2 litters. The control group was 13.5 heads.

4.6 riboflavin

Riboflavin is an important component of many oxidoreductases involved in energy and protein metabolism. Animals lacking riboflavin cause disturbances in body metabolism, especially in the absence of females, premature birth, embryo death and fetal malformation. Liu Bojun (1997) found that the addition of riboflavin to sow diets in early pregnancy may increase the percentage of litter. Gorodetsky (1991) reported that the addition of 5-6 mg/kg riboflavin to sow diets significantly increased the litter size and survival rate. Pettigrew et al. (1996) found that the addition of riboflavin 60 mg/d to 10 mg/d in the diet increased the sow's birth rate from 21 to 31 days of gestation.

In short, the nutritional status of sows significantly affects the physiological status of sows. Fertility, embryo implantation, embryo development and other physiological processes are inseparable from sows in good nutritional status. These physiological processes are the main factors affecting litter size. Factors, so we can increase the number of litters in sows through nutrient pathways.