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I. INTRODUCTION The productivity of pigs is determined by several factors that are primarily related to the management of sow reproductive performance. The first successful mating is early in pregnancy. There is a high number of births per litter, a short lactation period, and shortening of weaning to the next estrus breeding. The interval is a major factor in achieving high productivity (Aumaitre et al., 1976). In addition, the short-term delay between the end of the breeding period and the slaughter period is also an advantage for the maximum return of the sow herd (Huirne, 1991). Therefore, the reproductive performance is generally expressed by the average annual productivity or the number of weaned piglets produced by breeding sows during the breeding life. Economists express their productivity as the number of weaned pigs produced in stocking sows from the age of 180 days to the time of elimination (Sundgren et al., 1980). Genetic and environmental factors, including the ability of breeders to manage juvenile sows and sows, are also extremely important in controlling and increasing sows' prolificacy. This article focuses on the specific period of the sow's life cycle and assesses the timing of sow long-term reproductive performance management. In the context of the high costs of European countries in terms of management, feeding, and labor, the survival rate of animal production depends on the effectiveness of producing large numbers of physically significant and healthy piglets. The identification of the effects of management, house feeding and weaning programs on the reproductive performance of young sows and sows is intended to express some useful recommendations for high productivity in sows. Physiological parameters, management and feeding methods, and environmental factors are particularly factors that affect litter production performance at birth and during weaning; sow milk production, physical changes, and elimination rates are also factors that influence sow productivity performance. The main period of life in a sow is considered to be the management of the sow during the puberty of the sow, the sows during the farrowing period, the lactation period, and after the weaning to weaning. Second, to improve the management of young sow productivity (1) Determine the genetics and nutritional factors in the puberty period According to the slaughterhouse data and the latest macro data from pigs, only about 40% of young sows and sows Failed due to reproductive failure or too few litter size. However, more than 50 percent of them are undetectable anomalies that result in a serious waste of sow herd production potential. Management errors, improper building of the barn and/or inappropriate feeding methods, lack of health care or inadequate inspection of single pigs, such as difficulties in the examination of external estrus (Sterning et al., 1994), can all be attributed to this situation. Mistakes indicate a high frequency of sow populations that acquire productivity during the lifetime of the sow. Traditionally the greatest variability observed in the puerperal age of pigs and animals with important relationships with the production traits of young sows (Eliasson et al., 1991), also knows that puberty is almost accompanied by several management factors including Genetics, environmental and social conditions, control of common parameters related to stocking density (Martinat Botte et al., 1996). First, special differences in the average age of the prepuberal period of more than 100 days have been observed between Chinese pigs and European pigs. Among the European pig breeds, the super-high yielding sows showed unique advantages in two aspects: earlier age at the puberty, smaller pigs above the age of 2000, and smaller sow hybrids. However, compared to the average production performance of their parent European pigs, they were lighter in weight due to the advantages of hybridization. In contrast, however, Chinese pig bred paternal pigs had higher litter size at the weaner litter (Legault, 1998). This can be explained by the higher litter size at birth and the higher number of surviving embryos during pregnancy. In the past, the influence of feeding levels prior to puberty for sow-fed young sows has led to controversial recommendations. Restrictive feeding methods are used in non-selective and long-term finishing pigs in long-term practice recommendations. This suggests that the advantages of restricted feeding methods for young sows in contemporary lean meat and animal production Because the weight of the eight-kilogram body reached the age of puberty was wider than that of the free-feeding pigs, the pigs were significantly thinner when compared to the control group. The beneficial effects of the growth of young sows and the decrease in thickness of the back fat during initial mating and parturition resulted in increased food intake during lactation (Dourmad 1991; Le Cozler et al., 1998b). Due to the recovery of body reserves during the next gestation period, the piglets will eventually achieve similar litter performance but will always be leaner than the control group's young sows. (2) Management factors: The initial value of the most suitable age at the beginning of the first year is considered as an important management factor. The results of the recent research in France focus on the number of litters in subsequent litters, the annual productivity and the sow’s longevity. . According to the results collected from the national sow records program (Dagorm et al., 1992), a study evaluation was conducted among 35, 631 juvenile sows, from the birth of the pig to the first breeding conception, to the production performance that was eliminated. The data showed that the majority of the White Pork Landrace hybrid sows that were born before 30,000 days (13%) to 384 days (13%) had an increase in age at the time of first parity, making it the first The average litter size in the litter (fetus) has increased significantly and the sow has become thinner. The effect of the age of the first pregnancy of the sow on the performance during the life cycle has also been analyzed. The number of live piglets or number of weaned piglets per sow decreases linearly with age at the time of first delivery, and the youngest young mother at the time of delivery. Pigs get the highest value. Therefore, the annual productivity of each stocking sow is significantly reduced due to the increase in the age at first delivery of young sows. From these observations, important practical results in terms of the advantages of the sow herd can be obtained. In particular, Daza et al. (1996) confirmed that delaying one to two cycles from the beginning of the first estrus to the beginning of pregnancy can result in serious losses in animal productivity. From the perspective of all groups in the management, the average number of litters (wolves) at the time of culling of the sows decreased as the age of the young sows increased at the time of first delivery. However, the age at the time of culling increased in both groups of late sows that were later pregnant. From the final result, it should be noted that the early breeding young sows had a late breeding period of 42 days that was shorter than the number of weaned piglets. More young sows, each breeding pig can save one hundred and twenty kilograms of refined material. The current data confirms that the initial recommended age depends to a large extent on the criteria used to optimize the selection of reproductive performance in the herd. Although this type of management requires highly skilled techniques from breeders, no adverse effects of early delivery of first-time birthing have been observed in sows from European crosses. (3) Management of young sows: Observations of physiological and behavioral factors in the past decade showed that litter size at delivery is affected by two complementary factors, but the two complementary factors are not independent: the number of ovulation and the number of embryos died. In European pig breeds, the number of embryonic deaths accounts for 30% to 40% of the number of ovulations, which can lead to huge waste of reproductive potential of young sows and sows (Wrathall, 1971). There are two recent experimental models that provide interesting data for the preliminary interpretation of these two factors involving pig embryo mortality. The first model was a comparison between a control group of young sows and sows ligated and mated on the left fallopian tube. The third group of sows were surgically removed from the right uterus and ovaries. Early embryonic mortality, late embryonic mortality, and total embryonic mortality all increased with the average number of embryos per uterine horn. According to the Martin Rillo hypothesis, uterine capacity limits litter size and fetal development, and even limits the number of conventional sows in the sow. In the supplemental trial model, the use of two hereditary pigs with different prolificacy provided further confirmation and clarification of this hypothesis. This has led to a dramatic increase in embryonic mortality, and the number of early embryonic deaths has been affected by treatment and genotype (Legault et al., 1995). The number of embryonic deaths in the translocation process is reduced to close to zero, and the uterine space per fetus can be used as a factor, but it is not the only factor. This is related to piglet survival. In an overloaded uterus (half of uterine ovaries), hybrid embryos have a higher survival rate than purebred porcine embryos. A better understanding of the genetic factors determining the control of uterine anatomy and uterine abilities should be obtained before reaching the final conclusions in the management of young sows in the largest litter size. An in-depth discussion of the effects of nutritional factors associated with ovulation and survival rates has also been conducted in early pregnancy (Dyck et al., 1991; Prunier et al., 1999). In general, increased ovulation levels will increase the number of ovulation, and will limit embryonic mortality when bred after ovulation. The nutritional needs of young sows and sows who are pregnant during pregnancy are quite low and are always inversely proportional to the pig's feed intake. Under actual production conditions, pregnant sows are restricted to feed and sometimes feed only once a day, which can lead to pig welfare and health problems. Steer behavior occurs in pigs that lack drafts and stay in a limited space or tied with ropes ( Stereotyped behaviour), despite the fact that these pairs of 对 堑 堑 卟 卟 蜕 蜕 蜕 蜕 芰Ρ 芰Ρ 芰Ρ 芰Ρ 芰Ρ 芰Ρ 芰Ρ 藓 藓 藓 藓 藓 藓 藓?跫 校 校 校 校 校 呒 Yan 呒 呒 呒 呒 呒 呒 惺 惺 惺 惺 惺 惺 惺 惺 惺 噬 纳 纳 纳 纳 纳 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 踔燎 罱 罱 罱 罱 罱 砭 砭 砭 砭 砭 砭 砭 砭 砭 肯 肯 肯 肯 肯 肯 肯 肯 肯 肯 肯 肯 肯 肯The squat squat sloping squat sloping smashing smashing smashing slag smashing smashing steel smashing smashing smashing smashing smashing smashing smashing smashing squash smashing In addition, the non-feeding behavior traditionally referred to as stereotyped behavioral activities has been known as “Ramnet et al., 1999”. (Ramonet et al., 1999; Robert et al., 1997) showed a slight reduction before the meal and a more pronounced reduction after the meal. These results indicate that high-fiber diets needed to cover nutrition can reduce the number of pregnant mothers. Pigs feed on the surface and improve Subject to the benefit limits of breeding sows. III. Management of young sows and sows during lactating (1) Continuing choices reflected in the number of ovulations and litter size reflected in the management of the childbirth period. Significant increases in litter size have now been achieved (Cunningham et al., 1979). ; Legault et al., 1981). In addition, the potential use of super high-yielding hybrid sows derived from synthetic strains including Chinese pig breeds generally increases the tillering age and alters litter traits. The litter size is close to the number of sows' nipples. Cross fostering saves no mothers. Piglets and surplus piglets are the most natural and easy methods. Recent surveys from the population have confirmed that this method is popular and that the efficiency of sows with fewer than seven piglets in delivery is above 60 percent, and that of sows with more than 15 piglets in delivery exceeds 60 percent (Etienne & Aumaitre , 1998a). The efficiency of this method is optimal for sows that are within 48 hours of the tiller interval, but after the newborn piglets have taken colostrum, the piglet can be effectively fostered and nurtured by prolonging the lactating sow. In the mid-eighties of the United Kingdom and France, in the new management system, the system of outdoor feeding for pregnant and farrowing sows was gradually promoted (Edwards, 1994), and sows were up to 8 and 12%, respectively, despite the fact that piglets Mortality increased slightly, but mainly in early birth and cold season, the average production performance of outdoor feeding depends on the ability of the breeder to provide dry and heat-insulating materials, such as sheds and grass, in the first day of lactation. Strong interruptions. However, special care must be given before stocking in heavy clay areas. Animals must also be protected from excessive cold weather conditions or excessive temperatures to avoid delayed estrus after weaning and disturb reproductive performance. (2) Nursing sow management Relative to pregnant sows, nursing sows need to be more careful and must provide more comprehensive and more concentrated feed. Unlike dairy cows, the traditional relationship has been confirmed that pig milk production strongly depends on litter size. In addition, as reproductive performance increases, there can be a significant increase in milk production. Data show that during the two decades between the 1970s and the 1980s, the same production of litters increased the daily milk production by 2 kg. Moreover, the highest average weight of piglets at weaning is between nine and 10 piglets per litter (Koketsu and Dial, 1998). In the larger litters, it has been observed that the average weight of single-headed piglets weaned at the age of one day is continuously decreased, but the litter weight of the Sixteen-Tautou piglets is observed to be continuous due to the increased milk production efficiency based on litter weight gain. Increased sexuality, other classification factors that explain sow's milk production were identified as: As young sows have fewer litters, they produce less milk and eat less. The production of the sows after the third birth (litter) was the largest. In general, the milk composition is affected by the number of weeks of lactation, but the energy level in the feed is more intense (Etienne et al., 1998). 1. Nursing sow nutrition Due to the large amount of nutrient input into milk, nursing sows and sows cannot compensate for their needs through daily ingestion, especially during the early lactation period. Glue 庾 庾 居 居 居 鹗У 鹗У 鹗У 萑庾橹 萑庾橹 萑庾橹 萑庾橹 萑庾橹 萑庾橹 萑庾橹 萑庾橹 晕 晕 晕 晕 晕 晕 晕? When sows raise more litter size, they make the energy balance and fat loss worse. Conversely, obese sows or sows that have gained too much weight during gestation are hampered by low and moderate food intake during the first week of lactation (Dourmad, 1991). As a result, milk production was affected. As a result, the gain in litter weight was reduced. Further data showed that the restriction of feeding rate equivalent to 65 per cent of the free-feeding level emphasizes the loss of body weight and back fat during lactation, even though the body's reserve capacity can be maintained during breast-feeding. As a result of the obvious mitigation, and the high efficiency of converting these stocks into milk, the production performance of limited-feeding super-high yielding sows will also be affected during the longer lactation period. Therefore, the loss of fat thickness in restrictively reared young sows is more than double the loss of fat thickness in free sows compared with the negative fat loss in restricted breeders (Quesnel et al., 1998b). Therefore, the interval between weaning and the next estrus is prolonged due to breastfeeding and a larger litter size. 2. Environmental conditions during lactation It is well-known that being in a hot environment can seriously affect the reproductive performance of sows and extend their tillering duration. These adverse effects are particularly valued during the hot summer months in Mediterranean countries. In addition, the decline in milk production and litter weight gain among the primiparous sows and sows that have been continuously exposed to high temperature for long periods of time has been confirmed in many trials. These effects are mainly related to the reduction of feed intake. In particular, emphasis should be placed on sows in production (Prunier et al., 1997). Therefore, it has been observed that daily caloric intake of sows in heat stress (stress) is reduced by 廿6% compared to sows that are fed freely under normal temperature conditions (Table 10), relative to the behaviour of control pigs. In terms of food consumption after breastfeeding, it did not increase substantially over time. An increase of 2°C in the rectum temperature of animals that are continuously exposed to high temperatures can also affect feeding behavior. Hormone disorders have been observed in animals in heat-stressed environments at a degree Celsius, especially plasma thyroid hormone concentrations. The average daily litter growth has a similar decrease in the final stages of lactation under both conditions. In addition, due to significant loss of body weight and back fat during lactation, delays in estrus after weaning in sows restricted to high temperatures and in sows under high temperature conditions are consistent with earlier studies. Daily illumination in the farrowing pig house is extended to 16 hours, which will have an advantageous effect on the frequency of breast-feeding. Therefore, there is a substantial increase in milk production in the case of larger litter size. It is worth noting that it is important to stress that the sow's body reserves are highly plastic and that it can mobilize its reserves to meet higher nutritional needs under adverse conditions such as heat stress, limiting rearing or low feed intake, and higher litter size. A large amount of weight loss during lactation can only be restored after weaning, but it is not sufficient to prevent estrus delay due to continuous and severe weight loss during lactation (Zak et al., 1998). In the past, under the special test conditions, those scholars confirmed that artificially overfeeding sows that were given to the first-time lactating period increased the body weight and back fat, but there was still weight loss after weaning because the intake after weaning was low. Based on this fact, an “average” sow is usually assessed, and it is concluded that the sows and sows that are nursing mothers should be given free access to feed after limiting the gestation period. More specifically, the production of significant weaned piglets and heavy weaning litter weights requires sows to obtain nutritious and balanced feeds in an environment without stress. Due to the large differences between pig individuals in the group. Separate management of each breeding sow is also recommended to optimize the performance of each of the young sows and the sow. Therefore, the best breeding performance of the whole group is achieved. The effect of low food intake on sows’ performance during lactation and post-weaning piglets is related to insufficient supply of protein and/or amino acids, which is why it is recommended to increase the amino acid content of the lactating diet based on the expected milk production to meet the Daily enough demand (Dourmad et al., 1998). 3. Effects of lactation length on subsequent reproductive performance Long lactation lengthens the period between births and leads to severe weight loss. Therefore, many attempts have been made to shorten lactation time by developing continuous early weaning of piglets. Short-term effects of weaning on reproductive performance under experimental conditions and limited number of sows. The effect on breastfeeding during the first week is always through strong interference in re-estrus, increasing non-fertility breeding, and reducing litter size by increasing the number of embryonic deaths, compared to a single day of weaning, always through continuous breeding. Control (Aumaitre, 1978), but the strengths of weaning before the third week of age are also accompanied by increased problems (Dewey, 1997). Recently, based on a large number of recorded field data analysis, we assessed the short-term effects of shortening lactation time on litter size and weaning-to-delivery assessment, shortening lactation time-to- litter size, and weaning-to-tiller long-term effects, as well as subsequent sow annual productivity. The impact of the data clearly demonstrated and was almost consistent with the results of earlier data and the effect of Dewey (1997) on average litter size of sows weaned before 18 days of lactation. In addition, the short lactation period significantly interferes with dispersion and prolongs the recurrence period. Therefore, weaning is extended to the breeding period. For example, when the length of the lactation period in French herds increased from less than 18 days to one day, the percentage of estrus sows increased from 1.9 to 68.4% within six days after weaning. The adverse consequences of swine herd management in batches, or the increase in shedding rate of sows, can be predicted from these observations. Further disturbances in delaying weaning after weaning have also been observed, especially since early estrus after weaning is always accompanied by a larger number of litters, and extending to 7-11 days after weaning has a poor litter size in all breeds. This is consistent with the data observed in similar management conditions by Vesseur et al. (1994), but there is no clear physiological explanation. Therefore, the determinants of the length of the lactation period and the control of the litter size from weaning to the next breeding period must be strictly controlled in the proper management of high-yielding sows. The results validated from the literature provide recommendations for the optimal management of prolific sows and sows. Therefore, in line with the European guidelines on pig welfare, the three-week lactation weaning showed the best indication for obtaining the best annual productivity of the sow. In addition, the continuous recording of reproductive performance meets the needs of sow herd management (Martin Rillo et al., 1992). The results of single-head, group and continuous comparison among countries, regions and sows indicate that the effective control of sows is a basic need, and determine the advantages of its control. IV. Management of healthy sow herds at the same age and batchwise weaning As an effective production system for managing the distribution of weaned piglets has been proposed for several years, but still need to improve the health status of each pig in a specific construction The use of the "all-in, all-out" system makes improvement of hygiene conditions a key factor for success. Based on the reproductive physiology of sows, the design and proposal of three-week breeding and delivery systems have been started and have been implemented in France. This system requires seven groups of sows to be continuously bred every three weeks, entering the farrowing room one week before delivery and during lactation. With a length of three to four weeks, the system has the added advantage of improving fostering conditions for litter size pigs in the delivery group. Therefore, the weaned piglet group is transferred every three weeks, and then it is bred in batches according to the situation in three weaned piglets, and all-in and all-out systems will be implemented later. This system has proven to have a good effect on the sow population of 100-2000 sows. Work well through the organization of different specific tasks. One-week breeding and weaning systems have achieved great success in large farms, always classifying them according to specific operations and implementing full-entry and full-out methods. It is easy to use continuous batching for batch production based on the production performance recorded by the breeding sow group, to further batch and manage the breeding on the management and control, the animals are grouped in gestation, and the final delivery is performed in batches. This system also seems to be suitable for controlling infertility problems. Non-productive sow out-of-organization management and transfer of back-up young sows to herds, herd records are effectively completed through the control of slaughtered material and combined with healthy pig control. V. Conclusion In this article, in the definitive division of key periods in the short-term life span of breeding sows, young sows and sows are particularly sensitive to the management of the following three periods: pre-publishment period, delivery period and Breastfeeding to the next breeding breeding period. Therefore, the choice of management system must be based on the following topics: 嵌 饕 饕 饕 饕 蒲 蒲 蒲 蒲 蒲 蒲 蒲 蒲 蒲 匦胧 匦胧 牧 牧 牧 牧 牧 牧 牧 牧 牧 牧 1捎谩T捎谩 跫分跫 跫 ? 紫 紫 紫 紫 紫 紫 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 锏 锏 锏 锏 锏 锏 锏 锏 锏 锏 锏艿 艿 岢 岢 睦 睦 睦 睦 睦 睦 睦 睦 睦 睦 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 嗄昴 碌 碌 碌 碌 碌 碌 碌 谥淼 谥淼 谥淼 谥淼 谥淼 谥淼 谥淼 谥 谥 谥 谥 ? ? ? ? ? ? ? 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